Water treatment

Anal Chem, 2002 Mar 15, 74(6), 1458 - 61
UV resonance raman spectroscopic detection of nitrate and nitrite in wastewater treatment processes; Lanoul A et al.; The 204- and 229-nm excited UV resonance Raman spectra of wastewater solutions containing sodium nitrite and nitrate were measured in the concentration range 7 microM to 3.5 mM (0.1-50 ppm nitrogen) . The other chemical species present in wastewater do not interfere with Raman measurements of NO2-/NO3- bands . We observe detection limits of < 14 microM (< 200 ppb) for both NO2- and NO3- . UV resonance Raman spectroscopy appears to be an excellent tool for on-line monitoring of NO2-/NO3- in wastewater for the real-time control of water treatment plants.

Appl Environ Microbiol, 2002 Apr, 68(4), 1947 - 54
Shedding of Escherichia coli O157:H7 in dairy cattle housed in a confined environment following waterborne inoculation; Shere JA et al.; A study of Escherichia coli O157:H7 transmission and shedding was conducted with bull calves housed in individual pens within a confined environment . For comparative purposes, the numbers and duration of E . coli O157:H7 shedding in naturally infected calves were monitored after a single purchased calf (calf 156) tested positive prior to inoculation . During the next 8 days, the calves in adjacent pens and a pen directly across a walkway from calf 156 began to shed this serotype O157:H7 strain . Five of the eight calves in this room shed this O157:H7 strain at some time during the following 8 weeks . The numbers of E . coli O157:H7 isolates shed in these calves varied from 60 to 10(5) CFU/g of feces, and the duration of shedding ranged from 17 to >31 days . The genomic DNAs from isolates recovered from these calves were indistinguishable when compared by using XbaI digestion and pulsed-field gel electrophoresis . Inoculation of calves with 1 liter of water containing ca . 10(3) to 10(4) CFU of E . coli O157:H7/ml resulted in shedding in 10 of 12 calves (trial 1, 4 of 4 calves; trial 2, 6 of 8 calves) . The inoculated calves shed the inoculation strain (FRIK 1275) as early as 24 h after administration . The duration of shedding varied from 18 to >43 days at levels from 10(2) to 10(6) CFU/g of feces . The numbers of doses necessary to initiate shedding varied among calves, and two calves in trial 2 never shed FRIK 1275 after four doses (ca . 10(6) CFU per dose) . Results from this study confirm previous reports of animal-to-animal and waterborne dissemination of E . coli O157:H7 and highlight the need for an effective water treatment to reduce the spread of this pathogen in cattle.

Water Res, 2002 Mar, 36(5), 1379 - 84
Removal of THM precursors by GAC: Ankara case study; Capar G et al.; The effectiveness of granular activated carbon (GAC) adsorption for the removal of natural organic matter and trihalomethanes from Ivedik Water Treatment Plant of Ankara City is investigated . Freundlich Isotherm constants K and n were determined as 17.61 and 1.66, respectively . Bench-scale GAC columns were run with empty bed contact times (EBCT) varying from 0.40 to 2.67 min to evaluate adsorption performance . 50% exhaustion values were used for comparison . The treated volumes of water increased with EBCT, showing a linear increase in GAC service life . Correspondingly, the carbon usage rate decreased . The capacities calculated by the isotherm equation and achieved by columns were also compared . The column capacities were within 43-65% of the isotherm capacities at complete breakthrough . However, they were only within 8-17% of the isotherm capacities at 50% breakthrough.

Water Sci Technol, 2002, 45(3), 61 - 9
Erosion mechanisms in combined sewers and the potential for pollutant release to receiving waters and water treatment plants; McIlhatton TD et al.; The problems associated with solids in sewerage systems result in common difficulties such as blockages and flooding and the subsequent maintenance requirements have been well documented . Concerns regarding pollutant release have also been demonstrated, with the contribution from in-sewer solids to the quality of the flow during a storm event being especially significant . These events known as "foul flushes" in combined sewers typically occur in the initial period of storm flows, when the concentration of suspended sediments and other pollutants are significantly higher than at other times . Traditionally impacts from these events have been related to the suspended solids phase of the flow passing through a CSO structure . It is now apparent that much of the suspended load originates from solids eroded from the bed . The "near bed solids" which are re-entrained into the flow, together with solids eroded from the bulk bed, account for large changes in the suspended sediment concentration under time varying flow conditions . The influence of these eroded solids and their potential impact on receiving waters and treatment plants will be reviewed using data obtained from field studies carried out in the main Dundee interceptor sewer in Scotland . This paper describes some of the methods employed to investigate the characteristics of the pollutants associated with solids erosion in combined sewers.

Epidemiol Infect, 2002 Feb, 128(1), 73 - 81
Risk factors in HIV-associated diarrhoeal disease: the role of drinking water, medication and immune status; Eisenberg JN et al.; In a cross-sectional survey of 226 HIV-infected men, we examined the occurrence of diarrhoea and its relationship to drinking water consumption patterns, risk behaviours, immune status and medication use . Diarrhoea was reported by 47% of the respondents . Neither drinking boiled nor filtered water was significantly associated with diarrhoea (OR = 0.5 {0.2, 1.6}, 1.2 {0.6, 2.5} respectively), whereas those that drank bottled water were at risk for diarrhoea (OR = 3.0 {1.1, 7.8}) . Overall, 47% always or often used at least one water treatment . Of the 37% who were very concerned about drinking water, 62% had diarrhoea, 70% always or often used at least one water treatment . An increase in CD4 count was protective only for those with a low risk of diarrhoea associated with medication (OR = 0.6 {0.5, 0.9}) . A 30% attributable risk to diarrhoea was estimated for those with high medication risk compared to those with low medication risk . The significant association between concern with drinking water and diarrhoea as well as between concern with drinking water and water treatment suggests awareness that drinking water is a potential transmission pathway for diarrhoeal disease . At the same time we found that a significant portion of diarrhoea was associated with other sources not related to drinking water such as medication usage.

J Environ Sci (China), 2002 Jan, 14(1), 49 - 53
Double catholyte electrochemical approach for preparing ferrate-aluminum: a compound oxidant-coagulant for water purification; Qu JH et al.; Ferrate is an excellent water treatment agent for its multi-functions in oxidation, disinfection, coagulation and adsorption, but its coagulation ability depends on its dosage and is after its oxidation . This paper focuses on preparing a new kind of ferrate combined with alum to enhance its coagulation function for water purification . An effective electrolysis reactor was designed and employed in the test . Some key parameters in the process of electrolysis concerning the preparation efficiency, such as the current density, temperature and alkalinity were also investigated . The proper conditions for ferrate-alum preparation were determined . Under the condition of 5 V given voltage, 6 h electrolyzing interval, below 2% alum concentration (in weight), a combined liquid ferrate-alum products was successfully prepared, which contained 0.0294 mol/L FeO4(2-) and 0.0302 mol/L total soluble ferron with 2% Al2O3 . There was no insoluble ferron produced by controlling an optimum electrochemical condition.

Environ Monit Assess, 2002 Feb, 73(3), 253 - 62
Trihalomethane formation potential and concentration changes during water treatment at Mumbai (India); Thacker NP et al.; The treated water at the outlet of treatment plants and representative service reservoirs of Mumbai city have been evaluated for trihalomethane formation potential in 1995-1996 . Chloroform, dichlorobromomethane, chlorodibromomethane and bromoform have been monitored during monsoon, winter and summer . The levels of chloroform are found above the regulated WHO guideline value of 200 microg L(-1) in final water during postmonsoon at Ghatkopar (226 microg L(-1)), Malbar (210.3 microg L(-1)) and Tulsi (231.26 microg L(-1)).

Environ Sci Technol, 2002 Feb 15, 36(4), 662 - 8
Modeling the kinetics of ferrous iron oxidation by monochloramine; Vikesland PJ et al.; The maintenance of disinfectants in distribution systems is necessary to ensure drinking water safety . Reactions with oxidizable species can however lead to undesirable disinfectant losses . Previous work has shown that the presence of Fe(II) can cause monochloramine loss in distribution system waters . This paper further examines these reactions and presents a reaction mechanism and kinetic model . The mechanism includes both aqueous-phase reactions and surface-catalyzed reactions involving the iron oxide product . In addition, it considers competitive reactions involving the amidogen radical that lead to a nonelementary stoichiometry . Using the method of initial rates, the aqueous-phase reactions were found to have first-order dependencies on Fe(II), NH2Cl, and OH- and a rate coefficient (kNH2Cl,soln) of 3.10 (+/-0.560) x 10(9) M(-2) min(-1) . The surface-mediated reactions were modeled by assuming the formation of two surface species: >FeOFe+ and >FeOFeOH . Using numerical techniques, combined rate coefficients for the surface-mediated processes were determined to be 0.56 M(-3) min(-1) and 3.5 x 10(-18) M(-4) min(-1), respectively . The model was then used to examine monochloramine and Fe(II) stability under conditions similar to those observed in distribution systems . Our findings suggest the potential utility of monochloramine as an oxidant for Fe(III) removal in drinking water treatment.

Semin Dial, 2002 Jan-Feb, 15(1), 50 - 2
Water treatment for hemodialysis: ensuring patient safety; Ouseph R et al.; Patient safety has become an important focus of the Institute of Medicine and the medical community . Although hemodialysis is a routine therapy, it is nonetheless a complex procedure where errors can occur . In particular, errors related to water quality can lead to patient injury and to increased medical costs . Using the Institute of Medicine report on errors in medicine as a basis, this article discusses previously published incidents of patient injury related to water quality in terms of the types of errors that occurred . Epidemiologic techniques provide a framework to identify, correct, and possibly avert these types of errors in the future . While the ultimate responsibility for ensuring water quality rests with the medical director of the hemodialysis unit, patient safety should be a concern of all members of the nephrology community.

Appl Environ Microbiol, 2002 Mar, 68(3), 1025 - 32
Chlorine disinfection of atypical mycobacteria isolated from a water distribution system; Le Dantec C et al.; We studied the resistance of various mycobacteria isolated from a water distribution system to chlorine . Chlorine disinfection efficiency is expressed as the coefficient of lethality (liters per minute per milligram) as follows: Mycobacterium fortuitum (0.02) > M . chelonae (0.03) > M . gordonae (0.09) > M . aurum (0.19) . For a C.t value (product of the disinfectant concentration and contact time) of 60 mg.min.liter(-1), frequently used in water treatment lines, chlorine disinfection inactivates over 4 log units of M . gordonae and 1.5 log units of M . fortuitum or M . chelonae . C.t values determined under similar conditions show that even the most susceptible species, M . aurum and M . gordonae, are 100 and 330 times more resistant to chlorine than Escherichia coli . We also investigated the effects of different parameters (medium, pH, and temperature) on chlorine disinfection in a chlorine-resistant M . gordonae model . Our experimental results follow the Arrhenius equation, allowing the inactivation rate to be predicted at different temperatures . Our results show that M . gordonae is more resistant to chlorine in low-nutrient media, such as those encountered in water, and that an increase in temperature (from 4 degrees C to 25 degrees C) and a decrease in pH result in better inactivation.

J Appl Microbiol, 2002, 92(3), 566 - 73
Mechanisms contributing to hypochlorous acid resistance of a Salmonella isolate from a poultry-processing plant; Mokgatla RM et al.; AIMS: We have recently reported the isolation of Salmonella that have acquired tolerance to hypochlorous acid (HOCl) (Mokgatla et al . 1998) . The aim of this work was to investigate possible protective mechanisms involved in the increased tolerance to HOCl of a selected resistant strain . METHODS AND RESULTS: One resistant (Salmonella 104) and one sensitive (Salmonella 81) isolate in exponential phase were exposed to HOCl at a final active concentration of 28 mg l(-1) . Cultures were assayed for superoxide dismutase and catalase activity, as well as for four membrane-bound dehydrogenases (malate, lactate, glutamate and glucose-6-phosphate dehydrogenase) . The degree of single-strand breaks in genomic DNA was analysed and lipopolysaccharide profiles determined . The resistant Salmonella isolate differed from the sensitive isolate in a number of ways . It responded within 10 min of exposure by producing catalase and decreasing the activity levels of four membrane-bound dehydrogenases . This combination would lead to lower levels of hydroxyl radicals and singlet oxygen, moieties thought to be integrally involved in the antibacterial action of HOCl . Furthermore, the resistant strain did not display the same degree of DNA damage as did the sensitive strain . CONCLUSIONS: Strain 104 is believed to grow in the presence of 28 mg l(-1) HOCl by protecting itself against HOCl by decreasing the levels of species that could react with HOCl to generate toxic reactive oxygen radicals and by improved DNA damage repair mechanisms . SIGNIFICANCE AND IMPACT OF THE STUDY: The occurrence of Salmonella able to grow in the presence of 28 mg l(-1) HOCl is of relevance to the food-processing and drinking water treatment industries as these strains would survive sanitation regimes.

J Environ Monit, 2002 Feb, 4(1), 43 - 7
Monitoring dissolved organic carbon in surface and drinking waters; Volk C et al.; The presence of natural organic matter (NOM) strongly impacts drinking water treatment, water quality, and water behavior during distribution . Dissolved organic carbon (DOC) concentrations were determined daily over a 22 month period in river water before and after conventional drinking water treatment using an on-line total organic carbon (TOC) analyzer . Quantitative and qualitative variations in organic matter were related to precipitation and runoff, seasons and operating conditions . Following a rainfall event, DOC levels could increase by 3.5 fold over baseflow concentrations, while color, UV absorbance values and turbidity increased by a factor of 8, 12 and 300, respectively . Treated water DOC levels were closely related to the source water quality, with an average organic matter removal of 42% after treatment.

J Environ Monit, 2002 Feb, 4(1), 16 - 9
The role of size exclusion chromatography-flame atomic absorption spectrometry in the treatment chemistry of potable water; Koether MC; The percentage composition of Al13, {AlO4Al12(OH)24(H2O)12}7+, in water treatment coagulants is an important criterion in the development and use of polymeric coagulants . Polymeric coagulants are generally used in cold climates or with highly turbid waters . Size exclusion chromatography flame atomic absorption spectrometry (SEC-FAAS) can separate Al13 and monomeric Al within 6 min . The percentage composition of Al13 and monomeric Al is determined by solving two simultaneous equations . Due to overlapping peaks, a 10% error is associated with this method of quantification . This method can be used on coagulants of varying "r values" (r={OH-}/{Al3+}), or on mixtures of those coagulants and monomeric aluminium.

Pest Manag Sci, 2002 Feb, 58(2), 146 - 60
Predicted impact of transgenic, herbicidetolerant corn on drinking water quality in vulnerable watersheds of the mid-western USA; Wauchope RD et al.; In the intensely farmed corn-growing regions of the mid-western USA, surface waters have often been contaminated by herbicides, principally as a result of rainfall runoff occurring shortly after application of these to corn and other crops . In some vulnerable watersheds, water quality criteria for chronic human exposure through drinking water are occasionally exceeded . We selected three settings representative of vulnerable corn-region watersheds, and used the PRZM-EXAMS model with the Index Reservoir scenario to predict corn herbicide concentrations in the reservoirs as a function of herbicide properties and use pattern, site characteristics and weather in the watersheds . We compared herbicide application scenarios, including broadcast surface pre-plant atrazine and alachlor applications with a glyphosate pre-plant application, scenarios in which losses of herbicides were mitigated by incorporation or banding, and scenarios in which only glyphosate or glufosinate post-emergent herbicides were used with corn genetically modified to be resistant to them . In the absence of drift, in almost all years a single runoff event dominates the input into the reservoir . As a result, annual average pesticide concentrations are highly correlated with annual maximum daily values . The modeled concentrations were generally higher than those derived from monitoring data, even for no-drift model scenarios . Because of their lower post-emergent application rates and greater soil sorptivity, glyphosate and glufosinate loads in runoff were generally one-fifth to one-tenth those of atrazine and alachlor . These model results indicate that the replacement of pre-emergent corn herbicides with the post-emergent herbicides allowed by genetic modification of crops would dramatically reduce herbicide concentrations in vulnerable watersheds . Given the significantly lower chronic mammalian toxicity of these compounds, and their vulnerability to breakdown in the drinking water treatment process, risks to human populations through drinking water would also be reduced.

Water Res, 2002 Feb, 36(4), 891 - 8
Investigation of assimilable organic carbon (AOC) and bacterial regrowth in drinking water distribution system; Liu W et al.; This paper investigated the variation of assimilable organic carbon (AOC) concentrations in water from several typical water treatment plants and distribution systems in a northern city of China . It is concluded from this study that: (1) The AOC in most of the product water of the studied water treatment plants and the water from the associated distribution systems could not meet the biostability criteria of 50-100 microg/L . (2) Only 4% of the measured AOC concentrations were less than 100 microg/L . However, about half of the measured AOC values were less than 200 microg/L . (3) Better source water quality resulted in lower AOC concentrations . (4) The variation of AOC concentrations in distribution systems was affected by chlorine oxidation and bacterial activity: the former resulted in an increase of AOC value while the latter led to a reduction in AOC . (5) The variation of AOC concentration followed different patterns in different distribution systems or different seasons due to their respective operational characteristics . (6) Less than 30% of AOC could be removed by a conventional treatment process, whereas 30-60% with a maximum of 50-60% could be removed by granular activated carbon (GAC) . (7) The observation via scanning electron microscope (SEM) on distribution pipe tubercle samples demonstrated that the pipe inner wall was not smooth and bacteria multiplied in the crevice as well as in the interior wall of distribution pipes.

Water Res, 2002 Feb, 36(4), 1095 - 101
Removal of organophosphate pesticides from wastewater by supercritical carbon dioxide extraction; Yu JJ; Organophosphate pesticides including fenitrothion chlorpyrifos, diazinon, methamidophos, edifenphos, mevinphos, fenthion, and acephate present in agro-wastewater can be effectively removed by supercritical carbon dioxide (SC-CO2) extraction . Near quantitative removal of the pesticides from the aqueous solution can be achieved by SC-CO2 at 90 degrees C and 325 atm for 20 min of static extraction followed by 40 min of dynamic extraction . The extracted pesticides were collected in a small amount of Fenton's solution . The pesticides in Fenton's solution were degraded completely within an hour after the collection . A combination of SC-CO2 extraction and subsequent degradation by Fenton's reagent may provide an alternative water purification strategy for treating organophosphate pesticides in agro-wastewater.

J Environ Sci Health A Tox Hazard Subst Environ Eng, 2002, 37(2), 273 - 85
Effect of operational conditions on membrane permeability in a coagulation-microfiltration process for water purification; Mo L et al.; A coagulation-microfiltration combination process was used in treatment of simulative surface water . The effects of operational conditions such as filtration time, ceasing time and aeration intensity on the membrane permeability and organic removals were investigated . Experiment results showed that the membrane permeability could be improved through changing the operational conditions . Decreasing the filtration time or increasing the ratio of filtration time/ceasing time was favorable to enhance the membrane permeability . As the aeration intensity increased, the membrane permeability was also enlarged to some extent, but was not improved obviously anymore when the aeration intensity was over the critical value of around 4m3h(-1) . Different wash methods to remove membrane fouling were attempted . The results suggested that coagulation in the process mainly led to change of the deposit cake-caused membrane fouling, which could be physically removed by surface wash . Organic removals, in terms of OC and UV254, apparently varied with the operational conditions . An inverse relationship between organic removals and membrane permeability was found . Lower membrane permeability led to higher OC and UV254 removals.

Int J Food Microbiol, 2002 Jan 30, 72(1-2), 77 - 83
Antimicrobial effect of electrolyzed water for inactivating Campylobacter jejuni during poultry washing; Park H et al.; The effectiveness of electrolyzed (EO) water for killing Campylobacter jejuni on poultry was evaluated . Complete inactivation of C . jejuni in pure culture occurred within 10 s after exposure to EO or chlorinated water, both of which contained 50 mg/l of residual chlorine . A strong bactericidal activity was also observed on the diluted EO water (containing 25 mg/l of residual chlorine) and the mean population of C . jejuni was reduced to less than 10 CFU/ml (detected only by enrichment for 48 h) after 10-s treatment . The diluted chlorine water (25 mg/l residual chlorine) was less effective than the diluted EO water for inactivation of C . jejuni . EO water was further evaluated for its effectiveness in reducing C . jejuni on chicken during washing . EO water treatment was equally effective as chlorinated water and both achieved reduction of C . jejuni by about 3 log10 CFU/g on chicken, whereas deionized water (control) treatment resulted in only 1 log10 CFU/g reduction . No viable cells of C . jejuni were recovered in EO and chlorinated water after washing treatment, whereas high populations of C . jejuni (4 log10 CFU/ml) were recovered in the wash solution after the control treatment . Our study demonstrated that EO water was very effective not only in reducing the populations of C . jejuni on chicken, but also could prevent cross-contamination of processing environments.

Environ Health Perspect, 2002 Feb, 110(2), 157 - 64
3-Chloro-4-(dichloromethyl)-5-hydroxy-2(5H)-furanone (MX) and mutagenic activity in Massachusetts drinking water; Wright JM et al.; There is limited information on the prevalence of the potent mutagen 3-chloro-4-(dichloromethyl)-5-hydroxy-2(5H)-furanone (MX) in U.S . water supplies . We measured MX concentrations and mutagenic activity in tap water samples from 36 surface water systems throughout Massachusetts . We found MX levels much higher (up to 80 ng/L) than previously reported in the United States . We also evaluated the role of water treatment on mutagenic activity and disinfection by-product formation . After adjusting for other covariates, chloramination and filtration were the most important treatment options for reducing mutagenic activity and disinfection by-product formation . Multiple chlorine application (before and after filtration) was associated with increased mutagenicity . Chlorine dose, pH, and total organic carbon were also associated with mutagenicity, MX, and total trihalomethane (TTHM) concentration . Seasonal variation was evident for MX and mutagenic activity, with higher levels occurring in the spring compared to the fall . In contrast, TTHM concentrations were greater in the fall.

Water Res, 2002 Feb, 36(3), 744 - 54
Laboratory study of ballasted flocculation; Desjardins C et al.; Ballasted flocculation is applied successfully in the water treatment industry, but the concept has not yet been subject to extended experimental studies . The use of a microsand and a polymer together to increase the weight of the flocs and the rate at which they settle is radically changing the coagulation flocculation-settling methodology . The objective of this research is to study ballasted flocculation in the laboratory by means of a modified jar-test procedure . The first tests, conducted using a statistical approach, enabled us to identify those parameters that have a significant influence on the quality of settled water . The principal treatment parameters considered in this study were the chemical dosage, the contact times in the different basins, the pH of coagulation and the dosage of microsand . The parameters used to evaluate the quality of the settled water, and hence treatment performances, were turbidity, UV absorbance, TOC and membrane filterability . The results showed that the coagulant dosage and the coagulation pH have a preponderant effect on the variability of the quality of the settled water . By contrast, filterability as measured by the laboratory filter tests, was found to be more sensitive to coagulant and microsand dosages . It was dependent on the ratio of microsand to polymer dosage, and improved when this ratio increased.

Water Res, 2002 Feb, 36(3), 519 - 26
Prevalence of Cryptosporidium oocysts and giardia cysts in the drinking water supply in Japan; Hashimoto A et al.; A one-year monitoring of Cryptosporidium oocysts and Giardia cysts was conducted at a water purification plant . A total of 13 samples of 50 L river source water and 26 samples of 2,000 L-filtered water, treated by coagulation flocculation, sedimentation and rapid filtration, were tested . Prior to conducting a survey of a water purification plant, we developed a method for concentrating Cryptosporidium oocysts from a large volume of raw or filtered water using a hollow fiber ultrafiltration (UF) membrane, and this procedure was adapted to survey a water purification plant . Cryptosporidium oocysts were detected in all of the 13 raw water samples . The geometric mean concentration was 40 oocysts 100 L . Giardia cysts were detected in 12 of 13 raw water samples (92%) and the geometric mean concentration was 17 cysts/100 L . Probability distributions of both Cryptosporidium oocyst and Giardia cyst concentration in raw water were nearly lognormal . In filtered water samples, Cryptosporidium oocysts were detected in 9 of the 26 samples (35%) with the geometric mean concentration of 1.2 oocysts /1,000 L and Giardia cysts in 3 samples (12%) with 0.8 cysts/1,000 L . The estimated log10 removal efficiency of Cryptosporidium oocysts and Giardia cysts by rapid-sand filtration was 2.47 and 2.53, respectively . Empty particles were removed at a higher log10 than intact oocysts and cysts . The efficiency of particle removal in the rapid sand filtration process tends to be reduced under cold-water conditions . Close management is necessary in the winter when the water temperature is low.

Water Res, 2002 Feb, 36(3), 511 - 8
Influence of the character of NOM on the ozonation of MIB and geosmin; Ho L et al.; Tastes and odours (T&Os) are a major concern in drinking water as they are not efficiently removed by conventional water treatment . Ozonation has been effective for their destruction in some studies . However, the natural organic matter (NOM) in waters can affect the ozonation process and subsequently affect the destruction of T&Os . Five NOM fractions were isolated and ozonated in synthetic waters . The fraction containing the more highly coloured, higher molecular weight compounds exhibited the highest ozone (O3) demand, whereas the low aromatic fraction exhibited the lowest O3 demand . The character of the NOM fractions influenced the ozonation of MIB and geosmin . The destruction of MIB and geosmin was significantly higher in the fraction with the highest colour and UV/visible absorbance at all O3 doses . The destruction of the compounds in the other fractions showed the same trends, increasing MIB and geosmin destruction with increasing UV/visible absorbing character of the NOM . MIB was also ozonated in two real waters . with results showing a competing effect between NOM concentration and NOM character . The O3 reaction time was shown to be important for the destruction of both compounds.

J Chromatogr A, 2002 Jan 11, 943(1), 1 - 13
Determination of aldehydes in drinking water using pentafluorobenzylhydroxylamine derivatization and solid-phase microextraction; Cancho B et al.; A headspace solid-phase microextraction (HS-SPME) procedure followed by gas chromatography and electron capture detection (GC-ECD) has been developed for the determination of aldehydes in drinking water samples at microg/l concentrations . A previous derivatization with o-(2,3,4,5,6-pentafluorobenzyl)hydroxylamine hydrochloride (PFBHA) was performed due to the high polarity and instability of these ozonation by-products . Several SPME coatings were tested and the divinylbenzene-polydimethylsiloxane (DVB-PDMS) coating in being the most suitable for the determination of these analytes . Experimental SPME parameters such as selection of coating, sample volume, addition of salt, extraction time and temperature of desorption were studied . Analytical parameters such as precision, linearity and detection limits were also determined . HS-SPME was compared to liquid-liquid microextraction (proposed in US Environmental Protection Agency Method 556) by analyzing spiked water samples; a good agreement between results obtained with both techniques was observed . Finally, aldehydes formed at the Barcelona water treatment plant (N.E . Spain) were determined at levels of 0.1-0.5 microg/l . As a conclusion, HS-SPME is a powerful tool for determining ozonation by-products in treated water.

Nefrologia, 2001 Jul-Aug, 21(4), 342 - 8
{Chronic dialysis in Uruguay: mortality trends from 1981 to 1998}}; Gonzalez C et al.; Uruguay is a developing country with 3.16 million inhabitants . Chronic dialysis treatment (CDT) expanded after the creation of a National Fund of Resources in 1980 who receives contribution from all inhabitants to finance, among others, the CDT and renal transplantation . During the 1981-1998 period, about 4,819 patients were treatment, 2,365 patients had died, 454 were transplanted and 51 patients were lost to follow-up due to change in residence . At the start of the treatment, mean age was 57.0 +/- 17.7 years, 37% were 65 or older than 65 year old, 61.3% were male and 98% of patients were white persons . The most common diseases responsible for End Stage Renal Disease were: hypertension (22%), chronic glomerulonephritis (19%) and diabetic nephropathy (15%) . In 1998, there were 44 dialysis units in the country (13.6 units per million population--pmp), 100% of them had water treatment (reverse osmosis 96.8%) and reuse dialyzer . The most frequent causes of death were: cardiovascular and infection . In this paper, eighteen years of the mortality time course of CDT are analyzed . Annual mortality rate was expressed as deaths per 1,000 patients years at risk (M/1,000) . The indirect standardization method was applied to adjust the mortality rate . Two populations were used as standard: the 1996 population of USRDS to adjust for age, sex, race and nephropathy and the 1996 Uruguayan general population to adjust for age . Standardized mortality rate (SMR) for each year was obtained dividing observed deaths by expected deaths . From 1981 to 1998, the incident population increased from 32 to 133 patients per million populations and the prevalent population from 28 to 639 pmp . There was a simultaneously increase in the prevalence of diabetic patients and of patients older than 65 years . The annual mortality rate decreased from 249 to 138 deaths per 1,000 patient years (M/1,000) . The standardized mortality (SM) with the USRDS population as standard decreased from 452 in 1981 to 132 in 1998 and the SMR from 2.07 to 0.60 . The SMR with the Uruguayan general population decreased from 17 to 4 . In conclusion, these results are similar with those observed in developed countries . There has been a decrease both in the gross and the standardized mortality ratio in the period of observation.

Toxicol Sci, 2002 Feb, 65(2), 177 - 83
Acrylamide-induced cellular transformation; Park J et al.; Acrylamide is a monomer of polyacrylamide, whose products are used in biochemistry, the manufacture of paper, water treatment, and as a soil stabilizer . While polymeric acrylamide is nontoxic, the monomer can cause several toxic effects and has the potential for human occupational exposure . While acrylamide is not mutagenic in prokaryotic mutagenesis assays, chronic acrylamide treatment in rodents has been shown to produce tumors in both rats and mice . The mechanism for the induction of tumors by acrylamide is not known . In the present study, we examined the possibility that acrylamide might induce cellular transformation, using Syrian hamster embryo (SHE) cell morphological transformation as well as potential mechanisms for the cellular transformation . Results showed that treatment with 0.5 mM and higher concentrations of acrylamide continuously for 7 days induced morphological transformation . Cotreatment with acrylamide and N-acetyl-L-cysteine (NAC), a sulfhydryl group donor, resulted in the reduction of acrylamide-induced morphological transformation in SHE cells . Cotreatment with 1-aminobenzotriazole (ABT), a nonspecific P450 inhibitor, and acrylamide produced no change in morphological transformation when compared to acrylamide treatment only . Cotreatment with acrylamide and DL-buthionone-{S,R}-sulfoximine (BSO), a selective inhibitor of gamma-glutamylcysteine synthetase, increased the percent of morphologically transformed colonies compared to acrylamide treatment alone . Acrylamide reduced GSH levels in SHE cells, and cotreatment with acrylamide and NAC prevented the acrylamide-induced reduction of GSH . BSO treatment with acrylamide enhanced the depletion of GSH . These results suggest that acrylamide itself, but not oxidative P450 metabolites of acrylamide appear to be involved in acrylamide-induced cellular transformation and that cellular thiol status (possibly GSH) is involved in acrylamide-induced morphological transformation.

J Appl Toxicol, 2002 Jan-Feb, 22(1), 31 - 5
In vitro hepatotoxicity of alachlor and its by-products; El-Sakka S et al.; During water treatment, potentially hazardous chemical by-products may be formed . Alachlor (2-chloro-N-(2, 6-diethylphenyl)-N-(methoxymethyl) acetamide) is a widely used pre-emergence herbicide . The present study investigated the toxicity of alachlor and its disinfection by-products on freshly isolated rat hepatocytes . Hepatocytes were harvested by a collagenase perfusion technique and were exposed to different concentrations of alachlor and its by-products for up to 2 h . Cell viability, the leakage of aspartate transaminase (AST) and alanine transaminase (ALT) and glutathione (GSH) depletion were determined throughout the incubation period . The cell viability of the hepatocytes exposed to 100 microg ml(-1) alachlor was decreased by 20% compared with the control after 60 min of incubation . At the same concentration of alachlor the leakage of ALT and AST was increased by 56% and 45%, respectively . Cell viability of the hepatocytes was decreased upon exposure to 2-chloro-N-(3-chloro-2,6-diethylphenyl)-N-(methoxymethyl) acetamide (CCDMA) and 2-chloro-N-(3-chloro-2,6-diethylphenyl) acetamide (CCDA)--the by-products of alachlor and chlorine--after 60 min of exposure . At 100 microg ml(-1) CCDMA the AST leakage was increased significantly (73%) after 30 min of incubation . The reaction mixture of alachlor (100 microg ml(-1)) and chlorine dioxide (1 ppm) caused significant increases in cell loss and ALT and AST levels by 22%, 40% and 34%, respectively, as early as 15 min incubation . Alachlor (100 and 200 microg ml(-1)) caused significant decreases in GSH contents (62%) in isolated hepatocytes . The reaction mixture of alachlor and chlorine dioxide led to significant glutathione depletion (44%) after 60 min of incubation . The by-products of alachlor and chlorine--CCDMA and CCDA--depleted GSH almost completely (93%) . This investigation suggested that the by-products formed from the reaction of alachlor and chlorine decreased GSH and increased the leakage of liver enzymes, especially AST .

Chemosphere, 2002 Jan, 46(1), 109 - 13
Ozonation of hydrolyzed azo dye reactive yellow 84 (CI); Koch M et al.; The combination of chemical and biological water treatment processes is a promising technique to reduce recalcitrant wastewater loads . The key to the efficiency of such a system is a better understanding of the mechanisms involved during the degradation processes . Ozonation has been applied to many fields in water and wastewater treatment . Especially for textile mill effluents ozonation can achieve high color removal, enhance biodegradability, destroy phenols and reduce the chemical oxygen demand (COD) . However, little is known about the reaction intermediates and products formed during ozonation . This work deals with the degradation of hydrolyzed Reactive Yellow 84 (Color Index), a widely used azo dye in textile finishing processes with two monochlorotriazine anchor groups . Ozonation of the hydrolyzed dye in ultra pure water was performed in a laboratory scale cylindric batch reactor . Decolorization, determined by measuring the light absorbance at the maximum wavelength in the visible range (400 nm), was almost complete after 60 and 90 min with an ozone concentration of 18.5 and 9.1 mg/l, respectively . The TOC/TOC0 ratio after ozonation was about 30%, the COD was diminished to 50% of the initial value . The BOD5/COD ratio increased from 0.01 to about 0.8 . Oxidation and cleavage of the azo group yield nitrate . Cleavage of the sulfonic acid groups of aromatic rings caused increases in the amount of sulfate . Formic acid and oxalic acid were identified as main oxidation products by high performance ion chromatography (HPIC) . The concentrations of these major products were monitored at defined time intervals during ozonation.

Water Sci Technol, 2001, 44(11-12), 493 - 8
The effect of refinery effluent on the aquatic macrophytes Scirpus californicus, Typha subulata and Zizaniopsis bonariensis; Campagna AR et al.; Experimental wetlands were built to follow the implementation and permanence of three species of aquatic macrophytes (Scirpus californicus, Typha subulata and Zizaniopsis bonariensis) under different treatments (water, water + nutrients and water+ nutrients + refinery effluent) . Morphological variables (number of lateral shoots produced, height of the main lateral shoot and final density values) were used to check the influence of a petrochemical effluent . All the response variables showed significant differences (p = 5%) in their development, mainly between the water treatment and water + nutrient + effluent, followed by water with water + nutrients . In the Water treatment, the lowest variable values were found for the three species, possibly due to the lack of nutrients in the medium . Opposite results were found in the other treatments, indicating that the petrochemical effluent was not a limiting factor for the implementation of the species in the systems.

Environ Int, 2001 Dec, 27(6), 495 - 519
Combinatorial bio/chemical analysis of dioxin and dioxin-like compounds in waste recycling, feed/food, humans/wildlife and the environment; Behnisch PA et al.; The present review describes international activities using bioassays/biomarkers in combination with chemical analysis to measure the effects of dioxin and dioxin-like compounds (DLCs) in the environment . The above authors reviewed already the state-of-art bioanalytical detection methods (BDMs) for dioxins and DLCs {Environ Int (2001)} . The aim of this study will be to review applications of these bioassays/biomarkers to evaluate potential dioxins and DLCs . The present literature study lists relative potencies (REPs) of polyhalogenated dibenzo-p-dioxins and -furans (PXDD/Fs; X = Cl, Br, F), their thio analogues polychlorinated dibenzothiophenes (PCDTs) and thianthrens (PCTAs), polyhalogenated biphenyls (PXBs), polychlorinated naphthalenes (PCNs) and other Ah receptor agonists measured by several biodetectors (Tier 3 screening) . The authors will discuss some examples of the applications of some of these biodetectors in biomonitoring programmes and recently occurred dioxin crisis in feed/food . The diagnosis of the biopotency of these pollutants in technical processes like thermally treated waste, waste water treatment, landfill leachate treatment, commercial PCB-mixtures, the release into the environment (soil, air and water) and the final intake into wildlife and humans will be reviewed.

Fed Regist, 2002 Jan 14, 67(9), 1811 - 44
National primary drinking water regulations: Long Term 1 Enhanced Surface Water Treatment Rule . Final rule; Environmental Protection Agency (EPA); In this document, EPA is finalizing the Long Term 1 Enhanced Surface Water Treatment Rule (LT1ESWTR) . The purposes of the LT1ESWTR are to improve control of microbial pathogens, specifically the protozoan Cryptosporidium, in drinking water and address risk trade- offs with disinfection byproducts . The rule will require systems to meet strengthened filtration requirements as well as to calculate levels of microbial inactivation to ensure that microbial protection is not jeopardized if systems make changes to comply with disinfection requirements of the Stage 1 Disinfection and Disinfection Byproducts Rule (DBPR) . The LT1ESWTR applies to public water systems that use surface water or ground water under the direct influence of surface water and serve fewer than 10,000 persons . The LT1ESWTR builds upon the framework established for systems serving a population of 10,000 or more in the Interim Enhanced Surface Water Treatment Rule (IESWTR) . This rule was proposed in combination with the Filter Backwash Recycling Rule (FBRR) in April 2000.

Fresenius J Anal Chem, 2001 Dec, 371(8), 1124 - 9
Coupling pervaporation to AAS for inorganic and organic mercury determination . A new approach to speciation of Hg in environmental samples; Fernandez-Rivas C et al.; The design and development of a new approach for Hg speciation in environmental samples is described in detail . This method, consisting of the coupling of pervaporation and atomic absorption spectrometry, is based on a membrane phenomenon that combines the evaporation of volatile analytes and their diffusion through a polymeric membrane . It is proposed here as an alternative to gas chromatography for speciation of inorganic and organic Hg compounds, as the latter compounds are volatile and can be separated by applying the principles mentioned above . The interest of this method lies in its easy handling, low cost, and rapidity for the analysis of liquid and solid samples . This method has been applied to Hg speciation in a compost sample provided by a waste water treatment plant.

Antimicrob Agents Chemother, 2002 Feb, 46(2), 420 - 4
Protective efficacy of a sulfated sialyl lipid (NMSO3) against human rotavirus-induced diarrhea in a mouse model; Takahashi K et al.; Antiviral activity of sulfated sialyl lipid (NMSO3) against human rotavirus (RV) was examined in vitro and in vivo . NMSO3 inhibited the replication of four major serotypes (G1 to G4) of human rotavirus with a low 50% effective concentration of 1 to 5 microg/ml and 50% cytotoxic concentration of 153 microg/ml when determined by plaque assays with MA104 cells . Exposure of NMSO3 to HCl (pH 2.0) for 30 min exhibited no loss of anti-RV activity . Time-of-addition experiments revealed that NMSO3 inhibited the adsorption of four serotypes of RV to MA104 cells . Furthermore, an assay of virus binding with radiolabeled RVs revealed that NMSO3 inhibited the binding of virus to MA104 cells, suggesting that NMSO3 may bind to VP4 and/or VP7 . Prophylactic oral administration of NMSO3 (10 microg three times per day, 4 days) to five suckling mice starting 30 min before inoculation of MO strain (3 x 10(6) PFU/mouse) prevented the development of diarrhea . Four of five mice showed no stool or brown formed stool, and only one mouse showed brown soft stool, while water treatment caused watery diarrhea in all five mice . The mean titer of antibody to RV in mice which received NMSO3 at 10 microg three times per day for 4 days was significantly lower than that of untreated, infected mice . NMSO3 is a promising candidate for the prophylactic treatment of human RVs.

Water Sci Technol, 2001, 44(10), 321 - 5
Sludge dewatering using centrifuge with thermal/polymer conditioning; Lin CF et al.; Sludge dewatering is preceded by a conditioning operation to enhance water removal efficiency . In the conditioning operation, chemical coagulants or polymers are added to promote sludge particle aggregation for easier dewatering . In this study, an alternative conditioning method for sludge thermal treatment at temperatures up to 80 degrees C was extensively investigated . Dewatering characteristics such as sludge capillary suction time and specific resistance to filtration, sludge viscosity and concentration of solid cakes were examined thoroughly . A good correlation between capillary suction time and specific resistance to filtration was established for sludges from water treatment, but not for biological sludge . Cationic polymer exhibits the best enhancement on sludge moisture removal . The sludge rheogram varies from 60 to 5 cP as temperature changes from 20 to 80 degrees C for sludges from water treatment plant . The dewatering ability of sludge can be greatly enhanced by thermal treatment in conjunction with the use of polymers.

Water Sci Technol, 2001, 44(10), 273 - 7
Reuse of water treatment plant sludge and dam sediment in brick-making; Huang C et al.; In this study, an attempt was made to use water treatment plant (WTP) sludge and dam sediment as raw materials for brick-making through the sintering process . The sinter of dam sediment fired at 1,050 degrees C had a less than 15% ratio water absorption, and its compressive strength and bulk density met the Chinese National Standard (CNS) for first level brick . The WTP sludge sinter made under the same operating condition exhibited higher water absorption, larger shrinkage, but poorer compressive strength . When fired at 1,100 degrees C, the shrinkage of the WTP sludge sinter was as high as 45%, although its compressive strength and water absorption of WTP sludge brick still met the standard for the first level brick . To reuse WTP sludge in an economical way, mixtures of various proportions of WTP sludge to dam sediment are used as raw materials . A satisfactory result was achieved when the ratio of the WTP sludge was less than 20% of the mixture . Results of tests indicated that the sinter of dam sediments which are fired at a temperature of 1000 to approximately 1100 degrees C has reached the requirement for tile brick.

Water Sci Technol, 2001, 44(10), 231 - 6
Properties of flocs produced by water treatment coagulants; Gregory J et al.; Hydrolyzing coagulants are extensively used in water and wastewater treatment, often under conditions where hydroxide precipitation is important, giving "sweep flocculation" . Pre-hydrolyzed coagulants, such as polyaluminium chloride (PACl) are also widely used and have several advantages over traditional additives, such as aluminium sulfate . Their action is usually discussed in terms of cationic species and charge neutralization . However, precipitation may also be important and this aspect has not been considered in detail . The present work has compared the action of alum and three commercial PACl products on model clay suspensions . The conventional jar test procedure has been used, along with measurements of settled floc volume and dynamic monitoring of floc formation and break-up by an optical technique . The latter method gives very useful information on the nature of the flocs produced and their response to different shear conditions . It is clear from the results that the PACl products form larger and stronger flocs than alum . With all coagulants floc breakage appears to be essentially irreversible . Sediment volumes are slightly lower for flocs produced by PACl than by alum, but the value is proportional to the dosage in all cases.

Water Res, 2001 Dec, 35(17), 4126 - 36
Biodegradation of anthracene and fluoranthene by fungi isolated from an experimental constructed wetland for wastewater treatment; Giraud F et al.; Pilot-scale constructed wetlands were used to treat water contaminated by polycyclic aromatic hydrocarbons (PAHs), particularly fluoranthene, and the possible role of fungi present in these ecosystems was investigated . A total of 40 fungal species (24 genera) were isolated and identified from samples (gravel and sediments) from a contaminated wetland and a control wetland . All of them were assayed for their ability to remove anthracene (AC) and fluoranthene (FA) from liquid medium . FA was degraded efficiently by 33 species while only 2 species were able to remove AC over 70% . A selection of 10 strains of micromycetes belonging to various taxonomic groups was further investigated for FA and AC degradation, toxicity assays and phenoloxidases (POx) detection . Interesting and not previously reported species were revealed (Absidia cylindrospora, Cladosporium sphaerospermum, and Ulocladium chartarum) . They were all able to highly degrade the PAH-model compounds chosen . An interesting inducibility was noted for Ulocladium chartarum . Degradative ability of fungi was not related to their extracellular POx activity . This study may contribute to the improvement of constructed wetlands for water treatment, which may be enriched in efficient fungi.

Anal Chem, 2001 Dec 15, 73(24), 5886 - 95
Simultaneous determination of halogenated derivatives of alkylphenol ethoxylates and their metabolites in sludges, river sediments, and surface, drinking, and wastewaters by liquid chromatography-mass spectrometry; Petrovic M et al.; A quantitative solid-phase extraction-liquid chromatography/mass spectrometry (SPE-LC/MS) method is described for the simultaneous analysis of halogenated byproducts of alkylphenolic compounds and their degradation products formed during chlorine disinfection in the presence of bromide ions . Compounds analyzed include brominated and chlorinated nonylphenol ethoxylates (XN-PEOs); octylphenol ethoxylates (XOPEOs); nonylphenols (XNP); nonylphenoxycarboxylates (XNPECs) and their precursors nonionic surfactants, alkylphenol ethoxylates (APEOs); and their metabolites formed during sewage treatment, alkylphenoxycarboxylates (APECs) and alkylphenols (APs) . Target compounds were concentrated from water samples using a C18 SPE procedure . Extracts were analyzed using reversed phase LC/MS . The performances of both atmospheric pressure chemical ionization (APCI) and electrospray (ESI) interfaces were compared . ESI offered better sensitivity and specificity for a higher range of oligomers . Detection limits (LODs) for water samples were from 20 to 100 ng/L; and for sediment samples, from 2 to 10 microg/kg . Slightly higher LODs were obtained for sludge samples (5-25 microg/kg) . Halogenated byproducts were found in sludge from Barcelona drinking water treatment plant in concentrations of 220 microg/kg for BrNP, 430 microg/kg for BrNPEOs (nEO = 1 - 2), and 1600 microg/kg for BrNPEOs (nEO = 3 - 15) . The concentration of ClNPEOs was estimated to be in the order of 660 microg/kg (assuming the same response as BrNPEOs) . Halogenated OPEOs were also identified, and their concentration was approximately 50 times lower than the concentration of NPEOs analogues . To our knowledge, this is the first method described that allows simultaneous determination of alkyphenol ethoxylates and halogenated derivatives, including degradation products.

J Environ Monit, 2001 Dec, 3(6), 621 - 6
Occurrence of organophosphate esters in surface water and ground water in Germany; Fries E et al.; The present investigation was carried out to quantify the three organophosphate esters, tributyl phosphate (TBP), tris(2-chloroethyl) phosphate(TCEP) and tris(2-butoxyethyl) phosphate(TBEP), in river, rain and ground water obtained from several locations in Germany, and to compare the data with those obtained about 15 years ago . Additionally, one influent and one effluent sample of waste water from a local waste water treatment plant were investigated . The applied analytical method is based on solid phase extraction (SPE), in order to concentrate polar compounds from water samples, followed by gas chromatography-mass spectrometry (GC-MS) of the extracts . A total of 5 1 of the respective water samples was used for extraction purposes and analyte recoveries were all > or = 83% . The detection limit for the target analytes was 1 ng l(-1) and the relative standard deviations for replicate injections (n = 10) were 14.0% for TBP, 12.6% for TCEP and 9.9% for TBEP . The presence of the organophosphorus compounds, TBP, TCEP and TBEP, in Germany has resulted in water concentrations of 17-1,510 ng l(-1) in the Rhine, Elbe, Main, Oder, Nidda and Schwarzbach Rivers . The maximum value of TBP measured in the Rhine River was 17 times lower than the maximum value measured 10 years ago . The maximum value of TCEP measured in the Rhine River was 100 times lower than the maximum value measured in previous investigations . The maximum concentration of TBEP measured in the Elbe River was seven times higher than the value measured 16 years ago . Similar concentrations of TBP, TCEP and TBEP were also detected in ground water and rain water . The highest levels of these compounds were detected in samples of waste water.

Environ Sci Technol, 2001 Dec 15, 35(24), 4697 - 703
Removal of endocrine-disrupting chemicals in activated sludge treatment works; Johnson AC et al.; The release of endocrine-disrupting chemicals into the aquatic environment has raised the awareness of the central role played by sewage treatment in lowland water quality . This review focuses on the activated sludge process, which is commonly used to treat sewage in large towns and cities and which successfully removes the bulk of the organic compounds that enter the works . However, not all compounds are completely broken down or converted to biomass . For example, the estrogenic alkylphenols and steroid estrogens found in effluent are the breakdown products of incomplete breakdown of their respective parent compounds . Batch microcosm studies have indicated that estrone, ethinylestradiol, and alkylphenols will not be completely eliminated in activated sludge over typical treatment times . Field data suggest that the activated sludge treatment process can consistently remove over 85% of estradiol, estriol, and ethinylestradiol . The removal performance for estrone appears to be less and is more variable . Because of its relatively high hydrophobicity, the accumulation of alkylphenol in sludge has been observed . Although it has not been examined, accumulation of ethinylestradiol in sludge is a possibility due to its recalcitrance and hydrophobicity . A comparison between the concentrations of some of the major endocrine-active chemicals in effluents and their biological potencies has been made, to direct attention to the chemicals of most concern . While water purification techniques such as UV or activated charcoal could significantly remove these microorganic contaminants, the high costs involved suggest that research into the potential for treatment optimization should receive more attention.

Clin Infect Dis, 2002 Feb 1, 34(3), 355 - 64 Epub 2001 Dec 17.
Water disinfection for international and wilderness travelers; Backer H; Acquisition of waterborne disease is a substantial risk for international travelers to countries with inadequate sanitation facilities . It also poses smaller but still significant risks for wilderness travelers who rely on surface water in developed countries with low rates of diarrheal illness, such as the United States . This article reviews the etiology and risks associated with waterborne disease that might be encountered by both types of travelers . It also summarizes--and makes recommendations for--the various water-treatment methods available to travelers for reducing their risk of contracting waterborne disease.

J Chromatogr A, 2001 Dec 14, 938(1-2), 45 - 55
Determination of haloacetic acids in aqueous environments by solid-phase extraction followed by ion-pair liquid chromatography-electrospray ionization mass spectrometric detection; Loos R et al.; Haloacetic acids (HAAs) were determined in different water samples by a new, fast and simple analysis method based on enrichment of 50-ml water samples at pH 1.8 by solid-phase extraction (SPE) followed by liquid chromatography (LC) separation and electrospray ionization mass spectrometric detection in the negative ionization mode . Deprotonated (M-H)-haloacetates and decarboxylated (M-COOH)- ions were detected . Different polymeric SPE sorbents were tested, and LiChrolut EN was found to be the best material for the extraction . Complete LC separation of all compounds could only be achieved by ion-pair chromatography using triethylamine as volatile ion-pairing reagent . The detection limits were in the low microg/l range . High microg/l concentration levels for the chlorinated and brominated haloacetates were found in drinking water from a drinking water treatment plant in Barcelona, and the corresponding tap water . In swimming pool water samples from Catalonia mg/l levels and in surface river water from Portugal microg/l values were detected . These results confirm other recent reports on the ubiquitous occurrence of HAAs in aqueous environments.

Water Res, 2002 Jan, 36(1), 140 - 6
Degradation of microcystin toxins in a falling film photocatalytic reactor with immobilized titanium dioxide catalyst; Shephard GS et al.; The increasing incidence of algal blooms in fresh water supplies and the consequent possibility of cyanobacterial microcystin contamination of potable water is a cause of recent concern . Heterogeneous photocatalytic oxidation forms part of a family of advanced water treatment technologies comprising the generation of reactive oxidizing species in water media and results in the complete oxidative degradation (mineralization) of organic pollutants to yield carbon dioxide, water and inorganic ions . A new experimental laboratory-scale 'falling film' reactor has been developed to study the photocatalytic degradation of microcystins in aqueous solution . The reactor consisted of a fiberglass sheet impregnated with immobilized titanium dioxide (TiO2) catalyst over which the microcystin solution was pumped (as a falling film) while being irradiated from UV-C germicidal lamps . The design of the system obviated the necessity to separate suspended catalyst from treated water as required in slurry reactors . The photocatalytic degradation was characterized by pseudo-first order reaction kinetics . Rapid degradation of microcystins LR, YR and RR was observed in natural lake water with half lives less than 10 min, while even faster rates were achieved in laboratory distilled water . Although low pH (pH 3) marginally improved reaction rates . the presence of radical scavengers such as sulfate ions was detrimental to the photocatalytic oxidation process.

Water Res, 2002 Jan, 36(1), 330 - 42
Development of chlorine dioxide-related by-product models for drinking water treatment; Korn C et al.; Factorial experiments were conducted using source waters from seven drinking water treatment plants in Ontario, Canada to develop statistically based model equations capable of predicting chlorine dioxide consumption and chlorite and chlorate formation upon chlorine dioxide application . The equations address raw water quality and operational parameters including pH, temperature, chlorine dioxide concentration, reaction time and water organic content (as described by non-purgeable organic carbon x ultraviolet absorbance measured at 254 nm, NPOC x UV254) . Terms describing two-factor interaction effects were also included, improving the accuracy of the predictive equations in fitting measured response concentrations as evaluated through internal and external validations . Nearly 80% of the predictions for chlorine dioxide consumption and chlorite formation were observed to be within 20% of the measured levels . Over 90% of the predicted chlorate levels were within +/- 0.1 mg/L of the measured levels . Chlorine dioxide concentration and NPOC x UV254 were key parameters when developing the predictive models.

Water Res, 2001 Dec, 35(18), 4464 - 73
The impact of ferrous ion reduction of chlorite ion on drinking water process performance; Henderson R et al.; The use of chlorine dioxide (ClO2) as a primary disinfectant and pre-oxidant in drinking water treatment is being explored as an alternative to chlorine for reducing disinfection by-product formation and to assure compliance with United States Environmental Protection Agency's Stage 1 Disinfection/ Disinfection By-Products Rule . However, the ClO2 by-product chlorite ion (ClO2-) is also regulated by the same regulation . Ferrous iron (Fe(II)) has been shown to effectively reduce chlorite ion to chloride ion (Cl-) and this study was conducted to evaluate the impact on overall treatment process performance due to the ferric hydroxide solids that form from the reaction . Ferrous iron application was explored at three different points in a pilot-scale water treatment system: pre-rapid mix . pre-settling and pre-filter . Chlorite ion concentrations were effectively reduced from 2mg/L to less than 0.3mg/L using an Fe(II) dose of approximately 6mg/L for all trials . Fe(II) addition at the rapid mix caused no adverse effects and, in fact, allowed for reduction of the alum dose due to the newly formed ferric hydroxide acting as a supplemental coagulant . An increase of 241 and 247% of total suspended solids influent to the filter process was observed when Fe(II) was applied at the pre-settling and pre-filter locations . Pilot-scale filter runs during these trials were less than 2 h and never obtained true steady state conditions . Jar testing was performed to better understand the nature of the ferric hydroxide solids that are formed when Fe(II) was oxidized to Fe(III) and to explore the effectiveness of Fe(II) addition at intermediate stages in the flocculation process.

Water Res, 2001 Dec, 35(18), 4455 - 63
Influence of the characteristics of natural organic matter on the fouling of microfiltration membranes; Fan L et al.; Natural organic matter (NOM) plays a significant role in fouling microfiltration membranes in drinking water treatment processes even though the NOM is retained only to a small extent . The aim of this study was to obtain a better understanding of the interactions between the fractional components of NOM and microfiltration membranes . Filtration experiments were performed using 0.22 microm hydrophobic and hydrophilic polyvinylidene fluoride (PVDF) membranes in a stirred-cell system on the NOM isolated from three Australian surface waters . As expected, the fouling rate for the hydrophobic membrane was considerably greater than for the hydrophilic membrane . Focusing on the hydrophobic membrane, it was shown that the high molecular weight fraction of NOM ( > 30 kDa) was responsible for the major flux decline . Filtration tests on the four fractions of NOM isolated on the basis of hydrophobicity and charge using non-functionalised and anionic resins revealed that the fouling potential for the three waters was hydrophilic neutral > hydrophobic acids > transphilic acids > hydrophilic charged . The low-aromatic hydrophilic neutral compounds were the main determinant of the rate and extent of flux decline . This was linked to the colloidal size fraction ( > 30 kDa) and to the selective concentration of calcium in the fraction leading to organics-Ca2+ bridging . It was also shown that the higher the aromaticity of the NOM the greater the flux decline, and the aromatics mainly resided in the hydrophobic acids fraction . Overall, the fouling mechanism controlling the flux decline involved the combined effects of adsorptive and colloidal fouling by the hydrophilic neutral fraction in the internal pore structure of the membrane.

Water Res, 2001 Dec, 35(18), 4444 - 54
Assimilable organic carbon (AOC) and biodegradable dissolved organic carbon (BDOC): complementary measurements; Escobar IC et al.; The objective of this study was to evaluate the necessity of measuring both assimilable organic carbon (AOC) and biodegradable dissolved organic carbon (BDOC) as indicators of bacterial regrowth potential . AOC and BDOC have often been measured separately as indicators of bacterial regrowth, or together as indicators of bacterial regrowth and disinfection by-product formation potential, respectively . However, this study proposes that both AOC and BDOC should be used as complementary measurements of bacterial regrowth potential . In monitoring of full-scale membrane filtration, it was determined that nanofiltration (NF) removed over 90% of the BDOC while allowing the majority of the AOC through . Heterotrophic plate counts (HPC) remained low during the entire period of monitoring due to high additions of disinfectant residual . In a two-year monitoring of a water treatment plant that switched its treatment process from chlorination to chlorination and ozonation, it was observed that the plant effluent AOC increased by 127% while BDOC increased by 49% after the introduction of ozone . Even though AOC is a fraction of BDOC, measuring only one of these parameters can potentially under- or overestimate the bacterial regrowth potential of the water.

Water Res, 2001 Dec, 35(18), 4426 - 34
Membrane and solution effects on solute rejection and productivity; Zander AK et al.; Limited understanding of the physical and chemical processes involved in membrane processes affects their widespread application in drinking water treatment . Insight into these processes was attained through a systematic manipulation of solution chemistry in membrane filtration with three 'loose' nanofiltration membranes . Eighteen known solutions were created varying pH, ionic strength, and major cation valence in the presence of a commercial humic acid . The membrances varied as well, including a non-ionic hydrophobic, a non-ionic hydrophilic, and an anionic hydrophilic membrane surface . Specific membrane productivity and TOC and conductivity rejection were monitored . In all cases, the presence of divalent cations decreased the rejection of both conductivity and organic matter . Divalent cations also greatly increased the rate of productivity decline over equivalent tests in solutions with monovalent cations . The most hydrophobic membrane had the greatest productivity decline rate under all solution conditions . The lowest ionic strength solutions showed the greatest TOC and conductivity rejection and the greatest rate of productivity decline for each of the membranes.

Water Res, 2001 Dec, 35(18), 4253 - 60
Photochemical processes for atrazine degradation: methodological approach; Hequet V et al.; Numerous studies have been carried out on s-triazines, and more specifically on atrazine, with the long-term objective of resolving the problems caused by these herbicides: removing them from drinking water . However, applications have remained too limited . So far, processes based on photochemical degradation have been little implemented . We, therefore, investigated the development of photochemical processes, emphasizing their capacity to degrade triazine by photolytic and photocatalytic mode . The study sought to assess the performance of these ssstems . Experiments ts showed that according to a medium pressure mercury source (UV-Vis irradiation), the photolytic degradation of atrazine was very efficient, with a best atrazine degradation half-life shorter that 5 min . The main degradation pathway was deshalogenation . The photocatalytic degradation of atrazine under irradiation over 290 nm in the presence of titanium dioxide was shown to be efficient too, with a half-life of about 20 min . In this case an experimental design was conducted so as to assess the influence of various parameters: pH, water medium, and amount of catalyst . There has been observational evidence for the efficiency of the processes investigated here and for potential technological developments as regards drinking water treatment.

Water Sci Technol, 2001, 44(9), 173 - 80
Combination of advanced oxidation processes and gas absorption for the treatment of chlorinated solvents in waste gases; Dewulf J et al.; Treatment of chlorinated organic compounds in waste gases is difficult because of several reasons: these compounds are dioxin precursors when incinerated, and also biological treatment is difficult because of a limited number of suitable microbial degradation pathways . On the other hand, since the 1990s, a new generation of chemical oxidation techniques has been introduced in water treatment . Advanced Oxidation Processes (AOPs) are based on a combination of UV/H202, UV/O3 or H2O2/O3 . The combinations result in the generation of OH-radicals, which subsequently attack the organic pollutants . In this work, the treatment of a gas stream (240 L/h) loaded with 20-40 ppmv trichloroethylene (TCE) is presented . Therefore, a combination of an absorption process in a bubble column with a liquid H2O2/O3 initiated oxidation, was investigated . Removal efficiencies, depending on the dosed H2O2 and O3, up to 94% were found . The production of chloride ions was investigated: the Cl-atoms from the removed TCE could be found back as chloride ions . Next to the experimental work, attention was paid to the mechanisms taking place in the proposed concept . Here, a simulation model was developed, considering gas/liquid mass transfer of TCE and ozone, axial liquid dispersion, advective gas and liquid transport and about 29 chemica reaction steps . The modelling allowed a better understanding of the technique and gives insight in its possibilities and limitations . Finally, it can be concluded that the proposed technique shows interesting perspectives: it is able to transform chlorine in chlorinated solvents into chloride ions effectively at ambient temperature conditions.

Mar Pollut Bull, 2001 Jul-Dec, 43(7-12), 187 - 208
A new coastal marine ecosystem model study coupled with hydrodynamics and tidal flat ecosystem effect; Sohma A et al.; A new coastal marine ecosystem model was developed, which was composed of pelagic and benthic ecosystems, and was applied to Mikawa Bay, Japan . This model deals with variations of biochemical and physical interactions among dissolved oxygen and C-N-P species (composition formed out of carbon, nitrogen and phosphorus elements) so that it resolves the flux dynamics of carbon, nitrogen, phosphorus and oxygen elements . The physical and biochemical mechanism figured in this model is constructed for the purpose of simulating the estuarine lower trophic ecosystem, in areas where the sea was too deep for light to reach the sea-bottom . As a result of coupling the benthic with pelagic system, the effect of process of sedimentation and nutrient diffusion back to the pelagic system could be indicated . In addition, by implementing the tidal flat ecosystem model's calculation result, the integrated model can include the effect of water purification in tidal flats where the light can reach the sea-bottom, and where seaweed, sea grass and benthic algae exist . In this study, the model indicates that oxygen-depleted water exists at the sea-bottom especially in summer mainly caused by an increase of oxygen consumption in the benthic system and a decrease of the vertical mixing water process . Furthermore, by comparing the case--with the tidal flat ecosystem model and the case without it, the effect of water purification of tidal flat estuaries was indicated . From the viewpoint of a short time scale, the tidal flat has the potential to restrict red tide (rapid increase of phytoplankton), and from the viewpoint of a long time scale, it restricts the sedimentation of detritus . Restricting the sedimentation prevents oxygen-depleted water occurring in the coastal marine system of Mikawa Bay.

J Environ Sci Health A Tox Hazard Subst Environ Eng, 2001, 36(10), 1983 - 96
Rheological behavior of Phanerochaete chrysosporium broth during lignin degradation; Hernandez-Penaranda AM et al.; Rheological behavior of a lignin-degrading culture of Phanerochaete chrysosporium CDBB-H-298 was determined . Rheological characteristics revealed a Newtonian behavior in the culture medium without fungi, and a non-Newtonian dilatant behavior with fungi . In addition, the rheological behavior of the lignin-containing culture medium was complex, and changed from dilatant to pseudoplastic . During fungal growth without lignin in Kirk media rheological behavior exhibited a parabolic profile, and thixotropy showed a tendency to increase . Results indicated a small increase in the apparent viscosity in the presence of lignin; however, this may not affect the oxygen and mass transfer coefficients . The present findings can be applied to bioreactor desing for waste water treatment.

Water Sci Technol, 2001, 44(7), 51 - 6
Watershed monitoring to address contamination source issues and remediation of the contaminant impairments; Barnes PL et al.; The Big Blue River Basin is located in southeastern Nebraska and northeastern Kansas and consists of surface water in the Big Blue River, Little Blue River, Black Vermillion River, and various tributaries draining 24,968 km2 . Approximately 75% of the land area in the basin are cultivated cropland . The Big Blue River flows into Tuttle Creek Reservoir near Manhattan, Kansas . Releases from the lake are used to maintain streamflow in the Kansas River during low flow periods, contributing 27% of the mean flow rate of the Kansas River at its confluence with the Missouri River . Tuttle Creek Reservoir and the Kansas River are used as sources of public drinking water and meet many of the municipal drinking water supply needs of the urban population in Kansas from Junction City to Kansas City . Elevated concentrations of pesticides in the Big Blue River Basin are of growing concern in Kansas and Nebraska as concentrations may be exceeding public drinking water standards and water quality criteria for the protection of aquatic life . Pesticides cause significant problems for municipal water treatment plants in Kansas, as they are not appreciably removed during conventional water treatment processes unless activated carbon filtering is used . Pesticides have been detected during all months of the year with concentrations ranging up to 200 microg/l . If high concentration in water is associated with high flow conditions then large mass losses of pesticides can flow into the water supplies in this basin . This paper will investigate the use of a monitoring program to assess the non-point source of this atrazine contamination . Several practices will be examined that have shown ability to remediate or prevent these impairments.

Rev Saude Publica, 2001 Oct, 35(5), 481 - 6
{Outbreak of hemolytic reactions associated with chlorine and chloramine residuals in hemodialysis water}; Calderaro RV et al.; OBJECTIVE: To investigate the process of water contamination and to assess the subsequent outbreak in the hemodialysis center . METHODS: In September 2000, sixteen patients undergoing chronic hemodialysis at a dialysis center in Minas Gerais, Brazil, experienced hemolytic reactions compatible with toxic symptoms due to chlorine and chloramine water contamination . Chlorine and chloramine concentrations in samples obtained from various sites of the dialysis center's water treatment and distribution system were measured . Case-patients were identified by reviewing medical records and nursing notes for all dialysis sessions carried out during the study period . Interviews with technicians, nursing and medical staff members were conducted . RESULTS: Reaction rate was significantly higher (p<0.028) during the outbreak period (September 25 to 27, 2000) than the pre-outbreak period (September 18 to 20, 2000) . All patients with toxic symptoms had been under dialysis with water treated by reverse osmosis equipment and had used dialysers manually reprocessed . Chlorine and chloramine residuals concentrations found in the dialysis water as well as in the dialysers were at levels higher than regulations, </=0.5 mg/L for chlorine and </= 0.1 mg/L for chloramine . Individuals exposed to high chlorine and chloramine concentrations presented a relative risk of 2.58 (1.0-6.28) of having hemolytic reactions . CONCLUSION: There is a need to observe surveillance procedures to secure that the maximum allowable concentrations of regulated substances in the water used in the hemodialysis process are not exceeded.

Environ Sci Technol, 2001 Nov 1, 35(21), 4252 - 9
MTBE oxidation by conventional ozonation and the combination ozone/hydrogen peroxide: efficiency of the processes and bromate formation; Acero JL et al.; The present study investigates the oxidation of methyl tert-butyl ether (MTBE) by conventional ozonation and the advanced oxidation process (AOP) ozone/hydrogen peroxide under drinking water treatment conditions . The major degradation products identified were tert-butyl formate (TBF), tert-butyl alcohol (TBA), 2-methoxy-2-methyl propionaldehyde (MMP), acetone (AC), methyl acetate (MA), hydroxyisobutyraldehyde (HiBA), and formaldehyde (FA) . The rate constants of the reaction of ozone and OH radicals with MTBE were found to be 0.14 and 1.9 x 10(9) M(-1) s(-1), respectively . The rate constants for the same oxidation processes were also measured for the degradation products TBF, MMP, MA, and HiBA (k(O3-TBF) = 0.78 M(-1) s(-1); k(OH-TBF) = 7.0 x 10(8) M(-1) s(-1); k(O3-MMP) = 5 M(-1) s(-1); k(OH-MMP) = 3 x 10(9) M(-1) s(-1), k(O3-MA) = 0.09 M(-1) s(-1), k(O3-HiBA) = 5 M(-1) s(-1); k(OH-HiBA) = 3 x 10(9) M(-1) s(-1)) . Since all compounds reacted slowly with molecular ozone, only the degradation pathway of MTBE with OH radicals has been determined, including the formation of primary degradation products . In experiments performed with several natural waters, the efficiency of MTBE elimination and the formation of bromate as disinfection byproduct have been measured . With a bromide level of 50 microg/L, only 35-50% of MTBE could be eliminated by the AOP O3/H2O2 without exceeding the current drinking water standard of bromate (10 microg/L) . The transient concentrations of MTBE and its primary degradation products were modeled using a combination of kinetic parameters (degradation product distribution and rate constants) together with the ozone and OH radical concentration and were in good agreement with the experimental results.

Ground Water, 2001 Nov-Dec, 39(6), 921 - 30
Characterization of iron and manganese precipitates from an in situ ground water treatment plant; Mettler S et al.; Aquifer samples from the precipitation zone of an in situ iron and manganese removal plant that was operated for 10 years were analyzed for iron and manganese minerals . Measurements were performed by various chemical extraction techniques (5 M HCI, 0.008 M Ti(III)-EDTA, 0.114 M ascorbic acid), X-ray diffraction and Mossbauer spectroscopy . Chemical extractions showed that iron was precipitated as ferric oxides, whereas manganese was not oxidized but deposited as Mn(II) probably within carbonates . The ferric oxides in particular accumulate preferentially in the smaller grain- size fractions . This tendency was observed to a lesser extent for manganese . X-ray diffraction and Mossbauer spectroscopy showed that the ferric oxides were mainly crystalline (goethite, 50% to 100% of the iron) . Ferrihydrite was found as well, but only as a minor fraction (< or = 12%) . Pure manganese minerals were not found by X-ray diffraction . The precipitated amounts of iron (5 to 27 micromol/g Fe as ferric oxide) and manganese (1 to 4 micromol/g Mn) during 10 years operation of the treatment plant agree with values that were estimated from operational parameters (9 to 31 micromol/g Fe and 3 to 6 micromol/g Mn) . Considering the small amounts of precipitated iron and manganese, no long-term risks of clogging of the aquifer are expected.

Water Sci Technol, 2001, 44(6), 73 - 80
Sludge and washwater management strategies for the Vaalkop water treatment plant; Haarhoff J et al.; The Vaalkop plant, owned and operated by Magalies Water, provides a valuable South African case study of sludge and washwater management at a large water treatment plant . Starting out as a small plant of 18 Ml/day about thirty years ago, it has steadily grown to a plant with treatment capacity of 210 Ml/day; fairly large by South African standards . During the preceding years, it has not only been subject to a vastly larger scale of operation, but it also had to adapt to a tremendous increase in the cost of raw water, an increased environmental awareness amongst water treatment professionals and general public alike, and a much more sophisticated and complicated legislative framework . It is the objective of this paper to track the sludge and washwater management practices adopted over the years at Vaalkop, and to present the current strategies adopted for the medium to long term . The paper will summarize the previous methods of sludge and washwater disposal, with reasons why they were adopted . The multitude of technical analyses and alternatives that were performed over the years will be summarized, and may provide valuable pointers for other applications in South Africa . The current system, which has just been commissioned, will be presented; its technical design parameters, the anticipated mode of operation, its costs and how the current environmental and legislative requirements are being met.

Biol Trace Elem Res, 2001 Summer, 82(1-3), 185 - 200
Zinc supplementation prevents liver injury in chlorpyrifos-treated rats; Goel A et al.; The present study was performed to investigate the protective effects of zinc (227 mg/L in drinking water) treatment in chlorpyrifos (13.5 mg/kg body weight, orally) induced hepatotoxicity in male rats . Animals received chlorpyrifos and/or zinc treatments for 8 wk . A 99mTc-mebrofenin clearance test was done to determine the biological half-life (Tbiol) of the radiopharmaceutical in liver for the determination of the hepatobiliary function of the animals . At the end of treatment periods, samples were collected for the measurement of zinc levels in serum and liver . Electron microscopic studies were performed to study hepatic ultrastructure following various treatments . When compared to normal controls, chlorpyrifos treatment resulted in reduced hepatic and serum zinc levels (p < 0.01) . The biological half-life (Tbiol) of 99mTc-mebrofenin in liver was increased (p < 0.01) significantly in chlorpyrifos-treated animals, reflecting a poor excretion of the radiopharmaceutical from the liver . Simultaneous zinc supplementation retained the increased hepatic Tbiol values of 99mTc-mebrofenin within normal limits . Zinc treatment also protected hepatocytes from the marked disruptions in the membranous organelles and narrowing/blocking of biliary channels, which was otherwise a common observation following chlorpyrifos treatment . These data clearly show the protective effects of zinc in animals subjected to organophosphate poisoning.

Chemosphere, 2001 Nov, 45(6-7), 865 - 73
Molecular size distribution of natural organic matter in raw and drinking waters; Nissinen TK et al.; The purpose of this study was to compare the molecular size distribution (MSD) of natural organic matter (NOM) in raw waters (RW) and drinking waters (DW), and to find out the differences between MSD after different water treatment processes . The MSD of NOM of 34 RW and DW of Finnish waterworks were determined with high-performance size-exclusion chromatography (HPSEC) . Six distinct fractions were generally separated from water samples with the TSK G3000SW column, using sodium acetate at pH 7 as an eluent . Large and intermediate humic fractions were the most dominant fractions in surface waters (lakes and rivers), while in artificially recharged groundwaters and natural groundwaters intermediate and small fractions predominated . Water treatment processes removed the two largest fractions almost completely shifting the MSD towards smaller molecular size in DW . Granular activated carbon (GAC) filtration, ozonation, and their combination reduced all humic fractions compared to the conventional treatment . Humic fractions correlated with total organic carbon (TOC) content and chemical oxygen demand, this being especially true in RW . The results demonstrate that the HPSEC method can be applied for a qualitative and also for rough estimate quantitative analyzes of NOM directly from RW and DW samples without sample pretreatment.

Water Sci Technol, 2001, 44(5), 263 - 70
Water treatment by TiO2 photocatalysis and/or ultrasound: degradations of phenyltrifluoromethylketone, a trifluoroacetic-acid-forming pollutant, and octan-1 -ol, a very hydrophobic pollutant; Theron P et al.; TiO2 photocatalysis and ultrasound are advanced oxidation processes for water treatment . Our study aimed at showing, via the purposely chosen title compounds, that these techniques can be complementary . For C6H5COCF3 (PTMK), the photocatalytic removal rate was higher than the ultrasonic (515 kHz) removal rate in the presence of TiO2 in the dark, whereas it was the opposite for octan-1-ol under the conditions employed . Simultaneous UV and ultrasound irradiation of the TiO2 suspension led, for PTMK, to a removal rate about equal to the sum of the removal rates observed for separate irradiations, and decreased by a factor of approximately 20% for octan- 1 -ol as if the photocatalytic degradation was suppressed by the dominant distribution of octan-1-ol to the cavitation bubbles . This distribution was substantiated by the large detrimental effect of octan- 1-ol on the PTMK ultrasonic removal rate . The concurrent use of both techniques allowed a faster removal of both pollutants in binary mixtures . The amount of CF3COOH from PTMK was approximately eight times lower in sonicated, than in UV-irradiated, TiO2 suspensions . Several intermediate products showed the occurrence of chemical transformations occurring in and/or on the cavitation bubbles . COD decline and CO2 formation were initially higher for ultrasonic than for photocatalytic treatment . However, complete mineralization (except for CF3COOH) was achieved more rapidly by photocatalysis and even more rapidly by simultaneous use of both techniques.

J Nutr, 2001 Nov, 131(11), 2848 - 52
Oolong tea increases metabolic rate and fat oxidation in men; Rumpler W et al.; According to traditional Chinese belief, oolong tea is effective in the control of body weight . Few controlled studies, however, have been conducted to measure the impact of tea on energy expenditure (EE) of humans . A randomized cross-over design was used to compare 24-h EE of 12 men consuming each of four treatments: 1) water, 2) full-strength tea (daily allotment brewed from 15 g of tea), 3) half-strength tea (brewed from 7.5 g tea) and 4) water containing 270 mg caffeine, equivalent to the concentration in the full-strength tea treatment . Subjects refrained from consuming caffeine or flavonoids for 4 d prior to the study . Tea was brewed each morning; beverages were consumed at room temperature as five 300 mL servings . Subjects received each treatment for 3 d; on the third day, EE was measured by indirect calorimetry in a room calorimeter . For the 3 d, subjects consumed a typical American diet . Energy content of the diet was tailored to each subject's needs as determined from a preliminary measure of 24-h EE by calorimetry . Relative to the water treatment, EE was significantly increased 2.9 and 3.4% for the full-strength tea and caffeinated water treatments, respectively . This increase over water alone represented an additional expenditure of 281 and 331 kJ/d for subjects treated with full-strength tea and caffeinated water, respectively . In addition, fat oxidation was significantly higher (12%) when subjects consumed the full-strength tea rather than water.

Epidemiol Infect, 2001 Oct, 127(2), 237 - 44
Microbiologic effectiveness of hand washing with soap in an urban squatter settlement, Karachi, Pakistan; Luby SP et al.; We conducted a study in a squatter settlement in Karachi, Pakistan where residents report commonly washing their hands to determine if providing soap, encouraging hand washing, and improving wash-water quality would improve hand cleanliness . We allocated interventions to 75 mothers and collected hand-rinse samples on unannounced visits . In the final model compared with mothers who received no hand-washing intervention, mothers who received soap would be expected to have 65% fewer thermotolerant coliform bacteria on their hands (95% CI 40%, 79%) and mothers who received soap, a safe water storage vessel, hypochlorite for water treatment, and instructions to wash their hands with soap and chlorinated water would be expected to have 74% fewer (95% CI 57%, 84%) . The difference between those who received soap alone, and those who received soap plus the safe water vessel was not significant (P = 0.26) . Providing soap and promoting hand washing measurably improved mothers' hand cleanliness even when used with contaminated water.

FEMS Microbiol Lett, 2001 Oct 16, 204(1), 71 - 4
Evidence for additional genus-level diversity of Chlamydiales in the environment; Horn M et al.; The medically important order Chlamydiales has long been considered to contain a few closely related bacteria which occur exclusively in animals and humans . This perception of diversity and habitat had to be revised with the recent identification of the genera Simkania, Waddlia, Parachlamydia, and Neochlamydia with the latter two comprising endosymbionts of amoebae . Application of a newly developed PCR assay for the specific amplification of a near full length 16S rDNA fragment of these novel Chlamydia-related bacteria on activated sludge samples revealed the existence of at least four additional, previously unknown evolutionary lineages of Chlamydiales (each showing less than 92% 16S rRNA sequence similarity with all recognized members of this order) . These findings suggest that some waste water treatment plants represent reservoirs for a diverse assemblage of environmental chlamydiae, a discovery which might also be of relevance from the viewpoint of human public health.

J Chromatogr A, 2001 Sep 28, 930(1-2), 9 - 19
Determination of phenylurea herbicides in natural waters at concentrations below 1 ng l(-1) using solid-phase extraction, derivatization, and solid-phase microextraction-gas chromatography-mass spectrometry; Gerecke AC et al.; A procedure is presented which allows the ultratrace level determination of phenylurea herbicides (PUHs) in natural waters . Samples were enriched by solid-phase extraction (SPE) on Carbopack B and alkylated with iodoethane and sodium hydride to yield thermostable products . After derivatization, the aqueous samples were extracted and injected by SPME . The use of iodoethane instead of iodomethane allowed the differentiation between parent compounds and the N-demethylated metabolites . Limits of detection were between 0.3 and 1.0 ng/l for the parent compounds . Standard deviations below 10% were achieved for samples containing more than 4 ng/l in very different matrices including Nanopure water, lake water, and waste water treatment plant (WWTP) effluent . Moreover, the para-hydroxylated metabolite of diuron could be quantified with the same procedure . The presence of further metabolites was assessed qualitatively . Chromatography was stable over a large number of measurements even with dirty samples from WWTP effluent . The precision and sensitivity of the developed analytical method allowed the investigation of the fate of PUHs in lakes, their degradation during drinking water treatment and their transport within the North Sea.

Environ Toxicol, 2001 Oct, 16(5), 422 - 7
Testing the toxicity of influents to activated sludge plants with the Vibrio fischeri bioassay utilising a sludge matrix; Hoffmann C et al.; To protect the bioceonosis within activated sludge, a method of predicting the toxic effect of influents to the biological treatment stage of waste water treatment plants, based on DIN method 38412 L 34, has been developed . A population of the luminescent marine bacterium Vibrio fischeri was incorporated into a sludge testing matrix derived from a model laboratory and real activated sludge plants . The sludge was challenged with different concentrations of pure toxicants and complex aqueous samples, and light output by V . fischeri monitored . The results were compared to toxicant testing in the absence of sludge (standard test) . The modified method was found to be less sensitive for some toxicants tested than the standard DIN and other bioluminescent tests, but considered more realistic as it provides buffering and takes into account sorption which can affect the sensitivity of the test towards some compounds . The method is comparable in terms of ease of use, speed, reproducibility and cost effectiveness to standard V . fischeri luminescence methods.

J Environ Manage, 2001 Sep, 63(1), 87 - 102
The effect of limited options and policy interactions on water storage policy in south Florida; Mayer AL; Due to environmental constraints and reactive water management practices, water shortages exist across the Everglades ecosystem . A growing human population and continued wetlands damage and loss decrease the system's ability to provide water for sustained natural areas and for human uses . 'The Restudy' is an $8 billion plan to restore the Everglades while also continuing to provide water storage for urban and agricultural areas . The Restudy proposes a mix of water storage systems to provide for the predicted future growth in water demand . This mix is purported to be the most cost-efficient at providing water supplies, within the constraints of unchanged agricultural and urban land use . However, a sensitivity analysis of the Restudy's cost equation reveals that the total cost of water storage systems is influenced by real estate, land acquisition and water treatment costs . The interaction of land use and agricultural policies can affect these cost factors, and can change the relative cost-efficiency between storage systems . Real estate and land acquisition costs are affected by several 1996 Farm Bill provisions, which influence the cost of aboveground water storage systems versus Aquifer Storage and Recovery systems . The Governor's Commission for a Sustainable South Florida recommendations also influence the water storage options available to the Restudy . Due to the Restudy's initial assumptions and constraints, it may not advocate the most economically and ecologically sound remediation.

Nephrol Dial Transplant, 2001, 16 Suppl 7, 29 - 35
Dialysis: its role in optimizing recombinant erythropoietin treatment; Locatelli F et al.; Although iron deficiency is probably the most important factor affecting response to recombinant erythropoietin (Epo, epoetin), other factors are of significance, including dialysis adequacy . Additionally, water treatment and distribution, sterilizants and the quality of the dialysate in terms of trace elements (particularly chloramine) are of importance in relation to erythropoiesis inhibition . Microbiological or pyrogenic contamination can cause or aggravate anaemia in haemodialysis patients, and the impact of enhanced production of cytokines should be taken into consideration . By removing small and (possibly) medium/large molecules, adequate dialysis is of paramount importance in correcting anaemia and optimizing epoetin therapy . The biocompatibility of dialysis membranes and flux are other important factors . As yet unknown uraemic toxins may suppress erythropoiesis and contribute towards the development of anaemia . It is reasonable to hypothesize that, because anaemia improves after the start of dialysis with cellulose membranes, low molecular weight erythropoiesis inhibitors are involved, as well as medium/large molecular weight inhibitors, which are removed by more permeable membranes . However, in highly selected, adequately dialysed patients without iron or vitamin depletion, the effects of dialysis membrane type on haematological parameters and epoetin efficacy are smaller than might be expected from the results of uncontrolled studies . Improvement in anaemia has been observed using on-line haemofiltration, haemodiafiltration, and sterile dialysate . The results of prospective, randomized trials examining the impact of these factors on anaemia and the effectiveness of epoetin treatment are eagerly awaited.

CNS Drugs, 2001, 15(9), 691 - 9
Dementia in patients undergoing long-term dialysis: aetiology, differential diagnoses, epidemiology and management; Rob PM et al.; Dementia in patients undergoing long-term dialysis has not been clearly defined; however, four different entities have been described . Uraemic encephalopathy is a complication of uraemia and responds well to dialysis . Dialysis encephalopathy syndrome, the result of acute intoxication of aluminium caused by the use of an aluminium-containing dialysate, was a common occurrence prior to 1980 . However, using modern techniques of water purification, such acute intoxication can now be avoided . Dialysis-associated encephalopathy/dementia (DAE) is always associated with elevated serum aluminium levels . Pathognomonic morphological changes in the brain have been described, but the mechanism for the entry of aluminium into the CNS is incompletely understood . The mechanisms involved in the pathogenesis of the neurotoxicity associated with aluminium are numerous . Although only a very small fraction of ingested aluminium is absorbed, the continuous oral aluminium intake from aluminium-based phosphate binders, and also of dietary or environmental origin, is responsible for aluminium overload in dialysis patients . Age-related dementia, especially vascular dementia, occurs in patients undergoing long-term dialysis as frequently as it does in the general population . The differential diagnoses of dialysis-associated dementias should include investigation for metabolic encephalopathies, heavy metal or trace element intoxications, and distinct structural neurological lesions such as subdural haematoma, normal pressure hydrocephalus, stroke and, particularly, hypertensive encephalopathy and multi-infarct dementia . To prevent DAE, dietary training programmes should aim to achieve the lowest phosphate intake and pharmacological tools should be used to keep serum phosphate levels below 2 mmol/L . To prevent vascular dementia, lifestyle modification should be undertaken, including optimal physical activity and fat intake, nicotine abstinence, and targeting optimal blood glucose, cholesterol and triglyceride levels, and blood pressure, to those outlined in current recommendations.

Pediatr Clin North Am, 2001 Oct, 48(5), 1129 - 52, viii
Is the water safe for my baby?
Balbus JM, Lang ME.
Children's behavior and physiology place them at unique risk from waterborne microbial and chemical contaminants . This article reveals children's susceptibility factors and the microbial and chemical contaminants of greatest importance to this age group . It also provides a primer on water treatment and alternatives to tap water . This article concludes with recommendations and resources to aid the practicing pediatrician in addressing patient concerns about drinking water.

J Environ Qual, 2001 Sep-Oct, 30(5), 1693 - 8
Manure phosphorus extractability as affected by aluminum- and iron by-products and aerobic composting; Dao TH et al.; Shifts in manure phosphorus (P) chemical forms and pool sizes induced by water treatment residuals and industrial mineral by-products are largely undefined . We conducted a manure P fractionation study to determine mechanisms of reduction of dissolved reactive phosphorus (DRP) in poultry manure upon mineral by-product additions . The effects of composting on the P immobilization efficacy of the by-products were determined using laboratory self-heating composting simulators . The mineral by-products included an aluminum-water treatment residual (Al-WTR) and an iron-rich titanium-processing by-product . The noncomposted manure averaged 0.11 g g(-1) of total P as DRP forms . The by-products significantly reduced manure DRP, by an average of 39 and 48% in the Al- and the Fe-treated manure, respectively . The by-products also reduced the 0.5 M NH4F-extractable phosphorus (FEP) fraction . Shifts in P forms between FEP and 0.1 M NaOH-extractable phosphorus (SHEP) depended upon the Al and Fe contents of the by-products while the combined FEP + SHEP pool remained constant . Phosphate sorption measurements supported the observations that the Fe-rich by-product was more effective at reducing manure DRP and enhancing the formation of SHEP forms at the expense of FEP than the Al-WTR . Composting had no effect on the efficacy of either by-product to reduce DRP . Potential mechanisms of enhanced P stabilization in treated manure upon composting included chemical shifts from the DRP and FEP fractions to the citrate-bicarbonate-dithionite extractable P fraction . Thus, the choice of P immobilization agents affected the stability of immobilized P forms and should be taken into consideration in developing manure processing and nutrient stabilization methods.

Can J Microbiol, 2001 Aug, 47(8), 782 - 6
Detection of Aeromonas hydrophila in a drinking-water distribution system: a field and pilot study; Chauret C et al.; A 16-month study was conducted on the presence of Aeromonas hydrophila in drinking water in Indiana, U.S.A . Enumeration was conducted in source water, in various sites within a water treatment plant, and in the distribution system in both bulk water and biofilm, as well as in a simulated (annular reactors) drinking-water distribution system . Presumptive Aeromonas spp . counts on source waters regularly approached 10(3)-10(4) CFU/100 mL, during summer months and granular activated carbon - filtered water counts ranged from <1 to 490 CFU/100 mL . In source water, presumptive Aeromonas levels were related to water temperature . Aeromonas hydrophila was never detected in the treatment plant effluent or distributed bulk water, showing disinfectant efficiency on suspended bacteria; however, isolates of A . hydrophila were identified in 7.7% of the biofilm samples, indicating a potential for regrowth and contamination of drinking-water distribution systems.

Am J Public Health, 2001 Oct, 91(10), 1571 - 3
Challenges in implementing a point-of-use water quality intervention in rural Kenya; Makutsa P et al.; To prevent diarrheal diseases in western Kenya, CARE Kenya initiated the Water, Sanitation, and Education for Health (WASEH) Project in 1998 . The project targets 72 farming and fishing communities with a total population of 43 000 . Although the WASEH Project facilitated construction of shallow wells and pit latrines, the water quality still needed improvement . Consequently, in 2001, CARE implemented the Safe Water System (which consists of point-of-use water treatment with sodium hypochlorite, safe storage, and behavior change techniques) within the already established WASEH infrastructure, using existing community organizations in combination with a social marketing approach that introduced affordable products . The project has resulted in adoption rates of 33.5% for chemical water treatment and 18.5% for clay pots modified for safe water storage.

Am J Public Health, 2001 Oct, 91(10), 1565 - 70
Not just a drop in the bucket: expanding access to point-of-use water treatment systems; Mintz E et al.; Since 1990, the number of people without access to safe water sources has remained constant at approximately 1.1 billion, of whom approximately 2.2 million die of waterborne disease each year . In developing countries, population growth and migrations strain existing water and sanitary infrastructure and complicate planning and construction of new infrastructure . Providing safe water for all is a long-term goal; however, relying only on time- and resource-intensive centralized solutions such as piped, treated water will leave hundreds of millions of people without safe water far into the future . Self-sustaining, decentralized approaches to making drinking water safe, including point-of-use chemical and solar disinfection, safe water storage, and behavioral change, have been widely field-tested . These options target the most affected, enhance health, contribute to development and productivity, and merit far greater priority for rapid implementation.

Infect Dis Clin North Am, 2001 Sep, 15(3), 797 - 812, viii
Infection control in hemodialysis units; Tokars JI et al.; Infectious complications of hemodialysis include bacterial infections caused by contaminated water or equipment, other bacterial infections (including vascular access infections), and bloodborne viruses (primarily the hepatitis B and C viruses) . Infections caused by contaminated water and equipment can be prevented by a well-designed water-treatment system, routine cleaning and disinfection of system components, and routine bacteriologic monitoring of dialysis water and dialysis fluid . Standard precautions with additional measures recommended specifically for dialysis centers will prevent transmission of bacteria and viruses from patient to patient . These precautions include routine use of gloves, handwashing, and cleaning and disinfection of the external surface of the dialysis machine and other environmental surfaces . In addition, preventing transmission of hepatitis B virus infection requires vaccination of susceptible patients and staff, avoiding dialyzer reuse, and use of a dedicated room, dialysis machine, and staff members when treating patients chronically infected with this virus.

Huan Jing Ke Xue, 2001 Jul, 22(4), 95 - 9
{Super heavy oil produced water treatment by surface flow constructed wetland}; Ji G et al.; This paper adopts a new economic technology of treating super heavy oil produced water using surface flow reed wetland system . The field test was conducted at the average filtration rate of 3.33 cm/d . The average influent concentrations per year of COD, Oil, BOD5, TN were 459.16 mg/L, 27.65 mg/L, 33.52 mg/L, 13.74 mg/L, and the average effluent concentrations per year of above indices were 77.21 mg/L, 1.42 mg/L, 3.90 mg/L, 1.60 mg/L, respectively . Its respective removal ratios of COD, Oil, BOD5, TN and pH were 83.18%, 94.86%, 88.37%, 88.36%, 7.87-7.77 . Analyses showed that super heavy oil produced water had no obvious effect on soil and almost no effect on growth volume and quality of reeds . Results indicated that the surface flow reed wetland could provide an efficient economical, stable new means of treating super heavy oil produced water.

Huan Jing Ke Xue, 2001 Jul, 22(4), 123 - 7
{Development of the heterogeneous photocatalytic reactor in water treatment}; He X et al.; Based on the history and the functions of the heterogenous photocatalytic reactors, three categories were discussed . The emphasis was put on the employment of the reactors designed for the practice in recent years . It was pointed out that the study and the design of the reactors were one of the cores in the process of the application of the photocatalytic oxidation techniques . And the trend of this technology was also predicted.

Anal Biochem, 2001 Oct 1, 297(1), 94 - 8
Direct immunodetection of antigens within the precast polyacrylamide gel; Desai S et al.; Detection of specific proteins separated by SDS-PAGE is the basis for studying specific antigens . Immunodetection of antigens is commonly performed using Western blotting technique . In this paper we have shown that it is possible to eliminate Western blotting and to detect the antigens directly within the precast polyacrylamide gels by pretreating the gels with 50% isopropanol followed by distilled water treatment . This method would be valuable for large or difficult to transfer proteins .

Environ Sci Technol, 2001 Sep 1, 35(17), 3526 - 34
Utilization of zeolites synthesized from coal fly ash for the purification of acid mine waters; Moreno N et al.; Two pilot plant products containing 65 and 45% NaP1 zeolite were obtained from two Spanish coal fly ashes (Narcea and Teruel Power Station, respectively) . The zeolitic product obtained showed a cation exchange capacity (CEC) of 2.7 and 2.0 mequiv/g, respectively . Decontamination tests of three acid mine waters from southwestern Spain were carried out using the zeolite derived from fly ash and commercial synthetic zeolite . The results demonstrate that the zeolitic material could be employed for heavy metal uptake in the water purification process . Doses of 5-30 g of zeolite/L have been applied according on the zeolite species and the heavy metal levels . Moreover, the application of zeolites increases the pH . This causes metal-bearing solid phases to precipitate and enhances the efficiency of the decontamination process.

Environ Sci Technol, 2001 Sep 1, 35(17), 3476 - 81
Redox transformations of arsenic and iron in water treatment sludge during aging and TCLP extraction; Meng X et al.; Laboratory experiments and modeling studies were performed to investigate the redox transformations of arsenic and iron in water treatment sludge during aging, and to evaluate the impact of those transformations on the leachability of arsenic determined with the U.S . EPA toxicity characteristic leaching procedure (TCLP) . When the backwash suspension samples collected from a California surface water treatment plant were aged in closed containers for a few weeks, soluble arsenic increased from less than 5 microg/L to as high as 700 microg/L and then decreased dramatically because of biotic reduction of arsenate {As(V)}, ferric oxyhydroxide, and sulfate . The experimental results and the thermodynamic models showed that arsenic mobility can be divided into three redox zones: (a) an adsorption zone at pe > 0, which is characterized by strong adsorption of As(V) on ferric oxyhydroxide; (b) a mobilization (transition) zone at -4.0 < pe < 0, where arsenic is released because of reduction of ferric oxyhydroxide to ferrous iron and As(V) to arsenite {As(III)}; and (c) a reductive fixation zone at pe < -4.0, where arsenic is immobilized by pyrite and other reduced solid phases . The TCLP substantially underestimated the leachability of arsenic in the anoxic sludge collected from sludge ponds because of the oxidation of Fe(II) and As(III) by oxygen . The leaching test should be performed in zero-headspace vessels or under nitrogen to minimize the transformations of the redox-sensitive chemical species.

Water Res, 2001 Oct, 35(15), 3758 - 61
A simple modified membrane filtration medium for the enumeration of aerobic spore-bearing bacilli in water; Francis CA et al.; Aerobic spore-bearing bacilli have been proposed as a surrogate indicator for the removal of Cryptosporidium by drinking water treatment processes . Pasteurisation of samples followed by culture on non-selective media is the method of choice . Using white membranes for filtration of water samples makes colony counting difficult . Vital dyes such as neutral red or trypan blue can help when added to the growth medium but these dyes tend to colour the membrane and reduce the contrast between the colonies and the background . The incorporation of bromothymol blue at a concentration of 0.005% (w/v) into nutrient agar facilitated colony counting without inhibiting colony formation compared with unsupplemented nutrient agar . Statistical analysis of the data (ANOVA) confirms this observation . The modified technique was found to be satisfactory with spore suspensions of Bacillus globigii and B . cereus as well as with samples of surface water, settled water and drinking water.

Water Res, 2001 Oct, 35(15), 3738 - 42
Use of some natural and waste materials for waste water treatment; Ahsan S et al.; A fundamental study was conducted to assess removal and filtration capacity of waste and natural indigenous materials as treatment mediums e.g., shell, limestone, waste paper mixed with refuse concrete, refuse cement, also processed nitrolite, charcoal-bio and charcoal . Under room temperature condition removal of phosphoric, nitric and ammonium-ions, filtration of suspended substance (SS) together with removal of COD in waste water was investigated . Influence of particle size effect for all treatment mediums except for waste paper was pursued . Significant improvement of waste water quality with respect to SS, phosphoric ions and decrease in COD is possible by treating with these filtration mediums . With specific reference to some treatment mediums NO3-N and NH4-N showed reasonable improvement in quality, although generally removal effect was not very significant . Efficacy of treatment was dependent on the particle size of treatment mediums in general, however, nitrolite for NH4--N, charcoal-A for SS and COD, refuse cement mixed with waste paper for PO4 ion removal showed insignificant variability on the particle size effect . Results of this fundamental study demonstrate effectiveness and feasibility for applied application of these proposed waste and naturally available treatment ingredients at lower cost.

Water Res, 2001 Oct, 35(15), 3656 - 64
Preliminary toxicity assessment of water after treatment with UV-irradiation and UVC/H2O2; Parkinson A et al.; Photooxidation (UV radiation) and enhanced photooxidation (UVC/H2O2) are water treatment technologies which remove aquatic natural organic matter (NOM) by photodegradation, producing lower molecular weight components and CO2 . Since these technologies are being investigated for the treatment of drinking water, knowledge of the potential toxicity of the photooxidation by-products is vital . The potential toxicity of UVA-, UVB-, UVC-irradiated, and UVC/H2O2-treated aquatic NOM in two spot samples from two Australian reservoirs was analysed in two spot samples using Vibriofischeri in the Microtox test, African green monkey kidney cells (AS/NZS 4020:1999), and Daphnia carinata in an acute immobilisation test . Toxicity was not apparent for both the Microtox procedure and cytotoxicity analyses for the UVC-irradiated and UVC/H2O2-treated NOM samples, while UVA- and UVB-irradiated water samples were non-toxic to D . carinata . In contrast, acute toxicity was observed for UVC- and UVC/H2O2-treated water samples . The observed toxicity was attributed to photooxidative degradation of NOM-metal binding sites, which resulted in the release of bioavailable copper ions, as evidenced by higher concentrations of free copper ions in photooxidised water . As the total copper concentrations of the two raw water samples were well below the Australian Water Quality Guidelines for metals in domestic supplies, the release of copper from photooxidised NOM is unlikely to cause health concerns in these samples.

Water Res, 2001 Oct, 35(15), 3537 - 44
Polar nitrogen compounds and their behaviour in the drinking water treatment process; Pietsch J et al.; Aliphatic and alicyclic amines as well as ethanolamines are extremely polar compounds, frequently found in the environment, and some of them have high toxicity . To address the contamination of selected German surface waters examined and the importance of bank filtration in Eastern Germany, investigations on the behaviour of polar organic nitrogen compounds during water treatment were carried out . Test conditions were designed appropriately for drinking water treatment conditions, and the tests were carried out using model water as well as bank filtrate . Test filter studies of microbial degradation of selected compounds demonstrated the following order of biodegradability: ethanolamine > dimethylamine > pyrrolidine > ethylenediamine . piperidine > diethylamine > morpholine > piperazine > cyclohexylamine . Flocculation tests using iron salts as well as aluminium salts as coagulants showed very low removal rates for the amines . The best results for the removal of the polar organic nitrogen compounds from the water were obtained using ozonation . Based on the reaction-rate constants, the order of degradation by ozone is: piperazine > morpholine > ethylenediamine > piperidine, cyclohexylamine > dimethylamine > ethanolamine > pyrrolidine > diethylamine . Disinfection by chlorine-containing agents under drinking water treatment conditions did not give effective elimination of the selected polar nitrogen compounds.

Water Environ Res, 2001 Jan-Feb, 73(1), 52 - 7
Characterization of drinking water treatment residuals for use as a soil substitute; Dayton EA et al.; The beneficial use of drinking water treatment residuals (WTRs) as a potential source of topsoil for land reclamation was evaluated . Seventeen WTRs were characterized for use as soil substitutes by comparing chemical and physical properties and plant nutrients of the WTRs with soil . A tomato (Lycopersicon esculentum) bioassay was performed to determine the ability of soil chemical tests to measure WTR phosphorus (P) adequacy . The WTR chemical and physical properties were typically adequate for crop growth . None of the WTRs were considered unsuitable as soil substitutes based on plant nutrients, with the exception of P . Tomato vegetative yield and tissue P were poor either because of phytotoxic nitrite-nitrogen (NO2-N) (> 10 mg/kg) generated during the bioassay or because of WTR P deficiency . Limited data suggest that WTRs with NO2-N less than 10 mg/kg and Olsen P greater than 50 mg/kg, water soluble P greater than 580 micrograms/L, or Mehlich III P greater than 54 mg/kg support growth but still produce inadequate tissue P in tomatoes.

Lett Appl Microbiol, 2001 Sep, 33(3), 227 - 31
Bactericidal effect of chlorine on Mycobacterium paratuberculosis in drinking water; Whan LB et al.; AIMS: One possible route of transmission of Mycobacterium paratuberculosis from cattle to humans is via contaminated water supplies . The aim of this work was to determine whether this organism can survive standard water treatment processes . METHODS AND RESULTS: Two strains of M . paratuberculosis (bovine strain, NCTC 8578 and human strain Linda, ATCC 43015) were subjected to various chlorine concentrations (0.5, 1.0 and 2.0 microg ml(-1)) for 15 and 30 min . Chlorine test solutions were made up in two types of water, sterile water that had been deionized and subjected to reverse osmosis (DRO) and DRO water containing MgCl(2), CaCl(2), NaHCO(3) and bovine serum albumin (0.3% w/v), the latter to mimic conditions the organism would experience in commercial water treatment operations . CONCLUSION: The data showed that when initial inoculum levels were high (10(6) cfu ml(-1)) neither M . paratuberculosis strain was completely killed at the free chlorine concentrations and contact times applied . Log10 reductions in the range 1.32-2.82 were observed . The greatest log(10) reduction in cell numbers (2.82 and 2.35 for the bovine and human strains, respectively) was observed at the highest chlorine concentration (2 microg ml(-1)) and longest contact time (30 min) . SIGNIFICANCE AND IMPACT OF THE STUDY: This work highlights the need for further research into the survival of M . paratuberculosis during water treatment.

Water Sci Technol, 2001, 44(2-3), 269 - 76
Self-monitoring of water quality in sewer systems using absorbance of ultraviolet and visible light; Ruban G et al.; Continuous pollution measurement is interesting to optimize the operation of sanitary facilities as well as to minimize the stormwater discharges . An experimental study was carried out for the determination of Suspended Solids (SS) and Chemical Oxygen Demand (COD) concentrations in combined sewers using ultraviolet and visible absorbances . The maintenance of the measurement system requires six hours a month for the cleaning of the hydraulic feeding system and adjustment of the optical device . The feeding system developed increased the representativeness and reliability of the pollution measurement, but needs to be validated on other measurement sites . The determination of SS concentrations from visible absorbances requires 2 calibration curves for dry and rainy weather respectively . The corresponding accuracies appear satisfactory when compared with the results of standard sampling/laboratory analysis . The accuracy of COD determination from ultraviolet absorbance is less satisfactory, but could perhaps be improved taking into account another parameter . Then the optical measurement of SS and COD is interesting to determine average or long term pollution loads, for example the yearly impact of urban stormwater discharges . With this kind of continuous and on-line measurement, it is possible to react with short delay to unexpected phenomena which could damage the environment or water treatment efficiency.

Can J Microbiol, 2001 Jul, 47(7), 601 - 7
Adequacy of in situ glass slides and direct sand extractions to assess the microbiota within sand columns used for drinking water treatment; Langmark J et al.; Historically, Cholodny-Rossi buried glass slide techniques have been used to study the microbiota of subsurface environments, yet the bias of such a technique has not been compared against direct sand extraction using modern in situ probing . Over a period of 34 wk, four separate 4-m-deep sand columns receiving raw lake water were examined to compare direct extraction of sand filter biofilm material against in situ glass slide biofilms . Significantly different DAPI direct counts and fluorescent in situ hybridization signals for major phylogenetic groups were observed . Not only were lower proportions (P < 0.001) of EUB338-probed DAPI cells observed on in situ glass slides, but also fewer gamma-Proteobacteria (12%-21%) and more alpha-Proteobacteria (16%-33%) when compared to direct sand extracts . Hence, investigators of the microbial ecology of even simple sand biofilms must consider the inherent biases from "accepted" methods and seek further independent methods to identify those which may be most accurate.

Water Res, 2001 Oct, 35(14), 3317 - 24
Cucurbituril for water treatment . Part II: Ozonation and oxidative regeneration of cucurbituril; Kornmuller A et al.; In Part I it was shown, that cucurbituril has high sorption capacities for the removal of reactive dyes from textile wastewater; despite the partial dissolution of this sorbent . Ozonation has been suggested as a regeneration step for loaded cucurbituril . Ozonation of loaded and pure cucurbituril was therefore evaluated . Dissolved cucurbituril reacts with ozone forming oxidation products like nitrite, nitrate, formate, acetate and oxalate . Oxidation is enhanced at alkaline pH . Dye-loaded cucurbituril suspended in water can be decolorized by ozone, but the ozone consumption is tip to seven times higher than for ozonation of the dissolved dyes without cucurbituril . Loaded columns can be regenerated by ozone gas, but dissolution of cucurbituril results in a higher DOC content than the initial one to be removed . Therefore oxidative regeneration does not seem to be a feasible approach in this case.

Water Res, 2001 Oct, 35(14), 3309 - 16
Cucurbituril for water treatment . Part I: Solubility of cucurbituril and sorption of reactive dyes; Karcher S et al.; Cucurbituril was investigated regarding its potential as a sorbent for the removal of reactive dyes from model solutions and authentic wastewaters . The solubility of cucurbituril is low in pure water but increases in the presence of salts . When dyes sorbing onto cucurbituril are present, solubility is drastically decreased compared to dye-free media . Sorption efficiency depends on salt concentration and salt species . Moderate salt concentrations favor sorption, high concentrations lead to cucurbituril dissolution . Divalent ions have a stronger effect than monovalent ions and larger ions more than smaller ones . In tests with authentic wastewaters cucurbituril was partially (20-100%) dissolved and contaminant removal was inefficient . Because of its solubility, cucurbituril is not feasible as a sorbent in wastewater treatment unless it could be covalently fixed onto a suitable support material.

Water Res, 2001 Oct, 35(14), 3301 - 8
Cleaning strategies for flux recovery of an ultrafiltration membrane fouled by natural organic matter; Lee H et al.; One of the most common problems encountered in water treatment applications of membranes is fouling . Natural organic matter (NOM) represents a particularly problematic foulant . Membranes may be fouled by relatively hydrophilic and/or hydrophobic NOM components, depending on NOM characteristics, membrane properties, and operating conditions . To maximize flux recovery for an NOM-fouled ultrafiltration membrane (NTR 7410), chemical cleaning and hydraulic rinsing with a relatively high cross-flow velocity were investigated as cleaning strategies . The modification of the membrane surface with either an anionic or a cationic surfactant was also evaluated to minimize membrane fouling and to enhance NOM rejection . Foulants from a hydrophobic NOM source (Orange County ground water (OC-GW)) were cleaned more effectively in terms of permeate flux by acid and caustic cleanings than foulants from a relatively hydrophilic NOM source (Horsetooth surface water (HT-SW)) . An anionic surfactant (sodium dodecyl sulfate (SDS)) was not effective as a cleaning agent for foulants from either hydrophobic or hydrophilic NOM sources . High ionic strength cleaning with 0.1 M NaCl was comparatively effective in providing flux recovery for NOM-fouled membranes compared to other chemical cleaning agents . Increased cross-flow velocity and longer cleaning time influenced the efficiency of caustic cleaning, but not high ionic strength cleaning . The membrane was successfully modified only with the cationic surfactant; however, enhanced NOM rejection was accompanied by a significant flux reduction.

J Environ Sci Health A Tox Hazard Subst Environ Eng, 2001, 36(7), 1287 - 302
Removal of metal ions from water solutions by iron/cobalt oxide coated keramzite; Stefanova RY; A method for coating hydrated iron, cobalt and iron/cobalt oxide on the surface of keramzite sand was developed . The coating parameters (pH, amount of coated metal, molar ratio Co/Fe, temperature of modification and time of treatment) controlling sorption ability of the coated layer were determined . The iron/cobalt coated keramzite thermally activated at 450 degrees C obtained at a molar ratio Co/Fe-0.516 is characterized and use for the removal of metal ions . The effect of contact time, solution pH, sorbate concentration, ionic strength and competing metal concentration on the sorption of copper, lead, zinc and cadmium was studied in batch experiments . The results reveal that the sorption rate of metal ions increases more rapidly in the initial period and reach metastable equilibrium within three hours . The sorption on coated keramzite follows both Langmuir and Freundlich's models . The data on the effect of pH showed that the sorption of all metal ions studied was markedly influenced by the solution pH . According to the concept of surface complexation model the experimental results support the assumption that metal adsorption at oxide coated keramzite sand could be better modeled as an innersphere surface reaction . The modified sorbent has a high selectivity towards copper and lead ions . The coated keramzite sand can be recommended as an efficient adsorbent for advanced water treatment of metal-bearing solutions and industrial wastewaters.

Life Support Biosph Sci, 1999, 6(4), 287 - 91
Theoretical and practical considerations of staggered crop production in a BLSS; Stutte GW et al.; A functional Bioregenerative Life Support System (BLSS) will generate oxygen, remove excess carbon dioxide, purify water, and produce food on a continuous basis for long periods of operation . In order to minimize fluctuations in gas exchange, water purification, and yield that are inherent in batch systems, staggered planting and harvesting of the crop is desirable . A 418-day test of staggered production of potato cv . Norland (26-day harvest cycles) using nutrients recovered from inedible biomass was conducted at Kennedy Space Center . The results indicate that staggered production can be sustained without detrimental effects on BLSS life support functions . System yields of H2O, O2 and food were higher in staggered than batch plantings . Plants growing in staggered production or batch production on "aged" solution initiated tubers earlier, and were shorter than plants grown on "fresh" solution . This morphological response required an increase in planting density to maintain full canopy coverage . Plants grown in staggered production used available light more efficiently than the batch planting due to increased side lighting.

Adv Space Res, 1997, 20(10), 1851 - 4
Theoretical and practical considerations for staggered production of crops in a BLSS; Stutte GW et al.; A functional Bioregenerative Life Support System (BLSS) will generate oxygen, remove excess carbon dioxide, purify water, and produce food on a continuous basis for long periods of operation . In order to minimize fluctuations in gas exchange, water purification, and yield that are inherent in batch systems, staggered planting and harvesting of the crop is desirable . A 418-d test of staggered production of potato cv . Norland (26-d harvest cycles) using nutrients recovered from inedible biomass was recently completed at Kennedy Space Center . The results indicate that staggered production can be sustained without detrimental effects on life support functions in a CELSS . System yields of H2O, O2 and food were higher in staggered than batch plantings . Plants growing in staggered production or batch production on "aged" solution initiated tubers earlier, and were shorter than plants grown on "fresh" solution . This morphological response required an increase in planting density to maintain full canopy coverage . Plants grown in staggered production used available light more efficiently than the batch planting due to increased sidelighting.

Planta, 1984, 162, 342 - 4
Growth, graviresponsiveness and abscisic-acid content of Zea mays seedlings treated with fluridone; Moore R et al.; Ten-d-old seedlings of Zea mays L . cv . Tx 5855 treated with 1-methyl-3-phenyl-5-(3-{trifluoromethyl}phenyl)-4-(1H)-pyridinone (Fluridone) were analyzed for abscisic acid (ABA) content using high-performance liquid chromatography with an analysis sensitivity of 2.5 ng ABA g-1 fresh weight (FW) . Seedlings were divided into three portions: leaves, detipped roots, and root tips (terminal 1.5 mm) . Control plants (water treatment only; no Fluridone) were characterized by the following amounts of ABA: leaves, 0.114 +/- 0.024 (standard deviation) microgram ABA g-1 FW; detipped roots, 0.260 +/- 0.039 +/- microgram ABA g-1 FW; root tips, no ABA detected . We did not detect any ABA in tissues of Fluridone-treated plants . Primary roots of treated and untreated seedlings were strongly graviresponsive, with no significant differences between the curvatures or the growth rates of primary roots of Fluridone-treated and control seedlings . These results indicate that 1) Fluridone completely inhibits ABA synthesis, and 2) ABA is not necessary for positive gravitropism by primary roots of Zea mays.

Space Med Med Eng (Beijing), 1997 Oct, 10(5), 323 - 7
{An experimental study on regeneration device for urine and waste water in space station}; Zhou K et al.; The principle, structure and function of the regeneration system for urine and waste water treatment were introduced . The experimental results demonstrated that, the treatment capacity was 1.2-1.9 kg/h, and the regeneration efficiency exceeded 92% . The quality of the treated water were: TOC < 20 g/m3, (NH3 + NH4+) < 10 g/m3, electric conductivity < 100 micro s/cm, pH= 6-8.

HortScience, 1988 Apr, 23(2), 275 - 86
CELSS for advanced manned mission; Olson RL et al.; An overview of the major concepts of Controlled Ecological Life Support System (CELSS) includes an identification of environmental factors, such as gravity levels, light levels, and growth volume, that influence the type of CELSS system that can be developed . Various plant growth systems are described together with their possible space applications . Life support functions performed by plants include food production, atmosphere regeneration, and water purification . Selected relationships between biological and physical-chemical life support techniques are considered as a part of these functions . Consumers in a CELSS may be humans, animals, or microorganisms, but nutritional, water, and atmosphere requirements of humans are emphasized in this report, as they are the primary requirement drivers for a CELSS design . The human role in waste generation is discussed as it affects plant nutrient availability . The role of waste management systems in recovering nutrients for plant growth and requirements for CELSS are defined for air, water, and food . Both physical and a biological nutrient recovery/waste disposal systems are examined . The separate subsystems of a CELSS are identified and discussed . Nutrient recovery, plant irradiation, automation, and facilities equipment and applications are reviewed with special attention to direct solar irradiation using fiber optics . These subsystems, along with other environmental control systems, such as thermal, humidity, and ventilation, are essential to plant growth in the space environment.

Biofouling, 1990, 2, 113 - 20
Iodine susceptibility of pseudomonads grown attached to stainless steel surfaces; Pyle BH et al.; Pseudomonads were adapted to grow in phosphate-buffered water and on stainless steel surfaces to study the iodine sensitivity of attached and planktonic cells . Cultures adapted to low nutrient growth were incubated at room temperature in a circulating reactor system with stainless steel coupons to allow biofilm formation on the metal surfaces . In some experiments, the reactor was partially emptied and refilled with buffer at each sampling time to simulate a "fill-and-draw" water system . Biofilms of attached bacteria, resuspended biofilm bacteria, and reactor suspension, were exposed to 1 mg l-1 iodine for 2 min . Attached bacterial populations which established on coupons within 3 to 5 days displayed a significant increase in resistance to iodine . Increased resistance was also observed for resuspended cells from the biofilm and planktonic bacteria in the system suspension . Generally, intact biofilms and resuspended biofilm cells were most resistant, followed by planktonic bacteria and phosphate buffer cultures . Thus, biofilm formation on stainless steel surfaces within water systems can result in significantly increased disinfection resistance of commonly-occurring water-borne bacteria that may enhance their ability to colonise water treatment and distribution systems.

Waste Manag Res, 1991 Oct, 9(5), 445 - 51
Immobilized microbe bioreactors for waste water treatment; Portier RJ et al.; The application of adapted microbial populations immobilized on a porous diatomaceous earth carrier to pre-treat and reduce toxic concentration of volatile organics, pesticides, petroleum aliphatics and aromatics has been demonstrated for several industrial sites . In the pre-treatment of industrial effluents and contaminated groundwaters, these bioreactors have been used to optimize and reduce the cost of conventional treatment systems, i.e . steam stripping, carbon adsorption and traditional biotreatment . Additionally, these systems have been employed as seeding devices for larger biotreatment systems . The cost effective utilization of an immobilized microbe reactor system for water supply regeneration in a microgravity environment is presented . The feasibility of using immobilized biomass reactors as an effluent treatment technology for the biotransformation and biodegradation of phenols, chlorinated halocarbons, residual oils and lubricants was evaluated . Primary biotransformation tests of two benchmark toxicants, phenol and ethylene dichloride at concentrations expected in life support effluents were conducted . Biocatalyst supports were evaluated for colonization potential, surface and structural integrity, and performance in continuous flow bioreactors . The implementation of such approaches in space will be outlined and specific areas for interfacing with other non-biological treatment approaches will be considered for advanced life support, tertiary waste water biotreatment.

Waste Manag Res, 1991 Oct, 9(5), 435 - 43
Plants for water recycling, oxygen regeneration and food production; Bubenheim DL; During long-duration space missions that require recycling and regeneration of life support materials the major human wastes to be converted to usable forms are CO2, hygiene water, urine and feces . A Controlled Ecological Life Support System (CELSS) relies on the air revitalization, water purification and food production capabilities of higher plants to rejuvenate human wastes and replenish the life support materials . The key processes in such a system are photosynthesis, whereby green plants utilize light energy to produce food and oxygen while removing CO2 from the atmosphere, and transpiration, the evaporation of water from the plant . CELSS research has emphasized the food production capacity and efforts to minimize the area/volume of higher plants required to satisfy all human life support needs . Plants are a dynamic system capable of being manipulated to favour the supply of individual products as desired . The size and energy required for a CELSS that provides virtually all human needs are determined by the food production capacity . Growing conditions maximizing food production do not maximize transpiration of water; conditions favoring transpiration and scaling to recycle only water significantly reduces the area, volume, and energy inputs per person . Likewise, system size can be adjusted to satisfy the air regeneration needs . Requirements of a waste management system supplying inputs to maintain maximum plant productivity are clear . The ability of plants to play an active role in waste processing and the consequence in terms of degraded plant performance are not well characterized . Plant-based life support systems represent the only potential for self sufficiency and food production in an extra-terrestrial habitat.

Analyst, 2001 Aug, 126(8), 1312 - 7
Large-volume sample stacking for on-capillary sample enrichment in the determination of naphthalene- and benzenesulfonates in real water samples by capillary zone electrophoresis; Cugat MJ et al.; We investigated the on-line preconcentration of a test mixture of 15 substituted and unsubstituted naphthalene(NSs) and benzenesulfonates (BZSs) by large-volume sample stacking (LVSS) . Analyses were carried out by capillary zone electrophoresis (CZE) with on-column UV detection . In particular, we focused on how experimental variables such as the inside diameter of the capillary, the volume of sample introduced and polarity switching influenced the enrichment procedure . The best results were obtained when 300 nl were injected and stacked using a bubble cell capillary . Under these conditions, LVSS increased the detector response of conventional hydrodynamic injection by a factor of 40 . The limits of detection of the method were between 5 and 10 microg l(-1) . Determinations were reproducible, in terms of peak area and migration time, under such conditions . The performance of the method was examined by determining NS and BZS in real samples, such as tap, river and surface waters and inflow/outflow waters from a water treatment plant . Real samples were injected directly into the CZE column with little or no preparation.

J Environ Monit, 1999 Aug, 1(4), 70N - 74N
Synthetic musks in environmental samples: indicator compounds with relevant properties for environmental monitoring; Kallenborn R et al.; Synthetic musks (nitro and polycyclic musks) are a group of chemicals offering a wide range of important properties for environmental monitoring programs . They are produced as odorous chemicals and added to a wide variety of perfumes, toiletry products and other household products . As such, they are directly applied in cosmetic products or in washed textiles to the human body in considerable concentrations and accumulate owing to dermal resorption . In addition, synthetic musks also enter the environment via waste water treatment . Several polycyclic musks are chiral . By using chiral gas chromatographic methods, it is possible to determine the enantiomeric ratio and assess their bioavailability . Although an comprehensive quality assurance program must be followed during the analysis of synthetic musks in environmental samples, the determination of these compounds is not very demanding and can be carried out by a standard analytical laboratory specialising in trace analysis of organic pollutants . Owing to the pheromone-like behavior of some synthetic musks, the induction of receptors in olfactory systems should be investigated . For HHCB (1,3,4,6,7,8-hexahydro-4,6,6,7,8,8-hexamethylcyclopenta{g}-2-benzopyran, e.g., Galaxolide), three-dimensional structural similarities with androstenone (5 alpha-androst-16-en-3-one), a mammalian steroid pheromone, were found, which support the hypothesis of HHCB as an artificial pheromone . Owing to their environmental abundance, their relation to human activities and their potential for pheromone-like environmental behavior, synthetic musks are especially valuable as future indicator chemicals for environmental monitoring.

J Environ Monit, 1999 Apr, 1(2), 135 - 42
Detection of petroleum hydrocarbons at low ppb levels using quartz resonator sensors and instrumentation of a smart environmental monitoring system; Sugimoto I et al.; Petroleum hydrocarbon vapors at low ppb levels can be detected using a thickness shear mode resonator (TSMR) coated with a chemical-sensing overlayer, prepared by radiofrequency sputtering of porous sintered-polyethylene (PS-PE) . The sensing capabilities of PS-PE sensors were profoundly affected by the sputtering methods; they were enhanced by the photo-excitation effect, and were reduced by carbonization and water treatment . The photo-assisted PS-PE sensor was extremely sensitive and could detect linear hydrocarbon (> C12) vapors below the ppb level . The time constant of the sorption curve, however, was large, indicating a slow sensing speed . Toward creating instrumentation for a smart environmental monitoring system, the TSMR sensors were arrayed on a circuit board equipped with a serial interface and signal processing chips of the oscillation drive and frequency counter . Co-sorption with water vapor at a relative humidity of about 10% has almost no effect on the sensing ability of PS-PE sensors for 1,2,4-trimethylbenzene . Conversely, it enhances the sensitivity of the TSMR sensor coated with a D-phenylalanine film . Upward shifts in the baseline are evident with elapsed time . However, a rigorous ten-cycle iteration test for 100 ppm toluene vapor demonstrated good reproducibility of the sensor's signals.

Environ Monit Assess, 2001 Jul, 70(1-2), 71 - 81
The continuous monitoring of field water samples with a novel multi-channel two-stage mini-bioreactor system; Gu MB et al.; Toxicity monitoring of field water samples was performed using a novel multi-channel two-stage mini-bioreactor system and genetically engineered bioluminescent bacteria for the continuous monitoring and classification of the toxicity present in the samples . The toxicity of various samples spiked with known endocrine disrupting chemicals and phenol was also investigated for system characterization . The field samples used in this study were obtained from two different sites on a monthly basis--from a drinking water treatment plant, referred to as site N, and from a stream near a dam which is currently being constructed, referred to as site T . These samples were either pumped or injected into the second mini-bioreactors to initiate the toxicity test . Most of the samples did not show any specific toxicity . However, one sample showed to have, based upon the detection results, and was deemed toxic . The samples spiked with phenol showed possible responses in the DPD2540 and TV1061 channels, indicating the occurrence of both membrane and protein damage due to phenol . In the tests using an endocrine disrupting chemical, bisphenol A, DNA damage was detected in the DPD2794 channel with a concentration of 2 ppm . Finally, a simple but novel early warning protocol that can be used in a drinking water reservoir and a suspected place where effluents of toxic materials enter the water sourse was suggested with a schematic diagram . In conclusion, this system showed good feasibility for use as a toxicity monitoring system in the field and as an early warning system, indicating if effluents are toxic.

Environ Monit Assess, 2001 Jul, 70(1-2), 211 - 22
Monitoring and modeling of disinfection by-products (DBPs); Sohn J et al.; In the United States, the newly promulgated disinfectant/disinfection by-product (D/DBP) regulations force water treatment utilities to be more concerned with finished and distributed water qualities . In this study, monitoring of DBP formation was conducted from three French water treatment plants trying to assess DBP variations through time and space . Compared to the in-plant total trihalomethanes (TTHM) levels, TTHM levels in the distribution system increased from less than 150% to more than 300% . Significant variations for TTHM and bromate (BrO3-) levels throughout the seasons were also observed; generally higher levels in the summer and lower levels in the winter . Combining chemical DBP models (empirical power functional models) and hydraulic simulations, DBPs including TTHM and BrO3- were successfully simulated from the full-scale monitoring data, indicating that empirical DBP model can be a potential tool to access DBP formation in actual plants . This study also provides the protocols to assess DBP simulations in the water treatment systems.

Environ Sci Technol, 2001 Aug 1, 35(15), 3247 - 51
Oxidation of 4-chloro-3-methylphenol in pressurized hot water/supercritical water with potassium persulfate as oxidant; Kronholm J et al.; 4-Chloro-3-methylphenol (c = 2.0 mM), representing a model pollutant, was oxidized in pressurized hot water and in supercritical water in a continuous flow system . Potassium persulfate was used as oxidant in concentrations of 8.0 and 40.0 mM . Contact times (reaction times) were 3-59 s, temperatures 110-390 degrees C, and pressures 235-310 bar . A wide temperature range was tested to determine the range over which potassium persulfate can be used effectively . Good oxidation efficiencies for 4-chloro-3-methylphenol were obtained at both oxidant concentrations and with short contact times at temperatures clearly underthe critical temperature of water; total organic carbon content of the effluent was low under optimized conditions . Corrosion, measured as nickel and chromium concentrations of the effluent, was more severe at oxidant concentration of 40.0 mM . Sulfate was present in the effluent in high concentrations . Sulfate is the limiting factor in the use of potassium persulfate in wastewater treatment and requires further water treatment.

Cent Eur J Public Health, 2001 Aug, 9(3), 154 - 7
Viral water contamination as the cause of aseptic meningitis outbreak in Belarus; Amvrosieva TV et al.; In the recent years Echovirus-30 associated outbreaks have taken place in different European countries . Aseptic meningitis caused by Echovirus-30 was the main diagnosis of a large outbreak in Belarus in Summer-Autumn, 1997, involving 460 patients . Echovirus-30 was detected in cerebrospinal fluid of the patients with aseptic meningitis . This serotype played the dominant role in the outbreak . Minor serotypes and mixtures of enteroviruses were detected in faeces and nasopharyngeal lavages . Investigation of environmental samples gave evidence of expressed viral contamination of drinking water and water sources (river and ground sources) . River water sources were considerably contaminated with viruses . The incidence of virus isolation was 50% . After cleaning procedures, the incidence became two times lower, proving imperfect water purification and disinfection procedures . Sequence analysis of isolates from Belarus (isolates from water and patient's cerebrospinal fluid) showed the difference of 0.2% . The outbreak peculiarities such as high attack rate and wide-spread of the disease incidences, clinical form variability, isolation of outbreak strain from water and a good agreement between minor serotypes isolated from faeces and water samples as well as correlation in the dynamics of acute intestine infections, aseptic meningitis morbidity and bacterial water contamination can be considered as evidence of its water-borne . Echovirus-30 isolates from Belarus were very closely related to each other and to several European isolates . Sequence difference between isolates of 1994-1998 from European countries was found to be 4.3% . The data can point to the common primary source of enterovirus infection, connected to water and to the possibility of epidemic strain transmission from neighbouring states to the Republic of Belarus.

J Vet Med Sci, 2001 Jul, 63(7), 767 - 71
Mutagenicity of water samples from five cities in Korea; Park JH et al.; Four doses (equivalent to 4, 2, 1, and 0.5 liter water) of organic extracts from raw, treated and drinking waters sampled from seven different treatment plants in five cities in Korea were challenged to the Ames test using S . typhimurium strains TA98 and TA100 in the presence/absence of S9 mix . The mutagenicity was usually observed from chlorine-treated (28.6%) and drinking (42.9%) waters rather than raw (3.4%) waters . The strain TA98 (33.3%) was more sensitive to detect the mutagenicity of water samples than the strain TA100 (16.7%) . However, the absence of S9 mix showed higher mutagenic activity of waters compared to the presence of S9 mix, corresponding to the detection of 42.9% and 7.1%, respectively . These results indicate that the bacterial mutagenicity of treated and drinking waters may be derived from chlorination in water treatment plants but that the mutagenicity in humans may be limited due to enzymatic metabolism.

Water Sci Technol, 2001, 44(1), 7 - 14
Key tools to accelerate fulfilment of the EU Urban waste water treatment directive in the Flemish region of Belgium; Ockier P et al.; The EU Urban Waste Water Treatment Directive (UWWTD) has been transposed in 1992 . The whole area of the Flemish region was designated as a sensitive area . This implies nutrient removal for all works in agglomerations of more than 10,000 population equivalent (PE) . Thanks to an accelerated investment programme, which is in a final phase now, the wastewater treatment plants (WWTPs) will fulfil treatment in 2005 . Key tools for a quick and economic execution of the programme are standardisation for new WWTP's and increasing computerisation for retrofitting existing WWTPs . The UWWTD also stipulates the reuse of treated wastewater and sludge . Strategies are explained.

Water Sci Technol, 2001, 44(1), 195 - 9
A new concept for storm water treatment: full-scale experience in Flanders; Carrette R et al.; Current practice in Flanders (Belgium) is to limit the hydraulic capacity of the wastewater treatment plant to 6Q14 . A maximum of 3Q14 is treated in the activated sludge system, the excess flow undergoes only physical treatment (stepscreen, sand trap and settling) . This paper focuses on an alternative storm management operation strategy aiming at maintaining plant performance and reducing the total pollutant discharge towards the receiving waterbody . Given the observed dilution of incoming wastewater under storm conditions, the idea was put forward that higher hydraulic loadings could be treated within the biology if additional secondary clarifier volume was supplied . The new storm operation strategy would consist of treating 6Q14 biologically using the available storm tanks as additional clarifier volume . The outcome of this study clearly shows that 6Q14 can be treated biologically using the storm tank as an extra clarifier . It was shown that doing so the overall pollutant discharge was significantly reduced . The proposed strategy does not entail any extra operational costs . On the contrary it offers a potential cost saving of 244 million Euro in view of a possible future change of environmental legislation regarding storm tank spill frequencies.

Water Sci Technol, 2001, 44(1), 1 - 6
EU policy on nutrients emissions: legislation and implementation; Bloch H; After 25 years of EU water legislation the European Union has just thoroughly restructured its water policy . The European Parliament and the Council, following a tough conciliation procedure between the two legislators, have in summer 2000 agreed a proposal by the European Commission for a Water Framework Directive . This legislation will have the following main objectives: integrated river basin management across borders, with coordinated programmes of measures protection of all waters, surface waters and groundwater, in quality and quantity with a proper ecological dimension emissions and discharges controlled by a "combined approach" of emission limit values and quality standards, plus the phasing out of particularly hazardous substances introducing water pricing policies strengthening public participation This new Water Framework Directive adopted in September 2000 will complement existing EU water legislation on nutrients reduction--the 1991 Directive on nitrates pollution from agricultural sources and the 1991 Directive on urban waste water treatment . These Directives will remain main pillars of EU water policy whilst at the same time being integrated into the river basin management in a coherent way.

Water Res, 2001 Sep, 35(13), 3265 - 71
The BAC-process for treatment of waste water containing non-ionogenic synthetic surfactants; Sirotkin AS et al.; In this paper experimental results on the biological-activated carbon (BAC)-process for biological degradation and adsorption of non-ionogenic surfactants (NISS) in the waste water treatment are discussed . It is shown that the mechanism of the BAC-process is not the simple addition but the synergetic combination of biodegradation and carbon adsorption . The major aspects of such synergism are the biological regeneration (bioregeneration) of the adsorbent and the reduction of the toxic effect of waste water contaminants on microorganisms . It is shown that the basis of the bioregeneration process is the desorption of substances previously adsorbed on the activated carbon . The desorption from micropores takes place because of the reverse concentration gradient, due to the microbial degradation of waste water contaminants in the liquid phase . The desorption from mesopores is also supported by the activity of microorganisms exoenzymes . Thus, the process of bioregeneration is featured by two non-contradictory hypotheses.

Water Res, 2001 Sep, 35(13), 3249 - 59
Magnetic water treatment for scale prevention; Gabrielli C et al.; A home-made magnetic device was built with permanent magnets for treating scaling waters . Its efficiency was evaluated by measuring the remaining ionic calcium at the output of the device by means of an ion selective electrode . The scaling power of the treated water was estimated through an electrochemical scaling test . Chroamperometric curves and chronoelectrogravimetric curves were plotted to obtain the scaling time and the nucleation time of the scale deposition . The variation of the efficiency of the magnetic treatment was studied when the length of treatment, the flow velocity of the scaling water in the device, the material of the pipe where the scaling water flowed were changed . An empirical relationship, which gives the value of the efficiency in function of the length of treatment and the flow velocity, was proposed . Possible mechanisms of action of the magnetic treatment were discussed.

Water Res, 2001 Sep, 35(13), 3242 - 8
Improved AOX degradation in UV oxidative waste water treatment by dialysis with nanofiltration membrane; Seiss M et al.; In this article, the wastewater treatment by UV oxidation with and without preceding desalination is compared . The influence of different chloride concentrations on the TOC degradation and AOX concentration is analyzed . Nanofiltration membrane dialysis is used to separate the chloride ions from wastewater . It is demonstrated that a reduction of the chloride concentration leads to a faster TOC degradation compared to the treatment of non-desalinated wastewater . Furthermore, the additional formation of AOX during the process could be avoided in effect leading to a significant degradation of native AOX.

Water Res, 2001 Sep, 35(13), 3179 - 89
Interaction between Cryptosporidium oocysts and water treatment coagulants; Bustamante HA et al.; The electrokinetic properties of gamma-irradiated Cryptosporidium oocysts in the presence of coagulants (ferric chloride and alum) and coagulant aids (DADMAC based cationic polyelectrolytes) have been studied . The zeta potential of the oocysts was unaffected by the addition of ferric chloride at all pH values (3-10) studied . Addition of alum resulted in reversal of the oocysts charge, which suggests that the initial stage in the coagulation process leading to floc formation proceeds via the adsorption of hydrolysed aluminium species . The cationic polyelectrolyte Magnafloc LT35 was adsorbed onto iron flocs at doses of 0.1 mg/L even against an electrostatic barrier . The cationic polyelectrolyte only adsorbed and caused charge reversal at the oocyst surface at around 0.4 mg/L, suggesting a lower affinity for this surface . These results indicate that the oocysts, unlike inorganic colloidal materials such as metal oxides, appear to possess a lower surface density of active or charged sites . The lower density of sites, combined with the rapid precipitation of iron salts, may be responsible for the lack of specific adsorption of either hydroxylated ferric species or primary iron hydroxide particles on the oocysts . Further, this suggests that a process of sweep flocculation, where oocysts are engulfed in flocs during coagulation and floc formation, is the more likely mechanism involved . By comparison, it is likely that the specific interaction of hydrolysed aluminium species with the oocysts surface would result in a stronger link at the oocyst-floc interface and that the flocculation process may initially proceed via charge neutralisation.

Water Res, 2001 Sep, 35(13), 3071 - 6
Microbial reduction of perchlorate in pure and mixed culture packed-bed bioreactors; Kim K et al.; Perchlorate (ClO4-) has been detected in a large number of surface and ground waters in the US . Due to health concerns of perchlorate in drinking water, the California Department of Health Services has established a provisional action level of 18 microg/L . Several microbial isolates have been obtained capable of microbiological perchlorate reduction through cell respiration, but few of these have been tested for perchlorate removals to these low levels . The feasibility of using one isolate (KJ) for water treatment was tested in a packed-bed bioreactor by comparing minimum detention times necessary to achieve complete removal of perchlorate . Perchlorate was reduced approximately from 20 mg/L to non-detectable (< 4 microg/L) levels in acetate-fed columns inoculated with KJ or mixed cultures . The complete conversion of perchlorate to chloride was demonstrated by a stoichiometric ratio of perchlorate to chloride of 1.0 +/- 0.14 . Perchlorate removal to non-detectable levels required a minimum empty bed contact time (EBCT) of only 2.1 min for the column inoculated with KJ, vs . 31 min for the mixed culture column . Acetate was used at a molar ratio of C2H3O2-/ClO4- of 2.9 (n = 6) for the mixed culture, while more than twice as much acetate was consumed on average (6.6 +/- 2.0, n = 156) by the pure culture . These results demonstrate that detention times of packed-bed bioreactors can be substantially reduced using isolate KJ, but that larger concentrations of acetate will be necessary to reduce perchlorate to low levels necessary for drinking water.

Environ Health Perspect, 2001 Jul, 109(7), 663 - 8
Human fatalities from cyanobacteria: chemical and biological evidence for cyanotoxins; Carmichael WW et al.; An outbreak of acute liver failure occurred at a dialysis center in Caruaru, Brazil (8 degrees 17' S, 35 degrees 58' W), 134 km from Recife, the state capital of Pernambuco . At the clinic, 116 (89%) of 131 patients experienced visual disturbances, nausea, and vomiting after routine hemodialysis treatment on 13-20 February 1996 . Subsequently, 100 patients developed acute liver failure, and of these 76 died . As of December 1996, 52 of the deaths could be attributed to a common syndrome now called Caruaru syndrome . Examination of phytoplankton from the dialysis clinic's water source, analyses of the clinic's water treatment system, plus serum and liver tissue of clinic patients led to the identification of two groups of cyanobacterial toxins, the hepatotoxic cyclic peptide microcystins and the hepatotoxic alkaloid cylindrospermopsin . Comparison of victims' symptoms and pathology using animal studies of these two cyanotoxins leads us to conclude that the major contributing factor to death of the dialyses patients was intravenous exposure to microcystins, specifically microcystin-YR, -LR, and -AR . From liver concentrations and exposure volumes, it was estimated that 19.5 microg/L microcystin was in the water used for dialysis treatments . This is 19.5 times the level set as a guideline for safe drinking water supplies by the World Health Organization.

Environ Technol, 2001 Jun, 22(6), 653 - 9
Improvement of water treatment performance by using polyamine flocculants; Lee SH et al.; In this study, polyamine flocculants were synthesized and applied to Nak-dong river raw water in Korea to examine their efficiency in reducing turbidity, total organic carbon (TOC) and UV254 . Synthesized polyamines were effective as flocculants for water treatment and the addition of organic polymer caused a reduction of 50-80% of the consumption of polyaluminium chloride (PAC) . The effects of polyamine on the removal of turbidity, TOC and UV254 were investigated via both jar and pilot tests . The adsorption and separation mechanisms for the removal of turbidity and TOC by using the polymer flocculants were also observed.

Environ Sci Technol, 2001 Jul 15, 35(14), 3019 - 24
Applications of ultrasound in NAPL remediation: sonochemical degradation of TCE in aqueous surfactant solutions; Destaillats H et al.; Surfactant-enhanced pump-and-treat technologies increase the efficiency of nonaqueous-phase liquids (NAPLs) removal from soils . However, high concentrations of surfactants in groundwater impose severe limitations to water treatment . In this paper, we explore the applicability of ultrasonic irradiation as an alternative method for surfactant recovery and contaminant degradation . The combined effects of temperature, initial substrate concentration, and concentration of added surfactant (sodium dodecyl sulfate, SDS) were analyzed for the sonolysis of trichloroethylene (TCE) in batch experiments at an ultrasonic frequency of 500 kHz and 77 W/L applied power density . In the range of 5-30 degrees C, TCE sonolysis becomes faster at higher temperatures, both in the absence and in the presence of surfactant . This indicates that gas-phase pyrolysis prevails over other chemical reactions in the liquid phase . Inhibition of TCE sonolysis was observed in the presence of surfactant at all SDS concentrations . Changes in the initial TCE concentration (from 250 microM to 1.2 mM) showed no effect on the degradation rates in the presence of SDS . For surfactant levels below its critical micelle concentration (cmc), the inhibition of TCE sonolysis exhibited a highly nonlinear dependence with increasing SDS concentration . A correlation was observed in this range between the relative inhibition of sonolysis and the decreasing surface tension of the solutions . Above the cmc up to an SDS concentration of 5%, the reaction rate decreased less markedly . Micellar sequestration of the contaminant seems to be the main reason for this additional inhibition . Bubble growth prior to collapse may incorporate some of the TCE dissolved in the micelles through their adsorption in the expanding bubble walls, thus partially overcoming the scavenging effect due to micellar entrapment of the contaminant.

Water Res, 2001 Aug, 35(12), 2895 - 904
Optimisation of combined coagulation and microfiltration for water treatment; Judd SJ et al.; The effect of upstream coagulant dosing for full-flow microfiltration of an upland-reservoir water has been investigated . The process, run under conditions of constant flux and pH and based on a ferric salt, is compared with a published study of another full-flow process based on alum dosing and operated at constant pressure and coagulant concentration . The current study includes data for the residual deposit remaining following backflushing by reverse flow . Results are presented in terms of the specific-cake resistance (R'o, m(-2)) as a function of pH or coagulant dose . Reasonable correlation with classical cake filtration theory was obtained, such that R' was assumed to be independent of run time and cake thickness . The following trends have been noted: The optimum pH for the alum-based system appears to be between 7.5 and 8 on the basis of cake resistance . The effect of coagulant dose between 18 and 71 microM Fe3+ is much more significant than a change in pH between 5 and 9 for the alum system: a 53-fold increase in specific flux compared with a 7-fold increase with reference to the limiting R'o values at pH 4.8 and 7.7 . A low coagulant dose (0.018mM, 1.0 mg l(-1) Fe3+) appears to have a slightly detrimental effect on downstream microfiltration operation . The low coagulant doses apparently cause incomplete aggregation of colloidal particles such that internal fouling of the membrane takes place . The residual (cleaning cycle) deposit resistance followed roughly the same trend as the backflush cycle-cake resistance with coagulant concentration, but with a much reduced value (about 16 times lower, on average) . An optimum coagulant dose of 0.055 mM (3.1 mg/l) Fe3+ can be identified on the basis of operational cost based on coagulant cost and cake resistance, all other aspects of the system being substantially unchanged . It is concluded that coagulation with downstream microfiltration offers a cost-effective means of removing natural organic matter, achieving a THMFP removal of around 80% at the optimum dose.

Water Res, 2001 Aug, 35(12), 2861 - 72
A study on the distribution of chlorination by-products (CBPs) in treated water in Korea; Lee KJ et al.; Fifteen chlorination by-products were analyzed in 416 water samples collected from 35 water treatment plants in Korea from 1996 to 1998 . These samples were divided into five groups according to water sources (Han-river, Nakdong-river, Youngsan-river, Kum-river and Cheju) and detected CBPs were classified into six classes (trihalomethanes; THMs, haloacetic acids; HAAs, haloacetonitriles: HANs haloketones; HKs, chloralhydrate; CH, chloropicrin; CP) and then, it was observed the detection tendency and frequency of CBPs in each water source . The total concentration of CBPs in treated water from Nakdong-river or Han-river was higher than those from the other rivers . And the distribution pattern of each class of CBPs was similar in all water sources . THMs were the highest portion in the range of 40-50%, and HAAs and HANs were 28-35 and 9-15%, respectively . And there was a strong correlation between HANs and HKs (r=0.813) . Each and total concentrations of CBPs showed to be more affected by the water source in two-way analysis of variance (two-way ANOVA) among the concentration of CBPs, the source of water and season.

J Trauma, 2001 Jul, 51(1), 98 - 104
Autofluorescence of skin burns detected by fiber-optic confocal imaging: evidence that cool water treatment limits progressive thermal damage in anesthetized hairless mice; Vo LT et al.; BACKGROUND: Although full-thickness burns present no difficulty to clinical judgment, accurate assessment of burn depth immediately after injury in partial thickness burns has always been difficult . METHODS: Thermal burns (applied by a 3-mm-diameter brass rod heated to 50 degrees--80 degrees C for 20 seconds) were induced on the skin of anesthetized hairless mice . Anesthesia was maintained throughout all experiments . Both burns and normal skin were investigated noninvasively in vivo using fiber-optic confocal imaging (FOCI) microscopy (excitation, 488 nm; detection, 505 nm) . RESULTS: Autofluorescence was detected in burned skin, and the depth of the autofluorescent region was found to correlate with the intensity of heat applied . Cool water treatment (for 20 minutes immediately after burn induction) significantly reduced the progressive increase in autofluorescence in deeper layers of the skin over the 4-hour postburn observation period . Histology showed burn-associated changes at a lower temperature than that at which autofluorescence was first detected in vivo by FOCI . However, there was a good correlation (r = 0.78) between depth of damage revealed by FOCI compared with that by histology . CONCLUSION: These results suggest that FOCI may be used to provide an index of burn depth.

Water Sci Technol, 2001, 43(12), 89 - 92
Occurrence of Cryptosporidium oocysts and Giardia cysts in a conventional water purification plant; Hashimoto A et al.; A one-year monitoring of Cryptosporidium oocysts and Giardia cysts was conducted at a water purification plant . A total of thirteen 50 L samples of river source water and twenty-six 2,000 L samples of filtered water (treated by coagulation-flocculation, sedimentation and rapid filtration) were concentrated using a hollow fibre ultrafiltration membrane module at a purification plant . Cryptosporidium oocysts were detected in all raw water samples with a geometric mean concentration of 400 oocysts/m3 (range 160-1,500 oocysts/m3) . Giardia cysts were detected in 12/13 raw waters (92%) with a geometric mean concentration of 170 cysts/m3 (range 40-580 oocysts/m3) . Probability distributions of both Cryptosporidium oocysts and Giardia cyst concentration in raw water were nearly log-normal . In filtered water samples, Cryptosporidium oocysts were detected in 9/26 samples (35%) with a geometric mean concentration of 1.2 oocysts/m3 (range 0.5-8 oocysts/m3) and Giardia cysts in three samples (12%) with 0.8 cysts/m3 (range 0.5-2 oocysts/m3) . The estimated removal of Cryptosporidium oocysts and Giardia cysts was, respectively, 2.54 log 10 and 2.53 log10 on the basis of geometric means, 3.20 and 3.57 log10 on the basis of 50% observation level and 2.70 and 2.90 log10 on the basis of 90% observation level.

Water Sci Technol, 2001, 43(12), 225 - 8
Occurrence of microcystins in raw water sources and treated drinking water of Finnish waterworks; Lahti K et al.; Problems caused by cyanobacteria are common around the world and also in raw water sources of drinking water treatment plants . Strains belonging to genera Microcystis, Anabaena and Planktothrix produce potent hepatotoxins, the microcystins . Laboratory and pilot scale studies have shown that microcystins dissolved in water may pass the conventional surface water treatment processes . In 1998 the World Health Organization proposed a guide value of 1 microgram/L for microcystin-LR (MC-LR) in drinking water . The purpose of this research was to study the occurrence of microcystins in raw water sources of surface waterworks and in bank filtration plants and to evaluate the removal of microcystins in operating waterworks . Four bank filtration plants and nine surface waterworks using different processes for water treatment were monitored . Phytoplankton was identified and quantified, and microcystins analysed with sensitive immunoassay . Microcystin occurrence in selected water samples was verified with HPLC and a protein phosphatase inhibition method . Microcystins were detected sporadically in raw water sources of most of the waterworks . In two raw water supplies toxins were detected for several months . The highest microcystin concentrations in incoming raw water were approximately 10 micrograms/L MC-LR equivalents . In treated drinking water microcystins were detected occasionally but the concentrations were always below the guide value proposed by WHO.

Water Sci Technol, 2001, 43(12), 147 - 54
Comparison of static and dynamic disinfection models for bacteria and viruses in water of varying quality; Springthorpe S et al.; Disinfection studies rarely use natural waters due to demands exerted on the applied disinfectants and lack of consistent disinfectant residuals . This study compared the degree of disinfection achieved in natural waters between conventional batch (static) models and a system of similar volume where disinfectant residuals were maintained at constant levels (dynamic) . In the latter, disinfectant was delivered through a hollow fibre cartridge from a slipstream of a full-scale (chloramine) or pilot (chlorine) water treatment plant . The test organisms (hepatitis A virus, poliovirus, MS-2, Mycobacterium terrae and Enterococcus durans) were selected with different resistance to the disinfectants . In general, for water of "good" quality, the differences between the two systems were often small or not apparent for monochloramine . However, for low chlorine residuals, or when additional demand was placed on the disinfectant, differences between the two systems became more apparent . Little difference was seen between disinfection of the test organisms singly or in mixtures, but injury of vegetative bacteria with monochloramine was very apparent . This system could be useful for understanding the fluctuations in disinfection efficacy that may occur in source water of varying quality, or in distribution systems, as disinfectant residuals decline.

Water Sci Technol, 2001, 43(12), 125 - 32
Neural network modelling of Cryptosporidium and Giardia concentrations in the Delaware River, USA; Neelakantan TR et al.; Artificial neural networks are brain-like structures used in mathematical modelling that excel in pattern recognition . In this research, a simple feed-forward artificial neural network, trained by error back-propagation algorithm, was used as a tool to relate peak Cryptosporidium and Giardia concentrations with other biological, chemical and physical parameters in surface water . Multiple water quality parameters at a water treatment plant intake on the Delaware River, New Jersey, USA, collected in 1996, were provided to the authors for recognition analysis . Water samples were classified as "background" and "above background" based on the concentration of full and empty oocysts and cysts of Cryptosporidium and Giardia . The results of this preliminary effort were encouraging . Parameters significant to the identification of each protozoa were identified, eight for Cryptosporidium and seven for Giardia by a stepwise elimination technique . Data withheld from the model training was used to validate the trained models and evaluate the most effective internal architecture . In both cases, the best prediction performance was found when the number of internal nodes was twice that of the input parameters in single hidden-layer architecture . Predictions for the classification of the verification data set resulted in no false-negatives (mis-prediction of above background protozoa concentrations) when the models were optimally trained.

Water Res, 2001 Aug, 35(11), 2740 - 8
The regeneration of field-spent granular-activated carbons; Miguel GS et al.; The thermal regeneration of field-spent granular-activated carbons (GAC) is being increasingly adopted as a cost-effective alternative to disposal . The success of this practice requires the adjustment of process conditions to maximise the recovery of the original carbon characteristics while minimising carbon loss . This paper describes an investigation into the regeneration of several field-spent GAC representative of those typically generated by the drinking water treatment industry . The carbons were initially investigated for their ash contents and inorganic compositions in order to determine the accumulation of metallic species that affect the regeneration process . Regeneration was conducted in steam at 800 degrees C over reaction times between 0 and 60 min in order to achieve different degrees of carbon gasification . Weight losses were determined for each condition and the resulting carbons characterised for their apparent density, porosity, surface area and aqueous adsorption characteristics . Results showed that spent carbons recovered most of their adsorption characteristics when heated to 800 degrees C under inert conditions . Steam gasification in the range of 5-10 wt% burn-off had some positive effects on the characteristics of the spent carbons which were in most cases counteracted by a reduction in the carbon yield . Steam gasification in excess of 15 wt% burn-off caused a rapid increase in the carbon mesoporosity but a significant deterioration in the carbon microporosity, BET surface area and adsorption capacity for organic species of small molecular size.

Water Res, 2001 Aug, 35(11), 2621 - 8
Changes of activity inducing chromosomal aberrations and transformations of chlorinated humic acid; Itoh S et al.; The change of the toxicity of chlorinated water after chlorine injection was examined . For the measurement of toxicity, chromosomal aberration test and transforming test were carried out as indexes to initiating activity and to promoting activity in the carcinogenesis process, respectively . Activity inducing chromosomal aberrations of chlorinated humic acid gradually decreased with time after chlorination . In contrast, activity inducing transformations measured by the two-stage assay gradually increased . Thus, the toxicity that decreases or increases is present in chlorinated water . Furthermore, activity inducing transformations measured by the non-two-stage assay gradually decreased . This direction of change was reverse to that of activity inducing transformations by the two-stage assay and consistent with that of activity inducing chromosomal aberrations . It is speculated that the main reason of decreasing activity inducing transformations by the non-two-stage assay is because initiating activity detected as activity inducing chromosomal aberrations in chlorinated water decreases drastically . Directions of changes of total organic halogen and carbonyl group were qualitatively consistent with that of activity inducing chromosomal aberrations . Directions of changes of chloroform and dichloroacetic acid were qualitatively consistent with that of activity inducing transformations by the two-stage assay . Findings of this study suggest that further research is necessary to compare carcinogenicity of tap water near water purification plant and distant tap water.

Water Res, 2001 Aug, 35(11), 2607 - 14
Characterization of raw water for the ozone application measuring ozone consumption rate; Park HS et al.; This study was conducted to illustrate an ideal method for characterizing natural waters for ozonation processes in drinking water treatment plants . A specific instrument designed with the flow injection analysis (FIA) technique enabled us to measure accurately the ozone decomposition rate, which was found to consist of two stages: the instantaneous ozone consumption stage and the slower ozone decay stage . The ozone consumption rate was measured at the initial and secondary stages by determining certain parameters called the instantaneous ozone demand (ID) and the pseudo first-order decay rate constant (k(c)) . Using the OH*-probe, the yield of OH* per consumed ozone was also measured to determine its potential to produce OH* for the oxidation of micropollutants during the ozonation process . The ozone consumption of the ID values was significant in most natural waters, and substantial amounts of OH* were found to generate during the instantaneous ozone consumption stage . This study also investigated the effects of particulates, ozone doses, and sequential ozone injection on ozone decomposition kinetics and OH* formation yield.

Sci Total Environ, 2001 Jul 2, 274(1-3), 197 - 207
Infection transmission system models for microbial risk assessment; Chick SE et al.; Chemical risk assessments often focus on measuring exposure as if individuals were subject only to exogenous environmental sources of risk . For infectious diseases, exposure might not only depend on exogenous sources of microbes, but also on the infection status of other individuals in the population . For example, waterborne infections from agents such as Cryptosporidium parvum and Escherichia coli: O157:H7 might be transmitted from contaminated water to humans through drinking water; from interpersonal contact; or from infected individuals to the environment, and back to other susceptible individuals . These multiple pathways and the dependency of exposure on the prevalence of infection in a population suggest that epidemiological models are required to complement standard risk assessments in order to quantify the risk of infection . This paper presents new models of infection transmission systems that are being developed for the US Environmental Protection Agency as part of a project to quantify the risk of microbial infection . The models are designed to help inform water treatment system design decisions.

Health Estate, 2001 Jun, 55(6), 23 - 5
Reviewing efficacy of alternative water treatment techniques; Hambidge A; This section is designed to provide a brief summary of some of the findings . A good deal of work has been conducted by Mr N . L . Pavey and the team at BSRIA, Bracknell . The BSRIA publications are an excellent source of further information . Ultraviolet radiation: UV radiation of wavelength 254 nm destroys bacteria by a mechanism of damaging nucleic acids by producing thymine dimers which disrupt DNA replication {Gavdy and Gavdy, 1980} . L . pneumophila has been reported as sensitive to UV dosages of 2,500-7,000 uW.s/cm2 {Antopol & Ellner, 1979; Knudson, 1985} . Antopol and Ellner {1979} examined the susceptibility of L . pneumophila to UV dosage . Their results indicated that 50% of the organisms were killed by 380 uWs/cm2 and 90% were killed by 920 uWs/cm2 . Kills of 99 and 99.9% were obtained using 1,840 and 2,760 uWs/cm2 respectively . Muraca et al {1987} showed that continuous UV irradiation resulted in a 5 logarithm decrease in waterborne L . pneumophila in a circulating system . Gilpin {1984} reported that in laboratory buffer solutions, exposure to 1 uW of UV radiation per cm2 achieved a 50% kill of L longbeachae in 5 minutes, L . gormanii in 2-30 minutes and L pneumophila in 17 minutes . Exposure times for 99% kills for L . longbeachae, L pneumophila and L . Gormanii were 33, 48 and 63 minutes respectively . The same research worker conducted experiments using a 3 litre circulating water system, connected to a stainless steel housing containing a UV source . The UV lamp output was 7 ergs/mm2 per second per 100 cm at 254 nm . L . pneumophila was killed within 15 seconds, that is within their first pass through the system . Continuous disinfection with UV has the advantages of imparting no taste, odour or harmful chemical by-products and requires minimal operation and maintenance {Muraca et al 1988} . Keevil et al {1989} state that UV irradiation fails to clear systems of biofilm because of poor penetration into microflocs of the micro-organisms . Copper/silver ionisation: A recent study of full scale hot water test rigs incorporating copper-silver ionisation systems has been reported by Pavey, 1996 . Copper and silver ions were introduced into the water by electrolysis . One of the principal mechanisms of biocidal action of these ions is thought to be cell penetration . The positively charged copper ions form electrostatic bonds with negatively charged sites on the cell wall . The cell membrane is thus distorted, allowing ingress of silver ions which attack the cell by binding at specific sites to DNA, RNA, respiratory enzymes and cellular protein, causing catastrophic failure of the life support systems of the cell . Silver and copper ion concentrations of 40 and 400 ug/L respectively were effective against planktonic Legionellae in cold water systems and hot water systems containing soft water . In hard water, the ionisation was ineffective due to the inability to control silver ion concentrations . This was caused by scaling of the electrodes and silver ion complexation by the high concentration of dissolved solids . Bosch et al {1993} had earlier extended the application of copper-silver disinfection to human enteric viruses in water, such as adenovirus, rotavirus, hepatitis A virus, and poliovirus . Their work showed that copper and silver ions in the presence of reduced levels of free chlorine did not ensure the total elimination of viral pathogens from water . In the case of an amoeba, Naegleria fowleria {responsible for primary amoebic meningoencephalitis}, Cassells et al {1995} have demonstrated that a combination of silver and copper ions were ineffective at inactivating the amoebae at 80 and 800 ug/L respectively . However addition of 1.0 mg/L free chlorine produced a synergistic effect, with superior inactivation relative to either chlorine or silver-copper in isolation . A similar synergy was reported by Yahya et al {1989} in their study of Staphylococcus sp . and Pseudomonas aeruginosa . Yahya et al {1992} also suggested an additive or synergistic effect in the inactivation of coliphage MS-2 and poliovirus . Other techniques: There are a number of other techniques . We have conducted trials of most of these in the control of Legionella sp., but these fall out of the scope of this article, and as such less emphasis has been placed on them here . Ozonation: Ozone {O3} is an oxidising gas, generated electrically from oxygen {O2} . L . pneumophila can be killed at < 1 mg/L of ozone {Edelstien et al 1982} . Muraca et al {1987} found that 1-2 mg/L of continuous ozone over a six hour contact time, produced a 5 logarithm decrease of L . pneumophila . The effectiveness of ozone treatment against a range of bacteria and coliphages has been studied Botzenhart et al {1993} . E . coli was least resistant to ozone, followed by MS 2-coliphage and PhiX 174-coliphage, with L . pneumophila and Bacillus subtilis spores being the most resistant . (ABSTRACT TRUNCATED)

J Environ Radioact, 2001, 56(1-2), 11 - 32
A critical review of measures to reduce radioactive doses from drinking water and consumption of freshwater foodstuffs; Smith JT et al.; Following a radioactive fallout event, there are a number of possible intervention measures to reduce radioactive doses to the public via the surface water pathway . We have critically reviewed the options available to decision-makers in the event of radioactive contamination of surface waters . We believe that the most effective and viable measures to reduce radioactivity in drinking water are those which operate at the water treatment and distribution stage . Intervention measures to reduce concentrations of radioactivity in rivers and reservoirs are expected to be much less viable and efficient at reducing doses via the drinking water pathway . Bans on consumption of freshwater fish can be effective, but there are few viable measures to reduce radioactivity in fish prior to the preparation stage . Lake liming and biomanipulation have been found to be ineffective for radiocaesium, although the addition of potassium to lakewaters appears promising in some situations . Lake liming may be effective in reducing radiostrontium in fish, though this has not, to our knowledge, been tested . De-boning fish contaminated by strontium is probably the most effective food preparation measure, but salting and freezing can also reduce radiocaesium concentrations in fish . The provision of accurate information to the public is highlighted as a key element of countermeasure implementation.

Mar Environ Res, 2000 Mar, 49(2), 177 - 96
Micropollutants and organic carbon concentrations in surface and deep sediments in the Tunisian coast near the city of Sousse; Pavoni B et al.; A radioactive tracer was used to map the plume of the effluent of a municipal water treatment plant located on the Tunisian coast, close to the city of Sousse . A sampling campaign was programmed on the basis of the radioactivity distribution . The extent of sediment contamination was investigated to determine the impact of the plant effluent . Organic carbon and organic micropollutants (PCBs and chlorinated pesticides) were analysed on resuspendable particulate matter, on grab and core sediments . The area distributions of different compounds analysed were studied and relationships were investigated between radioactivity and organic carbon and micropollutant data . The study shows that sludge particles are deposited and accumulate in the zone south of the effluent outlet, contaminating sediments . Good correlations were found which demonstrate the efficiency of the technique used to plan the sampling and the link between organic carbon and organic micropollutants.

J Microbiol Methods, 2001 Sep, 46(3), 209 - 15
A luciferase-based method for assessing chlorine-susceptibility of Mycobacterium avium; Cowan HE et al.; A rapid and quantitative assay for the disinfection of the water-borne pathogen, Mycobacterium avium, was developed using firefly luciferase as a reporter gene . There was a correlation between the quantity of light produced and the number of colony-forming units . In chlorine-disinfection studies of a luciferase-carrying derivative of M . avium, there was a strong correlation (r2=0.96) between colony forming units and relative light units . It was discovered that chlorine was rapidly lost from suspensions containing 10(6) M . avium cells/ml . The luciferase-based test can be used to rapidly measure susceptibility of M . avium to different disinfectants used in water treatment.

Water Sci Technol, 2001, 43(10), 67 - 74
Technical-economic modelling of integrated water management: wastewater reuse in a French island; Xu P et al.; An integrated technical-economic model is used to address water management issues in the French island of Noirmoutier . The model simulates potable water production and supply, potable and non potable water demand and consumption, wastewater collection, treatment and disposal, water storage, transportation and reuse . A variety of water management scenarios is assessed through technical, economic and environmental evaluation . The scenarios include wastewater reclamation and reuse for agricultural and landscape irrigation as well as domestic non potable application, desalination of seawater and brackish groundwater for potable water supply . The study shows that, in Noirmoutier, wastewater reclamation and reuse for crop irrigation is the most cost-effective solution to the lack of water resources and the protection of sensitive environment . Some water management projects which are regarded as having less economic benefit in the short-term may become competitive in the future, as a result of tightened environmental policy, changed public attitudes and advanced water treatment technologies . The model provides an appropriate tool for water resources planning and management.

Water Sci Technol, 2001, 43(10), 327 - 34
The effects of water reclamation technologies on biological stability of industrial water; Ng WJ et al.; A modified Assimilable Organic Carbon (AOC) procedure was adopted in conjunction with Heterotrophic Plate Count (HPC) method to assess the effect of Single Effect Distillation (SED) and Reverse Osmosis (RO) lab-scale systems on the biological stability of industrial water . Industrial water was collected from a local Industrial Water Works, pre-treated with alum coagulation and cartridge filtration, before being subjected to advanced water treatment . The results obtained in this study indicated that AOCs in the SED product water were in the range of 70-80 micrograms acetate-C/L, while those in the RO product water ranged from 30-40 micrograms acetate-C/L in the 15-min permeate to 55-65 micrograms acetate-C/L in the 3-hr permeate . The above findings suggested that product water of both systems were potentially biologically unstable and would likely lead to bacteria regrowth during its distribution and storage . Removal efficiencies of lab-scale RO and SED systems on AOC were as high as 90%, dependent on the concentration of AOC-NOX in the industrial water . The RO system had much higher organic removal efficiencies in terms of AOC and DOC than the SED system . Organics removed from both feed waters were found to be concentrated in the brine water and rejected water in SED and RO systems respectively.

Water Sci Technol, 2001, 43(10), 241 - 8
New parameter for monitoring fouling during ultrafiltration of WWTP effluent; Roorda JH et al.; Variations in water quality of waste water treatment plant (WWTP) effluent complicate ultrafiltration of this feed water . Traditional parameters do not provide sufficient information to explain the fouling of membranes during ultrafiltration of WWTP effluent . New parameters for measuring and monitoring the fouling potential of feed water for ultrafiltration membranes need to be developed . The normalised membrane fouling index for ultrafiltration membranes (MFI-UFn) can be used as such and is according to the cake filtration theory calculated from the ratio of filtration time and filtration volume as a function of the filtration volume . MFI-UFn can be calculated from both experiments with constant Trans Membrane Pressure (TMP) and from experiments with constant flux . This parameter can also be calculated independent of the scale of the experiment . Results show that differences in fouling potential can be measured for various feed waters using the same membrane type and for various membrane types using the same feed water . Variation in feed water quality leads to a deviation of the MFI-UFn, as was found especially for WWTP effluent . The applied TMP influences the value of the MFI-UFn, indicating cake compression when applying a higher TMP . MFI-UFn can be used to identify the effect of pre-treatment methods, which is useful when using WWTP effluent as feed water for an ultrafiltration processes.

Water Sci Technol, 2001, 43(10), 101 - 7
From sewage water treatment to wastewater reuse . One century of Paris sewage farms history; Vedry B et al.; The irrigation fields of Paris have been used for 100 years . Their soils mainly contain heavy metals in the topmost layer . Metals come from raw sewage as well as from digested sludge of biological treatment plants which have been diluted for years in raw water . Vegetables that are cultivated in the irrigation fields concentrate metals but their average contents, however, are lower than the recommended limit values . Some vegetables concentrate more specifically one type of metal . Corn seeds accumulate less metal than green vegetables . The SIAAP keeps operating irrigation fields by delivering clariflocculated water with a low metal content from the new Seine Centre plant, with the purpose of keeping some 2,000 ha of green zone in an otherwise heavily constructed area and to prevent a metal release from the soil should irrigation be interrupted . Maintaining irrigation fields also relieves the biological treatment plant and then contributes to preserve the quality of the Seine river, especially in summer.

Appl Environ Microbiol, 2001 Jul, 67(7), 3029 - 32
Low-pressure UV inactivation and DNA repair potential of Cryptosporidium parvum oocysts; Shin GA et al.; Because Cryptosporidium parvum oocysts are very resistant to conventional water treatment processes, including chemical disinfection, we determined the kinetics and extent of their inactivation by monochromatic, low-pressure (LP), mercury vapor lamp UV radiation and their subsequent potential for DNA repair of UV damage . A UV collimated-beam apparatus was used to expose suspensions of purified C . parvum oocysts in phosphate-buffered saline, pH 7.3, at 25 degrees C to various doses of monochromatic LP UV . C . parvum infectivity reductions were rapid, approximately first order, and at a dose of 3 mJ/cm(2) (=30 J/m(2)), the reduction reached the cell culture assay detection limit of approximately 3 log(10) . At UV doses of 1.2 and 3 mJ/cm(2), the log(10) reductions of C . parvum oocyst infectivity were not significantly different for control oocysts and those exposed to dark or light repair conditions for UV-induced DNA damage . These results indicate that C . parvum oocysts are very sensitive to inactivation by low doses of monochromatic LP UV radiation and that there is no phenotypic evidence of either light or dark repair of UV-induced DNA damage.

Appl Environ Microbiol, 2001 Jul, 67(7), 2993 - 3001
Chlorine dioxide inactivation of Cryptosporidium parvum oocysts and bacterial spore indicators; Chauret CP et al.; Cryptosporidium parvum, which is resistant to chlorine concentrations typically used in water treatment, is recognized as a significant waterborne pathogen . Recent studies have demonstrated that chlorine dioxide is a more efficient disinfectant than free chlorine against Cryptosporidium oocysts . It is not known, however, if oocysts from different suppliers are equally sensitive to chlorine dioxide . This study used both a most-probable-number-cell culture infectivity assay and in vitro excystation to evaluate chlorine dioxide inactivation kinetics in laboratory water at pH 8 and 21 degrees C . The two viability methods produced significantly different results (P < 0.05) . Products of disinfectant concentration and contact time (Ct values) of 1,000 mg . min/liter were needed to inactivate approximately 0.5 log(10) and 2.0 log(10) units (99% inactivation) of C . parvum as measured by in vitro excystation and cell infectivity, respectively, suggesting that excystation is not an adequate viability assay . Purified oocysts originating from three different suppliers were evaluated and showed marked differences with respect to their resistance to inactivation when using chlorine dioxide . Ct values of 75, 550, and 1,000 mg . min/liter were required to achieve approximately 2.0 log(10) units of inactivation with oocysts from different sources . Finally, the study compared the relationship between easily measured indicators, including Bacillus subtilis (aerobic) spores and Clostridium sporogenes (anaerobic) spores, and C . parvum oocysts . The bacterial spores were found to be more sensitive to chlorine dioxide than C . parvum oocysts and therefore could not be used as direct indicators of C . parvum inactivation for this disinfectant . In conclusion, it is suggested that future studies address issues such as oocyst purification protocols and the genetic diversity of C . parvum, since these factors might affect oocyst disinfection sensitivity.

J Environ Sci Health A Tox Hazard Subst Environ Eng, 2001, 36(4), 483 - 99
Disinfection by-products and volatile organic compounds in the water supply system in Athens, Greece; Golfinopoulos SK et al.; On a monthly basis, on a one year period, disinfection by-products (DBPs) and volatile organic compounds (VOCs) were measured in raw water and in treated water of four water treatment plants (WTP) as well as from eight representative points of the distribution network of Athens . Liquid-liquid extraction (LLE) method followed by gas chromatography (GC) with electron capture detection (ECD) and mass spectrometry (MS) was used for the determination of the DBPs, while the purge-and-trap (PAT) technique followed by GC-MS was used for the determination of the VOCs . The DBPs that have been studied included trihalomethanes (THMs), haloacetonitriles (HANs), haloketones (HKs), chlorate hydrate (CH) and chloropicrin (CP), while forty-one VOCs were also studied including THMs . Chloroform (CM), dichlorobromomethane (DCBM), chlorodibromomethane (CDBM) were the major organic compounds found in all treated water samples . HANs, HKs, CH and CP were detected in treated samples but at lower concentrations.

J Environ Sci Health A Tox Hazard Subst Environ Eng, 2001, 36(4), 475 - 81
Formation and evolution of haloacetic acids in drinking water of Beijing City; Li S et al.; The formation and evolution of haloacetic acids (HAAs) in drinking water were examined in five water treatment plants in Beijing City, China . It was found that HAAs in water increased due to prechlorination and postchlorination . The conventional treatment processes removed the HAAs in less than 20% . By comparison, activated carbon bed removed 49-86% of HAAs and was considered to be an effective treatment unit for HAAs removal . The HAAs concentration in distribution system was associated with water sources, especially the total organic carbon in raw water, while its fluctuation appeared small.

Water Res, 2001 Jul, 35(10), 2460 - 74
Simplified analysis of contaminant rejection during ground- and surface water nanofiltration under the information collection rule; Chellam S et al.; A simple, closed-form analytical expression based on the homogenous solution diffusion model is derived for contaminant removal during nanofiltration (NF) of ground and surface water . Solute permeation and back-diffusion coefficients were used as fitting parameters to model rejection characteristics of four thin-film composite NF membranes under conditions typical of drinking water NF . Nonlinear fits of the model to experimental data suggests that the United States Environmental Protection Agency's (USEPA)'s Information Collection Rule protocol for bench-scale studies could be improved to obtain greater precision of the mass transfer coefficients . The model was found to fit rejection data for several water treatment contaminants including total organic carbon, precursors to total organic halide, four trihalomethanes and nine haloacetic acids containing chlorine and bromine, calcium and total hardness, alkalinity and conductivity . The simplified approach to mass transfer calculations from multisolute systems suggests that feed water recovery has a stronger influence on contaminant rejection than permeate flux . Evidence for coupled transport of divalent inorganic ions is also presented . Even though the model developed does not account for ion coupling and cannot be applied in a purely predictive mode, it can assist in the better design and interpretation of data obtained from site-specific pilot-scale water treatment NF studies conducted in support of plant design.

Water Sci Technol, 2001, 43(8), 9 - 18
Dissolved air flotation in drinking water production; Schofield T; Dissolved Air Flotation (DAF) has become increasingly important in the field of potable water treatment, as a preferred option for treating upland and stored lowland waters . This paper outlines the development of dissolved air flotation (DAF) in potable water treatment, the benefits and disadvantages and the recent advances that has taken the process technology from an art to a science.

Water Sci Technol, 2001, 43(8), 59 - 66
Treatment of spent filter backwash water using dissolved air flotation; Eades A et al.; There is increasing interest in treating recovered spent filter backwash water in the drinking water industry . In the USA the Filter Backwash Recycling Rule will come into effect in the near future . The purpose of the Rule is to prevent the concentrated pathogenic agents, potentially in the filter backwash water, from being returned to the head of the water treatment works without some form of treatment or dilution . By treating this flow both public health and financial liability can be better managed by the operating utility . Dissolved Air Flotation (DAF) was investigated as a possible technology alternative to simple or advanced sedimentation techniques . This application is not widespread but sits somewhere in between the two normal applications of DAF as a high solids sludge thickener and a low turbidity clarification system . Given this a pilot plant program, supported by jar testing, was undertaken to determine the process capability and the design parameters for this application . DAF proved to be very suitable for backwash water recovery . DAF effluent turbidities of < 1.0 NTU could be easily obtained, when raw water turbidities were in excess of 50 NTU . Chemical requirements were low with only a single low dose of polymer required to bind the floc particles to form a solids matrix suitable for flotation . Flocculation contact times ranged from 0-10 minutes depending on the nature of the raw water . Recycle rates as low as 5% performed satisfactorily with no significant improvement when increased to 20% . Sludge solids of 3.5-9.6% dry solids were found and very low volumes of sludge, < 0.1% of the incoming flow make the DAF solids handling system very compact.

Water Sci Technol, 2001, 43(8), 51 - 7
Removal and fate of Cryptosporidium in dissolved air drinking water treatment plants; Edzwald JK et al.; In the first part of the paper, data from pilot plant studies are used to evaluate Cryptosporidium removal by dissolved air flotation (DAF) clarification and dual media filters under challenge conditions . Oocyst removals were investigated for design detention times and hydraulic loadings for winter and spring seasons . Coagulation was optimized for turbidity and removal of natural organic matter . DAF performance was better for spring water temperatures achieving 2.5 +/- 0.3 log removal of oocysts compared to 1.7 +/- 0.3 log removal in the winter . Cumulative log removal across DAF and filtration exceeded 5.4, and was not affected by water temperature . Low turbidities and particle counts are indicators of good treatment and good removals of Cryptosporidium . The second part of the paper uses a mathematical model to predict the fate of Cryptosporidium through a DAF plant and the impact of filter backwash recycle on oocyst build-up in the plant influent . Model predictions show that the fate of Cryptosporidium and the build-up of oocysts in the plant influent depend on: DAF performance, the percent of filtered water production used for backwashing, and the percent of filter backwash recycle flow . A DAF plant with 2.5% filtered water production for backwashing and that achieves 1.6 log removal or greater of oocysts by DAF clarification will not have a build-up of oocysts in the plant influent regardless of the recycle rate . This is because the oocysts are concentrated in the DAF floated sludge and not within granular filters.

Water Sci Technol, 2001, 43(8), 43 - 9
High-rate dissolved air flotation for water treatment; Reall MA et al.; This paper presents the results of an experimental investigation about the performance of a horizontal flow high-rate pilot scale Dissolved Air Flotation (HRDAF) unit containing inclined parallel plates for treating a coloured and low turbidity raw water . Experiments were performed with the DAF unit in order to verify the influence on flotation of: (i) the water velocity (Vh) between the plates, in the range 18 to 96.5 cm.min-1 with corresponding Reynolds numbers between 240 and 1060; (ii) the supplied air (S*) value ranging from 2.2 to 8.5 g of air/m3 of water; (iii) the angle of the plates (60 degrees or 70 degrees) . The best pilot plant operational condition was obtained applying only 4.0 g/m3 (S*) with Vh around 18 cm.min-1 for treatment of water coagulated with a Al2(SO4)3 dosage of 40 mg.l-1 . In these conditions, the unit presented very good removal efficiencies of colour (90%, residual of 10 uC), turbidity (88%, residual of 0.8 NTU) and TSS (94%, residual of 1.8 mg.l-1) . Furthermore, the unit could operate at higher Vh values up to 76 cm.min-1 and still present good results . The DAF unit thus behaved as a high rate unit presenting good performance with low air requirement.

Water Sci Technol, 2001, 43(8), 35 - 41
Using lessons learned and advanced methods to design a 1,500 Ml/day DAF water treatment plant; Crossley IA et al.; The paper describes the method that led to the design of the 1,500 Ml/day dissolved air flotation (DAF) water treatment plant for Boston's water supply . In particular, the topics of flocculation techniques, floated solids removal and DAF recycle as they relate to very large capacity plant design are covered in detail . The use of mathematical models, including computational fluid dynamics (CFD) software, to refine the design is described.

Water Sci Technol, 2001, 43(8), 203 - 8
Characteristics of alumino-humic flocs in relation to DAF performance; Bache DH et al.; This paper examines the implications of pretreatment in the context of the likely behaviour of flocs in DAF units . Evidence indicates that the maximum floc size (dmax) of alumino-humic is scaled by the Kolmogorov length (eta) with dmax/eta approximately 1 . A larger ratio exists when polymer is present . Data from the literature suggests that velocity gradient in the inlet chamber may exceed 1000 s-1, suggesting eta approximately 40 microns . This view of the response of floc to shear is supported by shear tests carried out on samples of floc withdrawn from flocculators at full scale water treatment works . Using an underwater CCTV camera, coupled with image analysis, it is shown that floc sizes in conventionally designed flocculators are much bigger than the sizes which are likely to exist in DAF units . Circumstantial evidence gained from water treatment works suggests that DAF units perform satisfactorily whatever the size of the incoming floc . From such evidence, the authors question the conventional design of the flocculators in association with DAF units.

Environ Sci Technol, 2001 May 15, 35(10), 2114 - 21
Solar oxidation and removal of arsenic at circumneutral pH in iron containing waters; Hug SJ et al.; An estimated 30-50 million people in Bangladesh consume groundwater with arsenic contents far above accepted limits . A better understanding of arsenic redox kinetics and simple water treatment procedures are urgently needed . We have studied thermal and photochemical As(III) oxidation in the laboratory, on a time scale of hours, in water containing 500 micrograms/L As(III), 0.06-5 mg/L Fe(II,III), and 4-6 mM bicarbonate at pH 6.5-8.0 . As(V) was measured colorimetrically, and As(III) and As(tot) were measured by As(III)/As(tot)-specific hydride-generation AAS . Dissolved oxygen and micromolar hydrogen peroxide did not oxidize As(III) on a time scale of hours . As(III) was partly oxidized in the dark by addition of Fe(II) to aerated water, presumably by reactive intermediates formed in the reduction of oxygen by Fe(II) . In solutions containing 0.06-5 mg/L Fe(II,III), over 90% of As(III) could be oxidized photochemically within 2-3 h by illumination with 90 W/m2 UV-A light . Citrate, by forming Fe(III) citrate complexes that are photolyzed with high quantum yields, strongly accelerated As(III) oxidation . The photoproduct of citrate (3-oxoglutaric acid) induced rapid flocculation and precipitation of Fe(III) . In laboratory tests, 80-90% of total arsenic was removed after addition of 50 microM citrate or 100-200 microL (4-8 drops) of lemon juice/L, illumination for 2-3 h, and precipitation . The same procedure was able to remove 45-78% of total arsenic in first field trials in Bangladesh.

Environ Sci Technol, 2001 May 15, 35(10), 2026 - 32
Electrochemical and spectroscopic study of arsenate removal from water using zero-valent iron media; Farrell J et al.; This study investigated the mechanisms involved in removing arsenate from drinking water supplies using zero-valent iron media . Batch experiments utilizing iron wires suspended in anaerobic arsenate solutions were performed to determine arsenate removal rates as a function of the arsenate solution concentration . Corrosion rates of the iron wires were determined as a function of elapsed time using Tafel analysis . The removal kinetics in the batch reactors were best described by a dual-rate model in which arsenate removal was pseudo-first-order at low concentrations and approached zero-order in the limit of high arsenate concentrations . The presence of arsenate decreased iron corrosion rates as compared to those in blank 3 mM CaSO4 background electrolyte solutions . However, constant corrosion rates were attained after approximately 10 days elapsed, indicating that the passivation processes had reached steady state . The cathodic Tafel slopes were the same in the arsenate and the blank electrolyte solutions . This indicates that water was the primary oxidant for iron corrosion and that arsenate did not directly oxidize the iron wires . The anodic Tafel slopes were greater in the arsenate solutions, indicating that arsenate formed complexes with iron corrosion products released at anodic sites on the iron surfaces . Ion chromatography analyses indicated that there was no measurable reduction of As(V) to As(III) . X-ray absorption spectroscopy analyses indicated that all arsenic associated with the zero-valent iron surfaces was in the oxidation state . Interatomic arsenic-iron distances determined from EXAFS analyses were consistent with bidentate corner-sharing among arsenate tetrahedra and iron octahedra . Results from this study show that under conditions applicable to drinking water treatment, arsenate removal by zero-valent iron media involves surface complexation only and does not involve reduction to metallic arsenic.

Huan Jing Ke Xue, 2001 Jan, 22(1), 49 - 52
{The toxicity variation of organic extracts in drinking water treatment processes}; Mei M et al.; Source water samples and outlet water samples from different treatment processes of the Beijing Ninth Water Works were concentrated in situ with XAD-2 filled columns . GC-MS analysis and toxic assessment including acute toxicity evaluation by luminescent bacterium bioassay(Q67 strains) and mutagenicity assessment by Ames test(TA98 and TA100 strains with and without S9 addition) were conducted on these samples . The results showed that prechlorination caused the direct and indirect frame shift mutagenicity as well as indirect base pair substitute mutagenicity . Addition of coagulant may increase the base pair substitute mutagenic effects greatly . Sand and coal filtration and granular activated carbon filtration could effectively remove most of the formed mutagens . The rechlorination do not obviously increase the mutagenic effects . No mutagenic effect was observed in tap water . Acute toxicity showed the same variation with that of mutagenicity during the treatment processes . Sample from flocculation treatment process was found to be the most toxic sample . Results of GC-MS analysis showed that water in this plant was not contaminated by PCB . Concentrations of toluene, naphthalene and phenol increased in flocculation treatment process and in tap water . However, the concentrations of these substances were at the level of microgram/L, therefore, were not high enough to cause mutagenicity.

Huan Jing Ke Xue, 2001 Jan, 22(1), 114 - 6
{The sedimentation rate and fractional dimension during flocculation with modified natural polymer and polymeric aluminum chloride}; Ma W et al.; The sedimentation rate and fractional dimension of the floc was studied during the process of the organic waste water treatment with modified natural polymer (CMS) and polymeric aluminum chloride (PAC) . Irregular garrulous form of the floc was observed with microscope and electron-scanning microscope . The results showed that the sedimentation rate was 2.6 mm/min with the modified natural polymer (CMS) and 1.7 mm/min without CMS in condition of keeping the pH value to 6.86 and added quantity of PAC to 80 mg/L . The fractional dimension of the floc Df was calculated to be 1.70 in the best sedimentation rate.

Water Sci Technol, 2001, 43(6), 9 - 16
Relevance of microbial extracellular polymeric substances (EPSs)--Part II: Technical aspects; Flemming HC et al.; Extracellular polymeric substances (EPSs) are involved in both detrimental and beneficial consequences of microbial aggregates such as biofilms, flocs and biological sludges . In biofouling, they are responsible for the increase of friction resistance, change of surface properties such as hydrophobicity, roughness, colour, etc . In biocorrosion of metals they are involved by their ability to bind metal ions . In bioweathering, they contribute by their complexing properties to the dissolution of minerals . The EPSs represent a sorption site for pollutants such as heavy metal ions and organic molecules . This can lead to a burden in wastewater sludge; on the other hand, the sorption properties can be used for water purification . Other biotechnological uses of EPS exploit their contribution to viscosity, e.g., in food, paints and oil-drilling 'muds'; their hydrating properties are also used in cosmetics and pharmaceuticals . Furthermore, EPSs may have potential uses as biosurfactants, e.g., in tertiary oil production, and as biological glue . EPSs are an interesting component of all biofilm systems and still hold a large biotechnological potential.

Water Sci Technol, 2001, 43(2), 117 - 23
Detection of estrogenic activity in Flemish surface waters using an in vitro recombinant assay with yeast cells; Witters HE et al.; Numerous environmental chemicals possess estrogen-like properties . At elevated doses, natural estrogens and environmental estrogen-like chemicals are known to produce adverse effects on humans and wildlife . Sources of potential exposure to endocrine disrupting compounds have to be identified for risk and hazard assessment . Extracts prepared from 16 selected water samples taken in Flemish rivers, effluents of municipal wastewater treatment plants and reservoirs for drinking water production were analysed for estrogenic activity with a cellular bioassay . Yeast cells, which are stably transfected with the DNA sequence of hER and which contain expression plasmids with the reporter gene lac-Z, encoding the enzyme beta-galactosidase, were used to measure receptor binding . Flemish rivers showed the highest estrogenic potency, compared to effluents of waste water treatment plants and reservoirs which showed low induction factors (beta-galactosidase production) relative to solvent control conditions . By comparison with a standard curve for 17 beta-estradiol (E2), estrogenic potency in water samples was calculated as E2-equivalents and ranged from below detection limit (approximately 2.75 ng E2/l) up to 81.4 ng/l E2-equivalents . About 7 water samples had more than 10 ng/l E2-equivalents . These elevated levels of E2-equivalents are likely to exert significant adverse effects on reproduction success of wildlife, which should be verified with in vivo studies.

Water Sci Technol, 2001, 43(5), 301 - 8
Evaluation of appropriate system for reclaimed wastewater reuse in each area of Tokyo using GIS-based water balance model; Aramaki T et al.; The appropriate type of reclaimed wastewater reuse system in each area of Tokyo was evaluated from the aspect of economic efficiency, using a GIS-based water balances model . The following four reclaimed wastewater reuse systems and conventional waterworks and sewerage system were evaluated; "Rain water storage and use system", "Onsite wastewater treatment and reuse system", "Sewage treatment and reuse at an intermediate point on the sewer pipe" and "Treated water supply system in sewage treatment plant" . In the case that we install them to office and residential buildings, the supplied volume by reclaimed wastewater reuse systems is 693 thousands m3/d, this corresponds to 15% of total water demand in the area . Furthermore, the effects of the following scenarios brought about by technological innovation in water treatment were investigated; the case that flush water in toilet and wastewater from kitchen are also available as source in a "onsite wastewater treatment and reuse system" and the case that reclaimed water is used for laundering in residential buildings . When reclaimed water is used for laundering in residential buildings, the supplied volume by these systems increases to 814 thousand m3/d in the case that these systems are installed to office and residential buildings.

Water Sci Technol, 2001, 43(5), 169 - 74
Control of non-point source pollution by a natural wetland; Kao CM et al.; Wetland creation and restoration is a reliable and efficient technology for the remediation of contaminated water . Knowledge from the natural wetland systems would be necessary to enhance the operational efficiency of constructed wetlands . In this study, a mountainous wetland located in McDowell County, North Carolina, USA was selected to demonstrate the effects of the natural filtration and restoration system on the maintenance of surface water quality . The hydraulic retention time (HRT) for the wetland was 10.5 days based on the results from a dye release study . Water quality monitoring of the wetland was conducted from May to August 1997 . One major storm event and baseline water quality samples were collected and analyzed . Analytical results indicate that this wetland removed a significant amount of non-point source (NPS) pollutants {more than 80% N removal, 91% of total suspended solid removal, 59% of total phosphorus removal, and 66% of chemical oxygen demand (COD) removal} caused by the studied storm event . Sediment accretion monitoring results indicate that the accretion rate in the wetland was only 4 mm/year . Therefore, the wetland would require 100 years to fill at the measured sediment accretion rate . The high organic content of sediments (16%) indicates that the wetland is building the characteristic organic layer on the bottom of the wetland . Results from this study would be very useful in the maintenance of natural wetlands and design of constructed wetlands for water treatment.

Water Sci Technol, 2001, 43(1), 277 - 83
Algae-removal performance of a fluidized-bed biofilm reactor system for lake water treatment; Tanaka T et al.; The algae removal efficiency of a pilot plant--based on a fluidized-bed biofilm reactor system for treating--was investigated . This system does not require back-washing because the fluidized-bed suffers no clogging . Moreover, the system uses dissolved oxygen in the influent water for aerobic biological treatment without the need for additional aeration equipment . This, it is an easy-maintenance, low-energy system for purifying eutrophic lake water . The system was operated continuously at a flow rate of 1500 m3/d for nine months at Tsuchiura Port in Lake Kasumigaura . And concentrations of chlorophyll-a and dissolved oxygen in both the influent and effluent water were continuously monitored . In summer (August to September) when water bloom occurred, the average efficiency of chlorophyll-a removal was 64% at an average influent chlorophyll-a concentration of 137.8 micrograms/L . Over the entire experimental period of nine months, the average daily amount of removed chlorophyll-a was 40.3 g/d at an average influent chlorophyll-a concentration of 89.5 micrograms/L . By analyzing the relationship between the amount of removed chlorophyll-a and the consumption of dissolved oxygen, it was estimated that almost all of the algae trapped in the reactor was biologically degraded.

Water Res, 2001 Jun, 35(9), 2268 - 76
Numerical and experimental hydrodynamic studies of a lagoon pilot; Baleo JN et al.; The determination of residence time is of major interest in terms of the characterisation, design and modelling of most environmental engineering processes, where a proper and homogeneous fluid distribution is often essential, and especially in the domain of wastewater or waste material treatment . In this paper, two different numerical methods for obtaining theoretical predictions of residence time distributions using the finite volume method are used . The first one consists of solving a transport equation of the local mean age of the fluid, which is the average time that a fluid particle takes to reach any point of the domain from a supply inlet . The result obtained is a spatial distribution of the local mean age of the fluid, which may be displayed as isocontours in the space domain considered . The second one consists of injecting a virtual particle stream (i.e . a fluid particle having the same density as the surrounding fluid, and treated numerically as a tracer) and measuring the time elapsed between the injection and the termination of the trajectory using a Lagrangian reference frame . The result obtained is expressed as an exit time distribution and may be displayed as a histogram . Finally, a comparison with measurements of mean residence times of tracers in a lagoon is made in order to establish the relevance of this method in concrete form . The prediction enables the instantaneous determination of the geometrical characteristics of the flow that contribute actually to the residence time dispersion . Its appropriate use prior to the design of water treatment and waste material treatment installations should contribute to prevent undesirable flow patterns such as short-circuiting and dead spaces.

J Chromatogr A, 2001 Apr 20, 914(1-2), 123 - 9
Improved measurement of formaldehyde in water-soluble polymers by high-performance liquid chromatography coupled with post-column reaction detection; Michels JJ; An improved methodology for the analysis of free formaldehyde in water-soluble polymers used for industrial water treatment is reported . Previously, derivatization prior to HPLC or colorimetric techniques has been used . The data generated by these approaches are suspect in that the derivatizing agent can react with the polymer or other sample components to produce high results . Post-column reaction derivatization is applied after separation of the free formaldehyde from the product interferences . The type of polymer product analyzed influences the choice of column(s) . The degree of high bias of the commonly used 2,4-dinitrophenylhydrazine pre-column derivatization is reported and the results are compared to those with the post-column reaction for two polymer products . This method, being more selective, should be applicable to any polymer containing formaldehyde.

Environ Sci Technol, 2001 May 1, 35(9), 1875 - 9
Hydrophobic hollow fiber membranes for treating MTBE-contaminated water; Keller AA et al.; Soluble contaminants with low Henry's constant, such as methyl tert-butyl ether (MTBE), require innovative solutions for water treatment . Given the increased frequency at which MTBE is detected at contaminated sites, the development of new technologies is of considerable relevance . Hydrophobic hollow fiber membranes (HFM), used in industrial and medical applications, have interesting physicochemical properties that make them particularly suitable to deal with these contaminants . The hydrophobicity of the fiber maintains adequate separation between aqueous and gaseous phases, permitting an efficient separation of volatile and semivolatile compounds from water to gas . The hollow nature of the fiber and its high porosity permit high rates of mass transfer across the membrane . The mass transfer process can be accelerated using pervaporation and by increasing the solution's temperature to increase the Henry's constant and the overall mass transfer coefficient . In these studies, we evaluate the removal efficiency of MTBE from water using a commercial HFM module and develop the corresponding dimensionless mass transfer correlations necessary for the design of industrial-scale systems . We found that the Leveque correlation for the tube-side mass transfer coefficient is in general applicable for MTBE pervaporation through a hydrophobic HFM . MTBE removal is a strong function of membrane length, water flowrate, and solution temperature but is almost independent of gas-phase parameters.

Environ Technol, 2001 Feb, 22(2), 229 - 36
Characteristics of activated carbon produced from biosludge and its use in wastewater post-treatment; Pikkov L et al.; Experimental research into the bench-scale production of activated carbon from waste-activated sludge from water purification, sawdust, peat, and their mixtures, by carbonisation and activation was undertaken . The research work was carried out to determine possible methods of production of cheap activated carbon from local raw materials and to use it in water purification technology . Along with the samples produced, several commercial activated carbons (namely RB-1, F 100, CA (adsorbent from military gas masks), BAY (product of the USSR)) were tested to compare adsorption properties in the adsorption of phenols, xylidines, amines, methylene blue and molasses . It has been found that the activated carbon produced from waste biosludge was of higher quality than that produced from either sawdust or peat, and performed similarly to RB-1 and F100 in adsorption tests . It was also determined that the activated carbon produced from biosludge could possibly be used in the post-treatment of wastewater . Residual sludge from the biological treatment of the wastewater from the purification of oil-shale in the chemical processing industry could cover up to 80% of the need for activated carbon . Some of this activated carbon could be used in the post-treatment of the same water, adsorbing polyalcaline phenols from the initial content of 4 mg l-1 to the demanded level of 1 mg l-1.

Ground Water, 2001 May-Jun, 39(3), 371 - 9
Modeling preferential flow in reactive barriers: implications for performance and design; Benner SG et al.; Reactive barriers are passive and in situ ground water treatment systems . Heterogeneities in hydraulic conductivity (K) within the aquifer-reactive barrier system will result in higher flux rates, and reduced residence times, through portions of the barrier . These spatial variations in residence time will affect the treatment capacity of the barrier . A numerical flow model was used to evaluate the effects of spatial variations in K on preferential flow through barriers . The simulations indicate that the impact of heterogeneities in K will be a function of their location and distribution; the more localized the high K zone, the greater the preferential flow . The geometry of the reactive barrier will also strongly influence flow distribution . Aquifer heterogeneities will produce greater preferential flow in thinner barriers compared to thicker barriers . If the barrier K is heterogeneous, greater preferential flow will occur in thicker barriers . The K of the barrier will affect the flow distribution; decreasing the K of the barrier can result in more even distribution of flow . Results indicate that less variable flow will be attained utilizing thicker, homogeneous barriers . The addition of homogeneous zones to thinner barriers will be effective at redistributing flow only if installed immediately adjacent to both the up- and downgradient faces of the barrier.

Water Res, 2001 Jun, 35(8), 2095 - 9
By-products formation during drinking water disinfection: a tool to assess disinfection efficiency?
von Gunten U, Driedger A, Gallard H, Salhi E.
In drinking water treatment, the inactivation of microorganisms increases with increasing disinfectant exposure (product of concentration and contact time, CT) . Also, the formation of undesired (toxic) disinfection by-products increases with CT . The present study proposes a new concept that uses this undesired side effect of chemical water disinfection for a fast and reliable test of treatment efficiency . In laboratory systems, bromate formation during ozonation and the formation of trihalomethanes during chlorination were used to calculate the disinfectant exposure, which is a measure for the achieved degree of disinfection.

J Chromatogr A, 2001 Apr 6, 912(2), 191 - 209
Purification of microcystins; Lawton LA et al.; Microcystins are an increasingly important group of bioactive compounds produced by a number of mainly planktonic cyanobacteria . They are a family of cyclic heptapeptides that cause both acute and chronic toxicity . Purified microcystins are utilised in a range of research applications including toxicological and biochemical studies, development of detection systems and the investigation of water treatment strategies . The commercial availability of purified microcystins is still relatively limited and for many projects the cost of their purchase prohibitive . The purification of microcystins from both bloom material and laboratory cultures is reviewed including a discussion on extraction, separation, and the determination of purity and yield.

Environ Sci Technol, 2001 Apr 15, 35(8), 1680 - 7
A distributed reactivity model for sorption by soils and sediments 13 . Simulated diagenesis of natural sediment organic matter and its impact on sorption/desorption equilibria; Johnson MD et al.; Subcritical water treatment was used to effect rapid compositional and functional changes to peat organic matter that mimic those of the natural diagenesis process . Elemental, solid state 13C NMR, FTIR, and calorimetry analyses all indicated that the organic matter of the artificially aged peat was chemically similar to that of geologically mature coal kerogens . This paper extends the work of the previous paper in this series, which investigated the effects of subcritical water treatment of humic topsoil on subsequent phenanthrene sorption and desorption equilibria . As opposed to the previous study, however, changes in sorptive reactivity herein were unequivocally related to changes in organic matter rather than other soil constituents, and organic matter functional changes due to the simulated diagenesis were more accurately characterized . Phenanthrene sorption capacity and isotherm nonlinearity both increased with increasing degrees of artificial aging, supporting the viewpoint that hydrophobic organic contaminant sorption equilibrium properties can be directly related to the degree of diagenesis of geosorbent organic matter . In addition, this work investigated effects of subcritical water treatment of a geologically mature, kerogen-containing shale sample . In contrast to the peat, the functional characteristics of the shale were unchanged by this treatment, and subsequent phenanthrene sorption equilibria were altered far less.

Water Res, 2001 May, 35(7), 1851 - 4
Color removal in groundwater through the enhanced softening process; Coro E et al.; The source of water for Miami-Dade County, Florida is groundwater derived from the Biscayne aquifer . The raw water is rich in natural organic material producing correspondingly high color levels . Currently, breakpoint chlorination is used at the water treatment plant to control the color problem . However, this results in the formation of disinfection by-products . Proposed alternatives to reduce color and avoid by-product formation include the addition of coagulants such as ferric chloride and organic polymers, and the operation of the existing lime softening process at a higher pH . This study uses jar tests to evaluate the relative effectiveness of the proposed alternatives . Results indicate that significant color reduction is achieved using the existing lime softening process with activated silica coagulant by increasing the softening pH to 11 or more . Elevated pH also produced a > 30% reduction in total organic carbon . In the presence of higher raw water color (> or = 80 units), the addition of ferric chloride as coagulant at dosages of 80 mg/L is recommended.

Water Res, 2001 May, 35(7), 1705 - 13
By-products formation during degradation of isoproturon in aqueous solution . II: Chlorination; Mascolo G et al.; After a previous study in which the considered oxidant was ozone (Part I), a laboratory investigation has been carried out to study the degradation of the herbicide isoproturon during its reaction with another oxidant, i.e . chlorine, in aqueous solution (Part II; this paper) . The specific aim was to identify the by-products formed . The effects of pH and the presence of bromide ions were studied . Reactions have been carried out at room temperature, in phosphate buffered aqueous solutions, at four pHs (6, 7, 8 and 9) . By-products identification was first performed using relatively high initial reagent concentrations which were analytically convenient ({isoproturon} = 40 mg/l, {HClO + ClO-} = 160 mg Cl/l, {Br-} = 80 mg/l) . In follow-up studies, the by-products identified during this preliminary step were searched for when using concentration values closer to those actually encountered at real water treatment plants ({isoproturon} = 0.4 and 0.004 mg/l, {HClO + ClO-} = 1.6 mg Cl/l, {Br-} = 0.8 and 0.008 mg/l) . Under all of the studied conditions, the results showed that isoproturon is completely degraded and that it decays much faster in the presence of bromide . The pH has a negligible influence when bromide ions are absent . On the contrary, if bromide ions are present, the isoproturon decay is slower at higher pH values . High-performance liquid chromatography-mass spectrometry (HPLC-MS) analyses have led to the identification of several by-products as a result of simultaneous oxidation and substitution reactions, both occurring on the aromatic ring of the herbicide . However, the more abundant by-products are those resulting from the oxidation of the isoproturon aromatic ring . As far as halogenated by-products are concerned, the higher the bromide ion concentration the higher the ratio of brominated to chlorinated by-products . On the basis of the analytical results, a pathway for isoproturon degradation under the studied conditions is proposed.

Water Res, 2001 May, 35(7), 1659 - 64
Arsenic removal during conventional aluminium-based drinking-water treatment; Gregor J; The changing forms and concentrations of arsenic through aluminium-based coagulation treatment processes were tracked for three drinking-water treatment plants . This has provided direct evidence of where and how arsenic is removed . In general, soluble As(V) is converted to particulate As(V) by adsorption during rapid mixing, and is removed along with naturally occurring particulate arsenic predominantly by clarification . Soluble As(III) tracks through the treatment processes and is converted to soluble As(V) during final chlorination . The ability of a water treatment process to achieve the maximum acceptable concentration for arsenic in drinking water is dependent on the concentration of As(III) in the source water.

Water Res, 2001 May, 35(7), 1641 - 8
Development of a nested-PCR assay for the detection of Cryptosporidium parvum in finished water; Monis PT et al.; A nested-PCR assay, incorporating an internal positive control, was developed for Cryptosporidium monitoring in finished water . This assay was capable of reproducibly detecting 8 oocysts in spiked-filtered water samples collected from 5 South Australian water treatment plants . The RT-PCR assay of Kaucner and Stinear (Appl . Environ . Microbiol . 64(5) (1998) 1743) was also evaluated for the detection of Cryptosporidium parvum . Initially, under our experimental conditions, a detection level of 27 oocysts was achieved for spiked reagent water samples . This level was improved to 5 oocysts by modification of the method . Untreated South Australian source waters concentrated by calcium carbonate flocculation were found to be highly inhibitory to the RT-PCR assay . Concentration of similar samples using Envirochek filters appeared to eliminate PCR inhibition . While both methods possessed similar sensitivities the nested-PCR assay was more reproducible, more cost effective, simpler to perform and could detect both viable and non-viable intact Cryptosporidium parvum oocysts, which is an important consideration for plant operators . These factors make the nested-PCR assay the method of choice for screening large numbers of potable water samples, where a reliable low level of detection is essential.

Water Res, 2001 May, 35(7), 1635 - 40
Microbially available organic carbon, phosphorus, and microbial growth in ozonated drinking water; Lehtola MJ et al.; Ozonation is a disinfection technique commonly used in the treatment of drinking water . It destroys harmful microbes, but it also degrades organic matter in water, increasing the bioavailability of organic matter . Recently, it was found that not only organic carbon but also phosphorus can limit the microbial growth in drinking water, which contains high amount of organic matter . We used a bioassay to analyze whether ozone could also increase the microbially available phosphorus (MAP) in drinking water, and whether MAP in ozone-treated water was associated with the growth of heterotrophic microbes . We found that both assimilable organic carbon and MAP concentrations were increased by ozone treatment . In ozonated water, microbial growth was mainly limited by phosphorus, and even minor changes in MAP concentration dramatically increased the growth potential of heterotrophic microbes . In this study, ozonation increased the MAP by 0.08-0.73 microgram P/l, resulting in an increase of 80,000-730,000 CFU/ml in water samples . In contrast to MAP, the content of assimilable organic carbon (AOCpotential) did not correlate with microbial growth . The results show that in water treatment not only AOCpotential but also MAP should be considered as an important factor that can limit microbial growth in drinking water.

Water Res, 2001 May, 35(7), 1627 - 34
Method for measuring mutagen formation potential (MFP) on chlorination as a new water quality index; Takanashi H et al.; A novel water quality index, the mutagen formation potential (MFP) is proposed for use in evaluation of the quality of drinking water which may contain pollutants capable of forming mutagens when chlorinated under the conditions used in water purification processes . A method for measuring MFP was established as follows . The water sample to be tested is diluted until the TOC reaches 3-4 mg l-1, the pH is adjusted to 7.0 +/- 0.2, sodium hypochlorite is added to obtain conditions where Cl/TOC = 3-4 mg Cl (mg C)-1, and the water sample is left standing for 24 +/- 2 h at room temperature . Thereafter, 21 of the chlorinated water sample at pH 2.0 +/- 0.1 is passed through a Sep-Pak Plus CSP-800 cartridge to adsorb any mutagens formed, and DMSO is applied to the cartridge to desorb the mutagens . Then, a 2 ml sample of the eluate is collected after the DMSO had begun to flow out of the cartridge and evaluated by the Ames Salmonella mutagenicity assay (preincubation method).

Water Res, 2001 Apr, 35(6), 1509 - 17
Cost factors and chemical pretreatment effects in the membrane filtration of waters containing natural organic matter; Schafer AI et al.; This paper compares the membrane processes available for water treatment . Membranes have the advantage of currently decreasing capital cost, a relatively small footprint compared to conventional treatment, generally a reduction in chemicals usage and comparably low maintenance requirements . Three membrane processes applicable to water treatment, micro- (MF), ultra- (UF), and nanofiltration (NF), are compared in terms of intrinsic rejection, variation of rejection due to membrane fouling and increase in rejection by ferric chloride pretreatment . Twelve different membranes are compared on the basis of their membrane pore size which was calculated from their molecular weight cut-off . A pore size of < 6 nm is required to achieve substantial (> 50%) organics removal . For a fouled membrane this pore size is about 11 nm . UV rejection is higher than DOC rejection . Coagulation pretreatment allows a higher rejection of organics by MF and UF and the cut-off criterion due to initial membrane pore size is no longer valid . A water quality parameter (WQP) is introduced which describes the product water quality achieved as a function of colloid, DOC and cation rejection . The relationship between log (pore size) and WQP is linear . Estimation of membrane costs as a function of WQP suggests that open UF is superior to MF (similar cost at higher WQP) and NF is superior to tight UF . Chemical pretreatment could compensate for the difference between MF and UF . However, when considering chemicals and energy costs, it appears that a process operated at a higher energy is cheaper at a guaranteed product quality (less dependent on organic type) . This argument is further supported by environmental issues of chemicals usage, as energy may be provided from renewable sources.

Water Res, 2001 Apr, 35(6), 1387 - 98
Inactivation of Cryptosporidium parvum oocysts using medium- and low-pressure ultraviolet radiation; Craik SA et al.; The effect of ultraviolet radiation from low- and medium-pressure mercury arc lamps on Cryptosporidium parvum oocysts was studied using a collimated beam apparatus . Experiments were conducted using parasites suspended in both filtered surface water and phosphate buffered laboratory water . Inactivation of oocysts was measured as reduction in infectivity using a CD-1 neonatal mouse model and was found to be a non-linear function of UV dose over the range of germicidal doses tested (0.8-119 mJ/cm2) . Oocyst inactivation increased rapidly with UV dose at doses less than 25 mJ/cm2 with two and three log-units inactivation at approximately 10 and 25 mJ/cm2, respectively . The cause of significant leveling-off and tailing in the UV inactivation curve at higher doses was not determined . Maximum measured oocyst inactivation ranged from 3.4 to greater than 4.9 log-units and was dependent on different batches of parasites . Water type and temperature, the concentration of oocysts in the suspension, and the UV irradiance did not have significant impacts on oocyst inactivation . When compared on the basis of germicidal UV dose, the oocysts were equally sensitive to low- and medium-pressure UV radiation . With respect to Cryptosporidium, both low- and medium-pressure ultraviolet radiation are attractive alternatives to conventional chemical disinfection methods in drinking water treatment.

Q J Nucl Med, 2000 Dec, 44(4), 310 - 6
Naturally occurring radioactive materials (NORM): a matter of wide societal implication; Pescatore C et al.; Naturally occurring radioactive materials are ubiquitous on Earth and their radioactivity may become concentrated as a result of human activities . Numerous industries produce concentrated radioactivity in their by-products: the coal industry, petroleum extraction and processing, water treatment, etc . The present reference system of radiation protection does not provide a complete framework for the coherent management of all types of radioactively contaminated materials . Inconsistencies in waste management policy and practice can be noted across the board, and especially vis-a-vis the management of radioactive waste from the nuclear industry . This article reviews the present societal approach to manage materials that are radioactive but are often not recognised as being such, and place the management of radioactive materials from the nuclear industry in perspective.

J Infect Dis, 2001 May 1, 183(9), 1373 - 9 Epub 2001 Mar 29.
Cryptosporidium parvum-specific antibody responses among children residing in Milwaukee during the 1993 waterborne outbreak; McDonald AC et al.; A major gastroenteritis outbreak among >400,000 residents of Milwaukee, Wisconsin, in April 1993 was attributed to Cryptosporidium parvum oocysts in drinking water . Plasma specimens obtained from children (6 months to 12 years old) for routine blood lead level surveillance March-May 1993 were assayed by ELISA for levels of IgG antibody against the immunodominant Triton-17 and 27-kDa C . parvum antigens . Over a 5-week period, the seroprevalence for antibodies to the 2 antigens increased from 15% to 82% and from 17% to 87%, respectively, in samples from children living in southern ZIP code areas (n=218), whereas smaller increases (20% to 43% and 22% to 46%, respectively) were noted among samples from children living in northern ZIP code areas (n=335; P<.0001) . The results demonstrate that C . parvum infection was much more widespread than previously appreciated and confirm that infection was associated with residence in the area served by the southern water treatment plant.

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