Water Sci Technol, 2002, 45(12), 119 - 26 PHA (polyhydroxyalkanoate) production potential of activated sludge treating wastewater; Takabatake H et al.; The main purposes of wastewater treatment systems are to remove organic pollutants, but it would be very attractive if there were a way to recover the organic pollutants as valuable organic materials . One of the possible ways to recover organic pollutants in wastewater is to convert them into polyhydroxyalkanoates (PHAs), which are biodegradable plastics . In this study, 18 activated sludge samples in 4 wastewater treatment plants (WWTPs) in Tokyo, Japan, were evaluated for their potential to produce PHAs by aerobic batch experiments with excess supply of acetate as the sole carbon source . The activated sludge samples tested had the capability to accumulate PHA up to 18.8% of dry cell weight on average, with the range of 6.0% to 29.5% . The results showed that the maximum PHA content was dependent on the influent more than on the operational conditions of the activated sludge, and that conventional activated sludge produced PHA as much as anaerobic-aerobic activated sludge did . The PHA content achieved in this study is still low, and further improvement is needed to put into practice the recovery process of organic pollutants as biodegradable plastics by activated sludge. Appl Environ Microbiol, 2002 Sep, 68(9), 4629 - 36 Abundance and phylogenetic affiliation of iron reducers in activated sludge as assessed by fluorescence in situ hybridization and microautoradiography; Nielsen JL et al.; Microautoradiography (MAR) was used to enumerate acetate-consuming bacteria under Fe(III)-reducing conditions in activated sludge . This population is believed to consist of dissimilatory iron-reducing bacteria, because the applied incubation conditions and the use of specific inhibitors excluded consumption of radiolabeled acetate by other physiological groups such as sulfate reducers . By use of this approach, dissimilatory iron reducers were found in a concentration of 1.1 x 10(8) cells per ml, corresponding to approximately 3% of the total cell count as determined by DAPI (4',6'-diamino-2-phenylindoledihydrochloride-dilactate) staining . The MAR enumeration method was compared to the traditional most-probable-number (MPN) method (FeOOH-MPN) and a modified MPN method, which contains Ferrozine directly within the MPN dilutions to determine the production of small amounts of ferrous iron (Ferrozine-MPN) . The Ferrozine-MPN method yielded values 6 to 10 times higher than those obtained by the FeOOH-MPN method . Nevertheless, the MAR approach yielded counts that were 100 to 1,000 times higher than those obtained by the Ferrozine-MPN method . Specific in situ Fe(III) reduction rates per cell (enumerated by the MAR method) were calculated and found to be comparable to the respective rates for pure cultures of dissimilatory iron-reducing bacteria, suggesting that the new MAR method is most reliable . A combination of MAR and fluorescence in situ hybridization was used for phylogenetic characterization of the putative iron-reducing bacteria . All activated-sludge cells able to consume acetate under iron-reducing conditions were targeted by the bacterial oligonucleotide probe EUB338 . Around 20% were identified as gamma Proteobacteria, and 10% were assigned to the delta subclass of Proteobacteria. Anal Bioanal Chem, 2002 Apr, 373(8), 704 - 9 Epub 2002 Jul 25. Analysis and toxicity of methomyl and ametryn after biodegradation; Farre M et al.; The controlled biodegradation of ametryn and methomyl has been performed, in accordance with the OECD Zahn-Wellens/EMPA procedure, by use of an enriched mixture of activated sludge collected from three domestic waste-water-treatment plants (WWTP) . During the process concentrations of ametryn and methomyl in the water samples were isolated by solid-phase extraction (SPE); recovery rates were 98.9 and 93.2 for methomyl and ametryn, respectively . Liquid chromatography-mass spectrometry (LC-MS) was used to determine final pesticide concentrations and for metabolite identification.The efficiency of aerobic biodegradation of ametryn and methomyl was evaluated by measuring both the decrease in the concentration of the pesticides and global properties such as the chemical oxygen demand (COD) . The acute toxicity of ametryn and methomyl was evaluated by use of the ToxAlert100 biological test, which is based on inhibition of the bioluminescence of Vibrio fischeri . There was significant correlation between results from primary and ultimate biodegradation and those from determination of toxicity . Pesticide concentrations were always reduced to below the limit of detection in less than 17 days . High COD removal (90-96%) was achieved in 28 and 18 days for methomyl and ametryn, respectively. Water Res, 2002 Jul, 36(13), 3378 - 86 Biodegradation of oxo-alcohol ethoxylates in the continuous flow activated sludge simulation test; Szymanski A et al.; Biodegradation of two alpha-methyl branched oxo-alcohol ethoxylates (OAE) of different polydispersity: LIAL 125/14 BRD (LIALB) (broad M.W . distribution) and LIAL 125/14 NRD (LIALN) (narrow M.W . distribution), both having an average of 14 oxyethylene subunits (EO) and a C(12-15) alkyl moiety were tested under the continuous flow activated sludge conditions of the classical Husmann plant . Primary biodegradation and concentration of metabolites: free oxo-alcohol fraction (FOA) and poly(ethylene glycols) (PEG), were measured . PEG were divided into two fractions: short-chained PEG (PEGshch) (1-4 EO) and long-chained PEG (PEGlch) (>4 EO) . The indirect tensammetric technique combined with an adequate separation was used for analysis . Central fission was found to be a highly dominating pathway, as is the case with fatty alcohol ethoxylates . OAE are highly primarily biodegraded (above 95%) . High concentrations of FOA and PEG are formed . Once formed the PEGlch are further fragmented into the PEGshch . Free alcohol fraction compounds are biodegraded sooner when alkyl moiety is shorter . OAE polydispersity has an influence on the kinetics of biodegradation; PEG formed from LIALN are biodegraded slower and to a lower degree than those from LIALB. Water Res, 2002 Jul, 36(13), 3364 - 70 Bacteriophages isolated from activated sludge processes and their polyvalency; Khan MA et al.; In this study, bacteriophages were isolated from activated sludge and their host range was studied . Bacterial isolates were obtained from an activated sludge process treating urban sewage, and bacteriophages were obtained by plaque assay using the bacterial isolates obtained in this study as the host . Out of 15 bacteria isolated, 9 supported plaque formation . The host range test was conducted with a combination of 8 bacteriophage isolates and 9 bacterial isolates . All of the 8 bacteriophages tested were found to form plaques on more than 1 host, and 4 of them formed plaques on both gram-positive and gram-negative bacterial isolates . Three of the 8 bacteriophages failed to form plaques on their original bacterial host . The experimental result indicates that bacteriophages are an active part of the activated sludge microbial ecosystem, having a very close ecological relationship with their host bacteria. Water Res, 2002 Jul, 36(13), 3341 - 9 Effect of chromium(VI) on bacterial kinetics of heterotrophic biomass of activated sludge; Stasinakis AS et al.; The effect of hexavalent chromium, Cr(VI), on the maximum specific growth rate, mu(m) and biomass yield, Y(H), of heterotrophic biomass was studied in batch tests conducted under high (= 10) and low (= 1.5) substrate-to-biomass ratios (S0/X0) . The effects of sludge age and biomass acclimatization to Cr(VI) on the bacterial kinetics were also studied . The mu(m) values were determined by measuring oxygen uptake rate (OUR) and volatile suspended solids (VSS) increase . Cr(VI) concentrations equal or greater than 10 mg l(-1) inhibited the growth of unacclimatized activated sludge and caused a significant decrease in mu(m) and Y(H) values . The acclimatization of biomass and the selection of a high operating sludge age reduced the inhibitory effect of Cr(VI) . At a sludge age of 20 days, Cr(VI) concentrations of <10 mg l(-1) stimulated bacterial growth as evidenced by an increase in both the mu(m) and Y(H) values . Determining mu(m) values by OUR and VSS methods, revealed that the presence of Cr(VI) in unacclimatized biomass caused an inhibitory effect mostly on substrate oxidation, while in acclimatized biomass, anabolic pathways were inhibited more. Water Res, 2002 Jul, 36(13), 3245 - 52 A simple empirical model for activated sludge thickening in secondary clarifiers; Giokas DL et al.; A simple empirical model for the thickening function of the activated sludge secondary clarifiers is presented . The proposed approach relies on the integration of previous models and it is based on the phenomenon of dilution of the incoming activated sludge in the feeding well of the settling tanks . The method provides a satisfactory description of sludge stratification within the clarifier . The only requirements are limited to parameters which are readily incorporated into the routine analysis performed in an activated sludge plant, thereby eliminating the need for additional experimental or computational effort . The method was tested in a full-scale activated sludge plant and it was found that it describes fairly well the return sludge concentration, the diluted sludge blanket concentration, the sludge blanket solids concentration and the sludge blanket height of full-scale secondary clarifiers. Microb Ecol, 2002 Jul, 44(1), 69 - 77 Epub 2002 Apr 04. Enhanced phosphate uptake and polyphosphate accumulation in Burkholderia cepacia grown under low pH conditions; Mullan A et al.; Of bacterial cells in a sample of activated sludge, 34% contained detectable intracellular polyphosphate inclusions following Neisser staining, when grown on glucose/mineral salts medium at pH 5.5; at pH 7.5 only 7% of cells visibly accumulated polyphosphate . In a sludge isolate of Burkholderia cepacia chosen for further study, maximal removal of phosphate and accumulation of polyphosphate occurred at pH 5.5; levels were up to 220% and 330% higher, respectively, than in cells grown at pH 7.5 . During the early stationary phase of growth at pH 5.5 a maximum level of intracellular polyphosphate that comprised 13.6% of cellular dry weight was reached . Polyphosphate kinase activity was detected in actively growing cells only when cultured at pH 5.5 . The phenomenon of acid-stimulated phosphate uptake and polyphosphate accumulation in this environmental bacterial population parallels observations previously made by us in the yeast Candida humicola and may thus represent a widespread microbial response to low external pH values. Microbiology, 2002 Aug, 148(Pt 8), 2299 - 307 Functional analysis of microbial communities in aerobic-anaerobic sequencing batch reactors fed with different phosphorus/carbon (P/C) ratios; Kong YH et al.; Fluorescence in situ hybridization (FISH) was used to analyse the community composition of a sequencing batch reactor (SBR) operating with aerobic-anaerobic cycling and fed acetate as its sole carbon source . Phosphorus was removed from the SBR microbiologically . Marked shifts in the community structure occurred as the phosphorus/carbon (P/C) ratio in the feed was changed . When the P/C ratio was shifted from 1:10 to 1:50, FISH analysis showed that the percentage of beta-Proteobacteria fell from ca 77% of the total bacteria to ca 38% . This decrease in the beta-Proteobacteria coincided with a reduction in both the proportions of the beta-proteobacterial Rhodocyclus-related phosphorus-accumulating bacteria and the biomass phosphorus content . FISH/microautoradiography and FISH/poly beta-hydroxyalkanoate (PHA) staining showed that the Rhodocyclus-related bacteria assimilated acetate and synthesized PHAs anaerobically, and that they accumulated phosphorus aerobically . No Acinetobacter spp . could be detected in any of the communities, casting further doubt on their role in phosphorus-removing activated sludge systems . As the feed P/C ratio decreased there was a corresponding increase in the proportion of alpha-Proteobacteria and, to a smaller extent, in the proportion of gamma-Proteobacteria; both the alpha- and gamma-Proteobacteria consisted mostly of tetrad-forming cocci, fitting the description of the so-called 'G-bacteria' morphotype . The change in the proportions of Proteobacteria present paralleled increases in the biomass glycogen content . Both the alpha- and beta-proteobacterial 'G-bacterial' populations assimilated acetate and synthesized PHA anaerobically . The alpha-Proteobacteria are considered responsible for glycogen production in these SBR systems. Appl Microbiol Biotechnol, 2002 Aug, 59(4-5), 605 - 8 Epub 2002 Jun 26. Kinetics of soluble microbial product formation in substrate-sufficient batch culture of activated sludge; Liu Y et al.; The kinetics of soluble microbial product (SMP) formation under substrate-sufficient conditions appear to exhibit different patterns from substrate-limited cultures . However, energy spilling-associated SMP formation is not taken into account in the existing kinetic models and classification of SMP . Based on the concepts of growth yield and energy uncoupling, a kinetic model describing energy spilling-associated SMP formation in relation to the ratio of initial substrate concentration to initial biomass concentration ( S(0)/ X(0)) was developed for substrate-sufficient batch culture of activated sludge, and was verified by experimental data . The specific rate of energy spilling-associated SMP formation showed an increasing trend with the S(0)/ X(0) ratio up to its maximum value . The SMP productivity coefficient ( alpha(p/e)) was defined from the model on the basis of energy spilling-associated substrate consumption . Results revealed that less than 5% of energy spilling-associated substrate consumption was converted into SMP. Water Res, 2002 Jul, 36(12), 3110 - 20 Settling velocities and permeabilities of microbial aggregates; Li XY et al.; The hydrodynamics of microbial aggregates, including settling velocity and permeability features, were investigated through detailed settling experiments . Microbial aggregates ranging from 1.0 to 2.5 mm were generated in a lab-scale sequencing batch reactor (SBR) and also collected from a full-scale activated sludge (AS) treatment process . An apparatus of vertically connected double settling columns, filled with solutions of different densities, was used to measure the settling velocities and thus to characterise the internal permeation of individual microbial aggregates . It was demonstrated that the microbial aggregates were highly porous and fractal . However, their settling velocities observed in deionised water, EDTA and NaCl solutions were only slightly faster than predicted by Stokes' law for identical but impermeable particles . The fluid collection efficiencies calculated from measured settling velocities were less than 0.10 for most microbial aggregates, which was much lower than those previously determined for non-biological aggregates of latex microspheres . It is suggested that microbial aggregates could have a largely reduced permeability, as the pores between the microorganisms in the aggregates may be clogged by the cell's exopolymeric material with the water retained. Water Res, 2002 Jul, 36(12), 3063 - 73 Equilibrium modelling of individual and simultaneous biosorption of chromium(VI) and nickel(II) onto dried activated sludge; Aksu Z et al.; The biosorption of chromium(VI) and nickel(II) ions, both singly and in combination, by dried activated sludge was investigated in a batch system as a function of initial pH and single- and dual-metal ion concentrations . The working initial pH values for single chromium(VI) and nickel(II) biosorptions were determined as 1.0 and 4.5, respectively . It was observed that the co-ion effect on the equilibrium uptake became more pronounced as the co-ion concentration in solution increased and pH level increased for chromium(VI) and decreased for nickel(II) . Adsorption isotherms were developed for both the single- and dual-metal ion systems at these two pH values and expressed by the mono- and multi-component Langmuir and Freundlich adsorption models and model parameters were estimated by the non-linear regression . It was seen that the mono-component adsorption equilibrium data fitted very well to both the mono-component adsorption models for both the components and the pH values studied while the multi-component Freundlich adsorption model adequately predicted the multi-component adsorption equilibrium data at moderate ranges of initial mixture concentrations for both the studied pH values. Water Res, 2002 Jul, 36(12), 2949 - 58 A straight interpretation of the solids flux theory for a three-layer sedimentation model; Wett B; One-dimensional settling models based on the conservation law calculate the flux of particles via discrete horizontal layers . Commonly at least 10 of these spatial elements with constant volume are considered in order to achieve a satisfying fit with data . This paper deals with a conceptual approach of a simplified layer model, its theoretical confirmation and its applicability . The model differs three layers with variable volume--clarification-, hindered settling- and compression zone--which are not derived from numerical requirements but from the basic principles of solids flux theory for batch sedimentation . In accordance to the three types of propagation velocities of solids flux theory--hindered settling, signal speed and propagation of concentration discontinuities--three density layers of settling particles of a suspension have been defined . Model development has focused on a reduction of model complexity for on-line control purpose and for coupling with a biokinetic model . Another intention was the model's universal applicability to both batch and continuous settling in order to compare different types of activated sludge strategies . The model has been evaluated against the analytical solution of the flux function and against data from full-scale SBR experiments and from a secondary clarifier under hydraulic overload. Water Res, 2002 Jul, 36(12), 2931 - 40 The shear sensitivity of activated sludge: an evaluation of the possibility for a standardised floc strength test; Mikkelsen LH et al.; The presence of micron-sized primary particles is critical in many solid/liquid separation processes, and characterisation of stability with respect to the degree of dispersion is therefore relevant . Characterisation of floc strength so far has mainly dealt with the size of flocs and not addressed quantification with respect to primary particles . In the present work floc strength was quantified in terms of the shear sensitivity (kss) as a standardised parameter based on the recent adhesion-erosion model (AE-model) . The shear sensitivity quantifies the degree of dispersion for low total solids contents and intermediate turbulent shear rates . It reflects the affinity of adhesion/erosion of primary particles to and from flocs and thus provides a means of characterising the interaction energy between the sludge colloids. Environ Technol, 2002 Jul, 23(7), 823 - 38 Evaluating sustainable energy strategies for a water utility; Zakkour PD et al.; Research suggests that political will to deliver improvements in the quality of surface water in the UK and across the EU, alongside measures to place tighter controls on the quality of biosolids applied to agricultural land, will augment the levels of energy used in sewage and sludge treatment . This coincides with increasing concerns over the use of fossil fuel derived energy sources and their potential to enhance the Earth's greenhouse effect and promote global climate change, creating a serious paradox for these responsible for managing the aquatic environment . However, previous research also suggests that novel technologies and practices could potentially mitigate the problem in hand . This paper describes the development of a model for estimating future energy use and CO2 emissions in the wastewater treatment sector, and outlines the results of different projections using incumbent and novel practices . Indications are that using incumbent approaches could augment CO2 emissions by 15-30% in the medium- to long-term, while loss of the agricultural sludge route and deployment of an incineration strategy could mean increases are of the order of 50-70% . Alternatively, the construction of a greater number of sludge treatment facilities, with greater biogas recovery, could reduce this burden to around -8 to +7% over the same period, while the realisation of the full potential an anaerobic pre-treatment process could lead to reductions of up to 16% . Nevertheless, some of the options will come at a higher cost than incumbents, and the potential for making the business case for these investments is explored. Environ Technol, 2002 Jul, 23(7), 747 - 55 Microbial community structures of activated sludges dominated with polyphosphate-accumulating bacteria and glycogen-accumulating bacteria; Lee TJ et al.; The microbial community structures of anaerobic-aerobic activated sludges, which are dominated with polyphosphate-accumulating bacteria (PABs) and glycogen-accumulating bacteria (GABs), were investigated by quinone profile method and dual staining DAPI (4',6-diamidino-2-phenylindol dihydrochloride) with fluorescent in situ hybridization (FISH) . For both activated sludges, the predominant bacterial groups were the beta subclass of the Proteobacteria that contained mainly Q-8 as analyzed by the quinone profile method and gram-positive bacteria with a high DNA G+C content based on FISH . A 16S rRNA-targeted oligonucleotide probe (MP2) specific for M . phosphovorus, a known polyphosphate-accumulating bacterium, was also applied to PABs and GABs-enriched activated sludge to evaluate their possible role in the enhanced biological phosphorus removal (EBPR) process . Interestingly, the bacteria that hybridized with the probe specific to M . phosphovorus in the sludge dominated with PABs represent about 6.9% of the total microorganisms . In the sludge dominated with GABs, these bacteria were about 1.9% . These results suggest its possible involvement in the EBPR process. Ultrasonics, 2002 May, 40(1-8), 31 - 5 Ultrasonic cell disruption of stabilised sludge with subsequent anaerobic digestion; Onyeche TI et al.; The world-wide increasing environmental awareness and its subsequent regulations have led to the application of improved technologies in wastewater purification plants . This has resulted in higher wastewater and sludge productions . Sludge is the by-product of such plants and it is not only rich in organic carbon and pathogens but also in heavy metals and other environmental pollutants . In Europe, agricultural application of dried sludge (bio-solids) is confronted with negative reactions from the citizens, governmental organisations, farmers and the food industry . Ultrasonic disruption of sludge is a popular mechanical disruption process in sludge treatment . During ultrasonic treatment, high frequency acoustic signals are used to initiate the cavitation process . The applied ultrasonic field leads to a breakdown of cohesive forces of the liquid molecules resulting in the generation of cavitation bubbles . A shock wave is released by the collapse of the cavitation bubbles and propagates in the surrounding medium forming jet streams that cause the disruption of cells in sludge . Disruption of sludge cells enables the release of light organic substances into the sludge water thereby exposing them for further anaerobic digestion . This paper presents results on the disruption of conventionally stabilised sludge through the application of the ultrasonic field . In order to reduce the specific energy input (i.e . ratio of the consumed energy during ultrasonic disruption to the input sludge mass) and improve biogas production, the total solids content of the stabilised sludge was increased before disruption . The anaerobic digestion of sludge samples was carried out in a set of specially constructed laboratory anaerobic digesters . Results showed that subsequent anaerobic digestion of the ultrasonically disrupted sludge could improve biogas production with reduced sludge quantity that is vital to the economic consideration of the wastewater treatment plants . This process encourages the exploitation of valuable materials and energy from stabilised sewage sludge just before its final disposal . The negative effects of mixing disrupted sludge with its separated sludge water are also shown in this paper . This expresses the microbiological instability of the anaerobic process caused by the mixing process. Water Environ Res, 2002 May-Jun, 74(3), 306 - 15 Investigating a mechanistic cause for activated-sludge deflocculation in response to shock loads of toxic electrophilic chemicals; Bott CB et al.; It is hypothesized that a physiological bacterial stress response mechanism, called the glutathione-gated potassium efflux system, is a significant contributor to activated-sludge deflocculation caused by shock loads of toxic electrophilic chemicals . The results show significant potassium (K+) efflux from activated sludge flocs to the bulk liquid in response to sublethal (concentrations less than that required to reduce the specific oxygen uptake rate by 50%) shock loads of chloro-2,4-dinitrobenzene, N-ethylmaleimide, 2,4-dinitrotoluene, benzoquinone, and cadmium in a bench-scale sequencing batch reactor system . Electrophile-induced K+ efflux was correlated with significant deflocculation, as measured by an increase in effluent volatile suspended solids . The K+ efflux occurred immediately (within minutes) after toxin addition and preceded the observed increase in effluent turbidity . The transport of other cations, including sodium, calcium, magnesium, iron, and aluminum, either to or from the floc structure, was negligible as compared with K+ efflux, and cell lysis was determined to be minimal at the chemical shock loads applied . The current results are the first to suggest that activated-sludge upset (i.e., deflocculation) may be caused by a specific protective stress response in bacteria. Water Environ Res, 2002 May-Jun, 74(3), 221 - 5 Zero-valent iron pretreatment for enhancing the biodegradability of Azo dyes; Perey JR et al.; Azo dyes are a group of chemicals that are largely resistant to aerobic biodegradation and persist in wastewater treatment processes . This study proposed that zero-valent iron can be used to reduce the azo bond, cleaving the dye molecule into products that are more amenable to mineralization by bacteria in biological treatment processes such as activated sludge . Batch anaerobic reduction experiments were performed using two azo dyes, orange G and orange II, to determine reaction kinetics and to identify reduction products . Iron-treated dye solutions were subjected to batch biodegradation tests and respirometric analyses to screen for enhanced biodegradability over parent dyes . Results indicate that treatment of orange G and orange II with scrap iron produces aniline and sulfanilic acid as significant products that are degraded by an acclimated culture within 24 hours . Respirometric data illustrated that iron-treated dye solutions exert a significantly higher biochemical oxygen demand than the solutions containing orange G and orange II, demonstrating that recalcitrant azo dyes can be aerobically biodegraded after iron pretreatment. Int J Syst Evol Microbiol, 2002 Jul, 52(Pt 4), 1141 - 4 Bacillus funiculus sp . nov., novel filamentous isolates from activated sludge; Ajithkumar VP et al.; A novel filamentous Bacillus strain, NAF001T, was reported previously that produces endospores and spore-like resting cells; the latter outgrow by budding . Phylogenetic analysis based on 16S rDNA gene sequences reported in the same paper speculated on the proposal of a novel species for this isolate . This communication describes the DNA-DNA relatedness of strain NAF001T to various members of the genus Bacillus and its whole-cell fatty acid and quinone profiles, in order to authenticate the creation of a novel species, for which the name Bacillus funiculus sp . nov . is proposed . The type strain is NAF001T (= JCM 11201T = CIP 107128T) . Further, features of the binding points between filaments of strain NAF001T that enable it to form extremely long filaments are captured by electron microscopy. Int J Syst Evol Microbiol, 2002 Jul, 52(Pt 4), 1113 - 26 Emended description of the genus Trichococcus, description of Trichococcus collinsii sp . nov., and reclassification of Lactosphaera pasteurii as Trichococcus pasteurii comb . nov . and of Ruminococcus palustris as Trichococcus palustris comb . nov . in the low-G+C gram-positive bacteria; Liu JR et al.; Analyses of 165 rRNA gene sequences, restriction endonuclease digestion fingerprints of 16S-23S intergenic regions, DNA base compositions, fatty-acid profiles, cell-wall chemistry, cell physiology and fermentation end-product composition, along with other biochemical and phenotypic properties, supported the view that Trichococcus flocculiformis EchtT (DSM 2094T), Lactosphaera pasteurii KoTa2T (DSM 2381T), Ruminococcus palustris Z-7189T (DSM 9172T) and an isolate named 'Carnococcus allantoicus' NDP were all very similar and should be merged into a single genus . Detailed characterization of strains Ben 77, Ben 200 and Ben 201 described previously as 'Nostocoida limicola' I, a filamentous bacterium which causes bulking in activated sludge systems, revealed that these strains also belonged to the same genus as T . flocculiformis EchtT, L . pasteurii KoTa2T, R . palustris Z-7189T and 'C allantoicus' NDP . In fact, their shared properties suggested that these strains all belonged to a single species . However, DNA-DNA hybridization data indicated that T . flocculiformis EchtT, all of the 'N . limicola' I isolates and 'C allantoicus' NDP belonged to the same species, whereas L . pasteurii KoTa2T, R . palustris Z-7189T and two new isolates, 37AN3*T and 45AN2, represented three distinct species within the same genus . The priority of the genus name Trichococcus is established and since its validation predates the description of the genus Lactosphaera this name should take precedence . Under certain culture conditions, all of the strains mentioned above could produce chains of cocci . Furthermore, the morphology of T . flocculiformis EchtT could change to a non-filamentous form on certain media . This study proposes that the above strains be reclassified as members of the genus Trichococcus as four species, namely Trichococcus flocculiformis emend . (type strain EchtT = DSM 2094T), Trichococcus pasteurii comb . nov . (type strain KoTa2T = DSM 2381T = ATCC 35945T), Trichococcus collinsii sp . nov . (type strain 37AN3*T = DSM 14526T = ATCC BAA-296T, and Trichococcus palustris comb . nov . (type strain Z-7189T = DSM 9172T). Water Res, 2002 Jun, 36(11), 2920 - 5 Color removal from cotton textile industry wastewater in an activated sludge system with various additives; Pala A et al.; The low biodegradability of many dyes and textile chemicals indicates that biological treatment is not always successful in the treatment of cotton textile wastewater, in terms of color removal . In this study, a specific organic flocculant (Marwichem DEC), powdered activated carbon (PAC), bentonite, activated clay and commercial synthetic inorganic clay (Macrosorb) were directly added into the activated sludge laboratory pilot plant model . Before dosage, the optimum sludge retention time and hydraulic retention time were determined as 30 days and 1.6 days, respectively . The Monod kinetic constants were determined as Y = 0.76 kg MLSS/kg COD, Kd = 0.026 l/day, K(S) = 113.3 mg/L, k = 0.42 l/day and mu(max) = 0.32 kg MLSS/kg COD day . Under these conditions the average COD removal was 94% and color removal was 36% . The addition of these materials did not change COD removal significantly . The most effective materials were found to be DEC and PAC for color removal . While the color removal efficiency for 120 mg/L DEC addition was 78%, it was 65% for 100 mg/L, 77% for 200 mg/L and 86% for 400 mg/L PAC addition . The advantage of DEC compared to PAC was the lower sludge production . Statistical analyses using multiple linear regression indicate that there is no relationship between the effluent color with the influent color and total suspended solids (TSS) for DEC and PAC addition . On the other hand, when only bentonite, activated clay and Macrosorb were added, the effluent color was primarily dependent on the influent color and the TSS concentration had little effect . When the data is examined by using Kruskal-Wallis H and Mann-Whitney U tests and it was found that there was a significant difference between the color data groups. Water Res, 2002 Jun, 36(11), 2878 - 82 Fate of resin acids in pulp mill secondary treatment systems; Makris SP et al.; Profiles of resin and fatty acids (RFAs), COD, and aquatic toxicity were measured across the secondary treatment systems of three pulp mills . The RFAs sorb to suspended solids, principally fiber, and are partially removed through settling . An activated sludge system is more efficient in removing RFAs than an aerated stabilization basin (ASB) because of its higher solids level . Dehydroabietic acid accounts for a significant fraction of the effluent toxicity in the two ASBs studied . The microorganisms in an ASB are unable to respond rapidly to an RFA spill, and effluent toxicity can be elevated for a prolonged period because of hydraulic backmix . The applicability of several laboratory studies to field situations is assessed. J Microbiol Methods, 2002 Oct, 51(2), 141 - 8 Immunomagnetic separation of scum-forming bacteria using polyclonal antibody that recognizes mycolic acids; Morisada S et al.; Mycolic acid-containing bacteria (mycolata) are thought to be involved in scum formation in aeration basins of activated sludge plants due to their ability to produce biosurfactants and their cell surface hydrophobicity . To isolate these bacteria, immunomagnetic separation (IMS) using an anti-mycolic acid polyclonal antibody was investigated . IMS that targeted Gordonia amarae SC1 exhibited a 100% recovery at 5x10(3) CFU ml(-1) . At cell concentration of 7.8x10(6) CFU ml(-1), the recovery was lowered, but 80% of cells were still captured . Effect of bead concentrations on the recovery of SC1 at 10(6) CFU ml(-1) was examined . The results showed that addition of more than 6-7x10(6) beads for 1x10(6) CFU reached a maximum recovery (83%) . Furthermore, the IMS procedure optimized with SC1 cells was tested with another mycolata . The results suggested that variation of the recovery for each mycolata is dependent on the specificity of the polyclonal antibody and that mycolata which are recognized by the antibody can be recovered by this procedure. Environ Microbiol, 2002 Jul, 4(7), 383 - 91 In situ studies of the phylogeny and physiology of filamentous bacteria with attached growth; Thomsen TR et al.; Among the filamentous bacteria occasionally causing bulking problems in activated sludge treatment plants, three morphotypes with attached microbial growth are common, Eikelboom Type 0041, Type 1851 and Type 1701 . A better knowledge of the phylogeny and physiology of these filamentous bacteria is necessary in order to develop control strategies for bulking . In this study we have used a combination of fluorescence in situ hybridization (FISH) and microautoradiography (MAR) to investigate the identity and in situ physiology of the Type 0041-morphotype and its attached bacteria in two wastewater treatment plants . Identification and enumeration of Type 0041 using group-specific 16S rRNA-targeted FISH probes revealed that approximately 15% of the filaments hybridized with a gene probe specific for the TM7 group, a recently recognized major lineage in the bacterial domain . All other filaments morphologically identified as Type 0041 only hybridized to the general bacterial EUB338-probe, indicating that they probably do not belong to commonly isolated bacterial phyla such as the Proteobacteria, Firmicutes, Actinobacteria and Bacteroidetes, for which group-specific probes were used . The phylogenetic heterogeneity of Type 0041 again highlights the inadequacy of a morphology-based classification system . Like the filaments, most of the attached microbial cells were not identified beyond their affiliation to the Bacteria using the group-specific FISH probes . However, several different bacterial phyla were represented in the identified fraction suggesting that the attached microorganisms are phylogenetically diverse . The study of the in situ physiology of Type 0041 using MAR-FISH revealed that both the filaments and the attached bacteria on Type 0041 were versatile in the use of organic substrates and electron acceptors . It was observed that all Type 0041 could consume glucose, but none of the filaments were able to consume acetate under any conditions tested, in contrast to some of the attached bacteria . No significant physiological differences were found between TM7-positive and TM7-negative Type 0041 filaments, and only minor differences were observed between the two treatment plants tested . These are the first data on the physiology of the almost entirely uncharacterized TM7 phylum and show that TM7 filamentous bacteria can uptake carbon substrates under aerobic and anaerobic conditions. Environ Technol, 2002 Jun, 23(6), 677 - 84 Phosphorus removal and greenhouse gas N2O emission in a lime-induced aerobic sludge granule process; Wu XL et al.; Aerobic sludge granulation was achieved in an activated sludge process continuously fed with lime (Ca2+ 100 mg l(-1) influent) every other day . Eighteen days after lime addition, activated sludge granules with the size of 0.5-2.2 mm were formed, which occupied 10-25% of total sludge volume . Sludge volume index (SVI) was reduced to an average of 50 ml g(-1), which increased average sludge concentration to 3.6-5.0 g VSS l(-1), 1.6-2.1 times of that of control . Greenhouse gas N2O emission was also significantly reduced: N2O concentration from the lime-addition reactor was 5-15 ppmv, 47-61% of that of control, Effluent PO4-P concentration was generally lower than 1 mg l(-1) when average influent PO4-P concentration was 6.07-6.37 mg l(-1) . Total phosphorus (TP) and total nitrogen (TN) removal efficiencies were around 89.6% and 14.5-16.1%, over 3.5 and 1 times higher than those of control, respectively . COD removal rate in the lime-addition reactor was 2.05-2.48 kg COD m(-3) d(-1), higher than 1.34-1.61 kg COD m(-3) d(-1) in the control. Appl Microbiol Biotechnol, 2002 Jul, 59(2-3), 361 - 7 Epub 2002 Jun 01. Effects of 2,4-dichlorophenol on activated sludge; Sahinkaya E et al.; The effects of 2,4-dichlorophenol (2,4-DCP) on both acclimated and unacclimated activated sludge were investigated in batch reactors . The IC(50) values on the basis of maximum specific growth rate ( micro(m)), percent chemical oxygen demand (COD) removal efficiency and sludge activity were found to be 72, 60 and 47 mg l(-1), respectively, for unacclimated culture . The percent COD removal efficiencies of unacclimated culture were affected adversely, even at low concentrations, whereas culture acclimated to 75 mg 2,4-DCP l(-1) could tolerate about 200 mg 2,4-DCP l(-1)on the basis of COD removal efficiency . Although yield coefficient values of unacclimated culture increased surprisingly to very high values with the addition of 2,4-DCP, a linear decrease with respect to 2,4-DCP concentrations was observed for acclimated culture . Although no removal was observed with unacclimated culture, almost complete removal of 2,4-DCP up to a concentration of 148.7 mg l(-1) was observed with acclimated culture . It was showed that the culture could use 2,4-DCP as sole organic carbon source, although higher removal efficiencies in the presence of a readily degradable substrate were observed . Culture acclimated to 4-chlorophenol used 2,4-DCP as sole organic carbon source better than those acclimated to 2,4-DCP. Environ Toxicol Chem, 2002 Jul, 21(7), 1338 - 49 Aquatic toxicity of triclosan; Orvos DR et al.; The aquatic toxicity of triclosan (TCS), a chlorinated biphenyl ether used as an antimicrobial in consumer products, was studied with activated-sludge microorganisms, algae, invertebrates, and fish . Triclosan, a compound used for inhibiting microbial growth, was not toxic to wastewater microorganisms at concentrations less than aqueous solubility . The 48-h Daphnia magna median effective concentration (EC50) was 390 microg/L and the 96-h median lethal concentration values for Pimephales promelas and Lepomis macrochirus were 260 and 370 microg/L, respectively . A no-observed-effect concentration (NOEC) and lowest-observed-effect concentration of 34.1 microg/L and 71.3 microg/L, respectively, were determined with an early life-stage toxicity test with Oncorhynchus mykiss . During a 96-h Scenedesmus study, the 96-h biomass EC50 was 1.4 microg/L and the 96-h NOEC was 0.69 microg/L . Other algae and Lemna also were investigated . Bioconcentration was assessed with Danio rerio . The average TCS accumulation factor over the five-week test period was 4,157 at 3 microg/L and 2,532 at 30 microg/L . Algae were determined to be the most susceptible organisms . Toxicity of a TCS-containing wastewater secondary effluent to P . promelas and Ceriodaphnia was evaluated and no observed differences in toxicity between control and TCS-treated laboratory units were detected . The neutral form of TCS was determined to be associated with toxic effects . Ionization and sorption will mitigate those effects in the aquatic compartment. Environ Toxicol Chem, 2002 Jul, 21(7), 1323 - 9 Measurement of triclosan in wastewater treatment systems; McAvoy DC et al.; The objective of this study was to investigate the fate and removal of triclosan (TCS; 5-chloro-2-{2,4-dichloro-phenoxy}-phenol), an antimicrobial agent used in a variety of household and personal-care products, in wastewater treatment systems . This objective was accomplished by monitoring the environmental concentrations of TCS, higher chlorinated derivatives of TCS (4,5-dichloro-2-{2,4-dichloro-phenoxy}-phenol {tetra II}; 5,6-dichloro-2-{2,4-dichloro-phenoxy}-phenol {tetra III}; and 4,5,6-trichloro-2-(2,4-dichloro-phenoxy)-phenol {penta}), and a potential biotransformation by-product of TCS (5-chloro-2-{2,4-dicholoro-phenoxy}-anisole {TCS-OMe}) during wastewater treatment . These analytes were isolated from wastewater by using a C18 solid-phase extraction column and from sludge with supercritical fluid CO2 . Once the analytes were isolated, they were derivatized to form trimethylsilylethers before quantitation by gas chromatography-mass spectrometry . Recovery of TCS from laboratory-spiked wastewater samples ranged from 79 to 88% for influent, 36 to 87% for final effluent, and 70 to 109% for primary sludge . Field concentrations of TCS in influent wastewater ranged from 3.8 to 16.6 microg/L and concentrations for final effluent ranged from 0.2 to 2.7 microg/L . Removal of TCS by activated-sludge treatment was approximately 96%, whereas removal by trickling-filter treatment ranged from 58 to 86% . The higher chlorinated tetra-II, tetra-III, and penta closans were below quantitation in all of the final effluent samples, except for one sampling event . Digested sludge concentrations of TCS ranged from 0.5 to 15.6 microg/g (dry wt), where the lowest value was from an aerobic digestion process and the highest value was from an anaerobic digestion process . Analysis of these results suggests that TCS is readily biodegradable under aerobic conditions, but not under anaerobic conditions . The higher chlorinated closans were near or below the limit of quantitation in all of the digested sludge samples . Based on results from this study, the chlorinated analogues and biotransformation by-product of TCS are expected to be very low in receiving waters and sludge-amended soils. Water Res, 2002 May, 36(9), 2288 - 96 Microbial degradation of quinoline by immobilized cells of Burkholderia pickettii; Jianlong W et al.; A quinoline-biodegrading microorganism was isolated from activated sludge of coke-oven wastewater treatment plant using quinoline as sole carbon and nitrogen source . It is a gram negative, rod-shaped and aerobic strain, which was identified as Burkholderia pickettii . The biodegradation of quinoline was carried out with this isolated strain . Analysis by high performance liquid chromatography and gas chromatography/mass spectrum (GC/MS) revealed that 2-hydroxyquinoline (2-OH-Q) was the first intermediate in the course of quinoline biodegradation . A novel immobilization carrier, that is, polyvinyl alcohol (PVA)-gauze hybrid carrier, was developed . The isolated strain was immobilized by two different immobilizing techniques and used for the quinolinerdegradation . It was found that biodegradation rate of quinoline by the microorganisms immobilized on PVA-gauze hybrid carrier was faster than that by the microorganisms immobilized in PVA gel beads . Kinetics of quinoline biodegradation by cells of Burkholderia pickettii immobilized on PVA-gauze hybrid carrier was investigated . The results demonstrate that quinoline degradation could be described by zero-order reaction rate equation when the initial quinoline concentration was in the range of 50-500 mg l(-1). Water Res, 2002 Apr, 36(8), 2109 - 23 Improving the nitrogen removal efficiency of an A2/O based WWTP by using an on-line knowledge based expert system; Baeza JA et al.; The results obtained using an expert system to control an activated sludge process involving nutrient removal are reported . The study was conducted at a pilot plant using an Anaerobic/Anoxic/Oxic (A2/O) scheme for which a distributed control system was specially developed . The system allows various expert operational approaches to be developed with a view to minimize nitrogen levels in the outlet while using the minimum amount of energy . The proposed distributed control system is supervised by a Knowledge Based Expert System (KBES) constructed with G2 (a tool for expert system development) and permits the on-line implementation of every operating strategy of the experimental system . A set of experiments involving variable loads and flow-rates was carried out . It revealed that the amount of removed nitrogen could be increased by 11% compared to the usual operating conditions . This increase resulted in a decrease in the amount of total nitrogen and ammonium nitrogen in the outlet by 49% and 64%, respectively . These improvements were achieved with little energy cost because the performance of the treatment plant was optimised using operating rules implemented in real time. Water Res, 2002 Apr, 36(8), 2077 - 83 Utilization of a metabolic uncoupler, 3,3',4',5-tetrachlorosalicylanilide (TCS) to reduce sludge growth in activated sludge culture; Chen GH et al.; This paper studies the feasibility of using 3,3',4',5-tetrachlorosalicylanilide (TCS) as a metabolic uncoupler to reduce the sludge growth in activated sludge cultures . The results have confirmed that TCS is an effective chemical agent in limiting the sludge growth when its concentration is >0.4 mg/L . It was demonstrated that TCS was able to reduce sludge growth rate by around 40% when the TCS concentration was 0.8mg/L . It was also revealed that substrate removal capability was not affected adversely by the presence of TCS when TCS was continuously dosed in a range of 0.5-1.0 mg/L during the 30-day operation of activated sludge batch cultures . Such a sludge growth reduction is associated with the enhancement of microbial activities and an increase in the percentage of active bacteria over the total microbial population . In the 30-day operation of the cultures, the TCS dosing at a 1-mg/L level did not undermine the treatment performance in terms of the substrate removal efficiency . This work has demonstrated that it might be feasible to apply TCS in activated sludge systems to limit the excess sludge production. Environ Technol, 2002 May, 23(5), 547 - 51 Measuring and modelling VOC biotransformation rates; Kemp J et al.; A new protocol was used to determine biotransformation rate coefficients for volatile organic compounds in activated sludge systems . The values obtained from the protocol were compared to biotransformation rates obtained from a pilot plant . It was seen that biotransformation rates were easier to obtain from the protocol . Observations also showed that acclimation of the microorganisms to the volatile organic compounds did not change the biotransformation rates . The experimental conditions were then modelled using TOXCHEM+, a mechanistic model to predict volatile organic compound behaviour . The TOXCHEM+ predictions, using system default biotransformation rates, compared favourably with the low biotransformation rates measured by the protocol for bromoform and the chlorinated compounds, while under predicting the biotransformation rates for the non-chlorinated volatile organic compounds. Environ Technol, 2002 Apr, 23(4), 445 - 51 Semi-continuous anaerobic co-digestion of agro-wastes; Misi SN et al.; Anaerobic digestion is a well established process for treating many types of organic waste, both solid and liquid . As such, the digestion of cattle slurries and of a range of agricultural wastes has been evaluated and has been successful . Previous batch studies have shown that multi-component mixtures of agro-wastes can be digested successfully, although with some mixtures a degree of both synergism and antagonism occurred . A continuously stirred tank reactor (15 l) was used as a mesophilic (35 degrees C) anaerobic reactor to examine the effect of treating mixtures of fruit and vegetable wastes, cattle slurry, poultry waste and waste activated sludge in which the proportions of the latter two components only were varied . The retention time was kept at 20 days and the loading rate maintained in the range 1.51-1.89 kg VS m(-3) d(-1) . Increasing the proportion of poultry waste from 0% to 100% improved the methane yield from 0.164 to 0.244 m CH4 kg(-1) VS added, and caused the VS reduction to decrease slightly . There did not appear to be any synergism or antagonism in the mixtures examined. Environ Technol, 2002 Apr, 23(4), 363 - 72 Improvement of primary settling performance with activated sludge; Yetis U et al.; In biological treatment plants employing activated sludge processes, it is possible to recirculate some portion of the waste activated sludge that is not sent to the aeration basin, to the inlet of the primary sedimentation tanks . But in the literature there is no detailed information about the conditions, ratios and the characteristics of the waste sludge that can be recirculated back . However, depending on its settling characteristics, the addition of waste activated sludge to raw wastewater may improve primary settling . Settling tests have shown that the effect of waste activated sludge on primary settling is strongly dependent on the mean cell residence time (or sludge age), theta(c), of the waste activated sludge and also on the suspended solids concentration . Different sludge ages of 4, 6, 8, 10, 14, 20 and 26 days, and for each sludge age at least five different initial suspended solids concentrations were studied . A sludge age of 8-10 days achieved the optimum efficiency in terms of the remaining suspended solids concentration as well as percent-suspended solids removal . Also, the settled sludge volumes were measured throughout the experiments; so, the comparison was made between settled sludge volumes, initial suspended solids (SS) concentrations and theta(c). Sci Total Environ, 2002 May 6, 290(1-3), 59 - 67 Study of the characteristics of CH4 and N2O emission and methods of controlling their emission in the soil-trench wastewater treatment process; Kong HN et al.; In recent years, worldwide concern over global warming has been expressed . It has been reported that domestic wastewater and its treatment processes are sources of CH4 and N2O, designated as greenhouse gases, the reduction of which was noted to be extremely important at the Third Conference of the Framework Convention on Climate Change (Conference Of the Parties; COP3) . Here we report a study of a field that has been unexplored until now: analytical evaluation of the properties of the emission of CH4 and N2O and methods of restricting their emission in soil-trench wastewater treatment processes, the use of which is spreading, mainly in developing nations . The results have provided the following information . A field fact-finding survey has confirmed that soil trenches emit 9.3-13.9 g CH4 m(-3) and 8.2-12.2 gN2O m(-3) in Japan, and 3.0-4.5 g CH4 m(-3) and 3.3-5.0 g N2O m(-3) in China . The emission properties widely vary according to the structure of the treatment system . The conversion ratio for nitrogen in the wastewater influent to N2O by a soil trench is between 2 and a maximum of 8%, and ranges from a few- to several 10-fold as much as that with the activated sludge method, suggesting that this can be a large source of N2O emission . It has also clearly been shown that the aerobic-anaerobic state inside the treatment system is closely related to its CH4 and N2O emission characteristics . By performing ventilation to maintain the oxidation-reduction potential (ORP) near the trench at an aerobic condition of +200 mV or more, the quantities of CH4 and N2O emitted can be reduced by as much as 50% from the levels without this ventilation, and that this can make a large contribution. Chemosphere, 2002 May, 47(7), 765 - 75 Heavy metal extractable forms in sludge from wastewater treatment plants; Alvarez EA et al.; The analysis of heavy metals is a very important task to assess the potential environmental and health risk associated with the sludge coming from wastewater treatment plants (WWTPs) . However, it is widely accepted that the determination of total elements does not give an accurate estimation of the potential environmental impact . So, it is necessary to apply sequential extraction techniques to obtain a suitable information about their bioavailability or toxicity . In this paper, a sequential extraction scheme according to the BCR's guidelines was applied to sludge samples collected from each sludge treatment step of five municipal activated sludge plants . Al . Cd, Co, Cu, Cr, Fe, Mn, Hg, Mo, Ni, Pb, Ti and Zn were determined in the sludge extracts by inductively coupled plasma atomic emission spectrometry . In relation to current international legislation for the use of sludge for agricultural purposes none of metal concentrations exceeded maximum permitted levels . In most of the metal elements under considerations, results showed a clear rise along the sludge treatment in the proportion of two less-available fractions (oxidizable metal and residual metal). Appl Microbiol Biotechnol, 2002 Jun, 59(1), 112 - 7 Epub 2002 Mar 28. Aerobic degradation of 2,4,6-trichlorophenol by a microbial consortium - selection and characterization of microbial consortium; Kharoune L et al.; A microbial consortium that efficiently degrades 2,4,6-TCP (2,4,6-trichlorophenol), as the sole source of carbon and energy under aerobic conditions was selected from municipal activated sludge . Six bacterial strains, designated S(1), S(2), S(3), S(4), S(5) and S(6), were isolated from the selected consortium and five were identified as Sphingomonas paucimobilis (S(2), S(3)), Burkholderia cepacia(S(4)), Chryseomonas luteola (S(5)) and Vibrio metschnikovii (S(6)) . After prolonged cultivation followed by successive transfers, the consortium's degradation ability was improved and reached a specific degradation rate of 34 mg 2,4,6-TCP g(-1) dry weight h(-1) (about 51 mg 2,4,6-TCP g(-1) cell protein h(-1)) . The soluble chemical oxygen demand, chloride and oxygen uptake balance data clearly indicate the complete dechlorination and mineralization of 2,4,6-TCP . The consortium's activity was not inhibited by 2,4,6-TCP concentrations <or=400 mg l(-1) . The highest specific growth rate (micro(max) of 0.01 h(-1)) was achieved at 2,4,6-TCP concentration <or=200 mg l(-1), and the inhibition constant ( K(i)) was 610 mg l(-1) according to the Haldane inhibition kinetic model . An inoculum size up to 120 mg l(-1) cell dry weight is desirable in order to avoid a lag phase and to allow faster degradation of 2,4,6-TCP. Bioresour Technol, 2002 Jun, 83(2), 131 - 8 Operational factors and nutrient effects on activated sludge treatment of Pinus radiata kraft mill wastewater; Diez MC et al.; The biodegradability of Pinus radiata bleached kraft mill wastewater by an activated sludge treatment during a period of 280 days was evaluated . The effect of varying hydraulic retention time (HRT) in the range of 48 to 4.5 h and nitrogen (N) and phosphorus (P) addition on removal of biological oxygen demand (BOD5), chemical oxygen demand (COD), suspended solids (TSS and VSS), total phenolic compounds, tannin and lignin and reduction of toxicity was investigated . Removal of BOD5 was higher than 90% when HRT varied from 16 to 6 h, but decreased when HRT was less than 6 h . Similar performance was observed for COD removal, which was about 60% when HRT was varied from 16 to 6 h . Removal of total phenolic compounds and tannin and lignin was seriously affected by HRT . N and P addition to maintaining a ratio of 100:5:0.3 provided optimal BOD5, COD and suspended solids removal when HRT varied from 16 to 7 h, and no toxicity (using Daphnia) was detected in the treated effluent . When HRT was less than 6 h, the system showed destabilisation and pH, COD, BOD5 and suspended solids removal decreased. Int J Syst Evol Microbiol, 2002 May, 52(Pt 3), 883 - 7 Tetrasphaera elongata sp . nov., a polyphosphate-accumulating bacterium isolated from activated sludge; Hanada S et al.; A new meso-diaminopimelic acid-containing, gram-positive bacterium was isolated from an activated sludge reactor showing enhanced biological phosphorus removal activity . The isolate was an asporogenous oval to rod-shaped bacterium, but occasionally formed clumps . The Neisser staining was positive, suggesting intracellular polyphosphate granules . The isolate was an aerobic chemoheterotroph which was capable of utilizing various sugars, sugar alcohols and organic acids . It contained anteiso-C15:0, iso-C15:0, iso-C14:0 and C16:0 as the major cellular fatty acids, and menaquinone-8(H4) as the major quinone . The G+C content of the genomic DNA was 69.6 mol% . Analysis of the 16S rDNA sequence revealed that the isolate is a new member of the family Intrasporangiaceae . The closest relatives were Tetrasphaera species . On the basis of the phenotypic and phylogenetic distinctiveness of the isolate, it was concluded that the organism represents a new species in the genus Tetrasphaera, for which the name Tetrasphaera elongata sp . nov . is proposed . The type strain is strain Lp2T (= JCM 11141T = DSM 14184T). Ecotoxicol Environ Saf, 2002 May, 52(1), 13 - 20 Studies of masculinization, detoxification, and oxidative stress responses in guppies (Poecilia reticulata) exposed to effluent from a pulp mill; Larsson DG et al.; Potential masculinization, detoxification, and oxidative stress responses were assessed in domesticated female guppies (Poecilia reticulata) exposed for 42 days to diluted effluent from a modern Swedish kraft pulp mill or a model androgen . Methyltestosterone induced male-like coloration and transformation of the anal fin into a gonopodium-like structure . The effluent did not induce any apparent changes of the anal fin morphology; however, the exposed guppies became more colored than control fish, which could be an androgenic response . A better understanding of the physiological mechanisms involved in these responses would be required for a full evaluation . Both primary effluent and effluent which had undergone activated sludge treatment caused a moderate but significant induction of hepatic ethoxyresorufin-O-deethylase (EROD) activity . However, the general toxicity of both effluents was low, as mortality was negligible even at 25% dilutions . There was a continuous production of offspring in all groups (47-62% female fry), except by methyltestosterone-treated females, which did not reproduce . There were no indications that either effluent caused oxidative stress since hepatic glutathione reductase, glutathione S-transferase and DT-diaphorase activities remained unchanged compared with controls. J Environ Sci Health A Tox Hazard Subst Environ Eng, 2002, 37(4), 667 - 78 Influence of supplemental nutrient on aerobic decolorization of acid red 14 in activated sludge; Chen M et al.; Azo dyes are non-biodegradable in the textile effluent under aerobic condition . This study demonstrates that the addition of nutrients leads to degradation of a selected azo dye (AR14), and the major decolorization kinetic pathway of AR14 could be expressed as a pseudo first order kinetic model under the experimental conditions used in this study . An excellent correlation was obtained between the decolorization speed and additional nutrient concentration, as indicated by a coefficient of determination (r2) of 0.9899 . At a higher nutrient concentration, the relatively high color removal rate can be reached up to 92.9% in a short time . The degradation ability of azodye could be changed by supplemental nutrient . The destroy of chromophore was the first step of degradation of azo dye under the aerobic conditions, and the intermediates of the dye had significant toxic to the activated sludge, while AR14 of 150 mg/l had slight inhibitory effect on sludge respiration. Water Sci Technol, 2002, 45(6), 187 - 98 Optimization of activated sludge designs using genetic algorithms; Doby TA et al.; We describe a framework in which a genetic algorithm (GA) and a static activated sludge (AS) treatment plant design model (WRC AS model) are used to identify low cost activated sludge designs that meet specified effluent limits (e.g . for BOD, N, and P) . Once the user has chosen a particular process (Bardenpho, Biodenipho, UCT or SBR), this approach allows the parameterizations for each AS unit process to be optimized systematically and simultaneously . The approach is demonstrated for a wastewater treatment plant design problem and the GA-based performance is compared to that of a classical nonlinear optimization approach . The use of GAs for multiobjective problems such as AS design is demonstrated and their application for reliability-based design and alternative generation is discussed. Southeast Asian J Trop Med Public Health, 2001, 32 Suppl 2, 236 - 9 Examination for intestinal parasites and enteric bacteria in the wastewater and treated wastewater from the city of Chiang Mai, Thailand; Wongworapat K et al.; An attempt to use treated wastewater for agriculture in the Chiang Mai area was made, but the re-use process had to be performed under a condition that limited the risks liable to leave pathogens present in the water . The objective of our study was to examine the intestinal parasites and enteric bacteria in the wastewater and treated wastewater from the Chiang Mai University campus as well as the treated wastewater from the Chiang Mai municipality . The raw wastewater (RW), primary treatment effluent water (PE), treated wastewater using the activated sludge system (AS) from the Chiang Mai University campus and treated wastewater using the aerated lagoon (AL) system from the Chiang Mai municipality were examined for intestinal parasites and enteric bacteria by using the centrifugal sedimentation and conventional methods respectively . The ground water (GW) and the irrigation water (IW) were used for comparison . All kinds of water were collected and examined twice a month for 6 months (February to July 2000) . None of human intestinal parasites were found from any wastewater, whereas the RW and PE water contained hookworm larva, Ascaris egg and Taenia egg on some occasions . A small amounts of pathogenic bacteria that can cause severe diarrhea were detected . Salmonella enteritidis gr E was isolated from the AL water in April, while Vibrio cholerae type O139 was detected from the PE water in June . Some pathogenic bacteria that might cause gastroenteritis, such as Aerobacter spp, Citrobacter spp, Pseudomonas spp and Escherichia coli were also found in all kinds of water . Between the two types of treated wastewater, the bacteria found in AS water was less than that in AL water in terms of both amount and type of bacteria . The treated wastewater from the city of Chiang Mai, compared to natural water such as irrigation water, appears to be safe to use for agriculture. J Microbiol Methods, 2002 Aug, 50(3), 273 - 82 A toxicity testing protocol using a bioluminescent reporter bacterium from activated sludge; Lajoie CA et al.; A protocol for production, storage, and use of Shock 1 (Shk1) bioreporter cells for toxicity monitoring in wastewater treatment facilities was developed . Shk1 is a bioluminescent toxicity bioreporter for activated sludge previously constructed by the incorporation of lux genes into an activated sludge microorganism.A number of factors affecting Shk1 growth and bioluminescence were examined including the growth medium, tetracycline concentration, storage conditions, and test media . Based on the results of these experiments, a toxicity testing protocol was developed that involved growth of cultures in nutrient broth with tetracycline, storage of cultures at 4 degrees C, cell activation by reinoculation into nutrient broth, and toxicity testing by cell injection into the test media . Effective use of this approach required standardized time intervals for cell growth, storage, activation and exposure in the test media.Bioluminescence from Shk1 cells was measured in nutrient broth and influent wastewater and activated sludge mixed liquor from a municipal wastewater treatment plant . Using the Shk1 toxicity testing protocol, Zn EC(50) values for bioluminescence in nutrient broth, influent wastewater, and activated sludge mixed liquor were approximately 42, 7, and 32 mg/l, respectively . Zn concentrations as low as 1 mg/l could be detected in influent wastewater . The detection limit in influent wastewater is below the Zn concentrations typically reported to affect the activated sludge process. Appl Biochem Biotechnol, 2002 Spring, 98-100, 655 - 62 Production of specific copolymers of polyhydroxyalkanoates from industrial waste; Wong PA et al.; Polyhydroxyalkanoates, biodegradable plastics with the desired physical and chemical properties of conventional synthetic plastics, are extensively investigated . In this study, specific bacterial strains produced specific copolymers from food waste . Copolymers of HB and HV (poly{3-hydroxybutyrate-co-3-hydroxyvalerate}) were obtained using various ratios of butyric acid (C4) and valeric acid (C5) as carbon sources . The C4 to C5 ratio affected the melting points of the copolymers . Melting and glass transition temperatures and many other thermal properties are important parameters relative to in-service polymer applications . Higher ratios of butyrate to valerate gave higher melting points . When a mixed culture of activated sludge was employed to produce copolymers using food wastes as nutrients, the obtained copolymers showed various monomer compositions . Copolymers with a higher portion of HV were obtained using soy waste; copolymers with less HV were obtained using malt wastes . Pure strains, (i.e., Alcaligenes latus DSM 1122, and DSM 1124, Staphylococcus spp., Klebsiella spp.) produced specific copolymers from food waste . Only Klebsiella spp . produced different copolymers; the ratios of HB:HV were 93:7 and 79:21 from malt waste and soy waste, respectively . The other strains produced polymers of 100% HB . Selecting industrial food wastes as carbon sources can further reduce the cost of producing copolymers. Appl Biochem Biotechnol, 2002 Spring, 98-100, 1061 - 73 Sphaerotilus natans isolated from activated sludge and its production of poly(3-hydroxybutyrate-co-3-hydroxyvalerate); Liu K et al.; Sphaerotilus natans is a sheathed bacterium existing in the activated sludge of wastewater treatment plants . It is one of the filamentous bacteria causing the bulking and foaming difficulties of activated sludge . Isolating the strain and culturing it in an axenic environment could not only provide the metabolic knowledge of the strains that would be useful in the development of wastewater treatment methods, but also could enable us to gain an understanding of the mechanism by which poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (poly{3-HB-co-3-HV}) is produced by this strain . This article reports the screening and isolation of the strain from the activated sludge using the Nile blue staining method together with Fourier transform infrared analysis . We investigated the ability of the selected strain to produce poly(3-HB-co-3-HV) copolymer using glucose and peptone, or by adding valeric acid or sodium propionate as precursor . Proper precursor feeding could dramatically enhance its 3HV content in the copolymer P(3HB-co-3HV) . By controlling the different feeding times in fed-batch fermentation, different desired copolymers were obtained with 15, 40, and 70% 3HV mole fraction of the copolymer . Polymer properties were analyzed by gas chromatography, differential scanning calorimetry, thermo-gravimetry, and nuclear magnetic resonance analysis. J Appl Toxicol, 2002 May-Jun, 22(3), 173 - 6 Effect of olive mill wastewaters on the oxygen consumption by activated sludge microorganisms: an acute toxicity test method; Paixao SM et al.; The test for inhibition of oxygen consumption by activated sludge (ISO 8192-1986 (E)) was evaluated as a tool for assessing, the acute toxicity of olive mill wastewaters (OMW) . According to the ISO test, information generated by this method may be helpful in estimating the effect of a test material on bacterial communities in the aquatic environment, especially in aerobic biological treatment systems . However, the lack of standardized bioassay methodology for effluents imposed that the test conditions were modified and adapted . The experiments were conducted in the presence or absence of an easily biodegradable carbon source (glucose) with different contact times (20 min and 24 h) . The results obtained showed a remarkable stimulatory effect of this effluent to the activated sludge microorganisms . In fact, the oxygen uptake rate values increase with increasing effluent concentrations and contact times up to 0.98 microl O(2) h(-1) mg(-1) dry weight for a 100% OMW sample, 24 h contact time, with blanks exhibiting an oxygen uptake rate of ca . 1/10 of this value (0.07-0.10) . It seems that the application of the ISO test as an acute toxicity test for effluents should be reconsidered, with convenient adaptation for its utilization as a method of estimating the effect on bacterial communities present in aerobic biological treatment systems . Environ Microbiol, 2002 Mar, 4(3), 158 - 68 Occurrence and activity of Archaea in aerated activated sludge wastewater treatment plants; Gray ND et al.; The occurrence, distribution and activity of archaeal populations within two aerated, activated sludge wastewater treatment systems, one treating domestic waste and the second treating mixed domestic and industrial wastewater, were investigated by denaturing gradient gel electrophoresis (DGGE) analysis of polymerase chain reaction (PCR)-amplified ribosomal RNA gene fragments and process measurements . In the plant receiving mixed industrial and domestic waste the archaeal populations found in the mixed liquor were very similar to those in the influent sewage, though a small number of DGGE bands specific to the mixed liquor were identified . In contrast, the activated sludge treating principally domestic waste harboured distinct archaeal populations associated with the mixed liquor that were not prevalent in the influent sewage . We deduce that the Archaea in the plant treating mixed wastewater were derived principally from the influent, whereas those in the plant treating solely domestic waste were actively growing in the treatment plant . Archaeal 16S rRNA gene sequences related to the Methanosarcinales, Methanomicrobiales and the Methanobacteriales were detected . Methanogenesis was measured in activated sludge samples incubated under oxic and anoxic conditions, demonstrating that the methanogens present in both activated sludge plants were active only in anoxic incubations . The relatively low rates of methanogenesis measured indicated that, although active, the methanogens play a minor role in carbon turnover in activated sludge. Water Res, 2002 Mar, 36(6), 1649 - 50; discussion 1651-2 Comment on "experimental analysis of centrifugal dewatering process of polyelectrolyte flocculated waste activated sludge"; Dick RI; In summary, after supernatant liquid was exhausted in the author's experiments, menisci formed, and shrinkage, not pore evacuation and drying, was the mechanism causing removal of water thereafter . Results of centrifugal filtration experiments cannot be applied to solid bowl centrifugation because solid compression conditions are quite different in the two types of machines. Water Res, 2002 Mar, 36(6), 1493 - 502 An ATP luminescence method for direct toxicity assessment of pollutants impacting on the activated sewage sludge process; Dalzell DJ et al.; An ATP luminescence method was used to determine the toxicity of three reference toxicants to two sources of domestic activated sludge, and an activated sludge from a laboratory model plant . Repeatability in the ATP test was demonstrated for Cr (as K2Cr2O7), Zn (as ZnSO4 x 7H2O), and 3,5-dichlorophenol (3,5-DCP) using each source of activated sludge . The three sources of sludge showed sensitivity to Cr and 3,5-DCP, and insensitivity to Zn using the ATP luminescence method . Sludge source did not appear to effect test response . The toxic response to 3,5-DCP in model and domestic activated sludge was shown to be dependent on sludge solid concentration (measured as total suspended solids, gTSS(-1) . It is recommended that a standard solids concentration is used during toxicity evaluation. Biodegradation, 2001, 12(5), 325 - 35 Bioremediation of diesel-contaminated soils: evaluation of potential in situ techniques by study of bacterial degradation; Gallego JL et al.; The development of a simple laboratory methodology allows the implementation of in situ bioremediation of polluted soils with diesel fuel . In this investigation microbiological and chemical analyses and a suitable bioreactor design, were very useful for suggesting the best ways to improve biodegradation extents in a diesel-enriched soil . Biostimulation with inorganic nitrogen and phosphorus produced the best results in a simple bioreactor, with biodegradation extents higher than 90% after 45 days . Also, the addition of activated sludge from a domestic wastewater plant increased the degradation rate to a great extent . In both cases, microbiological studies showed the presence of Acinetobacter sp . degrading most of the hydrocarbons . Simultaneously, a diesel fuel release (approximately 400,000 l) was studied . Samples taken in polluted soil and water revealed that bacteria from the genus Acinetobacter were predominant . In plate studies, Acinetobacter colonies produced a whitish substance with the characteristics of a biosurfactant . Remarkably, the presence of this product was evident at the field site, both in the riverbanks and in the physical recovery plant . The study of the similarities between laboratory results and the diesel spill site strongly suggested that natural conditions at the field site allowed the implementation of in situ bioremediation after physical removal of LNAPL (light nonaqueous-phase liquids). J Environ Sci Health B, 2002 Jan, 37(1), 53 - 64 Toxicity and biodegradation of diamines; Kim MN et al.; Phytotoxicity and cytotoxicity of 2,4-diaminotoluene (2,4-D), 4,4'-methylenedianiline (4,4-D), and 1,6-hexanediamine (1,6-D) were investigated by observing the germination of young radish seeds and the viability of HeLa cells, respectively . 2,4-D showed the highest, 4,4-D intermediate, and 1,6-D lowest cytotoxicity . However, the phytotoxicity decreased in the order of 4,4-D > 2,4-D > 1,6-D . Contrary to the results previously reported, in the modified Sturm test the activated sludge degraded 2,4-D and 4,4-D as well as 1,6-D without any pre-acclimation . Ochrobacterium antropi was isolated for degradation of 2,4-D and 4,4-D and Pseudomonas citronellolis for 1,6-D degradation . Thielevia sp . was isolated as 2,4-D degrading fungus and Aspergillus sp . as 4,4-D and 1,6-D degrading fungus . The fungi degraded the diamines faster than the bacteria. Water Sci Technol, 2002, 45(6), 99 - 106 Use of phosphorus release batch tests for modelling an EBPR pilot plant; Tykesson E et al.; The aim of this study was to evaluate how routinely performed phosphorus release tests could be used when modelling enhanced biological phosphorus removal (EBPR) using activated sludge models such as ASM2d . A pilot plant with an extensive analysis programme was used as basis for the simulations . Without any calibration the prediction of phosphorus removal was poor and the initial release rates from the simulations were not similar to those found from the laboratory tests . A period with low organic loading was chosen as a calibration period . In this period averages of daily influent measurements were used as influent parameters . First, calibration was performed in order to fit effluent COD and MLVSS in the sludge . Next, the phosphorus content in the sludge was decreased to the measured level by decreasing the fermentation rate . Finally, the initial phosphorus release rate was calculated from a simulated batch test and the PHA uptake rate was increased to fit this release rate with the average initial rates from laboratory batch tests performed during the period . The calibrated model was verified with data from the subsequent period where acetate was dosed. Water Sci Technol, 2002, 45(6), 89 - 97 Wastewater COD characterization: biodegradability of physico-chemical fractions; Ginestet P et al.; Physico-chemical and biological characterization methods were applied to wastewater samples originating from 7 French WWTPs . The settleable fraction (S), unsettleable-coagulable fraction (US-C) and unsettleable-uncoagulable fraction (US-UC) were separated . Special emphasis was put on the determination of hydrolysis kinetics associated with coagulable- and settleable-fractions in order to model their behaviour in activated sludge processes, as both these fractions are influenced by the SRT . The "soluble" fraction (i.e . US-UC) was composed of readily biodegradable COD (2 to 27%), readily hydrolysable COD (37 to 90%) and inerts (2 to 47%) . The "colloidal" fraction (i.e . US-C) was composed of heterotrophic biomass (9 to 24%) and readily hydrolysable COD (6 to 82%), with the rest being inerts or very slowly biodegradable COD (0 to 70%) . The "particulate" fraction (i.e . settleable) was composed of biomass (14 +/- 6%), readily hydrolysable COD (21 +/- 14%), slowly hydrolysable COD (about 45-50%) and 15 to 20% which can be considered as inert matter (X(I)) . "Readily hydrolysable COD" was correctly modeled by a global first-order reaction . First-order constants (KH) were 9 +/- 2 d(-1) for raw-wastewater, 12 +/- 3 d(-1) for primary settled-wastewater and 16 +/- 5 d(-1) for coagulated-wastewater . "Slowly hydrolysable COD" was correctly modeled by a limited surface reaction . Concerning this fraction, the specific hydrolysis rate (kH) ranged from 0.25 to 1.05 d(-1), and the affinity constant (K(X)) ranged from 0.33 to 0.95 gCOD/gCOD based on settleable solids analysis. Water Sci Technol, 2002, 45(6), 61 - 76 The EAWAG Bio-P module for activated sludge model No . 3; Siegrist H et al.; An additional module for the prediction of enhanced biological phosphorus removal is presented on the basis of a calibrated version of ASM3 . The module uses modified processes from ASM2d but neglects the fermentation of readily degradable substrate . Biomass decay is modeled in the form of endogenous respiration as in ASM3 . The glycogen pool and biologically induced P-precipitation is not taken into account . The module was systematically calibrated with experimental data from various batch experiments, a full-scale WWTP and a pilot plant treating Swiss municipal wastewater . A standard parameter set allowed all data to be simulated. Water Sci Technol, 2002, 45(6), 51 - 60 Modelling wastewater transformation in sewers based on ASM3; Huisman JL et al.; A deterministic model for wastewater transformations in the sewer that includes activity in the wastewater and in the sewer wall biofilm was developed . It is based on the Activated Sludge Model No . 3 (ASM3) . The mass transfer processes in the biofilm were modelled with the effectiveness approach . This approach allowed for fast calculation, required only a limited number of parameters and gave good results . The ASM3 related parameters were calibrated and validated with laboratory experiments . An equation for the aeration of the wastewater through the water surface was determined with a method based on the inert gas sulphur hexafluoride . The other model parameters such as wall roughness, attachment of particles to the biofilm and biofilm erosion were calibrated and validated with field experiments in a main sewer . The resulting model described the oxygen concentration and wastewater respiration well . It can be easily linked for integrated urban hydrology modelling with the WWTP Activated Sludge Model and the newly proposed River Water Quality Model No . 1. Water Sci Technol, 2002, 45(6), 41 - 9 Modelling the activated sludge flocculation process combining laser light diffraction particle sizing and population balance modelling (PBM); Nopens I et al.; A technique based on laser light diffraction is shown to be successful in collecting on-line experimental data . Time series of floc size distributions (FSD) under different shear rates (G) and calcium additions were collected . The steady state mass mean diameter decreased with increasing shear rate G and increased when calcium additions exceeded 8 mg/l . A so-called population balance model (PBM) was used to describe the experimental data . This kind of model describes both aggregation and breakage through birth and death terms . A discretised PBM was used since analytical solutions of the integro-partial differential equations are non-existing . Despite the complexity of the model, only 2 parameters need to be estimated; the aggregation rate and the breakage rate . The model seems, however, to lack flexibility . Also, the description of the floc size distribution (FSD) in time is not accurate. Water Sci Technol, 2002, 45(6), 157 - 68 Effect of different carbon sources on aerobic storage by activated sludge; Beccari M et al.; A study of substrate removal by real activated sludge with several synthetic substrates (acetate, ethanol, glutamic acid) and wastewater (raw and filtered) was carried out . Substrate, stored compounds (polyhydroxyalkanoates, PHA and internal carbohydrates), ammonia and oxygen uptake rate (OUR) were analytically determined . Polyhydroxybutyrate (PHB) was stored when the substrate was acetate or ethanol, while no appreciable formation of storage compound was detected using glutamic acid . A low amount of PHB was also formed in tests with raw and filtered wastewater which was probably mainly due to its acetate content . As far as the sum of storage and growth (indirectly estimated through ammonia consumption) did not match the overall solids formation, other unidentified mechanisms of substrate removal were likely to occur (biosorption, accumulation and/or storage of unidentified compounds) . ASM3 and two derived models were used in the interpretation of experimental data with reference to synthetic substrates . With reference to synthetic substrates ASM3 can well describe the experimental data only assuming a stored product formation much higher than the analytically detected one, whereas the model that assumes a parallel growth and storage on the substrate can well describe the observed stored product profile only assuming a direct contribution of growth much higher than estimated from ammonia consumption . The model that assumes an accumulation/biosorption stage as first step of substrate removal can better describe the whole experimentally observed behaviour . However as well as in ASM3 this implies that some fraction of removed COD is still unidentified . With reference to real wastewater where the different phenomena were mixed up due to the presence of several substrates, the different models gave similar results. Water Sci Technol, 2002, 45(6), 145 - 56 Error diagnostics and data reconciliation for activated sludge modelling using mass balances; Meijer SC et al.; Research on activated sludge models is mainly directed towards the reliability and estimation of model coefficients . Model calculations however, rely heavily on accurate determination of operational conditions . Accurate measurement of operational conditions and mass flows is difficult, caused by large (full-scale) process flows and the absence of reliable measurements . Therefore operational data should be verified on (gross) errors before being implemented in model studies . Calibrating a model on erroneous mass flows leads to laborious calibration procedures and moreover, unjustified adaptation of the model (kinetic and stoichiometric) parameters . Gross error detection is possible when there are more measurements than strictly required to solve a system of linear conservation relations (mass balances) . A simple method for error detection is evaluating the mass balance residuals . For over determined systems data accuracy can be improved using balancing methods (i.e . minimising balance residuals) . This is referred to as data reconciliation . A reconciled data set contains fewer errors and is exactly in line with the mass balances of the system . In this paper we describe a method for gross error detection and data reconciliation . It is shown how data reconciliation improves the accuracy of the data set and how the use of a balanced data set simplifies the model calibration procedure . This is demonstrated on the basis of a modelling study of a full-scale WWTP. Water Sci Technol, 2002, 45(6), 13 - 23 Modelling of activated sludge processes with structured biomass; van Loosdrecht MC et al.; Bacterial communities when subjected to feast-famine conditions as occurring in many wastewater treatment systems store substrates as reserve polymers . Including storage polymers in a description of microbial growth processes makes important the choice of kinetic relations . Presently there is no sound description for the diversion of substrate towards biomass growth or substrate storage . Based on observations with pure cultures and mixed cultures growing under dynamic conditions a model is proposed to describe such behaviour . This description is based on the observation that bacteria in order to grow fast have to induce a high level of RNA and proteins in order to allow fast growth . We assume that this protein synthesising system is only induced in the presence of external substrates . Based on this assumption a model structure is proposed and evaluated . It seems that this model can predict the turnover of PHA in the cells correctly, and describes well the overall behaviour mixed culture SBR systems . However especially the growth rate in the famine phase seems to be overestimated . The model defined here is a contribution to a further development of mechanistically based models for activated sludge processes. Water Sci Technol, 2002, 45(6), 127 - 36 A practical protocol for dynamic modelling of activated sludge systems; Hulsbeek JJ et al.; Use of dynamic simulation models has become standard practice in The Netherlands . Since the introduction around 5 years ago more then 100 full scale wastewater treatment plants have been modelled . Initially very different approaches have been used varying in calibration approach, amount of sampling and time investment . Based on the accumulated practical experiences the Dutch Foundation of Applied Water Research STOWA has stimulated the development of a protocol to aid in the set-up and calibration of models for full scale wastewater treatment plants . Herein the aim was to develop a protocol, which in practice was easy to use, minimising time and costs effort, but give a reliable and useable method . In this paper this protocol is briefly described. Water Sci Technol, 2002, 45(6), 115 - 26 Oligonucleotide probe hybridization and modeling results suggest that populations consuming readily degradable substrate have high cellular RNA levels; Frigon D et al.; Analyses based on ribosomal RNA (rRNA)-targeted hybridization performed in our laboratory identified two types of bacterial populations: a population with a high RNA level per biomass and a population with a low level of RNA per biomass . To extend these descriptions, the diurnal dynamics of the RNA pool were monitored by rRNA-targeted oligonucleotide probe membrane hybridization . Under the typical diurnal variation in COD loading rate experienced by municipal wastewater treatment plants, the RNA level of the bacterial population with a high level of RNA per biomass varied with changes in the COD loading rate . Under the same conditions, the RNA level of the population with low RNA level per biomass remained constant . A structured biomass model was developed to describe these data . Substrate COD was divided into a readily biodegradable and a slowly biodegradable COD fraction . It was assumed that two specialized populations coexist in municipal activated sludge treatment systems . One population consumes readily degradable COD and the other consumes slowly degradable COD . According to model simulations, the population consuming readily degradable COD has a high level of RNA per biomass under variable substrate concentrations . Comparatively, the population consuming slowly degradable COD has a low level of RNA level per biomass . Furthermore, model simulations reproduced the two diurnal RNA profiles observed in a full-scale municipal activated sludge system . Therefore, we suggest that two populations can be distinguished in municipal activated sludge systems: a population consuming readily degradable substrate and a population consuming slowly degradable substrate. Water Sci Technol, 2002, 45(6), 107 - 13 Measurement of microorganisms with PHA production capability in activated sludge and its implication in activated sludge model no . 3; Hanada S et al.; In Activated Sludge Model No.3 (ASM3), it is hypothesized that all heterotrophic microorganisms (X(H)) can store substrate . However, in reality, both microorganisms with and without substrate storage capability (X(H/STO) and X(H/S), respectively) could exist . If the ratio of X(H/STO) in activated sludge is influenced by operational and environmental conditions, kSTO (storage rate constant of heterotrophic microorganisms which is defined in ASM3) may not be a universal parameter and can change from case to case . In this study, polyhydroxyalkanoate (PHA) is assumed as the principal storage product, and the ratio of microorganisms with PHA production capability (X(H/PHA)) in various activated sludges was estimated by the dual staining of Nile Blue A (NB) and DAPI . It was shown that the ratio of X(H/PHA) in sludge varied among different municipal and laboratory activated sludges. Water Sci Technol, 2002, 45(6), 1 - 11 Microscopic versus macroscopic biomass models in activated sludge systems; Gujer W; Today's models of activated sludge systems are based on average composition of biomass (macroscopic models) . With the introduction of cell internal storage compounds (structured biomass) in ASM2 and ASM3 cell composition influences the kinetic behavior of activated sludge . Since the kinetics of most processes is not linear, adding up the behavior of individual cells (microscopic models) does not result in the same model prediction as obtained when predictions are made with average cell composition . Based on first simple computations with microscopic models which consider up to 100,000 individual bacteria, differences in model prediction are identified . It becomes clear that kinetic parameters for lumped, macroscopic models are system specific: whereas biomass from SBR systems yields kinetic parameters suited for application in microscopic models--biomass from continuous flow systems can only be used for the calibration of macroscopic models . Application of SBR models to continuous flow systems requires the use of microscopic models. Can J Microbiol, 2002 Mar, 48(3), 245 - 55 Detecting structural and functional differences in activated sludge bacterial communities originating from laboratory treatment of elementally and totally chlorine-free bleaching effluents; Mounteer AH et al.; The ability to differentiate functional and structural diversity of bacterial communities present in activated sludges adapted to elementally (ECF) and totally (TCF) chlorine-free bleaching effluents was evaluated . Community function was evaluated through substrate utilization patterns in BiologGN microplates, and taxonomic structure was evaluated by fluorescent in situ hybridization using probes targeting the Eubacteria; the alpha, beta, and gamma subclasses of the Proteobacteria; and gram-positive bacteria with high GC content . Over 6-week sampling periods, ECF-and TCF-adapted sludge bacterial communities presented reproducible substrate utilization patterns that through principal components (PCs) analysis, separated the ECF samples from the TCF samples . Application of the fluorescent in situ hybridization technique was complicated by the intense autofluorescence of the bleaching effluent sludge samples that interfered with detection of specific hybridization signals . The most notable difference in community structure detected using the chosen set of probes was the relatively greater proportion of cells of the alpha subclass in TCF sludge (27%) than in ECF sludge (6%) . Nonspecific hybridization with beta and gamma probes was relatively high, but both sludges appeared to have similar proportions of cells of the beta (20-22%) and gamma (11-12%) subclasses . The two sludges presented relatively few gram-positive cells with high GC content (<0.2% of eubacterial counts) . Differences in both metabolic potential and taxonomic structure of the microbial communities in the ECF- and TCF-activated sludges were detected . The kinetics of the development of these differences in treatment plants and their relationships with treatment efficiency and production process conditions should now be evaluated. J Ind Microbiol Biotechnol, 2002 May, 28(5), 264 - 7 Cell surface hydrophobicity and mycolic acid composition of Rhodococcus strains isolated from activated sludge foam; Stratton HM et al.; The bacteria causing foaming in activated sludge plants are considered to be hydrophobic, and their hydrophobicity is assumed to be a crucial factor in their foam-forming ability . This study showed no consistent relationship between cell surface hydrophobicity (CSH), as determined by microbial adherence to hydrocarbons, of three Rhodococcus spp . isolated from activated sludge foam and their ability to produce a stable foam . There also appeared to be no correlation between the mycolic acid composition of these strains, in terms of chain length or degree of unsaturation, and either CSH or foaming ability . Zeolite and bentonite successfully prevented foaming by a Rhodococcus sp . in pure culture, which suggests that cell surface charge may also play a role in foam stabilisation. J Appl Microbiol, 2002, 92(5), 837 - 43 Diversity of chromium-resistant and -reducing bacteria in a chromium-contaminated activated sludge; Francisco R et al.; AIMS: This study attempts to establish a relationship between the Cr(VI) resistance of the culturable microbial community and the Cr(VI) resistance and Cr(VI)-reducing ability of representative strains of each population, in order to assess whether these are exclusive characteristics of one microbial group or abilities shared among many groups . METHODS AND RESULTS: A group of 48 Cr(VI)-resistant isolates, with different colony types, was isolated from chromium-contaminated activated sludge . Sodium dodecyl sulphate-polyacrylamide gel electrophoresis protein patterns and fatty acid methyl ester analysis identified six populations, representing 54% of the isolated bacteria, as belonging to the genera Acinetobacter and Ochrobactrum . The remaining populations included strains identified as species of the beta-Proteobacteria and high G + C Gram-positive bacteria . The Cr(VI) resistance and reduction ability of the strains were tested . All but two isolates grew in the presence of 1 mmol l(-1) Cr(VI) . During enrichment, all isolates were able to survive to 2 mmol l(-1) Cr(VI) and complete Cr(VI) reduction was achieved . Representative strains of each population were able to partially reduce (5.4-39.1%) the Cr(VI) present in the growth medium . CONCLUSIONS: Most of the identified isolates have never been reported to be Cr(VI)-resistant and/or Cr(VI)-reducing strains . The mechanisms of Cr(VI) resistance and reduction may differ from group to group; therefore, it is evident that both Cr(VI) resistance and reduction are shared abilities and not an exclusive characteristic of a single group, possibly reflecting horizontal genetic transfer resulting from selective pressure in this contaminated environment . SIGNIFICANCE AND IMPACT OF THE STUDY: To our knowledge, this is the first study of a microbial community under chronic chromate stress and, as the success of microbial-based metal remediation technologies requires a better understanding of the microbial community and the population response to metal stress, it may contribute to the implementation of a strategy of bioremediation of chromate-contaminated environments. J Appl Microbiol, 2002, 92(5), 828 - 36 Microbial quality of wastewater: detection of hepatitis A virus by reverse transcriptase-polymerase chain reaction; Morace G et al.; AIMS: The persistent circulation of hepatitis A virus (HAV) in the Mediterranean area suggests the need for monitoring its presence in the environment . A reverse transcriptase-polymerase chain reaction (RT-PCR) was used to detect the presence of HAV in several consecutive raw sewage and final effluent samples, collected over an 8-month period from an activated sludge treatment plant in southern Italy . METHODS AND RESULTS: Two distinct purification protocols, either based on antigen-capture with monoclonal antibody (AC) or RNA extraction, were compared . The possible influence of the antibody used in the AC phase was evaluated in preliminary experiments on HAV-spiked samples, using two different monoclonal antibodies . Hepatitis A virus RNA was detected in all but one sewage environmental sample examined . The contemporary presence of enteroviruses, reoviruses and phages was observed, while HAV growth in cell culture was hampered . CONCLUSIONS: The RT-PCR technique was confirmed to be a valuable tool for the rapid monitoring of HAV in sewage samples . In addition, this study demonstrated that application of different sample purification methods can result in different levels of sensitivity of the assay and that, in the antigen-capture method, the choice of antibody can have a crucial role . SIGNIFICANCE AND IMPACT OF THE STUDY: This work underlines the need for technical uniformity in environmental studies from different laboratories for a correct and useful comparison of the results. Appl Biochem Biotechnol, 2001 Spring, 91-93, 515 - 24 Production of polyhydroxybutyrate by Bacillus species isolated from municipal activated sludge; Law KH et al.; Plastic wastes are considered to be severe environmental contaminants causing waste disposal problems . Widespread use of biodegradable plastics is one of the solutions, but it is limited by high production cost . Biologic wastewater treatment generates large quantities of biomass as activated sludge . Only a few reports focus on the potential of utilizing resident Bacillus species from activated sludge in polyhydroxbutyrate (PHB) production as well as the production of PHB from food wastes . They have attractive properties such as short generation time, absence of endotoxins, and secretion of both amylases and proteinases that can well utilize food wastes for nutrients, which can further reduce the cost of production of polyhydroxyalkanoates (PHAs) . Two PHA-producing strains, HF-1 and HF-2, were isolated from activated sludge . HF-1 outperformed HF-2 in terms of growth and PHB production in hydrolyzed soy and malt wastes . The isolated bacteria was characterized by DNA sequence alignment . Cell extracts of HF-1 were also compared to Bacillus megaterium cell extracts on sodium dodecyl sulfate polyacrylamide gel electrophoresis . The biopolymers accumulated were analyzed by gas chromatography, nuclear magnetic resonance, and Fourier transform infrared methods. Appl Biochem Biotechnol, 2001 Spring, 91-93, 447 - 57 Removal and recovery of copper (II) ions by bacterial biosorption; Wong MF et al.; Studies were conducted to investigate the removal and recovery of copper (II) ions from aqueous solutions by Micrococcus sp., which was isolated from a local activated sludge process . The equilibrium of copper biosorption followed the Langmuir isotherm model very well with a maximum biosorption capacity (q(max)) of 36.5 mg of Cu2+/g of dry cell at pH 5.0 and 52.1 mg of Cu2+/g of dry cell at pH 6.0 . Cells harvested at exponential growth phase and stationary phase showed similar biosorption characteristics for copper . Copper uptake by cells was negligible at pH 2.0 and then increased rapidly with increasing pH until 6.0 . In multimetal systems, Micrococcus sp . exhibited a preferential biosorption order: Cu approximate to Pb > Ni approximate to Zn . There is virtually no interference with copper uptake by Micrococcus sp . from solutions bearing high concentrations of Cl-, SO4(2-), and NO3- (0-500 mg/L) . Sulfuric acid (0.05 M) was the most efficient desorption medium, recovering >90% of the initial copper sorbed . The copper capacity of Micrococcus sp . remained unchanged after five successive sorption and desorption cycles . Immobilization of Micrococcus sp . in 2% calcium alginate and 10% polyacrylamide gel beads increased copper uptake by 61% . Biomass of Micrococcus sp . may be applicable to the development of potentially cost-effective biosorbent for removing and recovering copper from effluents. Appl Biochem Biotechnol, 2001 Spring, 91-93, 171 - 84 Biosorption of heavy metals by bacteria isolated from activated sludge; Leung WC et al.; Twelve aerobic bacteria from activated sludge were isolated and identified . These included both Gram-positive (e.g., Bacillus) and Gram-negative (e.g., Pseudomonas) bacteria . The biosorption capacity of these strains for three different heavy metals (copper, nickel, and lead) was determined at pH 5.0 and initial metal concentration of 100 mg/L . Among these 12 isolates, Pseudomonas pseudoalcaligenes was selected for further investigation owing to its high metal biosorption capacity . The lead and copper biosorption of this strain followed the Langmuir isotherm model quite well with maximum biosorption capacity (q(max)) reaching 271.7mg of Pb2+/g of dry cell and 46.8 mg of Cu2+/g of dry cell at pH 5.0 . Study of the effect of pH on lead and copper removal indicated that the metal biosorption increased with increasing pH from 2.0 to 7.0 . A mutual inhibitory effect was observed in the lead-copper system because the presence of either ion affected the sorption capacity of the other . Unequal inhibitions were observed in all the nickel binary systems . The increasing order of affinity of the three metals toward P . pseudoalcaligenes was Ni < Cu < Pb . The metal biosorptive potential of these isolates, especially P . pseudoalcaligenes, may have possible applications in the removal and recovery of metals from industrial effluents. FEMS Microbiol Lett, 2002 Feb 5, 207(2), 179 - 83 Phylogeny of the filamentous bacterium Eikelboom Type 1851, and design and application of a 16S rRNA targeted oligonucleotide probe for its fluorescence in situ identification in activated sludge; Beer M et al.; Micromanipulation was used to obtain an isolate (BEN 52) of Eikelboom Type 1851 from a bulking activated sludge plant . Its 16S rDNA sequence reveals its closest relative is 'Roseiflexus castenholzii', a member of the phylum 'Chloroflexi', class 'Chloroflexi', previously called the green non-sulfur bacteria . The 16S rRNA targeted oligonucleotide probe designed for fluorescence in situ hybridisation against this sequence successfully identified filamentous bacteria with the morphological features of Type 1851 in activated sludge samples from plants in several countries and different operational configurations. Appl Microbiol Biotechnol, 2002 Apr, 58(5), 679 - 82 Epub 2002 Feb 14. Degradation of aniline by newly isolated, extremely aniline-tolerant Delftia sp . AN3; Liu Z et al.; A bacterial strain, AN3, which was able to use aniline or acetanilide as sole carbon, nitrogen and energy sources was isolated from activated sludge and identified as Delftiasp . AN3 . This strain was capable of growing on concentrations of aniline up to 53.8 mM (5000 mg/l) . Substituted anilines such as N-methylaniline, N, N-dimethylaniline, 2-methylaniline, 4-methylaniline, 2-chloroaniline, 3-chloroaniline, o-aminoaniline, m-aminoaniline, p-aminoaniline, and sulfanilic acid did not support the growth of strain AN3 . The optimal temperature and pH for growth and degradation of aniline were 30 degrees C and 7.0, respectively . The activities of aniline dioxygenase, catechol 2,3-dioxygenase and other enzymes involved in aniline degradation were determined, and results indicated that all of them were inducible . The K (m) and V (max) of aniline dioxygenase were 0.29 mM and 0.043 mmol/mg protein/min, respectively . The K (m) and V (max) of catechol 2, 3-dioxygenase for catechol were 0.016 mM and 0.015 mmol/mg protein/min, respectively . Based on the results obtained, a pathway for the degradation of aniline by Delftiasp . AN3 was proposed . The importance of the strain to the operation of municipal wastewater treatment plants is discussed. Environ Technol, 2002 Feb, 23(2), 149 - 62 Impact of hydrogen peroxide oxygen transfer tests on the performance of the biological nutrient removal process; Mahendraker V et al.; Knowledge of in-process oxygen transfer is essential to the optimum design and operation of aeration systems in activated sludge processes . In this study, non-steady state H2O2 oxygen transfer tests were performed in a laboratory scale, University of Cape Town configuration biological nutrient removal process (BNR) to measure the in-process oxygen transfer rates . Given the small quantity (about 1 ml @30% concentration) of H2O2 used in the aerobic reactor with a mixed liquor volume of 161 (total system working volume of 33.65 l), no effect on the process performance itself was expected . However, the process performance data obtained indicated results to the contrary . Use of H2O2 in measuring process oxygen transfer rates may not be suitable for BNR processes, as all the major process performance indicators (carbon, nitrogen and phosphorus removal by the system and carbon uptake and phosphorus release in the anaerobic zone) were negatively affected . Evidence in thiswork leads to the conclusion that external addition of H2O2 leads to excessive production of the hydroxyl radical . Since microorganisms do not have enzyme systems capable of acting upon this additional reactive radical, it resulted in loss of process performance . It is also possible that H2O2 could have upset the normal aerobic respiration process by introducing oxidative stress conditions on the catalase, peroxidase and superoxide dismutase enzymes that deal with other oxygen radicals generated as part of the overall process of reducing oxygen to water . Any test that interferes with the system in which the test is being performed is suspect . Therefore, in light of these results, the H2O2 method to test in-process oxygen transfer should be re-evaluated. Anal Bioanal Chem, 2002 Feb, 372(4), 569 - 75 Epub 2001 Dec 21. Metabolites from the biodegradation of pharmaceutical residues of ibuprofen in biofilm reactors and batch experiments; Zwiener C et al.; The three metabolites hydroxyibuprofen (OH-Ibu), carboxyibuprofen (CA-Ibu), and carboxyhydratropic acid (CA-HA), also known from human metabolism of ibuprofen, could be identified in biodegradation experiments . Identification was based on EI mass spectra and comparison with literature data . Detection was performed by selective MS-MS measurements by GC-ion-trap MS and online methylation . Ibuprofen (Ibu), OH-Ibu, and CA-Ibu could be detected with a signal-to-noise ratio of 10:1 at a concentration of 2 nmol L(-1), CA-HA at 0.5 nmol L(-1) . Degradation experiments in both biofilm reactors (BFR) and batch experiments with activated sludge (BAS) reveal OH-Ibu as the major metabolite under oxic conditions, and CA-HA under anoxic conditions . CA-Ibu was found under oxic and anoxic conditions almost only in the BAS . The metabolites together do not account for more than 10% of the initial concentration of Ibu. Water Sci Technol, 2002, 45(4-5), 69 - 76 On-line determination of nitrite in wastewater treatment by use of a biosensor; Nielsen M et al.; A newly developed biosensor for nitrite having a 90% response time of about 1 min was used to monitor nitrite concentration in activated sludge exposed to oxic/anoxic cycles . The NO2- biosensor contains bacteria that reduce NO2-, but not NO3-, to N2O that is subsequently monitored by a built-in electrochemical sensor . Nitrite plus nitrate (NOx-) was simultaneously monitored by a NOx- biosensor . The maximum operational lifetime of the NO2- biosensor was 6 weeks, but much longer lifetimes can be expected as malfunctioning by the 3 sensors used for longer periods was due to either mechanical damage or ineffective internal sterilization during the construction . Insufficiently sterilized sensors became sensitive also to NO3- after some time due to development of NO3(-)-reducing bacterial populations within the sensor . The fraction of NO2- as compared to NO3- in the activ