Water Sci Technol, 2001, 44(11-12), 507 - 14 Heavy metal contents and mobility of artificially inundated grasslands along River Weser, Germany; Erber C et al.; At the beginning of the 20th century municipal wastewater was used to fertilize grassland in the freshwater marsh of the river Weser . In 1987, 150 ha of the marsh became part of a mitigation area with artificial inundation during winter and spring . Heavy metal input may be expected from former wastewater treatment and artificial flooding nowadays . In addition, inundation may increase the availability of heavy metals that were accumulated during municipal wastewater treatment . In order to get an idea of heavy metal content and availability, the content of Cd, Cr, Cu, Ni, Pb, and Zn of the soil, the vegetation, and the input due to inundation were determined . Metal enrichment in the epipedon is evident for Cr, Cu, Pb, and Zn . Total content of Pb and Zn exceed the precaution limit . Soils treated with wastewater seems to contain more heavy metals than the ones without . Inundation causes an input of metals, but it is very low and varies in a broad range . Metal input is higher by atmospheric deposition than the one due to inundation . Degree of enrichment can be arranged in the order: atmospheric deposition > municipal wastewater >> inundation . In shallow ditch soils heavy metals are becoming more available. Water Sci Technol, 2001, 44(11-12), 499 - 506 Treatment of laboratory wastewater in a tropical constructed wetland comparing surface and subsurface flow; Meutia AA; Wastewater treatment by constructed wetland is an appropriate technology for tropical developing countries like Indonesia because it is inexpensive, easily maintained, and has environmentally friendly and sustainable characteristics . The aim of the research is to examine the capability of constructed wetlands for treating laboratory wastewater at our Center, to investigate the suitable flow for treatment, namely vertical subsurface or horizontal surface flow, and to study the effect of the seasons . The constructed wetland is composed of three chambered unplanted sedimentation tanks followed by the first and second beds, containing gravel and sand, planted with Typha sp.; the third bed planted with floating plant Lemna sp.; and a clarifier with two chambers . The results showed that the subsurface flow in the dry season removed 95% organic carbon (COD) and total phosphorus (T-P) respectively, and 82% total nitrogen (T-N) . In the transition period from the dry season to the rainy season, COD removal efficiency decreased to 73%, T-N increased to 89%, and T-P was almost the same as that in the dry season . In the rainy season COD and T-N removal efficiencies increased again to 95% respectively, while T-P remained unchanged . In the dry season, COD and T-P concentrations in the surface flow showed that the removal efficiencies were a bit lower than those in the subsurface flow . Moreover, T-N removal efficiency was only half as much as that in the subsurface flow . However, in the transition period, COD removal efficiency decreased to 29%, while T-N increased to 74% and T-P was still constant, around 93% . In the rainy season, COD and T-N removal efficiencies increased again to almost 95% . On the other hand, T-P decreased to 76% . The results show that the constructed wetland is capable of treating the laboratory wastewater . The subsurface flow is more suitable for treatment than the surface flow, and the seasonal changes have effects on the removal efficiency. Water Sci Technol, 2001, 44(11-12), 463 - 8 Retention of selected heavy metals: Cd, Cu, Pb in a hybrid wetland system; Obarska-Pempkowiak H; The budget of heavy metals was investigated in a constructed wetland in a hybrid wetland system near Gdansk . It is a pilot wastewater treatment plant (WWTP) designed for 150 PE (person equivalent) . The system consists of two sections: a vegetated submerged bed (VSB) with horizontal flow of sewage and a cascade filter situated on a slope of a hill . Total area of the constructed wetland is about 870 m2 . Domestic sewage, after a conventional pretreatment (consisting of an Imhoff tank and a trickling filter) is pumped to the VSB filter located on the top of the hill and then flows through subsequent segments of the constructed wetland . In the period 1995-98 the measurements of several heavy metals (Cd, Cu, Pb) were carried out in sewage inflowing, outflowing and collected from the in between sections of the system . Moreover analysis of sediment collected in ditches of the cascade filter, VSB filter and reed were carried out . The content of heavy metals in suspended solids decreased along the course of treatment, starting from VSB filter, through the first ditch to the last ditch . Measurable concentrations of dissolved heavy metals were found in sewage collected from several subsequent ditches . Sorption was deemed the main mechanism of dissolved metals removal in subsequent ditches. Water Sci Technol, 2001, 44(11-12), 455 - 62 Nutrient and heavy metal uptake and storage in constructed wetland systems in Arizona; Karpiscak MM et al.; The Constructed Ecosystems Research Facility (CERF) was conceived in the early 1980s as a test facility to explore the potential for using plants to treat wastewater in the arid west of the USA . One of the major issues that has been identified in the use of constructed wetland technology is plant nutrient uptake and tissue storage of nutrients as well as heavy metals . Our approach to understanding plant uptake and storage has been to look at both controlled conditions in constructed systems and background concentrations in natural systems . Plant tissues have been collected and analyzed from natural systems and from controlled systems receiving either wastewater or municipal water . Plants studied included the herbaceous species Anemopsis californica (Yerba mansa), Scirpus spp . (bulrush) and Typha domingensis (cattail), and tree species Fraxinus velutina (ash), Populus fremontii (cottonwood) and Salix spp . (willow) . Data indicate that uptake varies not only among plant species, but also among chemical species, depending upon water quality within the wetlands . Leaf tissues of Fraxinus, Salix and Populus, contained the lowest amounts of nutrients and heavy metals studied (Na, P, K, Cu, Pb and Zn), while the root tissues of the herbaceous plants generally had the highest concentrations. Water Sci Technol, 2001, 44(11-12), 435 - 40 Rerating capacity of a constructed wetland treatment system; Jackson JA et al.; The 482-hectare (ha) City of Orlando (Florida) Easterly Wetlands (OEW) was designed to reduce nutrient concentrations in 0.90 m3/s of wastewater from the Iron Bridge Regional Water Reclamation Facility . Design influent nutrient concentrations were 6 mg/L total nitrogen (TN) and 0.75 mg/L total phosphorus (TP) . Actual TN and TP concentrations have been less than design, averaging 2.6 mg/L and 0.29 mg/L, respectively from January 1988 through December 1999 . If influent concentrations remain at these levels, the OEW may have the potential to treat significantly higher flows since less than 20% of the total area was utilized for nutrient reduction . To test this theory, a capacity study was performed for approximately nine months in 1997 and 1998 . Simulated flows of approximately 1.26 m3/s, 1.66 m3/s, and 1.93 m3/s were tested . It was found that approximately 15% of the area was utilized for nutrient reduction during the 1.26 m3/s simulation, 35% in the 1.66 m3/s, and 1.93 m3/s simulations . Based on these testing results, an application was submitted to the state in early 2000 to increase the permitted capacity to 1.57 m3/s. Water Sci Technol, 2001, 44(11-12), 427 - 33 Wastewater treatment by algal turf scrubbing; Craggs RJ; Algal turf scrubbing (ATS) is a novel wetland technology that has been designed and engineered to promote natural wastewater treatment processes . Algal turf scrubbing improves water quality by passing a shallow stream of wastewater over the surface of a gently sloped floway . The floway is colonised by a natural heterogeneous assemblage of periphyton consisting of cyanobacteria, filamentous algae and epiphytic diatoms together with aerobic bacteria and fungi . Algal photosynthesis provides oxygen for aerobic breakdown of wastewater by heterotrophic bacteria . Pollutants are extracted from the wastewater by several processes including assimilation, adsorption, filtration and precipitation . The algal turf is harvested periodically to remove the accumulated periphyton biomass and associated pollutants from the system . This paper will present results from a demonstration ATS facility in Patterson, California which was used to polish secondarily treated wastewater . The design and operational factors that influence the treatment performance of ATS systems is discussed . Results indicate the potential of the ATS for nutrient removal from secondarily treated wastewater and agricultural drainage waters. Water Sci Technol, 2001, 44(11-12), 413 - 20 Long-term performance summary for the Boot Wetland Treatment System; Martin JR et al.; The Boot WTS is a 46.5-ha, hydrologically altered cypress-gum wetland in Polk County, Florida . Poinciana Wastewater Treatment Plant No . 3 has discharged advanced secondary treated effluent to the Boot WTS since August 1984 . Comprehensive operational monitoring has been ongoing since 1990 . The Boot WTS has provided consistent removal of nitrogen and phosphorus . Influent total nitrogen (TN) and total phosphorus (TP) concentrations averaged approximately 10.0 mg/L and 2.5 mg/L at an average hydraulic loading rate (HLR) of 0.2 cm/d . Wetland effluent concentrations for TN and TP averaged 1.8 mg/L and 1.2 mg/L . Available flow and water quality data were used to develop estimates of the first-order removal rate, k, for TN (14 m/y) and TP (1.8 m/y) . These removal rates are within the range of values for other forested treatment wetlands . Biochemical oxygen demand (2.2 mg/L) and total suspended solids (4.9 mg/L) in the influent are near background levels for forested wetlands and are not significantly reduced with passage through the system. Water Sci Technol, 2001, 44(11-12), 407 - 12 Zero-discharge of nutrients and water in a willow dominated constructed wetland; Gregersen P et al.; A novel constructed wetland system has been developed to treat sewage, evaporate water and recycle nutrients from single households at sites where effluent standards are stringent and soil infiltration is not possible . Main attributes of the willow wastewater cleaning facilities are that the systems have zero discharge, the willows evapotranspire the water, and nutrients can be recycled via the willow biomass produced in the system . The willow wastewater cleaning facilities generally consist of c . 1.5 m deep high-density polyethylene-lined basins filled with soil and planted with clones of willow (Salix viminalis L.) . The surface area of the systems depends on the amount and quality of the sewage to be treated and the local annual rainfall . For a single household the area needed typically is between 200-300 m2 . Settled sewage is dispersed underground into the bed under pressure . When correctly dimensioned, the willow will--on an annual basis--evapotranspire all water from the sewage and rain falling onto the system, and take up all nutrients and heavy metals from the sewage . The stems of the willows are harvested on a regular basis to remove nutrients and heavy metals and to stimulate the growth of the willows . Initial experiences from full-scale systems in Denmark show promising results. Water Sci Technol, 2001, 44(11-12), 399 - 405 Reciprocating constructed wetlands for treating industrial, municipal and agricultural wastewater; Behrends L et al.; Scientists at the Tennessee Valley Authority (TVA), and in collaboration with the U.S . Environmental Protection Agency (EPA), are continuing to develop and refine an innovative wastewater treatment system referred to as reciprocating subsurface-flow constructed wetlands . Reciprocation relates to patented improvements in the design and operation of paired subsurface-flow constructed wetlands, such that contiguous cells are filled and drained on a frequent and recurrent basis . This operating technique turns the entire wetland system into a fixed-film biological reactor, in which it is possible to control redox potential in alternating aerobic and anaerobic zones . Reciprocating systems enable manipulation of wastewater treatment functions by controlling such parameters as hydraulic retention time, frequency of reciprocation, reciprocation cycle time, depth of reciprocation, and size and composition of substrate . These improved wetland technologies have been used for treating municipal/domestic wastewater, high strength animal wastewater, and mixed wastewater streams containing acids, recalcitrant compounds, solvents, antifreeze compounds, heavy metals, explosives, and fertilizer nutrients . Results from selected treatability studies and field demonstrations will be summarized with respect to conceptual design and treatment efficacy. Water Sci Technol, 2001, 44(11-12), 39 - 46 The use of macrophyte-based systems for phosphorus removal: an overview of 25 years of research and operational results in Florida; DeBusk TA et al.; Phosphorus (P) removal from wastewaters and surface runoff using macrophyte-based systems (MBS) has been a topic of great interest in Florida for over 25 years . During this period, P removal by both treatment wetlands and floating aquatic macrophyte systems has been evaluated from both a research and operational standpoint . Several factors have contributed to the increased focus on the use of MBS for P removal . First, there exist no conventional technologies that can cost-effectively achieve the low outflow P concentrations required to protect the integrity of Florida's relatively pristine surface waters . Second, because MBSs typically provide some water storage, they can accommodate the wide ranges of flows typical for runoff sources such as agricultural drainage waters . Finally, many regions in Florida have sufficient area for deployment of the relatively land-intensive MBS technologies . The first P removal work in Florida was initiated in the mid-1970s, and involved pilot-scale research on domestic wastewater treatment by natural wetlands . Parallel studies were performed with managed (periodically harvested) floating plant systems (i.e., Eichhornia crassipes) for tertiary treatment . Since that time, the range of operational systems that have been deployed include emergent macrophyte-based and forested wetlands, managed floating plant systems, and submerged macrophyte-based systems . Waters treated by MBS include domestic effluents, agricultural runoff and eutrophic lake waters . Phosphorus removal targets for MBS in Florida have been as low as 10 microg/L . In this paper, we summarize research and operational results for MBS in Florida over the past 25 years. Water Sci Technol, 2001, 44(11-12), 381 - 6 Application of constructed wetlands for wastewater treatment in Nepal; Shrestha RR et al.; Surface water pollution is one of the serious environmental problems in urban centers in Nepal due to the discharge of untreated wastewater into the river-system, turning them into open sewers . Wastewater treatment plants are almost non-existent in the country except for a few in the Kathmandu Valley and even these are not functioning well . Successful implementation of a few constructed wetland systems within the past three years has attracted attention to this promising technology . A two-staged subsurface flow constructed wetland for hospital wastewater treatment and constructed wetlands for treatment of greywater and septage is now becoming a demonstration site of constructed wetland systems in Nepal . Beside these systems, five constructed wetlands have already been designed and some are under construction for the treatment of leachate and septage in Pokhara municipality, wastewater in Kathmandu University, two hospitals and a school . This paper discusses the present condition and treatment performance of constructed wetlands that are now in operation . Furthermore, the concept of the treatment wetlands under construction is also described here . With the present experience, several recommendations are pointed out for the promotion of this technology in the developing countries. Water Sci Technol, 2001, 44(11-12), 369 - 74 Constructed wetlands for wastewater treatment in the Czech Republic; Vymazal J; The first constructed wetland (CW) for wastewater treatment was built in the Czech Republic in 1989 . This recent survey shows that at the end of 1999 101 systems are in operation and several more are under construction . 95 CWs are designed with sub-surface horizontal flow, 6 systems are hybrid with a combination of vertical and horizontal flow beds . Most systems (56) were designed for the treatment of municipal and domestic sewage while 38 CWs were designed for the treatment of wastewater from combined sewer systems . The most commonly used size of vegetated beds is 1,001-2,500 m2 (31 systems) followed by the area between 51-250 m2 (19%) . The area of vegetated bed of the largest system is 4,493 m2 . Size distribution is quite evenly spread from very small systems (PE = 3 or 4) up to 1,000 PE . However, most systems (44) were sized to treat wastewater from sources between 101 and 500 PE . The most commonly used macrophyte is Common reed (Phragmites australis) which is used in 34 systems as a monotypic stand and in 44 systems in combination with other macrophytes, most frequently with Reed canarygrass (Phalaris arundinacea) (31 systems) and cattails (Typha spp.) (8 systems). Water Sci Technol, 2001, 44(11-12), 361 - 7 Removal of hydrogen sulphide BOD from brackish water using vertical flow wetlands in a Caribbean environment; Giraldo E et al.; Wastewater from a 550-inhabitant community had been treated and discarded using an anaerobic filter . Due to seawater intrusion in the aquifer that supplies the water, high concentrations of hydrogen sulphide were detected in the effluent . A vertical flow wetland was designed in 1998 for treating this effluent . Four parallel reed beds with a total area of 556 m2 were constructed . During the first months of operation, a mean BOD5 removal efficiency of 91% was obtained, with loads to the wetland system up to 4 g/m2/d of grease and oils (G&O) . In 1999, problems of soil clogging were found due to high G&O content in the wastewater, with loads up to 15 g/m2/d of G&O, which highly influenced the hydraulic conductivity of the beds, generating the clogging problems . The low hydraulic conductivity and the high effluent G&O content, caused low BOD5 and COD removal efficiencies . As G&O accumulated in the soil, the removal efficiencies decreased . Despite the clogging problems, there has been a high sulphide removal throughout the system operation . The wetlands removed sulphides successfully, under loads up to 20 g S=/m2/d . Four native species of macrophytes were planted: Paspalum penisetum, Typha sp, Conocarpres erectus and Scirpus lacustris . All of them but Typha sp . were established in the system. Water Sci Technol, 2001, 44(11-12), 331 - 8 Natural wastewater treatment in Hungary; Szabo A et al.; Over the last few decades more and more natural wastewater treatment systems have been built in Hungary . The present study is the first step in creating a broad database on the water quality parameters and on the pollutant removal efficiency of these systems . The investigation included 78 plants out of which we analysed 16 systems in detail . Four types of natural methods are evaluated: wetlands, ponds, biomechanical combined oxidation (BMKO) systems, and poplar plantations . Pond systems are efficient in ammonium-nitrogen (NH4-N) removal, reducing it with 83% (41-88%) . Their chemical oxygen demand (COD(Cr)) removal capacity is only 55% (37-81%) . The only BMKO system that could be evaluated performs high COD(Cr) (77%) and total suspended solid (TSS) (89%) removal . Removal of NH4-N and total nitrogen (TN) declines during the years of operation giving an average value of 39% and 49%, respectively . The system is not efficient in phosphorus removal (13%) . In wetlands the 71% COD(Cr) (53-96%), and 57% TSS (33-91%) removal provides satisfactory effluent quality most of the time . Wetlands performed low nutrient removal, i.e., 17% (-21-46%) for TN and 26% (-20-92%) for phosphorus . Poplar plantations are very effective in pollutant removal . Even the average removal of each nutrient type is above 75% . Several problems have occurred in the operation of natural treatment systems . However, if carefully planned and constructed, and the required maintenance work is done properly, they can be possible alternatives for wastewater treatment. Water Sci Technol, 2001, 44(11-12), 317 - 24 Ecological characteristics of a natural wetland receiving secondary effluent; Martin JR et al.; The Boot wetland treatment system is a 115-acre, hydrologically altered cypress-gum wetland in Polk County, Florida . The Poinciana Wastewater Treatment Plant No . 3 has discharged secondary effluent to the bermed Boot wetland since August 1984 . Before that time this natural wetland had been affected adversely by forestry, drainage, and surrounding development which contributed to dying trees and a groundcover of invasive upland plants . In accordance with the Florida Department of Environmental Protection's Wetlands Application Rule (Chapter 62-611, F.A.C.), a routine biological and water quality monitoring program has been in effect since October 1990 . Components of the biological monitoring program include surveys of canopy and subcanopy, herbaceous and shrub groundcover species, benthic macroinvertebrates, fish, and nuisance mosquitoes . Effluent addition to the Boot wetland has resulted in continuous wetland inundation with atypical water depth of 2.5 to 3.0 feet for the past 15 years . Dominance and density of trees has steadily increased, upland invader species were eliminated, and stable plant, fish, and invertebrate communities were established . The long term biological data from this treatment wetland is compared to data from other natural treatment wetlands and a control wetland. Water Sci Technol, 2001, 44(11-12), 281 - 7 Accumulation of organic matter fractions in a gravel-bed constructed wetland; Nguyen L; The function of a gravel-bed wetland in treating wastewaters is dependent on the turn-over rate of organic matter (OM) fractions in accumulated solids . Organic deposits from a gravel-bed planted (Schoenoplectus tabernaemontani) wetland, which had experienced pore clogging after 5 years of receiving farm dairy wastewater were therefore collected and determined for labile (water-soluble) and stable (humic acid, fulvic acid and humin) OM fractions, total carbon (C), microbial biomass and microbial respiration rate . Over 90% of the accumulated organic solids was present as stable fractions, with humic compounds at least 2-fold higher in surface deposits and the top 100 mm of the gravel bed than the lower gravel substratum . Clogging of the gravel pore spaces over a 5-year wetland operation was probably due to the accumulation of refractory (stable) organic solids, particularly in the top 100 mm of the gravel bed . Microbial respiration rate and microbial biomass were significantly correlated with stable OM fractions, suggesting that these microbial parameters may be used to predict the nature of accumulated OM fractions . Further research is required to evaluate the use of these parameters as indicators of labile and stable fractions in wetlands with a range of OM loadings and accumulation. Water Sci Technol, 2001, 44(11-12), 273 - 80 Development of a conceptual model for vertical flow wetland metabolism; Giraldo E et al.; Four parallel vertical constructed wetlands, with a total area of 556 m2, are used to treat domestic wastewater, coming from a community of 550 inhabitants . The system includes pre-treatment with an anaerobic filter and post-treatment with chlorine, before discharging the effluent to the ocean . Four native species of macrophytes were planted: Paspalum penisetum, Typha sp, Conocarpres erectus and Scirpus lacustris . In situ measurements of gas content were performed for each bed during an operation cycle . After a feeding discharge, an unaltered sample of sand from each bed was taken, and a respirometric test was implemented to measure the metabolic activity in terms of oxygen consumption kinetics, CO2 production and organic matter degradation . The results were used to develop a conceptual model of the microbiologic metabolism for the process of organic matter removal from wastewater . Sorption in the bed is the main mechanism for organic matter removal from the wastewater, with subsequent biological oxidation during the resting period . The degradation rate for dissolved organic matter is found to be dependent on its concentration and on oxygen content in the gaseous phase . During the days of major activity, the oxygen content was not fully recovered when a new discharge occurred, finding anaerobic activity within the bed. Water Sci Technol, 2001, 44(11-12), 267 - 72 Behavior of organic carbon during subsurface wetland treatment in the Sonoran Desert; Quanrud DM et al.; We examined the fate of organics during wetland treatment of secondary effluent and groundwater (control) flows in parallel, research-scale, subsurface-flow (SSF) wetland raceways at the Constructed Ecosystem Research Facility (CERF) located in Tucson, Arizona . The CERF facility enabled us to distinguish experimentally among effects on effluent quality due to season-dependent processes of evapotranspiration (ET) and wetlands-derived production of organics . Organics of wastewater and wetlands origin were compared in terms of their contributions to dissolved organic carbon (DOC) in wetland effluent . Elevated temperatures and associated biochemical activities increased DOC levels in wetland effluents during summer . In other words, DOC removal efficiency was negatively correlated to temperature . The contributions of ET and wetland-derived organics to elevation of DOC in wetland effluents during summer were roughly comparable . The elevation of organic carbon concentration during wetland polishing of wastewater effluent will lead to higher levels of disinfection by-products when treated waters are chlorinated prior to reuse . Results of this work are relevant to water managers in arid regions, which may incorporate wetlands into sequential wastewater treatments leading to potable reuse of reclaimed water. Water Sci Technol, 2001, 44(11-12), 259 - 65 Cold climate wetlands: design and performance; Wallace S et al.; Constructed wetlands are gaining widespread use as a simple, low cost means of wastewater treatment . Introduction of constructed wetlands technology into the northern United States has been limited by the ability of conventional wetland systems to operate without freezing during the winter . A design approach using subsurface-flow constructed wetlands covered with an insulating mulch layer has been demonstrated to prevent freezing . However, introduction of a mulch layer will affect oxygen transfer rates, pollutant removal performance, and plant establishment . These factors must be addressed for successful application of constructed wetlands technology in cold climates. Water Sci Technol, 2001, 44(11-12), 231 - 5 Performance modeling of subsurface-flow constructed wetlands systems; Dahab MF et al.; A subsurface flow constructed wetlands (CW) system, located at a neighborhood consisting of a small housing development and golf courses outside of Lincoln, NE, was studied for its effectiveness as a small community wastewater system . Extensive monitoring was conducted biweekly between June 1996 and December 2000 . Prediction models for soluble CBOD5 NH3-N, and TP removal in CW were employed for comparison with the field data . It was found that the disappearance of BOD5 and NH3-N could be approximated using first-order kinetics, but the kinetics of TP removal were unclear . The reduction rate constants regressed from the field data were found to be lower than literature reported values. Water Sci Technol, 2001, 44(11-12), 211 - 4 Biota participating in wastewater treatment in a horizontal flow constructed wetland; Vymazal J et al.; During the period 1996-1997, three constructed wetlands with sub-surface horizontal flow were investigated . All systems are designed to treat municipal sewage from small villages (150, 200 and 300 PE) . The survey included microscopical identification of organisms in both wastewater and filtration substrate . The organisms were used as an indication of oxygen conditions (aerobic, anoxic and anaerobic) in the particular microenvironment . Saprobiological terms characterizing different levels of saprobity were employed to characterize inflowing wastewater, filtration bed and outflowing water . The occurrence of organisms was correlated with BOD5 values in particular profiles . It has been found that the biocenosis in the inflowing wastewater differs from those found in the filtration bed and water outflowing from the vegetated beds . The organisms were grouped into those living under anaerobic and anoxic conditions and those living under aerobic conditions . More than 70 species of bacteria, amoebae, ciliates, rotifers, colorless flagellates, cyanobacteria and algae were found and the most important 45 species were figured in a plate together with saprobiological information for each species . Biota of the inflowing water is usually restricted to bacteria, ciliata and colorless flagellata while the organisms found in outflowing water as well as in periphyton growing on outflow structures indicate 2-3 levels better quality. Water Sci Technol, 2001, 44(11-12), 191 - 8 Protozoan predation as a mechanism for the removal of cryptosporidium oocysts from wastewaters in constructed wetlands; Stott R et al.; The removal of the protozoan parasite, Cryptosporidium parvum, from wastewaters is becoming of increasing importance in the UK, especially since contamination of raw waters by sewage effluents has been implicated in major waterborne outbreaks of cryptosporidiosis in recent years . Compared to conventional wastewater-treatment processes, constructed wetlands have demonstrated favourable removal rates for Cryptosporidium oocysts . The removal mechanisms, however, remain unknown . Predation by free-living ciliated protozoa, which are commonly found in constructed wetlands, was investigated as a possible mechanism for oocyst removal . In laboratory feeding experiments, ciliates (Euplotes patella, Stylonychia mytilus, Paramecium caudatum and an unidentified wetland ciliate species), were exposed to doses ranging from 10 to 10(6) oocysts/ml for between 5 and 60 minutes . Ciliate predatory activities were assessed by enumerating fluorescently labelled ingested oocysts using epifluorescence microscopy . Oocysts were found to be ingested by all species investigated . Paramecium demonstrated the highest mean ingestion rates (up to 170 oocysts/hr) followed by Stylonychia (up to 60 oocysts/hour) . Euplotes and the wetland ciliate had lower mean grazing rates (4 and 10 oocysts/hr respectively) . These results indicate that protozoan predation may be an important factor in the removal of Cryptosporidium oocysts from wastewaters in constructed wetlands. Environ Toxicol Chem, 2002 Jan, 21(1), 37 - 46 Occurrence and distribution of nonionic surfactants, their degradation products, and linear alkylbenzene sulfonates in coastal waters and sediments in Spain; Petrovic M et al.; Spain is one of the European countries that still discharges untreated wastewaters and sewage sludge to the sea . A total of 35 samples of coastal waters and 39 samples of harbor sediments was analyzed . Samples were collected from several hot spots on the Spanish coast, such as the harbors of Tarragona, Almeria, and Barcelona, the mouths of the Besos and Llobregat rivers, the Bay of Cadiz, and various yacht harbors at the Mediterranean coast . A generic analytical procedure based on solid-phase extraction-liquid chromatography-atmospheric pressure chemical ionization/electrospray ionization mass spectrometry (SPE-LC-APCI/ESI-MS) was employed for determining the concentrations of alcohol ethoxylates (AEO), nonylphenol ethoxylates (NPEO), coconut diethanol amides (CDEA), nonylphenoxy-monocarboxylates (NPEC), nonylphenol (NP), octylphenol (OP), and linear alkylbenzene sulfonates (LAS) in sediment and water samples . The analysis revealed the presence of considerably high concentrations of NPEOs and NP near the points of discharge of industrial and urban wastewaters . Nonylphenol was found in 47% of water samples and in 77% of all sediment samples analyzed . Values for NP ranged from <0.15 to 4.1 microg/L in seawater and from <8 to 1,050 microg/kg in sediments . Levels of AEOs and CDEAs in seawater and marine sediments are reported for the first time . Concentrations of CDEAs in sediment, which were predominated by C11 through C15 homologues, ranged from 30 to 2,700 microg/kg, while in seawater, concentrations found were up to 24 microg/L . The AEOs were found to accumulate in a bottom sediment and they were detected in all analyzed sediment samples in concentrations from 37 to 1,300 microg/kg. Bioresour Technol, 2002 Feb, 81(3), 201 - 6 Uptake and recovery of gold ions from electroplating wastes using eggshell membrane; Ishikawa S et al.; The animal byproduct, hen eggshell membrane (ESM), was evaluated for its ability to sorb gold ions (dicyanoaurate(I) and tetrachloroaurate(III)) from solutions and electroplating wastewater . The gold uptake was dependent on pH, temperature and co-ions present in the solutions, with pH 3.0 being the optimum value . The equilibrium data followed the Langmuir isotherm model with maximum capacities of 147 mg Au(I)/g dry weight and 618 mg Au(III)/g, respectively . Desorption of sorbed gold(I) with 0.1 mol/l NaOH resulted in no changes of the biosorbent gold uptake capacity through five consecutive sorption/desorption cycles . In column experiments, selective recovery of gold from electroplating wastewater containing various metal ions was noted . The affinity of metal sorption was in the order Au > Ag > Co > Cu > Pb > Ni > Zn. Water Sci Technol, 2001, 44(10), 9 - 18 Conditioning, thickening, and dewatering: research update/research needs; Dentel SK; The production of sludges that are amenable to beneficial reuse (and thereby merit the term "biosolids") has become a high priority concern in wastewater treatment . Regulations in many countries have become stringent in this regard, and the production of suitable biosolids now influences the selection, design, and operation of upstream processes . Among these are the conditioning, thickening, and dewatering of sludges . This paper briefly reviews current technology trends in these process areas, placing them in the context of overall needs for improved biosolids management . It is foreseen that conditioning, thickening and dewatering processes will need to operate at higher performance and reliability levels to maintain disposal and reuse flexibility . The chemistry of conditioning must be more clearly determined since secondary interactions of the conditioning additives may be important in ways that are not currently recognized. Water Sci Technol, 2001, 44(10), 47 - 52 Factors affecting the distribution of heavy metals in wastewater treatment processes: role of sludge particulate; Huang CP et al.; The distribution of heavy metals, namely, Ag(I), Cd(II), Co(II), Cr(III,VI), Cu(II), Hg(II), Ni(II), Pb(II), and Zn(II) in 4 municipal wastewater treatment plants was evaluated as a function of several parameters including pH, COD, ionic strength and SS . Although there are variations in pH, alkalinity, COD and ionic strength, the results show that wastewater samples containing less than 5 g/L suspended solids concentration have similar characteristics . Correlations among heavy metal distribution (as the ratio between dissolved to total metals) and wastewater characteristics were attempted . Correlation between the parameters monitored and metal distribution is poor . In the case of pH, no apparent relationship could be seen . In general, increasing COD and ionic strength decreases the metal distribution . Metal distribution relies almost entirely on the concentration of solids in wastewater samples . Total metal removal in primary treatment process is lower than that reported in the literature . This could be attributed to the low average solids removal observed in the treatment plants investigated . Solids reduction at the effluent were larger than 80% and total metals removal was identical to that of the primary treatment process. Water Sci Technol, 2001, 44(10), 333 - 9 Thermal processing of sewage sludge by drying, pyrolysis, gasification and combustion; Stolarek P et al.; Thermal processing of sewage sludge including drying, pyrolysis and gasification or combustion may be an alternative to other ways of utilising it . In this paper thermogravimetric analysis (TGA) was employed in the investigation of thermal decomposition of sewage sludge . The kinetic parameters of drying, pyrolysis and gasification or combustion of sewage sludge have been determined in an inert-gas (argon) and additionally some series of the sludge decomposition experiments have been carried out in air, in order to compare pyrolysis and combustion . The pyrolysis char has been gasified with carbon dioxide . A typical approach to the kinetics of thermal decomposition of a solid waste is to divide the volatile evolution into a few fractions (lumps), each of which is represented by a single first-order reaction . If these lumps are assumed to be non-interacting and evolved by independent parallel reactions the first-order kinetic parameters such as activation energy Ei and pre-exponential factor Ai can be determined from mathematical evaluation of TG or DTG curves . The object of our investigations was a municipal sludge from the two wastewater treatment plants (WTP) in Poland . The experiments have been carried out in the thermobalance Mettler-Toledo type TGA/SDTA851 LF, in the temperature range 30-1,000 degrees C . Five different values of heating rate have been applied beta = 2, 5, 10, 15 and 20 K/min . The values of Ei and Ai have been determined for all recognised lumps of gaseous products . The method employed has also revealed its usefulness for the determination of kinetic parameters for municipal sludge, that possess an undefined content . An alternative route to combustion of sewage sludge is its gasification, which significantly increases the gaseous product (pyrolytic gas + syngas) . Besides pyrolysis kinetics, gasification or combustion process kinetics have also been determined. Water Sci Technol, 2001, 44(10), 269 - 72 Reuse of industrial sludge as construction aggregates; Tay JH et al.; Industrial wastewater sludge and dredged marine clay are high volume wastes that needed enormous space at landfill disposal sites . Due to the limitation of land space, there is an urgent need for alternative disposal methods for these two wastes . This study investigates the possibility of using the industrial sludge in combination with marine clay as construction aggregates . Different proportions of sludge and clay were made into round and angular aggregates . It was found that certain mix proportions could provide aggregates of adequate strength, comparable to that of conventional aggregates . Concrete samples cast from the sludge-clay aggregates yield compressive strengths in the range of 31.0 to 39.0 N/mm2 . The results showed that the round aggregates of 100% sludge and the crush aggregates of sludge with up to 20% clay produced concrete of compressive strengths which are superior to that of 38.0 N/mm2 for conventional aggregate . The study indicates that the conversion of high volume wastes into construction materials is a potential option for waste management. Water Sci Technol, 2001, 44(10), 245 - 52 Effectiveness of anaerobic biomass in adsorbing heavy metals; Haytoglu B et al.; This study focuses on the effectiveness of waste anaerobic dead biomass (ADB) in adsorbing heavy metals, namely Pb(II), Cr(VI), Cu(II), Ni(II) and Zn(II) . The metal uptake capacity of ADB was investigated and compared with the values for various biomass types from the literature . The biomass, which was grown under laboratory conditions using a synthetic wastewater, was used throughout the study after sterilization . The maximum metal adsorptive capacities were evaluated by running isotherm tests at 25 degrees C and initial pH of 4 . It was observed that Pb(II) was adsorbed with the highest capacity . The maximum adsorptive capacity of ADB for Pb(II), Zn(II), Cu(II), Ni(II) and Cr(VI) was determined as 1250, 625, 357, 227 and 384 mg/g dry biomass, respectively . These values were significantly higher than the corresponding capacities reported in the literature for other types of biomass . In describing the adsorption equilibrium, both the Langmuir and Freundlich isotherm models were examined . The experimental data for Pb(II), Zn(II), Cr(VI), and Ni(II) fitted both the Langmuir and Freundlich models with correlation coefficients of 0.80-0.99 while Cu(II) only fitted the Langmuir model with a correlation coefficient of 0.99 . Therefore, different and distinct aspects of the interactions between the cell surfaces and the metal ions might have occurred for Cu(II) and the rest of the metals . The equilibrium pH values attained were all higher than the initial pH value of 4.0, and this indicated that both the type and the initial concentration of the metal influenced the equilibrium pH . Furthermore, there was a decrease in equilibrium pH with increasing initial metal concentration at varying levels. Water Sci Technol, 2001, 44(10), 19 - 26 Possibilities to improve the quality of wastewater sludges; Balmer P; Falling heavy metal concentrations in wastewater sludges are an indicator of the improvements in sludge quality achieved over the past thirty years . Studies of the sources of heavy metals in wastewater sludges, particularly the loads introduced by domestic and industrial wastewater and storm water, show the potential improvement that may still be made. Water Sci Technol, 2001, 44(10), 149 - 56 Treating an aged pentachlorophenol- (PCP-) contaminated soil through three sludge handling processes, anaerobic sludge digestion, post-sludge digestion and sludge land application; Chen ST et al.; The extensive pentachlorophenol (PCP) contamination and its increasing treatment costs motivate the search for a more competitive treatment alternative . In a municipal wastewater treatment plant, anaerobic sludge-handling processes comprises three bio-processes, namely the anaerobic sludge digestion, post-sludge digestion and sludge land application, which reduce sludge organic content and make sludge a good fertilizer for land application . Availability and effectiveness make the anaerobic sludge handling processes potential technologies to treat PCP-contaminated soil . The technical feasibility of using anaerobic sludge bioprocesses was studied by treating PCP soil in two pilot digesters to simulate the primary sludge digestion, in serum bottles to mimic the post-sludge digestion, and in glass pans to represent the on-site sludge application . For primary digestion, the results showed that up to 0.98 and 0.6 mM of chemical and soil PCP, respectively, were treated at nearly 100% and 97.5% efficiencies . The PCP was transformed 95% to 3-MCP, 4.5% to 3,4-DCP, and 0.5% to 3,5-DCP . For post-digestion, 100% pure chemical PCP and greater than 95% soil PCP were removed in less than 6 months with no chlorophenol residues of any kind . Complete removal of PCP by-products makes this process a good soil cleanup method . For on-site treatment, PCP was efficiently treated by multiple sludge application; however, the PCP residue was observed due to the high initial PCP content in soil . Overall, more mass PCP per unit sludge per day was processed using the primary sludge digestion than the on-site soil treatment or post-sludge digestion . And, sludge acclimation resulted in better PCP treatment efficiencies with all three processes. Water Res, 2001 Dec, 35(17), 4226 - 30 Treatment of dye wastewater containing acid orange II using a cell with three-phase three-dimensional electrode; Xiong Y et al.; The removal of color and chemical oxygen demand (COD) from simulated dye wastewater containing Acid Orange II was experimentally investigated using coagulation-electrooxidation . Two kinds of coagulation methods, ferrous-mediated coagulation and electrocoagulation were tested as pretreatment . The electrooxidation was carried out in a cell with a three-phase three-dimensional electrode using granular activated carbon as particle electrodes . Particular attention was paid to probe the effect of cell voltage, airflow rate, solution conductivity and treatment time on the electrochemical treatment efficiency . The experimental results showed that the coagulation-electrooxidation process could efficiently remove the color and the COD from the simulated dye wastewater . The overall COD and color removal efficiencies reached as high as 99% and 87%, respectively, by ferrous coagulation (molar rate of Fe(II)/ dye: 0.5) and 30-min electrolysis (cell voltage: 20.0 V and airflow: 0.1 m3 h(-1)). Water Res, 2001 Dec, 35(17), 4191 - 9 Conditions influencing the precipitation of magnesium ammonium phosphate; Stratful I et al.; Struvite precipitation in wastewater treatment works has caused substantial operational problems since the early 1960s . Struvite, magnesium ammonium phosphate hexahydrate (MgNH4PO4 6H2O), is a white inorganic crystalline mineral that precipitates in places with increased turbulence such as pumps, aerators and pipe bends . Batch experiments were conducted to examine the influence of a number of physical and chemical parameters on struvite crystallisation . This was undertaken by dosing a medium of de-ionised water with varying concentrations of Mg2+, NH4+ and PO4(3-) ions . Preliminary experiments found that struvite could be precipitated out of solution at pH 10 and increasing the ion concentration stoichiometrically could increase crystal yield . Increasing the NH4+ concentration increased purity of the precipitate . As reaction time was increased from 1 to 180 min, crystal size was found to increase from 0.1 to 3mm. Water Res, 2001 Dec, 35(17), 4150 - 8 Anaerobic treatment of fibreboard manufacturing wastewaters in a pilot scale hybrid usbf reactor; Fernandez JM et al.; The treatment of fibreboard manufacturing (FBM) wastewaters was carried out in an industrial pilot plant, which consisted of a hybrid upflow sludge bed filter (USBF) anaerobic reactor and a coagulation-flocculation unit as a pre-treatment . COD removal efficiencies of 90-93% were attained in the anaerobic reactor operating at 37degrees C at organic loading rates (OLR) of 6.5-8.5 kg COD/m3 d . Flocculant sludges were used as inoculum, and granulation was observed in the USBF reactor after 120 days of operation . The overall linear upward velocity (result of liquid and gas flow) was the key factor controlling biomass retention and, therefore, a stable operation at high OLR . According to ecotoxicity values (measured by means of bioluminescence assays), the wastewaters were partially detoxified, being EC50 values for the liquid effluent 25 times lower than those corresponding to the influent . Besides, phenolic compounds removal efficiencies of 90% were attained . The hybrid reactor configuration is an interesting alternative to treat these wastewaters since it is less sensitive to biomass clogging or floatation. Water Res, 2001 Dec, 35(17), 4137 - 49 Anaerobic treatment of domestic wastewater in temperate climates: treatment plant modelling with economic considerations; Zakkour PD et al.; Although research suggests that anaerobic treatment of low-strength domestic wastewater is possible in temperate climates, to date, full-scale applications have only been pioneered in hot regions . However, burgeoning environmental legislation in developed countries is giving the impetus to develop anaerobic wastewater treatment systems due to potential economic and environmental benefits they hold over traditional aerobic techniques . In this paper a design rationale for low-temperature, low-strength (COD < 1,000 mgl(-1)), two-phase anaerobic wastewater treatment is developed through empirical modelling of data from published research, and from assumptions arising from a literature review . Model calculations are applied to typical domestic sewage characteristics at two different flow rates, based on population equivalents . Results indicate that soluble COD production in the model hydrolytic tank are similar to those achieved in pilot scale plants in the Netherlands . Model anaerobic reactor sludge characteristics are similar to those achieved in pilot and full-scale anaerobic reactors treating low-strength wastewaters . Indicative cost figures for a two-phase anaerobic treatment plant are given, but are incomplete without an assessment of the cost of post-treatment processes . Anaerobic treatment is likely to become more attractive in the future as new legislation relating to sludge disposal and renewable energy generation are introduced. Water Res, 2001 Dec, 35(17), 4095 - 101 Flux enhancement with gas injection in crossflow ultrafiltration of oily wastewater; Um MJ et al.; The gas injection technique was introduced to achieve flux improvement in cross-flow ultrafiltration of oil emulsion . By the nitrogen gas injection, homogeneous liquid phase oil/water emulsion was changed to heterogeneous gas- liquid phase . The injected gas causes positive effect of promoting turbulence, but it also has negative effect of decreasing the effective membrane area due to the partial occupation of membrane pores by bubbles . The efficiency of the gas injection was found out to be dependent on bubble fractions in the mixture: at sufficient bubble fractions the higher flux was observed . but at lower bubble fractions the flux rather decreased compared with that without gas injection . An attempt was made to explain the mechanisms for the dual aspects of gas injection . Turbulence dampening effect was also observed when the dependence of mass transfer coefficient on cross-flow rate was investigated with gas injection. Water Res, 2001 Dec, 35(17), 4079 - 85 Biosorption of chromium(VI) from aqueous solutions by green algae Spirogyra species; Gupta VK et al.; Biosorption of heavy metals is an effective technology for the treatment of industrial wastewaters . Results are presented showing the sorption of Cr(VI) from solutions by biomass of filamentous algae Spirogyra species . Batch experiments were conducted to determine the adsorption properties of the biomass and it was observed that the adsorption capacity of the biomass strongly depends on equilibrium pH . Equilibrium isotherms were also obtained and maximum removal of Cr(VI) was around 14.7 x 10(3) mg metal, kg of dry weight biomass at a pH of 2.0 in 120 min with 5 mg/l of initial concentration . The results indicated that the biomass of Spirogyra species is suitable for the development of efficient biosorbent for the removal and recovery of Cr(VI) from wastewater. J Environ Qual, 2001 Nov-Dec, 30(6), 2188 - 94 Seven years of biosolids versus inorganic nitrogen applications to tall fescue; Cogger CG et al.; Repeated applications of municipal wastewater biosolids is cost effective for biosolids managers, but may lead to undesirable accumulations of nutrients or contaminants . We evaluated the effects of seven years of biosolids applications on tall fescue (Festuca arundinacea Schreb.) production and nutrient availability . We compared two types of Class A biosolids applied to tall fescue on a sandy loam in western Washington . Mean annual biosolids rates of 290, 580, and 870 kg total N ha(-1) yr(-1) were compared with inorganic N and zero-N controls using a randomized complete block design . We measured yield and N uptake for each forage harvest, plant tissue metals at selected harvests, soil nitrate each fall, diethylenetriaminepentaacetic acid (DTPA)-extractable metals after five years of applications, and soil pH, available P, and organic C after seven years . Forage yields increased with biosolids rate . Apparent nitrogen recovery (ANR) for biosolids averaged 18% in 1993 (Year 1), 35% in 1994, and 46% in 1999 . The ANR for inorganic N averaged 62% from 1994-1999 . Residual soil nitrate was less than 25 kg ha(-1) for all treatments through 1995, but increased beginning in 1996 for the high biosolids rate . Biosolids increased soil organic C levels by 2 to 5 g kg(-1) and Bray-1 P levels by 300 to 600 mg kg(-1) (0-15 cm depth) . Plant tissue Zn increased from 24 to 66 mg kg(-1) at the highest application rate . Nearly all of the DTPA-extractable metals remained in the 0- to 8-cm soil depth. J Environ Qual, 2001 Nov-Dec, 30(6), 2037 - 46 Fluorescence analysis of a standard fulvic acid and tertiary treated wastewater; Westerhoff P et al.; Fluorescence measurements (emission scan, synchronous scan, and excitation-emission matrix {EEM} scan) were used to compare characteristics of two sources of dissolved organic carbon (DOC) from distinctly different origins: (i) a standard fulvic acid from the Suwannee River (SRF sample) and (ii) an unfractionated DOC sample from a tertiary wastewater treatment plant (MWW sample) . Two methods were demonstrated that quantitatively differentiated allochthonous DOC (e.g., SRF) from autochthonous DOC (e.g., MWW) . The MWW sample exhibited fluorescence peaks undetected in the SRF sample, at shorter wavelength pairs (e.g., 220 nm:300 to 350 nm) than the dominant peaks in the SRF sample (e.g., 220 nm:450 nm) . These peaks may be associated with base or neutral fractions, potentially enriched in organic nitrogen . Effects of DOC concentration and solution pH were discussed . A simple procedure was recommended (pH = 3; DOC = 1 mg/L; dilution with 0.01 M KCl) that minimizes the need to correct spectra for inner-filter absorbance effects . A method, using synchronous fluorescence, to estimate the percentage of DOC from different sources when mixed together was also presented . Further work to understand the structural properties of DOC that fluoresce in wastewater samples, especially at shorter EEM wavelength pairs, will enable water managers to better understand the influence of wastewater on DOC in receiving waters (e.g., rivers, lakes). J Environ Qual, 2001 Nov-Dec, 30(6), 1933 - 9 A field study of virus removal in septic tank drainfields; Nicosia LA et al.; Two field studies were conducted at a research station in Tampa, Florida to assess the removal of bacteriophage PRD1 from wastewater in septic tank drainfields . Infiltration cells were seeded with PRD1 and bromide and the effects of effluent hydraulic loading rate and rainfall on virus removal were monitored . Septic tank effluent samples were collected after passage through 0.6 m of unsaturated fine sand and PRD1 was detected over an average of 67 d . Bacteriophage PRD1 breakthrough was detected at approximately the same time as bromide in all three cells except for the low-load cell (Study 1), where bromide was never detected . Log10 removals of PRD1 were 1.43 and 1.91 for the high-load cells (hydraulic loading rate = 0.063 m/d) and 2.21 for the low-load cell (hydraulic loading rate = 0.032 m/d) . Virus attenuation is attributed to dispersion, dilution, and inactivation . Significant increases in PRD1 elution with rainfall were observed in the first 10 d of the study . Approximately 125 mm of rainfall caused a 1.2 log10 increase of PRD1 detected at the 0.6-m depth . Current Florida onsite wastewater disposal standards, which specify a 0.6-m distance from the drainfield to the water table, may not provide sufficient removal of viruses, particularly during the wet season. J Environ Qual, 2001 Nov-Dec, 30(6), 1904 - 10 Hurricane-loaded soil: effects on nitric oxide emissions from soil; Tabachow RM et al.; The nitric oxide (NO) flux from eastern North Carolina soils subjected to flooding from hurricanes were studied in laboratory experiments . Three sites along the Neuse River basin in eastern North Carolina that sustained different intensities of flooding in September 1999 from Hurricane Floyd were examined . Hurricane Floyd impacted the Neuse River basin by inducing flooding that damaged and disabled hog (Sus scrofa) lagoons and municipal wastewater treatment plants . Between approximately 53 and 325 million liters (14 and 86 million gallons) of untreated hog waste and between approximately 5.7 and 34.4 billion liters (1.5 and 9.1 billion gallons) of untreated municipal wastewater are projected to have entered the Neuse River basin, increasing the concentrations of nitrogen (N), phosphorus (P), and total solids . Phosphorus and total solids are projected to have increased 3.2 and 199.2 mg/L, respectively . Total N was projected to have increased by 9.8 mg/L, which is posited to have increased the NO flux from flooded soils for months after the hurricane . Nitric oxide emissions from soil can adversely affect ozone levels in the lower troposphere . Minimization of NO flux from soil is advantageous, protecting air quality as well as conserving valued nitrogen fertilizers . Hurricane-loaded soils were found to produce more than 30 times greater NO emissions than nonflooded soils with NO fluxes ranging from 0.1 to 102.5 ng N/(m2 s). Environ Sci Technol, 2001 Sep 15, 35(18), 3786 - 91 Biomass byproducts for the remediation of wastewaters contaminated with toxic metals; Schneegurt MA et al.; Pollution of the environment with toxic metals is widespread and often involves large volumes of wastewater . Remediation strategies must be designed to support high throughput while keeping costs to a minimum . Biosorption is presented as an alternative to traditional physicochemical means for removing toxic metals from wastewater . We have investigated the metal binding qualities of two biomass byproducts that are commercially available in quantity and at low cost, namely "spillage", a dried yeast and plant mixture from the production of ethanol from corn, and ground corn cobs used in animal feeds . The biomass materials effectively removed toxic metals, such as Cu, Cs, Mo, Ni, Pb, and Zn, even in the presence of competing metals likely to be found in sulfide mine tailing ponds . The effectiveness of these biosorbents was demonstrated using samples from the Berkeley Pit in Montana . Investigations included column chromatography and slurry systems, and linear distribution coefficients are presented . X-ray spectroscopy was used to identify the binding sites for metals adsorbed to the spillage material . The results of our experiments demonstrate that the biosorption of metals from wastewaters using biomass byproducts is a viable and cost-effective technology that should be included in process evaluations. Environ Sci Technol, 2001 Sep 15, 35(18), 3620 - 5 Identification and quantification of estrogen receptor agonists in wastewater effluents; Snyder SA et al.; Total concentrations of several known xenobiotic estrogen receptor (ER) agonists and natural and synthetic estrogen were measured in water by use of a combination of instrumental and bioanalytical approaches . Samples from 3 municipal wastewater treatment plants (WWTPs) in south central Michigan (upstream and effluent); 4 point source locations on the Trenton Channel of the Detroit River, MI; and 5 locations in Lake Mead, NV were analyzed . Organic compounds were extracted from 5 L water samples using solid-phase extraction disks and separated into three fractions based on polarity . Whole extracts and fractions were tested for ER agonist potency using the MVLN in vitro bioassay . ER agonist potency was characterized by comparing the magnitude of induction elicited by the extract or fraction to the maximum induction caused by 17beta-estradiol (E2) . The greatest concentrations of ER agonists were associated with the most polar fraction (F3) . Instrumental analyses and further fractionation were used to identify specific ER agonists associated with bioassay responses . Bioassay data were compared to extract concentrations in order minimize variability associated with the extraction procedure . Concentrations of endogenous estrogen, E2, and the synthetic estrogen ethynylestradiol (EE2) ranged from nondetectable to 14.6 ng/mL extract (nondetectable to 3.66 ng/L water) and represented from 88 to 99.5% of the total estrogen equivalents in the water samples analyzed . Concentrations of alkylphenols (APs) ranged from nondetectable to 148 microg/mL extract (nondetectable to 37,000 ng/L water) . In general, alkylphenols contributed less than 0.5% of the total estrogen equivalents in the water samples . Both bioassay-directed fractionation results and comparison of ER agonist concentrations, adjusted for their known relative potencies, support the conclusion that E2 and EE2 were the dominant environmental estrogens in water samples from mid-Michigan and Lake Mead, NV. J Hazard Mater, 2002 Feb 14, 90(1), 51 - 62 Decomposition of aniline in supercritical water; Qi XH et al.; The decomposition of aniline in supercritical water (SCW) was studied . Experiments were performed at various temperatures, pressures, residence times, dosage of oxidant H2O2 and initial aniline concentrations to investigate their effect on the destruction efficiency . Manganous sulfate and ferrous sulfate were screened out during the experiment to study the effect of the homogenous catalysts on destruction efficiency . The effect of pH was also studied . The experiments showed that the dosage of oxidant H2O2, experimental temperature, pressure, reaction residence time and even initial concentration of the aniline in wastewater have a significant affect on the TOC removal; manganous sulfate and ferrous sulfate improve the oxidation; TOC removal improves slightly with a decrease in the initial pH value . At a system temperature 450 degrees C, pressure 28 MPa, initial pH 4.0, residence time 46 s and K value 1.1, TOC removal can reach 100%. Environ Sci Technol, 2001 Dec 15, 35(24), 4916 - 21 Flocculation/flotation/ultrafiltration integrated process for the treatment of cork processing wastewaters; Minhalma M et al.; Membrane fouling is the major problem in the treatment by ultrafiltration (UF) of the cork processing wastewaters . This problem leads to drastic reduction on the permeate fluxes and has been associated with wastewaters phenolic/tannic colloidal matter . The present work proposes a flocculation/flotation/ultrafiltration integrated process for the treatment of these wastewaters . A flocculation study was carried out in jar-test equipment with chitosan . The zeta-potential and the particle size were monitored at different pH values and for different chitosan concentrations . The results showed an increase of the zeta-potential when chitosan is added and a significant increase of the effluent particle size with the decrease of the pH . A dissolved-air flotation study was performed with the flocculated wastewater . The parameters varied were the operating pressure and the recycle ratio . It was observed that for higher pressures and at a recycle ratio of 0.19 the polyphenols removal was higher . The UF experiments were carried out in flat-sheet cells of 13.2 cm2 of membrane surface area at transmembrane pressures of 1-3 bar . A commercial membrane (Ropur-TS60) and four cellulose acetate membranes with molecular weight cutoff (MWCO) ranging from 4.5 to 86 kDa were used . The flocculation/flotation pretreatment led to the enhancement of the UF permeate fluxes . For the membrane with higher MWCO, the permeate flux enhancement reached 130%. Environ Sci Technol, 2001 Dec 15, 35(24), 4805 - 16 Nature and transformation of dissolved organic matter in treatment wetlands; Barber LB et al.; This investigation into the occurrence, character, and transformation of dissolved organic matter (DOM) in treatment wetlands in the western United States shows that (i) the nature of DOM in the source water has a major influence on transformations that occur during treatment, (ii) the climate factors have a secondary effect on transformations, (iii) the wetlands receiving treated wastewater can produce a net increase in DOM, and (iv) the hierarchical analytical approach used in this study can measure the subtle DOM transformations that occur . As wastewater treatment plant effluent passes through treatment wetlands, the DOM undergoes transformation to become more aromatic and oxygenated . Autochthonous sources are contributed to the DOM, the nature of which is governed by the developmental stage of the wetland system as well as vegetation patterns . Concentrations of specific wastewater-derived organic contaminants such as linear alkylbenzene sulfonate, caffeine, and ethylenediaminetetraacetic acid were significantly attenuated by wetland treatment and were not contributed by internal loading. Environ Sci Technol, 2001 Dec 15, 35(24), 4798 - 804 Alkylphenol ethoxylate degradation products in land-applied sewage sludge (biosolids); La Guardia MJ et al.; Alkylphenol ethoxylates, widely used in commercial and household detergents in the United States, can degrade during the wastewater treatment process to more toxic, estrogenic, and lipophilic compounds . These include octylphenol (OP), nonylphenols (NPs), nonylphenol monoethoxylates (NP1EOs), and nonylphenol diethoxylates (NP2EOs) . These compounds have received considerable attention due to their acute toxicity and ability to disrupt the endocrine system . In Europe, regulations have been established to control their impact on the environment . In this study, biosolids derived from all 11 U.S . wastewater treatment plants examined contained detectable levels of OP, NPs, NP1EOs, and NP2EOs . Nine exceeded the current Danish land application limit (30 mg/kg; sum of NPs, NP1EOs, and NP2EOs) by 6-33x . NPs were the major component, and their concentrations therein ranged from 5.4 to 887 mg/kg (dry weight) . OP, reportedly 10-20x more estrogenic than NP, was detected in these same nine biosolids at levels up to 12.6 mg/kg . Three biosolids were also subjected to the U.S . Environmental Protection Agency Toxicity Characteristic Leaching Procedure Method 1311 . NPs and NP1EOs were both detected in the leachate; the former at concentrations from 9.4 to 309 microg/L . On the basis of effect levels published in the literature, alkylphenol ethoxylate degradates in U.S . biosolids may cause adverse environmental impacts. Environ Sci Technol, 2001 Dec 15, 35(24), 4726 - 30 Biohydrogen production as a function of pH and substrate concentration; Ginkel SV et al.; The conversion of organics in wastewaters into hydrogen gas could serve the dual role of renewable energy production and waste reduction . The chemical energy in a sucrose rich synthetic wastewater was recovered as hydrogen gas in this study . Using fractional factorial design batch experiments, the effect of varying pH (4.5-7.5) and substrate concentration (1.5-44.8 g COD/L) and their interaction on hydrogen gas production were tested . Mixed bacterial cultures obtained from a compost pile, a potato field, and a soybean field were heated to inhibit hydrogen-consuming methanogens and to enrich sporeforming, hydrogen-producing acidogens . It was determined that the highest rate (74.7 mL H2/(L*h)) of hydrogen production occurred at a pH of 5.5 and a substrate concentration of 7.5 g COD/Lwith a conversion efficiency of 38.9 mL H2/(g COD/L) . The highest conversion efficiency was 46.6 mL H2/(g COD/L). J Chromatogr A, 2001 Dec 14, 938(1-2), 79 - 91 Analysis of nonylphenol and nonylphenol ethoxylates in environmental samples by mixed-mode high-performance liquid chromatography-electrospray mass spectrometry; Ferguson PL et al.; A new method is described based on mixed-mode high-performance liquid chromatography with electrospray mass spectrometry detection for comprehensive quantitative analysis of nonylphenol (NP) and nonylphenol ethoxylates (NPEOs) in wastewater and sediment . Efficient separation, reduced band broadening, and high sensitivity were achieved by employing a methanol-water gradient on a mixed-solvent gel filtration column designed for MS interfacing . Quantitative accuracy and precision of the method were improved by the use of custom-synthesized {13C6}NPEO analogs as isotope-dilution surrogate standards . Method detection limits for NP and individual NPEOs ranged from I to 55 pg injected on column. J Chromatogr A, 2001 Dec 14, 938(1-2), 57 - 65 Quantitative analysis of polycyclic aromatic hydrocarbons in sewage sludge from wastewater treatment plants; Perez S et al.; Polycyclic aromatic hydrocarbons (PAHs) are an important group of organic contaminants present in sewage sludge . Due to their persistence and toxic potential, information about their presence in sewage sludge is needed in order to assess applicability on agricultural land . A method for the gas chromatographic-mass spectrometric (GC-MS) determination was developed and applied to the trace determination of PAHs present in sewage sludge samples from six wastewater treatment plants (WWTPs) differing in the type of treatment and the origin of wastewater . PAHs were extracted from freeze-dried samples by a dichloromethane-methanol (2:1) mixture in a sonication bath . The sludge extracts were cleaned-up by an alumina column . The method showed recovery values varying from 60 to 98% . Four surrogate standards ({2H8}naphthalene, {2H10}anthracene, {2H12}benzo{a}anthracene, and {2H12}benzo{ghi}perylene) were used for quantitation by GC-MS . A reference sludge sample was analysed in order to validate the method . The sum of the 16 US Environmental Protection Agency PAHs analysed in the sewage sludge samples varied from 1.13 to 5.52 mg/kg . No significant difference between the different WWTPs was found. J Chromatogr A, 2001 Dec 14, 938(1-2), 175 - 85 Determination of neutral pharmaceuticals in wastewater and rivers by liquid chromatography-electrospray tandem mass spectrometry; Ternes T et al.; An analytical method is presented enabling the determination of nine neutral pharmaceuticals in groundwater, and for most of the compounds, in rivers and wastewater down to the lower ng/l range . The analytes belong to different medicinal groups such as antiphlogistics, psychiatric drugs and antidiabetics . Samples are enriched using solid-phase extraction (SPE) with RP-C18ec material . Analysis is performed by liquid chromatography with detection by electrospray tandem MS . Mean recoveries generally exceed 80% in groundwater, and the quantification limits are down to 50 ng/l in wastewater and down to 10 ng/l in groundwater . Losses were observed to occur either from ion suppression in the electrospray ionisation or SPE . Losses for all compounds could not be compensated for by the surrogate standard dihydrocarbamazepine . In raw municipal wastewater, concentration levels were detected for caffeine up to 147 microg/l and for propyphenazone up to 1.3 microg/l. Environ Sci Technol, 2001 Dec 1, 35(23), 4691 - 6 Salinity effect on mechanical dewatering of sludge with and without chemical conditioning; Lo IMC et al.; The salinity levels of wastewater and sludge are relatively high in some coastal cities as they may use saline water for toilet flushing, and as such,the sludge dewaterability can be affected by it . The salinity effect on sludge dewaterability was therefore investigated through experimental testing of specific resistance in filtration (SRF), time to filter (TTF), and final solid content of sludge . SRF and TTF were determined using Buchner funnel tests . The final solid content was estimated by centrifuging the sludge at four levels of rotational speed . Sludge with three salinity levels (5,000, 10,000 and 20,000 ppm) were considered in this study . Coagulants such as alum, iron(II) sulfate, and organic polyelectrolytes were added to the sludgetostudythe dewaterability of such sludge with chemical conditioning . Experimental results show that doubling the salinity level of the sludge from 10,000 to 20,000 ppm shows not much change in SRF and TTF . Compared with the sludge without chemical conditioning, the addition of the coagulants to the sludge at a salinity level of 5,000 ppm drastically reduces its SRF and TTF . However, sludge with and without chemical conditioning at a salinity of 20,000 ppm has similar SRF and TTF . The final solid content of sludge increases almost linearly with salinity . Among the coagulants used in this study, the cationic polyelectrolyte is found to be better in improving sludge dewaterability, while iron(II) sulfate performs slightly better in enhancing the final solid content of the sludge. Huan Jing Ke Xue, 2001 Sep, 22(5), 99 - 101 {Degradation of nitrobenzene in water by electrohydrodynamic DC discharge}; Li J et al.; In this paper, the experimental results with respect to the degradation of nitrobenzene in water using electrohydrodynamic DC discharge were presented . The DC voltage was 40 kV, the degradation efficiency in the first discharge process reached 50%, the total degradation efficiency in the second discharge process reached 80% . The products contained acetone . At the same time, the degradation efficiency variation with the voltage polarity, flux, and concentration were studied . These studies will be helpful to the treatment of organic wastewater. Huan Jing Ke Xue, 2001 Sep, 22(5), 87 - 90 {Sulfa-drug wastewater treatment with anaerobic/aerobic process}; Wu L et al.; Sulfa drug wastewater was treated with anaerobic/aerobic process . The removal ratios of TOC reached about 50% in anaerobic phase and about 70% in aerobic phase respectively, while volume loading rate of TOC was about 1.2 kg/(m3.d) in anaerobic phase and about 0.6 kg/(m3.d) in aerobic phase . Removal of TOC in anaerobic phase was attributed to the reduction of sulfate. Huan Jing Ke Xue, 2001 Sep, 22(5), 83 - 6 {The application of air-lift loop column filling with porous carrier in wastewater treatment}; Fan Y et al.; An air lift loop reactor filling with porous carrier particles was utilized as aeration column . Experiments were carried out in wide operating conditions . The experimental results showed that in the range of gas flow rate from 0.117 to 0.156 m3/(min.m3), a higher efficiency of removal of ammonium-N was achieved, and when the gas flow rate was above 0.039 m3/(min.m3), the COD was completely degraded in about 1 h . The filling ratio of the porous carriers in the column was an important factor for the removal of C and N compounds, and a filling ratio of 15% was proved to be most suitable in the operation ranges . The experimental results also indicated that the effect of aeration temperature on the removal efficiency was significant and the highest efficiency was obtained at around 25 degrees C. Huan Jing Ke Xue, 2001 Sep, 22(5), 79 - 82 {Pretreatment of benzoic acid wastewater}; Li Z et al.; The benzoic acid wastewater produced from toluene by liquid-phase oxidation is one of the difficult wastewater to treat because of multi-component, high CODcr value (20,000-100,000 mg/L) and nonbiodegradability . A pretreatment way of this wastewater by extraction based on chemical complexation was carried out, and tributyl phosphate (TBP), trialkylamine (7301) and trialkyphosphine oxide (TRPO) were used as complexing agent with n-octanol, kerosene as cosolvent and diluent respectively . Results showed that benzoic acid was recovery successfully and the CODcr value of wastewater was reduced to 1/6 of the initial value through multi-stages cross-flow extraction . Back-extraction was quite easy and the solvent could be reused. Huan Jing Ke Xue, 2001 Sep, 22(5), 74 - 8 {Recovery of zinc ion and cadmium ion with hollow fiber membrane extraction}; Wang Y et al.; The efficiency of hollow fiber membrane solvent extraction for the system of Meaq/bis(2-ethylhexyl) phosphate in heptane(Me = Cd2+, Zn2+) was studied for wastewater treatment and hydrometallurgy . It was found that the two phases velocity, the initial concentration and the pH value of the aqueous phase greatly influenced the extraction ratio . For very dilute solution with concentration lower than 500 mg/L, the mass transfer resistance was mainly in aqueous phase . When the aqueous phase concentration was relative higher than that of dilute solution, all the individual mass transfer resistances would not be ignored . For the concentrated solution, the mass transfer in the organic phase and the diffusion in membrane pores controlled the transport process . In the back extraction, the mass transfer resistance lied in the organic phase and the diffusion in membrane pores . The experimental results showed that it was possible that the extraction percentage achieved 90% when the metal ion concentration was lower than 400 mg/L . When the cadmium concentration was lower than 200 mg/L, its concentration can decrease 2 orders by extraction in a single-pass flow mode . The values of (HTU)w were between 15 cm and 30 cm, which was much lower than those of traditional extraction columns . The results indicated that membrane extraction with hollow fiber modules could efficiently remove or recover metal ions in the aqueous phases. Huan Jing Ke Xue, 2001 Sep, 22(5), 65 - 9 {Adsorption of weak deep blue GR on hydroxy-aluminum montmorillonite}; Zeng X et al.; Hydroxy-alumium montmorillonite may serve as potential adsorbents for organic pollutants from wastewater . It was synthesized by titrating Na-montmorillonite with hydroxy-aluminum solution (OH-/Al3+ molar ratio was 2.4) . From powder XRD data, it was shown that the interlayer(d001) of montmorillonite was increased greatly from 12.58A to 18.63A . Seven modified montmorillonite samples, including hydroxy-aluminum montmorillonite, were used to remove the dye of weak deep blue GR from water . The results showed that hydroxy-alumium montmorillonite had very high adsorption ability, only 0.0200 g could treat 25 ml weak deep GR with 95% removal . The different adsorption mechanisms of weak deep blue GR on modified montmorillonite: surface adsorption, ion-exchanging and partion, were suggested. Huan Jing Ke Xue, 2001 Sep, 22(5), 60 - 4 {Characteristics of nitrobenzene containing wastewater catalytic oxidation degradation by Fenton reagent}; Wei C et al.; Through the alteration of the concentration of catalyst and oxidant, the rulers and dynamics of nitrobenzene oxidized by Fenton reagent in different concentrations were studied . The correlativity of the reaction time and relatively remain nitrobenzene was analyzed by the unitary linear regress equation . The result of the analysis proves that the coefficient was over the critical constant . The oxidation of nitrobenzene by Fenton reagent was in conformity with first-order dynamics model and the reaction rate constant was got at the same time . The idea, using the complex of Fe as the catalyst replacing Fe2+ in the Fenton Reaction, not only got a higher reaction velocity and efficiency, but also had a distinct exclusive to the degradation of nitrobenzene . The remove velocity of nitrobenzene was improved from 17.48 mg/(L.min) to 71.22 mg/(L.min), the remove rate in 5 minutes was from 9.74% to 91.79% . The nonhomogeneous catalyst made by the artificial zeolite with Fe-complex adsorbed had the same catalyzing behavior . In addition, ultraviolet radiation can also improves the Fenton reaction to some degree . These research works could demonstrate the good application potentiality of Fenton reagent in treating wastewater. Huan Jing Ke Xue, 2001 Sep, 22(5), 45 - 9 {The influence of hydraulic characteristics on wastewater purifying efficiency in vertical flow constructed wetlands}; Wu Z et al.; The hydraulic characteristics of vertical flow constructed wetlands was investigated, and the influence of these characteristics on wastewater purifying efficiency was studied as an emphasis . The results of the experiments in small scale plots and medium scale plots showed the plant roots, with the physical and biological effects, play a significant role in hydraulics and the wastewater purifying efficiency . The other characteristics such as retention time, effluent velocity and influent load also directly affect the wastewater purifying efficiency of constructed wetland . To get a better understanding of the hydraulics will be crucial to the improvement of purifying efficiency and facilitate the practical use of constructed wetland. Fresenius J Anal Chem, 2001 Nov, 371(6), 849 - 54 Multi-element sewer slime impact pattern--a quantitative characteristic enabling identification of the source of heavy metal discharges into sewer systems; Kintrup J et al.; The capability of sewer slime to accumulate heavy metals from municipal wastewater can be exploited to identify the sources of sewage sludge pollution . Former investigations of sewer slime looked for a few elements only and could, therefore, not account for deviations of the enrichment efficiency of the slime or for irregularities from sampling . Results of ICP-MS multi element determinations were analyzed by multivariate statistical methods . A new dimensionless characteristic "sewer slime impact" is proposed, which is zero for unloaded samples . Patterns expressed in this data format specifically extract the information required to identify the type of pollution and polluter quicker and with less effort and cost than hitherto. Water Res, 2002 Jan, 36(1), 95 - 104 Oilfield wastewater treatment by combined microfiltration and biological processes; Campos JC et al.; This work deals with the treatment of offshore oilfield wastewater from the Campos Basin (Rio de Janeiro State, Brazil) . After coarse filtration, this high saline wastewater was microfiltrated through mixed cellulose ester (MCE) membranes, resulting in average removals of COD, TOC, O&G and phenols of 35%, 25%, 92% and 35%, respectively . The permeate effluent was fed into a 1-L air-lift reactor containing polystyrene particles of 2mm diameter, used as support material . This reactor was operated for 210 days, at three hydraulic retention times (HRT): 48, 24 and 12h . Even when operated at the lowest HRT (12 h), removal efficiencies of 65% COD, 80% TOC, 65% phenols and 40% ammonium were attained . The final effluent presented COD and TOC values of 230 and 55 mg/L, respectively . Results obtained by gas chromatography analyses and toxicity tests with Artemia salina showed that a significant improvement in the effluent's quality was achieved after treatment by the combined (microfiltration/biological) process. Water Res, 2002 Jan, 36(1), 257 - 65 A mathematical model of a high sulphate wastewater anaerobic treatment system; Knobel AN et al.; As an aid to the design and operation of anaerobic digesters treating high sulphate waste waters, a mathematical model describing this treatment process has been developed . Apart from sulphate reduction, the model includes those reactions which occur either prior to sulphate reduction or in competition with it . These include, hydrolysis of solid substrates, acidogenesis . beta oxidation of long chain fatty acids, acetogenesis and methanogenesis . By incorporating terms for these reactions the model is able to simulate sulphate reduction using a wide range of carbon sources . Acid/base equilibrium chemistry is included in order to predict the pH and unionized component concentrations, needed for calculating inhibition . An activity based model is used, with the activity coefficients calculated using Debye-Huckle theory . The mass transfer rates of hydrogen, methane, carbon dioxide and hydrogen sulphide from the liquid to the vapour phase are also included . A number of different reactor types may be simulated, including a dynamic batch . steady state CSTR and dynamic CSTR . By separating the hydraulic and solids residence times, high rate reactors such as UASB and packed bed reactors may also be simulated . The model has been used to successfully predict the dynamic and steady state behaviour of a number of different reactor types, utilizing both simple and complex carbon sources. Water Res, 2002 Jan, 36(1), 212 - 8 On-line titration of volatile fatty acids for the process control of anaerobic digestion plants; Feitkenhauer H et al.; The on-line titration of volatile fatty acids (VFA) was found to be a reliable method to measure the substrate (metabolite) concentration without the use of expensive analytical devices . A measurement cell was designed that ensures stable long-term operation, high throughputs and copes with both very low and very high VFA concentrations . Using synthetic textile wastewater, a recalibration of the pH probe was necessary only twice a week . A good reproducibility of the VFA concentrations was determined and standard deviations were below +/- 1% of the measured concentration . Changing salt concentrations of the wastewater in the range of 2.5-150 gl(-1) NaCl did not influence the determined VFA concentration significantly . The method was suitable to control the hydraulic retention time in an acidic phase reactor and to determine the acidification rates of wastewater compounds in batch experiments. Water Res, 2002 Jan, 36(1), 201 - 11 State detection and control of overloads in the anaerobic wastewater treatment using fuzzy logic; Murnleitner E et al.; The two-stage anaerobic wastewater pre-treatment was modelled and controlled . The biological state of the reactors could be predicted using a fuzzy logic system and based upon this, proper control actions were taken automatically in order to avoid an overload . The system was designed to handle very strong fluctuations in the concentration of the substrate and the volumetric loading rate . Hydrogen concentration together with methane concentration, gas production rate . pH and the filling level of the acidification buffer tank were used as input variables for the fuzzy logic system . The manipulated variables were the flow rate from the acidification buffer tank into the methane reactor, the temperature and pH of both reactors, the circulation rate of the fixed bed reactor, back flow from the methane reactor into the acidification, and the control of the feed into the acidification buffer tank . The developed control system was successfully tested on a fully automated lab scale two-stage anaerobic digester . Different types of wastewater from food processing industries were successfully applied . Even a restart of feeding with very high COD concentrations (100 gl(-1) after several days of stand by was handled successfully . Effluent concentrations could be kept low without using TOC, COD or equivalent measurements. Water Res, 2002 Jan, 36(1), 123 - 30 Rejection of organic compounds by ultra-low pressure reverse osmosis membrane; Ozaki H et al.; The introduction of ultra-low pressure reverse osmosis (ULPRO) membrane has widened the horizon of reverse osmosis (RO) in purification of surface water and wastewater as well as desalination of brackish water . The ULPRO membrane chemistry can provide a high water flux at low operating pressure, while maintaining a very good salt and organics rejection . This paper deals with the investigation on the rejection of low molecular weight organic compounds by ULPRO membrane . Laboratory scale experiments were carried out at a pressure of 3 kg/cm2 with a feed flow rate of 1.20 l/min . The rejection of undissociated organic compounds did not show a close relationship with the feed pH . The percentage removal of undissociated organic compounds increased linearly with the molecular weight as well as with the molecular width . The removal efficiency can be predicted by these relationships . But neither molecular weight nor molecular width can be considered as an absolute factor for rejection . The feed pH also influenced the removal efficiency of dissociated organic compounds . The efficiency decreased linearly with the increase in the dissociation constant. Ying Yong Sheng Tai Xue Bao, 2000 Feb, 11(1), 141 - 5 {Biological purification of saline chemical wastewater and variation of algological indicatiors}; Gao Y; Simulation pond experiment shows that from the entrance to the exit of the pond, the concentration of pollutants was decreased, while the species, diversity index and primary productivity of algae were gradually increased with increasing purification duration . The dominant algae species changed from high tolerance species to medium tolerant species . Algae quantity and chlorophyll-a concentration remarkably increased . Through 32 days, the purified water flowed out from the third grade pond . The relationships between algae quantity, biomass and chlorophyll-a concentration and the contents of BOD5, COD, NH3-N and PO4-P could be described with the second order equation . Temperature had an obvious effect on the algae growth and purification effectiveness . The optimum temperature condition for algae growth and wastewater purification was in the range of 20-25 degrees C. Environ Technol, 2001 Oct, 22(10), 1137 - 46 Kinetics of oxidation of odorous sulfur compounds in aqueous alkaline solution with H2O2; Feliers C et al.; Sulfur species oxidation is a crucial issue wastewater treatment . The production of sulfur compounds like H2S,CH3SH, C2H5SH, disulfides and dimethyle sulfide generates odorous nuisances for the neighborhood . The oxidation of these species by H2O2 in alkaline solution has been investigated . The results showed that thiols CH3SH and C2H5SH react with H202 only in their dissociated form RS- with rate constants respectively k = 8.81 +/- 0.48 M-1s-1 and 8.37 +/- 0.63 M-1.s-1 . Mercaptans oxidation produces 100 % of dimethyldisulfide or diethyldisulfide . The oxidation of disulfides shows a difference of reactivity between H2O2 and HO2- towards sulfur species . Increasing the pH accelerates significantly the reactions in the case of CH3SSCH3 . The oxidation rate can be described as: r = k{RSSR}{H2O2}{RSSR}{H2O2} + k{RSSR}{HO2-} {RSSR}{HO2-} with k{RSSR}{H2O2} = 1.2 x 10(-4) +/- 0.2 x 10(-4) M-1s-1 and k{RSSR}{HO2-} = 3.4 x 10(-4) +/- 0.6 x 10(-4) M-1.s-1 for CH3SSCH3 . Dimethyl sulfide presents a reactivity different from disulfides . The oxidation rate can also be described as: r = k{CH3SCH3}{H2O21}{CH3SCH3}{H2O2} + k{CH3SCH3}{HO-} {CH3SCH3}{HO2-}, however, oxidation rate decreases with pH increase . k{CH3SCH3}{H2O2} = 12.8 x 10(-3) +/- 0.96 x 10(-3) M-1.s-1 and k{CH3SCH3}{HO2-} = 4 x 10(-3) +/- 0.3 x 10(-3) M-1.s-1. Water Environ Res, 2001 Sep-Oct, 73(5), 622 - 32 Upflow anaerobic sludge blanket treatment of starch wastewater containing cyanide; Annachhatre AP et al.; Treatment of tapioca starch wastewater containing cyanide using an upflow anaerobic sludge blanket (UASB) process was investigated . Sludge from an anaerobic lagoon treating tapioca starch wastewater was used as seed . Performance of the UASB reactor with influent cyanide concentrations up to 25 mg/L was assessed . The inhibitory effects of cyanide were temporary and reversible . The process required longer recovery period for higher cyanide dosage . For 25 mg/L of cyanide concentration in the feed, the reactor required 15 days for complete recovery . Process performance was sensitive to operating parameters such as upflow velocity, cyanide loading rate, and chemical oxygen demand (COD) loading rate . A maximum cyanide loading rate of 0.38 kg/m3 x d was achieved in the process at a COD loading rate of 50 kg COD/m3 x d . Experiments with tapioca starch wastewater containing up to 10 mg/L of cyanide yielded satisfactory cyanide removal of approximately 93 to 98% and gas productivity of 7.5 m3/m3 x d with a COD loading rate of 30 to 40 kg COD/m3 x d. Water Environ Res, 2001 Sep-Oct, 73(5), 597 - 606 Time-dependent retardation model for chemical oxygen demand removal in a subsurface-flow constructed wetland for winery wastewater treatment; Shepherd HL et al.; The relative success of chemical oxygen demand (COD) removal models to describe measured rates of COD removal in a pilot-scale constructed wetland designed for treatment of high-strength winery wastewater are evaluated using retention times determined from tracer studies . Not surprisingly, two-parameter residual and retardation models better fit the measured removal data than single-parameter, first-order decay models for wastewater at average COD loadings up to nearly 5000 mg/L . The residual and retardation models yielded nearly equivalent fits to the measured data . However, the retardation model had more consistent parameters for COD removal data across different depth levels in the constructed wetland and at different loadings, and a slightly smaller sum of least-squared errors . The retardation model seems to be appropriate for constructed wetland design because it allows a steady decrease in COD with increased treatment time rather than a constant residual COD (C*) value . From the least-squares optimization procedure used to estimate model parameters (a volumetric rate constant, Kv, range of 3 to 12 d(-1)), nonrealistic, or physically meaningless, large C* values (C* range of 23 to 450 mg COD/L) that were dependent on COD loading were obtained, potentially underestimating the constructed wetland system's actual winery wastewater treatment potential . The optimal parameters for the retardation model applied to the pilot-scale constructed wetland ranged from 9 to 12 d(-1) for the initial degradation rate constant, Ko, and 2 to 5 d(-1) for the time-based retardation coefficient, b . These values should be verified for full-scale field systems based on field measurements currently underway. Water Environ Res, 2001 Sep-Oct, 73(5), 567 - 74 Anaerobic migrating blanket reactor treatment of low-strength wastewater at low temperatures; Angenent LT et al.; The feasibility of the compartmentalized anaerobic migrating blanket reactor (AMBR) was studied for the treatment of low-strength soluble wastewater under low-temperature conditions . During an operating period of 186 days, a 20-L AMBR was fed nonfat dry milk substrate as a synthetic wastewater at low temperatures (15 and 20 degrees C) . The concentration of the influent was constant at chemical oxygen demand (COD) and 5-day biological oxygen demand (BOD5) concentrations of 600 and 285 mg/L, respectively . The soluble COD (SCOD) removal efficiency was 73% at the end of the operating period (15 degrees C) at a 4-hour hydraulic retention time (HRT), while the total COD (TCOD) removal efficiency was 59% . At a 4-hour HRT, staged conditions promoted complete removal of propionic acid in the final compartments of the reactor . The specific methanogenic activity of granules increased slowly until the end of the operating time, improving the removal rate . Biomass was retained effectively, as evidenced by the solids retention time (SRT) that was always greater than 50 days even during step decreases of the reactor HRT from 12 hours to 4 hours . A long SRT also promoted system stability during changes in flow, which was observed by SCOD removal efficiencies staving greater than 70% . During a hydraulic stress test, the HRT was reduced from 4 hours to 1 hour for one day (24 HRTs) in which volatile suspended solids (VSS) in the effluent increased from an average background level of 8.7 g/d to 35 g/d and the SRT decreased from 50.5 days to 12.6 days . However, mixed liquor volatile suspended solids concentration decreased only by 1 g/L, and hence a similar COD removal efficiency and biogas production was found one day after the hydraulic stress (as compared to one day before the hydraulic stress). Space Med Med Eng (Beijing), 1999 Feb, 12(1), 46 - 50 {Biological effects of space flight on purple nonsulfur photosynthetic bacteria}; Yang HF et al.; Objective: To study biological effects of space flight on purple nonsulfur photosynthetic bacteria . Methods: Two purple nonsulfur photosynthetic bacteria, Rhodopseudomonas palustris H3 and Rhodobacter sphaeroides ZGY, were carried on satellite for 15 days and some of their biological effects were studied after recovery . Results: In space condition, survival rate of bacteria was promoted . The purification of organic wastewater, removal of nitrite, degradation of phenol and decolorization of acid red B were enhanced, and the resistance of both strains to medicine was stable . Conclusion: The major morphological and physiological characteristics of loaded strains H3-S and ZGY-S were not changed after space flight. J Chromatogr A, 2001 Dec 7, 937(1-2), 21 - 9 Use of porous graphitic carbon coupled with mass detection for the analysis of polar phenolic compounds by liquid chromatography; Vial J et al.; Phenolic compounds present in olive mill wastewater (OMW) need to be quantified because of their pollution capacity toward the environment . In the present study, six representative phenolic compounds of OMW were chosen to develop a LC-MS method . The high polarity of the compounds caused problems when using traditional reversed-phase liquid chromatography (RPLC) . Consequently, a method was developed on another kind of chromatographic phase: Porous Graphitic Carbon (PGC) involving the use of a tetrahydrofuran (THF) gradient . The influence of THF as mobile phase in LC-MS coupling, which is not common practice, was evaluated . In Atmosperic Pressure Chemical Ionisation (APCI) in the negative ion mode, the presence of THF in the mobile phase did not degrade the MS signal of the target compounds in the conditions studied . On the contrary, an improvement was even observed when the percentage of THF increased . The proposed PGC-LC-MS method was selective and linear for the six phenolic compounds analysed with limits of quantification lower than 5 ppm in all cases . The precision was satisfactory (pooled RSD around 6%) . The analyses of OMW matrix spiked sample confirmed the good performance of the proposed method. Mar Pollut Bull, 2001 Nov, 42(11), 1133 - 8 Oxygen, sulphide and nutrient uptake of the mangrove mud clam Anodontia edentula (Family: Lucinidae); Lebata MJ; Oxygen, sulphide and nutrient (ammonia, nitrite and phosphate) uptake of Anodontia edentula was measured . Oxygen and sulphide were measured from sealed containers provided with 1 l fresh mangrove mud (sulphide source) and seawater (oxygen source) with two treatments (with and without clam) at 16 replicates each . Oxygen, sulphide and other parameters were measured at days 1 (initial), 3 and 5 (final) . Nutrients were measured from containers filled with 1.5 l wastewater from a milkfish broodstock tank with two treatments (with and without clam) at eight replicates each . Ammonia, NO2 and P04 were measured at days 0 (initial) 3, 6, 9 and 12 (final) . Results showed significantly decreasing oxygen and sulphide concentrations in treatment with clams (ANOVA, p < 0.001) . A significantly higher ammonia concentration (ANOVA, p < 0.05) was observed in treatment with clams while no significant difference was observed in nitrite and phosphate between the two treatments . A decreasing ammonia and an increasing nitrite trend was also observed in both treatments starting at day 3. Mar Environ Res, 2001 Dec, 52(5), 397 - 411 Recent trends in organochlorine residues in mussels (Mytilus edulis) from the Mersey Estuary; Connor L et al.; Blue mussels (Mytilus edulis) taken from several sites in the Mersey Estuary, an urban-industrial water body in NW England, have been analyzed for residues of the persistent organochlorines, DDT, PCB congeners nos . 28, 52, 101, 118, 138, 153 and 180 (ICES7), and alpha-MHCH (alpha-methyl hexachlorocyclohexane) . The concentration range for sigmaPCB (ICES7) was 13.9-34.9 microg kg(-1) in 1994 compared with 9.6-31.9 microg kg(-1) in 1998, whilst the equivalent concentrations of sigmaDDT were 8.9-32.4 microg kg(-1) and 4.5-16.8 microg kg(-1), respectively . The concentration of alpha-MHCH, an organochlorine largely restricted to the Mersey Estuary, was 1.2-11 microg kg(-1) in 1994 and 0.3-1.3 microg kg(-1) in 1998 . At both sampling dates the inner estuary sites of Rock Ferry and Egremont were more contaminated than the outer estuary sites of New Brighton . Dove Point and Caldy Blacks . The lower concentrations of organochlorines in mussels in 1998 compared with 1994 are thought to be early evidence of significant improvements in water quality derived from major capital investment in the treatment of industrial effluents and sewage wastewater, linked to a combination of stricter legislative controls and the environmental benefits from the adoption of new, clean technologies in manufacturing. Analyst, 2001 Nov, 126(11), 2078 - 81 X-ray fluorescence spectrometric determination of sulfur-containing anionic surfactants in water after their enrichment on a membrane filter as an ion-pair complex with a cationic surfactant; Taguchi S et al.; Anionic surfactants containing sulfur in their structure were enriched on a mixed cellulose ester membrane filter (MF) by filtration as an ion-pair complex with a cationic surfactant . After their enrichment, the anionic surfactants were determined by X-ray fluorescence spectrometry of the sulfur enriched on the MF . A linear calibration was obtained over a concentration range from 0.05 to 0.8 mg L(-1) of sodium dodecyl sulfate as a standard material with less than 6% RSD . The detection limit based on 3s for the reagent blank was 2 microg L(-1) . This method is very simple, rapid and highly selective for sulfur-containing surfactants, and does not require any organic solvent extraction . This method was applied to the determination of anionic surfactant in some urban river waters where domestic wastewater was discharged . The results were compared with those obtained by conventional solvent extraction-spectrophotometry . The distribution of the analyte complexes within the MF where the ion-pair was retained is also discussed. Water Res, 2001 Dec, 35(18), 4359 - 69 Transport and fate of Cryptosporidium parvum oocysts in intermittent sand filters; Logan AJ et al.; The transport potential of Cryptosporidiim parvum (C . parvum) through intermittent . unsaturated, sand filters used for water and wastewater treatment was investigated using a duplicated . 2(3) factorial design experiment performed in bench-scale, sand columns . Sixteen columns (dia = 15 cm, L = 61 cm) were dosed eight times daily for up to 61 days with 65,000 C . parvum oocysts per liter at 15 degrees C . The effects of water quality, media grain size, and hydraulic loading rates were examined . Effluent samples were tested for pH, turbidity, and oocyst content . C . parvum effluent concentrations were determined by staining oocysts on polycarbonate filters and enumerating using epifluorescent microscopy . At completion, the columns were dismantled and sand samples were taken at discrete depths within the columns . These samples were washed in a surfactant solution and the oocysts were enumerated using immunomagnetic separation techniques . The fine-grained sand columns (d50 = 0.31 mm) effectively removed oocysts under the variety of conditions examined with low concentrations of oocysts infrequently detected in the effluent . Coarse-grained media columns (d = 1.40 mm) yielded larger numbers of oocysts which were commonly observed in the effluent regardless of operating conditions . Factorial design analysis indicated that grain size was the variable which most affected the oocyst effluent concentrations in these intermittent filters . Loading rate had a significant effect when coarse-grained media was used and lesser effect with fine-grained media while the effect of feed composition was inconclusive . No correlations between turbidity, pH, and effluent oocyst concentrations were found . Pore-sizc calculations indicated that adequate space for oocyst transport existed in the filters . It was therefore concluded that processes other than physical straining mechanisms are mainly responsible for the removal of C . pavum oocysts from aqueous fluids in intermittent sand filters used under the conditions Studied in this research. Water Res, 2001 Dec, 35(18), 4307 - 16 Modelling the sewage discharge and dispersion of Cryptosporidium and Giardia in surface water; Medema GJ et al.; Modelling the discharge of parasitic protozoa into surface water and the dispersion in rivers and streams gives insight into the contribution of the different sources of environmental contamination and in the transmission of these organisms from the point of discharge to drinking water abstraction points and bathing sites . We tested the applicability of emission (PROMISE) and dispersion (WATNAT) models developed for chemical pollutants to describe the environmental behaviour of Cryptosporidium and Giardia in the Netherlands . The annual load of Cryptosporidium and Giardia in domestic wastewater was 3.2 x 10(13) and 3.8 x 10(14) respectively . The majority (85%) of the Cryptosporidium oocysts was discharged with effluent of wastewater treatment plants . while the majority (82%) of the Giardia cysts was discharged with untreated wastewater discharges and sewer overflows . The estimated annual import through the river Rhine and Meuse was 3.2 x 1014 Cryptosporidium oocysts and 2.1 x 10(15) Giardia cysts, of which the river Rhine contributed 87 and 66%, respectively . This outweighed the total load of the discharges of treated and untreated wastewater in the Netherlands . The combination of PROMISE and WATNAT predicted concentrations of Cryptosporidium and Giardia in surface water that were in the same order of magnitude as the concentrations that were observed at 5 of the 6 sites compared . At a site with primarily agricultural contamination, the models predicted concentrations that were 1 10log-unit lower than the observed concentrations . This is a first step in the direction of a quantitative description of the transmission cycle of Cryptosporidum and Giardia through water . The use of these models combines observational occurrence data and experimental data from laboratory survival studies into a single integrated description . The description needs further improvement by incorporation of agricultural run-off and increasing the number and time frame of input monitoring data. Water Res, 2001 Dec, 35(18), 4267 - 76 Pre-acidification in anaerobic sludge bed process treating brewery wastewater; Ahn YH et al.; The effect of pre-acidification on anaerobic granule bed processes treating brewery wastewater was the focus of a comparison study employing two configurations, (a) a single stage upflow anaerobic sludge bed (UASB) and (b) an upflow acidification reactor in series with a methanogenic UASB . The pre-acidification reactor achieved 20 +/- 4% SCOD removal and 0.08 +/- 0.003 L of methane produced per gram of SCOD removal at a hydraulic retention time (HRT) of 0.75-4 h . Butyric acid was not detected and short chain fatty acids (SCFAs) were mainly acetic and propionic acids . The acidification ratio was about 0.42 +/- 0.02g SCFAs as COD,g of influent COD . Both systems' critical loading rate to achieve 80% COD removal was established at 34-39kgCOD/nm3 of total sludge bed volume per day . SCOD removal efficiency of 90 +/- 3% was achieved by both systems at an organic loading rate of 25 +/- 1 kg COD/m3 of total sludge bed volume per day, indicating that the installation of an acidification reactor had no effect in terms of the maximum granular activity, biomass granulation and the settleability of granules . At an organic loading rate of 67 kg COD/m3 of total sludge bed volume per day at an HRT of 1 h, the series system outperformed the single UASB by a removal of 62 compared to 57%. Toxicol Ind Health, 2000 Nov, 16(9-10), 335 - 438 Determination of a site-specific reference dose for methylmercury for fish-eating populations; Shipp AM et al.; Environmental risk-management decisions in the U.S . involving potential exposures to methylmercury currently use a reference dose (RfD) developed by the U.S . Environmental Protection Agency (USEPA) . This RfD is based on retrospective studies of an acute poisoning incident in Iraq in which grain contaminated with a methylmercury fungicide was inadvertently used in the baking of bread . The exposures, which were relatively high but lasted only a few months, were associated with neurological effects in both adults (primarily paresthesia) and infants (late walking, late talking, etc.) . It is generally believed that the developing fetus represents a particularly sensitive subpopulation for the neurological effects of methylmercury . The USEPA derived an RfD of 0.1 microg/kg/day based on benchmark dose (BMD) modeling of the combined neurological endpoints reported for children exposed in utero . This RfD included an uncertainty factor of 10 to consider human pharmacokinetic variability and database limitations (lack of data on multigeneration effects or possible long-term sequelae of perinatal exposure) . Alcoa signed an Administrative Order of Consent for the conduct of a remedial investigation/feasibility study (RI/FS) at their Point Comfort Operations and the adjacent Lavaca Bay in Texas to address the effects of historical discharges of mercury-containing wastewater . In cooperation with the Texas Natural Resource Conservation Commission and USEPA Region VI, Alcoa conducted a baseline risk assessment to assess potential risk to human health and the environment . As a part of this assessment . Alcoa pursued the development of a site-specific RfD for methylmercury to specifically address the potential human health effects associated with the ingestion of contaminated finfish and shellfish from Lavaca Bay . Application of the published USEPA RfD to this site is problematic; while the study unde