Water Sci Technol, 2003, 48(11-12), 199 - 206 Treatment of domestic sewage at low temperature in a two-anaerobic step system followed by a trickling filter; Elmitwalli TA et al.; The treatment of domestic sewage at low temperature was studied in a two-anaerobic-step system followed by an aerobic step, consisting of an anaerobic filter (AF) + an anaerobic hybrid (AH) + polyurethane-foam trickling filter (PTF) . The AF+AH system was operated at a hydraulic retention time (HRT) of 3+6 h at a controlled temperature of 13 degrees C, while the PTF was operated without wastewater recirculation at different hydraulic loading rates (HLR) of 41, 15.4 and 2.6 m3/m2/d at ambient temperature (ca . 15-18 degrees C) . The AF reactor removed the major part of the total and suspended COD, viz . 46 and 58% respectively . The AH reactor with granular sludge was efficient in the removal and conversion of the anaerobically biodegradable COD . The AF+AH system removed 63% of total COD and converted 46% of the influent total COD to methane . At a HLR of 41 m3/m2/d, the COD removal was limited in the PTF, while at HLR of 15.4 and 2.6 m3/m2/d, a high total COD removal of 54-57% was achieved without a significant difference between the two HLRs . The PTF was mainly efficient in the removal of particles (suspended and colloidal COD removal were 75-90% and 75-83% respectively), which were not removed in the anaerobic two-step . The overall total COD removal in the AF+AH+PTF system was 85% . Decreasing the HLR from 15.4 to 2.6 m3/m2/d, only increased the nitrification rate efficiency in the PTF from 22% to 60% . Also, at HLR of 15.4 and 2.6 m3/m2/d, PTF showed a similar removal for E . coli by about 2 log . Therefore, the effluent of AF+AH+PTF system can be utilised for restricted irrigation in order to close water and nutrients cycles . Moreover, such a system represents a high-load and a low-cost technology, which is a suitable solution for developing countries. Water Sci Technol, 2003, 48(11-12), 161 - 7 A small scale hydroponics wastewater treatment system under Swedish conditions; Norstrom A et al.; A treatment plant using conventional biological treatment combined with hydroponics and microalgae is constructed in a greenhouse in the area of Stockholm, Sweden . The treatment plant is built for research purposes and presently treats 0.559 m3 of domestic wastewater from the surrounding area per day . The system uses anoxic pre-denitrification followed by aerobic tanks for nitrification and plant growth . A microalgal step further reduces phosphorus, and a final sand filter polishes the water . During a three week period in July 2002 the treatment capacity of this system was evaluated with respect to removal of organic matter, phosphorus and nitrogen . 90% COD removal was obtained early in the system . Nitrification and denitrification was well established with total nitrogen reduction of 72% . Phosphorus was removed by 47% in the process . However, higher phosphorus removal values are expected as the microalgal step will be further developed . The results show that acceptable treatment can be achieved using this kind of system . Further optimisation of the system will lead to clean water as well as valuable plants to be harvested from the nutrient rich wastewater. Water Sci Technol, 2003, 48(11-12), 147 - 52 Intermittent sand filtration for wastewater treatment in rural areas of the Middle East--a pilot study; Sabbah I et al.; This paper concentrates on Intermittent Sand Filtration (ISF) as a polishing stage for effluent from a facultative pond . During the three-year research program, the system operated with an influent flow-rate of 500-1,000 L/day and an average BOD concentration of 200-400 hydraulic and BOD loadings of 110-200 L/m2/day and 20-40 gBOD/m2/day, respectively . Flow to the ISF was applied intermittently with a different number of doses in each run . In addition, the effects of the frequency and the duration of rest periods (no feeding) were studied . Removal of 90-95% of BOD and 75-90% of COD and TSS was achieved consistently throughout the study period . Elevated levels of nitrification were observed with 95-100% removal of NH3 . The ISF performed best when fed with 5-10 doses/day . Reducing the daily number of doses to 3/day at the same hydraulic loading rate resulted in a 20-30% reduction in removal efficiency . The 2-4 week rest period had no effect on the biological activity in the subsequent run . However, rest periods of more than 30 days were found to negatively affect removal efficiency. Lett Appl Microbiol, 2004, 38(2), 106 - 12 Growth kinetics of aerobic granules developed in sequencing batch reactors; Yang SF et al.; AIMS: This paper attempts to develop a kinetic model to describe the growth of aerobic granules developed under different operation conditions . METHODS AND RESULTS: A series of experiments were conducted by using four-column sequencing batch reactors to study the formation of aerobic granules under different conditions, e.g . organic loading rates, hydrodynamic shear forces and substrate N/COD ratios . A simple kinetic model based on the Linear Phenomenological Equation was successfully derived to describe the growth of aerobic granules . It was found that the growth of aerobic granules in terms of equilibrium size and size-dependent growth rate were inversely related to shear force imposed to microbial community, while a high organic loading favoured the growth of aerobic granules, leading to a large size granule . The effect of substrate N/COD ratio on the growth kinetics of aerobic granules was realized through change in microbial populations, and enriched nitrifying population in aerobic granules developed at high substrate N/COD ratio resulted in a low overall growth rate of aerobic granules . CONCLUSIONS: The proposed model can provide good prediction for the growth of aerobic granules indicated by the correlation coefficient >0.95 . SIGNIFICANCE AND IMPACT OF THE STUDY: The kinetic model proposed could offer a useful tool for studying the growth kinetics of cell-to-cell immobilization process . The study confirmed that the growth of aerobic granules and biofilms are subject to a similar kinetic pattern . This work would also be helpful for better understanding the mechanism of aerobic granulation. Environ Manage . 2004 Jan 28; {Epub ahead of print} Effects of Silvicultural Practices on Soil Carbon and Nitrogen in a Nitrogen Saturated Central Appalachian (USA) Hardwood Forest Ecosystem; Gilliam FS et al.; Silvicultural treatments represent disturbances to forest ecosystems often resulting in transient increases in net nitrification and leaching of nitrate and base cations from the soil . Response of soil carbon (C) is more complex, decreasing from enhanced soil respiration and increasing from enhanced postharvest inputs of detritus . Because nitrogen (N) saturation can have similar effects on cation mobility, timber harvesting in N-saturated forests may contribute to a decline in both soil C and base cation fertility, decreasing tree growth . Although studies have addressed effects of either forest harvesting or N saturation separately, few data exist on their combined effects . Our study examined the responses of soil C and N to several commercially used silvicultural treatments within the Fernow Experimental Forest, West Virginia, USA, a site with N-saturated soils . Soil analyses included soil organic matter (SOM), C, N, C/N ratios, pH, and net nitrification . We hypothesized the following gradient of disturbance intensity among silvicultural practices (from most to least intense): even-age with intensive harvesting (EA-I), even-age with extensive harvesting, even-age with commercial harvesting, diameter limit, and single-tree harvesting (ST) . We anticipated that effects on soil C and N would be greatest for EA-I and least with ST . Tree species exhibited a response to the gradient of disturbance intensity, with early successional species more predominant in high-intensity treatments and late successional species more predominant in low-intensity treatments . Results for soil variables, however, generally did not support our predictions, with few significant differences among treatments and between treatments and their paired controls for any of the measured soil variables . Multiple regression indicated that the best predictors for net nitrification among samples were SOM (positive relationship) and pH (negative relationship) . This finding confirms the challenge of sustainable management of N-saturated forests. Water Res, 2004 Feb, 38(3), 523 - 30 Bioaugmentation for nitrification at cold temperatures; Head MA et al.; Bioaugmentation of nitrifying bacteria for short solids retention time (short-SRT) nitrification is an attractive alternative for wastewater treatment plants in cold climates or for those in the process of upgrading to include nitrification . One possible source of ammonia for the production of nitrifying bacteria is the liquor generated during the dewatering of anaerobically digested sludges . The objectives of this study was to determine the impact of sudden decrease in temperature on nitrification rates and to determine if nitrification could be accomplished in sequencing batch reactors (SBRs) at 10 degrees C by seeding nitrifying bacteria acclimated to 20 degrees C . In this research, biomass produced during warm nitrification of dewatering liquor was seeded into cold SBRs at various hydraulic retention times from 43.3 to 96 h . The average decreases in nitrification rates were 58%, 71% and 82% for biomass cooled to 10 degrees C when the biomass was acclimated to 20 degrees C, 25 degrees C and 30 degrees C, respectively . The seeded SRTs of the cold SBRs were raised above the minimum solids retention time (SRT(min)) required for nitrification . Full ammonia nitrogen removal was achieved in cold SBRs that were operated at an apparent SRT less than SRT(min). Huan Jing Ke Xue, 2003 Sep, 24(5), 97 - 101 {Performance and its influencing factors of a zeolite biofilter for dilute domestic wastewater treatment}; Tian W et al.; To reuse dilute domestic wastewater in power plant region as the makeup of recirculating cooling water, a renovate reactor--zeolite media biological aerated filter (ZBAF) was developed . A pilot scale ZBAF of 0.2 m in diameter and 3 m in media height was tested to treat dilute domestic wastewater . The results showed that turbidity, BOD5, CODcr and NH4(+)-N in effluent was 3.2 NTU, 3.2 mg/L, 14.5 mg/L and 0.5 mg/L when the corresponding influent concentration was 59 NTU, 30 mg/L, 81 mg/L and 16 mg/L, respectively, under the conditions of t = 12 degrees C-17 degrees C, HRT = 1.4 h and gas/liquid = 4:1 . The effluent quality met the water quality standards of the treated water reused for cooling water makeup . The removal rate of BOD5, COD and turbidity did not change much with the change of HRT and the ratio of gas to liquid, but NH4(+)-N removal rate changed greatly . The parameters along the depth of ZBAF showed that the biofilm phase was abundant in carbon-oxidation/nitrification(C/N) zone and simplex in nitrification (N) zone . Ciliate was plentiful in C/N zone . Biofilm in N zone was mainly consists of nitrifiers . The point that the number of ciliate decreased apparently was the boundary of the two zones. Huan Jing Ke Xue, 2003 Sep, 24(5), 92 - 6 {Rural sewage treatment performance of constructed wetlands with different depths}; Liu C et al.; The treatment performance, for low concentration rural sewage, through constructed wetlands of different depths(60 cm and 40 cm), was comparatively investigated by using pilot-scale apparatus in Lake Dian-chi area, Yunnan province, China . The experiment results showed, under a high hydraulic loading rate of 30 cm/d, that the removal efficiencies of COD, total nitrogen, ammonia-nitrogen and total phosphorus in the constructed wetland of 60 cm depth were 66.4%, 57.7%, 78.7% and 63.2%, respectively, and were 63.8%, 59.1%, 82.1% and 61.3% in the 40 cm depth, respectively . The removal efficiencies of COD and total phosphorus in the constructed wetland of 60 cm depths were higher than those in the 40 cm depth, but the nitrogen removal efficiency in the latter was higher than that in the former . Nitrogen and phosphorus removal mechanisms were studied . The results showed that nitrogen removal through nitrification/denitrification and the phosphorus removal through absorb and sedimentation were their main removal mechanisms . The nitrogen and phosphorus removed by plant harvesting were amounting to 10% and 9% of input TN and TP, respectively, which was also an important removal pathway for nitrogen and phosphorus. Huan Jing Ke Xue, 2003 Sep, 24(5), 75 - 80 {Effect and mechanism of removal of nitrogen in the mimic sewage using bio-zeolite system}; Zhang X et al.; On the spot, the removal effect of pollutants such as NH3-N, N, NO3(-)-N, NO2-(-)N, TN and COD in the mimic sewage by bio-zeolite system was studied . The following results were obtained: it was obvious and stable for the removal of NH3-N by bio-zeolite with a removal efficiency over 95%, but the removal effect of NO3(-)-N was affected deeply by hydraulic retention time, according to the different removal mechanism; chemical adsorption and ion exchange were the main reasons for the removal of NH3-N as well as nitrification by microbe, while denitrification was the main reason for the removal of NO3(-)-N . Nitrification intensity of bio-zeolite was affected by the concentration of dissolved oxygen in the solution, so the nitrification intensity of bio-zeolite on the surface of the zeolite bed was two times of that in the middle in vertical direction . Denitrification intensity changed with different values of C/N in the study, and it could reach the maximum while COD/TN was 5; as for denitrification velocity, it was largest in the first six hour. Huan Jing Ke Xue, 2003 Sep, 24(5), 70 - 4 {Effects of colloidal organic substrate on nitrification in biofilms}; Li J et al.; The effects of colloidal and soluble organic substrates on nitrification in biofilms were investigated in biological aerated filters . The results showed that the hydrolysis process of colloidal organic matter took place rapidly, which could not be the limiting step of its oxidation in the biofilm . Some 70% organic matter oxidation was accomplished at the 40 cm at the bottom of the both filters, while the increase of organic matter in the influent resulted in the displacement of nitrification from the bottom to the upper part of filter bed . It was observed that the greater reduction on nitrification was caused by colloidal organic matter than by soluble organics at the same COD concentration. J Plant Physiol, 2003 Dec, 160(12), 1517 - 23 Dicyandiamide and 3,4-dimethyl pyrazole phosphate decrease N2O emissions from grassland but dicyandiamide produces deleterious effects in clover; Macadam XM et al.; The application of nitrogen fertilisers leads to different ecological problems such as nitrate leaching and the release of nitrogenous gases . N2O is a gas involved in global warming, therefore, agricultural soils can be regarded as a source of global warming . Soil N2O production comes from both the nitrification and denitrification processes . From an ecological viewpoint, using nitrification inhibitors with ammonium based fertilisers may be a potential management strategy to lower the fluxes of N2O, thus decreasing its undesirable effect . In this study, the nitrification inhibitors (NIs) dicyandiamide (DCD) and 3,4-dimethyl pyrazole phosphate (DMPP) have been evaluated as management tools to mitigate N2O emissions from mineral fertilisation and slurry application in grassland systems (experiments 1 and 2), and to assess the phytotoxic effect of these inhibitors per se on clover (experiment 3) . Both nitrification inhibitors acted in maintaining soil nitrogen (N) in ammonium form, decreasing cumulative N2O emissions . DCD, but not DMPP, produced phytotoxic effects and yield reduction in white clover . A nutrient imbalance, which led to a senescence process visually observed as chlorosis and necrosis at the border of the leaves, was noted. Biotechnol Bioeng, 2004 Jan 5, 85(1), 86 - 95 Analysis of size distribution and areal cell density of ammonia-oxidizing bacterial microcolonies in relation to substrate microprofiles in biofilms; Okabe S et al.; A fine-scale in situ spatial organization of ammonia-oxidizing bacteria (AOB) in biofilms was investigated by combining molecular techniques (i.e., fluorescence in situ hybridization (FISH) and 16S rDNA-cloning analysis) and microelectrode measurements . Important parameters of AOB microcolonies such as size distribution and areal cell density of the microcolonies were determined and correlated with substrate microprofiles in the biofilms . In situ hybridization with a nested 16S rRNA-targeted oligonucleotide probe set revealed two different populations of AOB, Nitrosomonas europaea-lineage and Nitrosospira multiformis-lineage, coexisting in an autotrophic nitrifying biofilm . Nitrosospira formed looser microcolonies, with an areal cell density of 0.51 cells microm(-2), which was half of the cell density of Nitrosomonas (1.12 cells microm(-2)) . It is speculated that the formation of looser microcolonies facilitates substrate diffusion into the microcolonies, which might be a survival strategy to low O(2) and NH(4) (+) conditions in the biofilm . A long-term experiment (4-week cultivation at different substrate C/N ratios) revealed that the size distribution of AOB microcolonies was strongly affected by better substrate supply due to shorter distance from the surface and the presence of organic carbon . The microcolony size was relatively constant throughout the autotrophic nitrifying biofilm, while the size increased by approximately 80% toward the depth of the biofilm cultured at the substrate C/N = 1 . A short-term ( approximately 3 h) organic carbon addition experiment showed that the addition of organic carbon created interspecies competition for O(2) between AOB and heterotrophic bacteria, which dramatically decreased the in situ NH(4) (+)-uptake activity of AOB in the surface of the biofilms . This result might explain the spatial distribution of AOB microcolony size in the biofilms cultured at the substrate C/N = 1 . These experimental results suggest O(2) and organic carbon were the main factors controlling the spatial organization and activity of AOB in biofilms . These findings are significantly important to further improve mathematical models used to describe how the slow-growing AOB develop their niches in biofilms and how that configuration affects nitrification performance in the biofilm . Water Sci Technol, 2003, 48(8), 195 - 202 Application of a membrane bioreactor system for opto-electronic industrial wastewater treatment--a pilot study; Chen TK et al.; The membrane bioreactor (MBR) system has become more and more attractive in the field of wastewater treatment . It is particularly attractive in situations where long solids retention times are required, such as nitrifying bacteria, and physical retention is critical to achieving more efficiency for biological degradation of pollutants . Although it is a new technology, the MBR process has been applied to industrial wastewater treatment for only the past decade . The opto-electronic industry, developed very fast over the past decade in the world, is a high technological manufacturing industry . The treatment of the opto-electronic industrial wastewater containing a significant quantity of organic nitrogen compounds, with a ratio over 95% in organic nitrogen (Org-N) to total nitrogen (T-N), is very difficult to meet the discharge limits . The purpose of this research is mainly to discuss the treatment capacity of high-strength organic nitrogen wastewater, and to investigate the capabilities of the MBR process . A 2 m3/day capacity MBR pilot plant consisting of anoxic and aerobic tanks and a membrane bioreactor was installed for evaluation . The operation was continued for 130 days . Over the whole experimental period, a satisfactory organic removal performance was achieved . The COD could be removed with an average of over 94.5% . For TOC and BOD5, the average removal efficiencies were 96.3 and 97.6%, respectively . The nitrification and denitrification were also successfully achieved . The effluent did not contain any suspended solids . Only a small concentration of ammonia nitrogen was found in the effluent . The stable effluent quality and satisfactory removal performance mentioned above were ensured by the efficient interception performance of the membrane device incorporated within the biological reactor . The MBR system shows promise as a means of treating very high organic nitrogen wastewater without dilution . The effluent of TKN, NOx-N and COD can fall below 20 mg/L, 30 mg/L and 50 mg/L. Water Sci Technol, 2003, 48(8), 143 - 50 Enrichment of nitrifying microbial communities from shrimp farms and commercial inocula; Paungfoo C et al.; Nitrifying bacteria were selected from shrimp farm water and sediment ("natural" seed) in Thailand and from commercial seed cultures . The microbial consortia from each source giving the best ammonia removal during batch culture pre-enrichments were used as inocula for two sequencing batch reactors (SBRs) . Nitrifiers were cultivated in the SBRs with 100 mg NH4-N/l and artificial wastewater containing 25 ppt salinity . The two SBRs were operated at a 7 d hydraulic retention time (HRT) for 77 d after which the HRT was reduced to 3.5 d . The amounts of ammonia removed from the influent by microorganisms sourced from the natural seed were 85% and 92% for the 7 d HRT and the 3.5 d HRT, respectively . The ammonia removals of microbial consortia from the commercial seed were 71% and 83% for these HRTs respectively . The quantity of ammonia-oxidizing bacteria (AOB) and nitrite-oxidizing bacteria (NOB) was determined in the SBRs using the most probable number (MPN) technique . Both AOB and NOB increased in number over the long-term operation of both SBRs . According to quantitative fluorescence in situ hybridisation (FISH) probing, AOB from the natural seed and commercial seed comprised 21 +/- 2% and 30 +/- 2%, respectively of all bacteria . NOB could not be detected with currently-reported FISH probes, suggesting that novel NOB were enriched from both sources . Taken collectively, the results from this study provide an indication that the nitrifiers from shrimp farm sources are more effective at ammonia removal than those from commercial seed cultures. Water Sci Technol, 2003, 48(8), 119 - 26 Molecular assessment of ammonia- and nitrite-oxidizing bacteria in full-scale activated sludge wastewater treatment plants; Robinson KG et al.; Nitrification was assessed in two full-scale wastewater treatment plants (WWTPs) over time using molecular methods . Both WWTPs employed a complete-mix suspended growth, aerobic activated sludge process (with biomass recycle) for combined carbon and nitrogen treatment . However, one facility treated primarily municipal wastewater while the other only industrial wastewater . Real time PCR assays were developed to determine copy numbers for total 16S rDNA (a measure of biomass content), the amoA gene (a measure of ammonia-oxidizers), and the Nitrospira 16S rDNA gene (a measure of nitrite-oxidizers) in mixed liquor samples . In both the municipal and industrial WWTP samples, total 16S rDNA values were approximately 2-9 x 10(13) copies/L and Nitrospira 16S rDNA values were 2-4 x 10(10) copies/L . amoA gene concentrations averaged 1.73 x 10(9) copies/L (municipal) and 1.06 x 10(10) copies/L (industrial), however, assays for two distinct ammonia oxidizing bacteria were required. Water Sci Technol, 2003, 48(8), 103 - 10 Membrane bioreactors for final treatment of wastewater; Galil NI et al.; The full-scale existing treatment plant in a paper mill in Hedera, Israel, includes equalization, solids separation by either straining or by dissolved air flotation and biological treatment by activated sludge . The operation of the existing biological process is often characterized by disturbances, mainly bad settling, voluminous bioflocs, followed by wash-out of the biosolids . This paper summarizes the results obtained in a study based on a pilot plant including a membrane biological reactor (MBR) compared to the "conventional" activated sludge process in the aerobic treatment of the effluent obtained from an anaerobic reactor . During the pilot operation period (about 90 days after achieving steady state) the MBR system provided steady operation performance, while the activated sludge produced effluent characterized by oscillatory values . The results are based on average values and indicate much lower levels of suspended solids in the MBR effluent, 2.5 mg/L, as compared to 37 mg/L in the activated sludge . As a result, the total organic mater content was also substantially lower in the MBR effluent, 129 vs 204 mg/L as COD, and 7.1 vs 83 mg/L as BOD . The MBR enabled better nitrification . The ability to develop and maintain a concentration of over 11,000 mg/L of mixed liquor volatile suspended solids in the MBR bioreactor enabled an intensive bioprocess at relatively high cell residence time . As a result the biosolids which had to be removed as excess sludge were characterized by relatively low volatile/total suspended solids ratio, around 0.78 . This could facilitate and lower the cost of biosolids treatment and handling . The results of this comparative study indicate that in the case of MBR there will be no need for further treatment, while after activated sludge additional filtration will be required . The study leads to the conclusion that MBR will be the best technology for aerobic treatment of the anaerobic effluent of the paper mill. Water Sci Technol, 2003, 48(8), 35 - 41 Long term effects of temperature and substrate level on BNR with an external nitrification reactor; Ha JS et al.; This study was conducted with a BNR (biological nutrient removal) process with an external nitrification and switching arrangement of anoxic and oxic stages . It was observed that the SPRR (specific phosphorus release rate) and SDNR (specific denitrification rate) were greatly affected by the organic loads, and SDNR had a higher temperature effect than other kinetic rates including nitrification . It was further observed that the stoichiometric values like PHA (poly hydroxyalkanoate) stored for P release and PHA consumed for P uptake also varied . Variations of % Px (phosphorus content) and PHA as intracellular matter suggest the PAOs were more active at lower temperatures with this process configuration, where more than 70% of NH4-N and phosphorus were removed at temperatures below 10 degrees. Water Sci Technol, 2003, 48(8), 27 - 34 Biological nitrification and denitrification of opto-electronic industrial wastewater; Chen TK et al.; Development and application of biological nutrient removal processes accelerated significantly over the past decade due to more stringent nutrients (nitrogen and phosphorus) discharge limits being imposed on wastewater treatment plants . The opto-electronic industry has developed very fast over the past decade in the world . The wastewater often contains a significant quantity of organic nitrogen compounds and has a ratio of over 95% in organic nitrogen (Org-N) to total nitrogen (T-N) . In this study, a 2-stage Anoxic/Aerobic pre-denitrification process was established and the efficiency of wastewater treatment was evaluated . Wastewater from an actual LCD-plant was obtained as the sample for looking into the feasibility of opto-electronic industrial wastewater treatment . Hydraulic retention time (HRT) and mixed liquor recycle rate (MLR) were controlled independently to distinguish between the effects of these two factors . Under suitable HRT and mixed liquor recycle ratio, effluents of NH4-N, NOx-N and COD can fall below 20 mg/l, 30 mg/l and 80 mg/l. Water Sci Technol, 2003, 48(8), 19 - 26 Advanced nitrogen elimination by encapsulated nitrifiers; Sievers M et al.; By introducing a mixed population of nitrifiers encapsulated in gel lens beads a more selective nitrification process was found in treatment of settled sewage in lab scale at a hydraulic retention time (HRT) of about 30 to 60 minutes . The reaction rates for oxidation of soluble chemical oxygen demand (SCOD) were found to vary between 25 to 150 mg/L x h while nitrification takes place around 50 mg nitrogen per hour and litre reaction volume . However, based on this SCOD removal in the nitrification step, a consequent post-denitrification process without nitrate recycle and dosage of external carbon sources has been proven to reach substantial nitrate elimination of up to 20 mg nitrogen per litre at COD/N-ratios of approx . 6 in settled sewage . At such COD/N-ratios, suitable nitrogen elimination seems to be possible, because the bioflocs of settled sewage, produced so far by SCOD oxidation and entrapment of particulate COD, are passing through the nitrification process having a substantial contribution to the denitrification rate additionally to the remaining SCOD. Water Res, 2004 Jan, 38(2), 475 - 85 A comparative study of Cyperus papyrus and Miscanthidium violaceum-based constructed wetlands for wastewater treatment in a tropical climate; Kyambadde J et al.; The treatment efficiencies of constructed wetlands containing Cyperus papyrus L . (papyrus) and Miscanthidium violaceum (K . Schum.) Robyns (synonymous with Miscanthus violaceum (K . Schum) Pilg.) were investigated in a tropical climate (Kampala, Uganda) . Papyrus showed higher ammonium-nitrogen and total reactive phosphorus (TRP) removal (75.3% and 83.2%) than Miscanthidium (61.5% and 48.4%) and unplanted controls (27.9% ammonium-nitrogen) . No TRP removal was detected in control effluent . Nutrients (N and P) were significantly higher (p<0.015) in papyrus than Miscanthidium plant tissues . Plant uptake and storage was the major factor responsible for N and P removal in treatment line 2 (papyrus) where it contributed 69.5% N and 88.8% P of the total N and P removed . It however accounted for only 15.8% N and 30.7% P of the total N and P removed by treatment line 3 (Miscanthidium violaceum) . In addition, papyrus exhibited a significantly larger (p=0.000) number of adventitious roots than Miscanthidium . Nitrifying bacteria attached to papyrus (2.15 x 10(6)+/-1.53 x 10(5) MPN/g DW) and Miscanthidium roots (1.30 x 10(4)+/-8.83 x 10(2) MPN/g DW) and the corresponding nitrification activities were consistent with this finding . Epiphytic nitrifiers appeared more important for total nitrification than those in peat or suspended in water . Papyrus root structures provided more microbial attachment sites, sufficient wastewater residence time, trapping and settlement of suspended particles, surface area for pollutant adsorption, uptake, assimilation in plant tissues and oxygen for organic and inorganic matter oxidation in the rhizosphere, accounting for its high treatment efficiency. Water Res, 2004 Jan, 38(2), 347 - 54 Enhanced ammonia nitrogen removal using consistent biological regeneration and ammonium exchange of zeolite in modified SBR process; Jung JY et al.; The modified zeo-SBR is recommended for a new nitrogen removal process that has a special function of consistent ammonium exchange and bioregeneration of zeolite-floc . Three sets of sequencing batch reactors, control, zeo-SBR, and modified zeo-SBR were tested to assess nitrogen removal efficiency . The control reactor consisted of anoxic-fill, aeration-mixing, settling, and decanting/idle phases, meaning that nitrogen removal efficiency was dependent on the decanting volume in a cycle . The zeo-SBR reactor was operated in the same way as the control reactor, except for daily addition of powdered zeolite in the SBR reactor . The operating order sequences in the zeo-SBR were changed in the modified zeo-SBR . Anoxic-fill phase was followed by aeration-mixing phase in the zeo-SBR, while aeration-mixing phase was followed by anoxic-fill phase in the modified zeo-SBR to carry NH4(+)-N over to the next operational cycle and to reduce total nitrogen concentration in the effluent . In the modified zeo-SBR, nitrification and biological regeneration occurred during the initial aeration-mixing phase, while denitrification and ammonium adsorption occurred in the following anoxic-fill phase . The changed operational sequence in the modified zeo-SBR to adapt the ammonium adsorption and biological regeneration of the zeolite-floc could enhance nitrogen removal efficiency . As a result of the continuous operation, the nitrogen removal efficiencies of the control and zeo-SBR were in 68.5-70.9%, based on the 33% of decanting volume for a cycle . The zeo-SBR showed a consistent ammonium exchange and bio-regeneration in the anoxic-fill and aeration-mixing phases, respectively . Meanwhile, the effluent total nitrogen of the modified zeo-SBR showed 50-60 mg N/L through ammonium adsorption of the zeolite-floc when the influent ammonium concentration was 315 mg N/L, indicating the T-N removal efficiency was enhanced over 10% in the same HRT and SRT conditions as those of control and zeo-SBR reactors . The ammonium adsorption capacity was found to be 6-7 mg NH4(+)-N/g FSS that is equivalent to 40 mg NH4(+)-N/L of ammonium nitrogen removal. Water Res, 2004 Jan, 38(2), 335 - 46 Development of a biological filtration model applied for advanced treatment of sewage; Hidaka T et al.; A mathematical model of biological filtration process is developed in this paper . A biological filtration process has advantages that filtration action and biological activities are combined in a single reactor with aid of filter media . Both physical and biological functions are incorporated in this developed model to simulate both mechanisms . Backwashing is expressed by the assumption that a mean captured solids concentration is input as data, and a captured solids concentration is kept at that value during each filtration run . The developed model is applied to explain the experimental performance with biological filtration reactors, in which batch cultivation of autotrophic bacteria and continuous treatment of actual sewage are carried out . Its applicability is discussed by comparing the simulated results with the experimental data . This model can favourably estimate maximum accumulation of autotrophic bacteria on the medium in batch cultivation, long-term treatment performance in continuous treatment, details of water quality profiles through the filter bed, and biomass . Required hydraulic retention time for nitrification and an appropriate recirculation ratio in a winter season are discussed with this model . This model predicts that a HRT of 1.1 h or above is required to achieve nitrification with remaining NH4(+)-N of less than 1 mgN/L and that an appropriate recirculation ratio is 2-3. J Environ Qual, 2003 Nov-Dec, 32(6), 2436 - 43 Nitrification and denitrification rates of Everglades wetland soils along a phosphorus-impacted gradient; White JR et al.; Little information is available on the effect of phosphorus (P) enrichment on nitrogen (N) biogeochemical cycling in wetland soil . Of particular importance are the coupled nitrification-denitrification reactions that regulate the microbially mediated loss of N from wetland systems . Soils from the northern Florida Everglades have been affected by P loading from surface waters over the past 40 years . Elevated P levels have been show to have an effect on the size and activity of the microbial pool and a decrease in the N to P ratio of the microbial biomass . The objective of the study was to determine if P enrichment in soils affected microbial activities related to nitrification and denitrification in these flooded, peat soils . Potential nitrification rates of soil and detritus were determined using constantly stirred reactors under aerobic conditions while denitrification rates were determined from anaerobic incubations of slurry . Nitrification rates showed two distinct linear phases, a slower initial rate, signifying activity of nitrifiers present, followed by a sharp increase in the NH4+ conversion rate indicative of maximum potential rates . Initial rates of nitrification were highest in the surficial detrital layer decreasing with soil depth and did not correlate to soil total P . The potential rates of nitrification were 13 times greater than the initial rates . Potential denitrification rates were highest in the detritus and 0- to 10-cm soil interval with significantly lower values in the 10- to 30-cm soil interval, significantly correlated to total P of the soil . A significant (P < 0.01) relationship was seen between potential denitrification rates and soil total P suggesting an increased rate of N removal from P-enriched regions of the northern Everglades. J Environ Qual, 2003 Nov-Dec, 32(6), 2414 - 20 Potential nitrification and denitrification on different surfaces in a constructed treatment wetland; Kallner Bastviken S et al.; Improved understanding of the importance of different surfaces in supporting attached nitrifying and denitrifying bacteria is essential if we are to optimize the N removal capacity of treatment wetlands . The aim of this study was therefore to examine the nitrifying and denitrifying capacity of different surfaces in a constructed treatment wetland and to assess the relative importance of these surfaces for overall N removal in the wetland . Intact sediment cores, old pine and spruce twigs, shoots of Eurasian watermilfoil (Myriophyllum spicatum L.), and filamentous macro-algae were collected in July and November 1999 in two basins of the wetland system . One of the basins had been constructed on land that contained lots of wood debris, particularly twigs of coniferous trees . Potential nitrification was measured using the isotope-dilution technique, and potential denitrification was determined using the acetylene-inhibition technique in laboratory microcosm incubations . Nitrification rates were highest on the twigs . These rates were three and 100 times higher than in the sediment and on Eurasian watermilfoil, respectively . Potential denitrification rates were highest in the sediment . These rates were three times higher than on the twigs and 40 times higher than on Eurasian watermilfoil . The distribution of denitrifying bacteria was most likely due to the availability of organic material, with higher denitrification rates in the sediment than on surfaces in the water column . Our results indicate that denitrification, and particularly nitrification, in treatment wetlands could be significantly increased by addition of surfaces such as twigs. Ann Chim, 2003 Sep-Oct, 93(9-10), 791 - 5 Biohydrolysis of urea from urea-bearing wastewater; Pathe PP et al.; Biological stabilization of urea is a two staged process; (i) urea hydrolysis and (ii) ammonia stripping/nitrification-denitrification . Ammonia thus produced is either stripped off by usual methods or after converting into nitrate using chemoautotrophic bacteria . On denitrification, nitrate is finally converted into nitrogen gas by means of heterotrophic bacteria . Details of stabilization of urea from urea bearing wastewater using urea biohydrolyser are presented in this paper. J Environ Sci Health A Tox Hazard Subst Environ Eng, 2003, 38(12), 2933 - 42 Using oxidation-reduction potential (ORP) and pH value for process control of shortcut nitrification-denitrification; Gao DW et al.; A new low cost technology for simultaneous carbon-nitrogen removal from soybean wastewater has been developed in this study . The technology is performed through shortcut nitrification-denitrification . The process operated under realtime control of aeration and mixing time . The shortcut nitrification-denitrification in sequencing batch reactor (SBR) was achieved efficiently and steadily by controlling temperature (28 +/- 0.5 degrees C) and using real-time control strategies . This enabled the prevention of nitrite oxidation, leading to lower operational costs . The feasibility of oxidation-reduction potential (ORP) and pH value as control parameter for shortcut nitrification-denitrification process was also investigated . Results showed that the average removal efficiency of ammonium was more than 95%, and nitrosation rate (NO2(-)-N/NOx(-)-N) was reached to 96% . At the same time, the variation of oxidation--reduction potential (ORP) and pH value was well related to organic matter degradation and ammonium oxidation in SBR . So that judgment on the ending of nitrification and denitrification can be based on the inflection point on the varied curve of ORP and pH throughout each SBR processing cycle, and thus reducing aeration and mixing time for saving energy source . The method saves organic energy up to 40% of chemical oxygen demand (COD) in denitrification process, which should reduce the need for an extra external source of organic carbon . Shorter hydraulic retention time should allow the volume of the reactors to diminish, and thus diminish investment costs . Lower oxygen demand of about 25% gives lower exploitation costs. Environ Technol, 2003 Oct, 24(10), 1283 - 90 Performance evaluation of leachate treatment system using innovative sulfur circulation method; Kim SK et al.; A pilot-scale experimental study was carried out to evaluate the performance of an innovative method for early stabilization of landfill . This method employs sequential processes of: leachate collection; nitrification through aeration; sulfate addition in effluent tank; and leachate injection back to the landfill . This study focused on: 1) decomposition of recalcitrant organic matters, 2) the characteristics of denitrification, 3) sulfide oxidation for sulfate recovery, and 4) nitrification by aerating discharged leachate . It was found that, when sulfate (SO4(2-)) added leachate was introduced inside the landfill, sulfate-reducing bacteria decomposed recalcitrant organic matters like lignocellulose by using SO4(2-) as an electron acceptor and simultaneously sulfur-oxidizing bacteria denitrified the leachate using sulfides (H2S, HS-, S2-) as electron donors . These two types of bacteria existed not competitively but symbiotically on substrate utilization . Sulfate-reducing bacteria produced S2- while sulfur-oxidizing bacteria oxidized S2- to SO4(2-) . During aeration, the concentration of NO3(-)-N increased from near zero up to 925 mg l(-1) . Eventual denitrification efficiency in the simulated waste landfill was observed to be approximately 92.3% . Also, S2- present in the discharged leachate was converted to SO4(2-) again in the aeration process . Sulfate needed in this process could be recirculated . Therefore, the amount of sulfate required in the operation of this method could be maintained marginal after the initial addition of sulfate in the effluent tank . Decomposition of recalcitrant organic matters and denitrification hastened the stabilization of landfill . The results of this study indicated that this innovative method was effective and economic. Plant Soil, 2003 Oct, 256(2), 371 - 8 Nitrification in a zeoponic substrate; McGilloway RL et al.; Clinoptilolite is a zeolite mineral with high cation exchange capacity used in zeoponic substrates that have been proposed as a solid medium for growing plants or as a fertilizer material . The kinetics of nitrification has not been measured for NH4+ saturated zeoponic substrate . Experiments were conducted to evaluate the production of NO2- and NO3-, and nitrifier populations in zeoponic substrates . Small columns were filled with zeoponic substrate inoculated with a commercial inoculum or soil enrichment culture of nitrifying bacteria . In addition to column studies, a growth chamber study was conducted to evaluate the kinetics of nitrification in zeoponic substrates used to grow radishes (Raphanus sativus L.) . The zeoponic substrate provided a readily available source of NH4+, and nitrifying bacteria were active in the substrate . Ammonium oxidation rates in column studies ranged from 5 to 10 micrograms N g-1 substrate h-1, and NO2- oxidation rates were 2 to 9.5 micrograms N g-1 substrate h-1 . Rates determined from the growth chamber study were approximately 1.2 micrograms N g-1 substrate h-1 . Quantities of NH4+ oxidized to NO2- and NO3- in inoculated zeoponic substrate were in excess of plant up-take . Acidification as a result of NH4+ oxidation resulted in a pH decline, and the zeoponic substrate showed limited buffering capacity. Appl Environ Microbiol, 2003 Dec, 69(12), 7091 - 100 Nitrification and nitrifying bacteria in the lower Seine River and estuary (France); Cebron A et al.; The Acheres wastewater treatment plant, located just downstream of Paris, discharges its effluents into the lower Seine River . The effluents contain large numbers of heterotrophic bacteria, organic matter, and ammonium and are a source of nitrifying bacteria . As a result, degradation of organic matter by heterotrophic bacteria and subsequent oxygen depletion occur immediately downstream of the effluent outlet, whereas nitrifying bacteria apparently need to build up a significant biomass before ammonium oxidation significantly depletes the oxygen . We quantified the potential total nitrifying activity and the potential activities of the ammonia- and nitrite-oxidizing communities along the Seine River . In the summer, the maximum nitrifying activity occurs in the upper freshwater estuary, approximately 200 km downstream of Acheres . The quantities of nitrifying bacteria, based on amoA gene copy numbers, and of Nitrobacter organisms, based on 16S rRNA gene copy numbers, were correlated with the potential nitrifying activities . The species composition of ammonia-oxidizing bacteria was investigated at two sites: the Triel station just downstream from Acheres (km 84) and the Seine freshwater estuary at the Duclair station (km 278) . By means of PCR primers targeting the amoA gene, a gene library was created . Phylogenetic analysis revealed that the majority of the analyzed clones at both sites were affiliated with the genus NITROSOMONAS: The Nitrosomonas oligotropha- and Nitrosomonas urea-related clones represented nearly 81% of the community of ammonia-oxidizing bacteria at Triel and 60% at Duclair . Two other ammonia-oxidizing clusters of the beta subclass of the Proteobacteria, i.e., Nitrosomonas europaea- and Nitrosospira-like bacteria, were found in smaller numbers . The major change in the ammonia-oxidizing community between the two stations along the Seine River-upper estuary continuum was the replacement of the N . oligotropha- and N . urea-related bacteria by the Nitrosospira-affiliated bacteria . Although the diversities of the ammonia oxidizers appear to be similar for the two sites, only half of the restriction patterns are common to both sites, which could be explained by the differences in ammonium concentrations, which are much lower in the upper estuary than in the river at the effluent outlet . These results imply a significant immigration and/or selection of the ammonia-oxidizing bacterial population along the continuum of the Seine River from Paris to the estuary. Environ Microbiol, 2003 Nov, 5(11), 1155 - 67 Linking autotrophic activity in environmental samples with specific bacterial taxa by detection of 13C-labelled fatty acids; Knief C et al.; A method for the detection of physiologically active autotrophic bacteria in complex microbial communities was developed based on labelling with the stable isotope 13C . Labelling of autotrophic nitrifying, sulphur-oxidizing and iron-oxidizing populations was performed in situ by incubation with NaH{13C}O3 . Incorporated label into fatty acid methyl esters (FAMEs) was detected and quantified using gas chromatography-mass spectrometry in single ion monitoring mode . Before the analyses of different environmental samples, the protocol was evaluated in pure culture experiments . In different environmental samples a selective labelling of fatty acids demonstrated which microbial taxa were responsible for the respective chemolithoautotrophic activity . The most strongly labelled fatty acids of a sample from a sulphide treating biofilter from an animal rendering plant were cis-7-hexadecenoic acid (16:1 cis7) and 11-methyl hexadecanoic acid (16:0 11methyl), which are as-yet not known for any sulphide-oxidizing autotroph . The fatty acid labelling pattern of an experimental biotrickling filter sample supplied with dimethyl disulphide clearly indicated the presence and activity of sulphide-oxidizing bacteria of the genus Thiobacillus . For a third environmental sample from an acid mining lake sediment, the assignment of autotrophic activity to bacteria of the genus Leptospirillum but not to Acidithiobacillus could be made by this method, as the fatty acid patterns of these bacteria show clear differences. Water Sci Technol, 2003, 48(6), 301 - 9 A membrane assisted hybrid bioreactor for the post treatment of an anaerobic effluent from a fish canning factory; Oyanedel V et al.; An innovative membrane assisted hybrid bioreactor was used to treat a mixture of two streams produced in a fish canning factory: a highly loaded stream that had previously been treated in an anaerobic contact reactor, and a second stream with a relatively low COD and N concentration . Experiments were carried out during two experimental stages: an aerobic stage, which is focused in the study on the aerobic oxidation of ammonia and COD and a nitrification-denitrification stage in which the study was mainly focused on the removal of nitrogen . Results of the aerobic period pointed out that it was feasible to achieve ammonia and COD removals of around 99% at OLR of 6.5 kg COD/m3 x d and NLR of 1.8 kg N-NH4+/m3 x d . Specific nitrifying activities of up to 0.78 g N-NH4+/g protein x d and 0.25 g N-NH4+/g VSS x d, were recorded for the attached and suspended biomass, respectively . Around 50-60% of the nitrifying capacity of the reactor was a result of the nitrifying capacity of the biofilm . During the nitrification-denitrification stage 76% of nitrogen removal was attained at an NLR of 0.8 kg N-NH4+/m3 x d . The biofilm nitrifying activity was not affected by the operating conditions of the system, as a result of the preferential consumption of COD by suspended biomass in the reactor . Thus, the combination of a hybrid system, with both suspended and attached biomass, and an ultrafiltration membrane module might be an alternative for treating wastewaters in compact biological systems . The intrinsic characteristics of the system made it feasible to operate at high OLR without problems related with the settling properties of the sludge or the drop in the nitrogen conversion . There were no solids in the effluent as a result of the use of the membrane filtration module. J Biotechnol, 2003 Dec 5, 106(1), 77 - 86 A novel granular sludge sequencing batch reactor for removal of organic and nitrogen from wastewater; Yang SF et al.; Microbial granules were developed at different substrate N/COD ratios in sequencing batch reactors (SBR) . Results showed that heterotrophic, nitrifying, and denitrifying populations could peacefully co-exist in microbial granules, while increased substrate N/COD ratio led to significant shifts among three populations in granules . Enhanced activities of nitrifying and denitrifying populations were obtained in microbial granules developed at high substrate N/COD ratios, however, heterotrophic populations in granules tended to decrease with the increase of substrate N/COD ratio . It was found that dissolved oxygen (DO) concentration had a pronounced effect on the efficiency of denitrification by microbial granules, meanwhile the results also indicated that a certain mixing power would be provided to ensure mass transfer between liquid and granules during denitrification . It was demonstrated that complete organics and nitrogen removal can be achieved in single granule-based SBR with high efficiency and stable performance . This is the first study to show the capability of microbial granules in simultaneous removal of organic carbon and nitrogen from wastewater. Sci Total Environ, 2003 Dec 30, 317(1-3), 149 - 57 Seasonal change in the level and the chemical forms of aluminum in soil solution under a Japanese cedar forest; Umemura T et al.; The level of dissolved aluminum and its chemical forms in soil solutions consecutively collected by a porous cup vacuum sampler were monitored over a period from January 2001 to December 2001 at a Japanese cedar (Cryptomeria japonica) forestry area susceptible to acid deposition to characterize current soil dynamics and to evaluate potential tree damages . Distinction and characterization of Al species with differential toxicities were performed by two complementary speciation techniques; cation-exchange HPLC with fluorometric detection using 8-hydroxyquinoline-5-sulfonic acid (HQS) and size-fractionation/inductively coupled plasma atomic emission spectrometry (ICP-AES) . The concentrations of free Al (mainly Al3+ and Al(OH)2+) and inert Al (existing as the complexed and/or colloidal forms) ranged between 0-150 microM and 10-50 microM, respectively . The concentrations of inert Al were mostly below 40 microM during an annual cycle and showed no marked seasonal variation, while free Al concentrations showed a clear tendency to increase in the spring and summer seasons (in the period from April to August) probably due to the enhanced activity of microbial nitrification and the resultant soil acidification . Major cations and anions were also regularly determined and their seasonal changes were correlated with that of the dissolved Al concentration . Correlations between total Al (mainly existing as free Al) and the related species (and environmental conditions) were as follows: Al and Mg (R=0.96, P<0.01), Al and Ca (R=0.97, P<0.01), Al and NO3- (R=0.68, P<0.01), Al and temperature (R=0.68, P<0.01), Al and solution pH (R=-0.61, P<0.01), solution pH and NO3- (R=-0.65, P<0.01). J Basic Microbiol, 2003, 43(6), 483 - 98 Increased solubility of (heavy) metals in soil during microbial transformations of sucrose and casein amendments; Gramss G et al.; Unsterile soil samples pH 6.8 were amended with 10% sucrose or 0.1% NH4NO3/2% casein to influence solubility of metal cations . Microbial formation of aliphatic carboxylic acids reduced pH of sucrose soil to 4.3 and increased the solubility of heavy metals by 60-fold due to the increased presence of H+, and the metal-chelating and humic-molecule fragmenting properties of carboxylic acids . Soil pH increased finally to 7.8 upon the degradation of the carboxylic acids . In casein soil, ammonia production increased pH initially to 8.5 and promoted solubility of metal-containing humic compounds . Subsequent nitrification reduced pH to 5.6 to increase concentations of Ca and Mg in the soil solution, which prevented a comparable increase in the solubility of heavy metals competitively . It is concluded that amendment with sugar and nitrogen occasionally increases the concentrations of (hazardous) elements in the soil solution to facilitate their uptake by metal hyperaccumulating plants. Appl Microbiol Biotechnol, 2004 Feb, 63(6), 715 - 21 Epub 2003 Nov 18. Use of the ammonia-oxidizing bacterial-specific phylogenetic probe Nso1225 as a primer for fingerprint analysis of ammonia-oxidizer communities; Calvo L et al.; Autotrophic ammonia-oxidizing bacteria (AOB) are an essential component of nitrifying wastewater treatment systems . The molecular tools used in group-specific studies are mostly based on the sequence of the 16S rRNA gene, but they have not proved to be fully specific . In this study, the sequence of the FISH probe Nso1225R was used as a reverse primer in order to analyze the AOB composition of several environmental samples by denaturing gradient gel electrophoresis (DGGE) . For this purpose, samples from several environments, including aerated reactors, water treatment wetlands, and pilot plants, both aerobic and anaerobic, were analyzed . PCR fragments displayed a DGGE pattern consisting of bands melting between 30 and 40% denaturant, and a series of unresolved bands above 45%, mostly corresponding to AOB and beta-non-AOB, respectively . This second set of bands corresponded to environments subjected to severe oxygen restrictions . AOB sequences showed similarity percentages higher than 92% with those of known beta-AOB . Nso1225R, therefore, proved to be a good molecular phylogenetic marker for AOB samples from well-aerated systems, showing a higher specificity than the group-specific primers used previously. Water Sci Technol, 2003, 48(5), 191 - 8 Oxygen flux implications of observed nitrogen removal rates in subsurface-flow treatment wetlands; Tanner CC et al.; Nitrification, an oxygen-requiring microbial process, is generally considered the rate-limiting step for N removal in subsurface-flow constructed wetlands treating organic wastewaters . We used a simplified model of sequential N transformations and sinks to infer required rates of oxygen supply at 5 stages along experimental wetland mesocosms supplied with four different organic wastewaters with contrasting ratios of COD: N and forms of N . Mass balances of water-borne organic, ammoniacal and nitrate N, and plant and sediment N uptake showed average net rates of N mineralisation ranging from 0.22-0.53 g m(-2) d(-1), nitrification 0.56-2.15 g m(-2) d(-1), denitrification 0.47-1.99 g m(-2) d(-1) (60-84% of measured N removal) and plant assimilation 0.28-0.47 g m(-2) d(-1) . The nitrogenous oxygen demand (NOD) required to support the observed nitrification rates alone was high compared to expected fluxes from surficial and plant-mediated oxygen transfer . In the presence of high levels of degradable organic matter (COD removal rates up to 66 g m(-2) d(-1)), heterotrophs with significantly higher oxygen affinities and energy yields are expected to outcompete nitrifiers for available oxygen . Problems with commonly held assumptions on the nature of coupled nitrification-denitrification in treatment wetlands are discussed. Water Sci Technol, 2003, 48(5), 175 - 82 Nitrogen removal from domestic effluent using subsurface flow constructed wetlands: influence of depth, hydraulic residence time and pre-nitrification; Bayley ML et al.; This paper describes two studies into the BOD and TN removal performance of horizontal subsurface flow wetlands (reed beds) in subtropical Australia . The aim of the first study was to determine the influence of HRT and vertical position on BOD and TN concentration and removal performance in a 0.5 m deep reed bed (System 1) by taking samples from three levels (or layers) in the water column at five points along the length of the bed . The aim of the second study was to investigate the TN removal performance of a treatment train consisting of a vertical flow intermittently dosed sand filter preceding a reed bed (System 2) . Both systems were dosed with primary settled municipal wastewater (BOD 194 mg L(-1); TN 49 mg L(-1)) . System 1 achieved a TN load removal of 58% under a HLR of 22 mm day(-1) (HRT 10.5 days), producing effluent BOD concentrations consistently less than 8 mg L(-1) . There was no significant difference in BOD attenuation rate between the three layers . While there were differences in both the nitrification and denitrification rates between the three layers, the TN concentration was found to decline steadily in all layers up to an HRT of 8.7 days . System 2 reduced TN influent load by 33%, less than half of which was removed by the reed bed . The lack of substantial TN removal within this reed bed was attributed to the low concentrations of BOD and consequent lack of dissolved organic carbon to drive the denitrification process. Water Sci Technol, 2003, 48(5), 167 - 74 Controlling a combined lagoon/reed bed system using the oxidation-reduction potential (ORP); Kayser K et al.; Lagoon systems achieve good and stable effluent data in regard to organic pollutants, but they charge the receiving waters with relatively high ammonium loads . Therefore an existing lagoon-plant was extended by a vertical flow reed-bed for the special purpose of nitrification . This paper presents the efficiency of the combination plant as well as the possibility to monitor and control the reed-bed operation by the oxidation-reduction potential (ORP) . The results show that the combination plant achieved excellent purification results, the average efficiency degrees were 97% for COD, 77% for N(total) and 94% for the TKN elimination . The ORP in the effluent of the reed bed showed a clear dependence in its characteristic course and its absolute values on the current nitrification performance, the oxygen supply and the hydraulic behaviour of the reed bed . Therefore the ORP is a very good indicator for the state of the reed bed, which ultimately results from the accumulation of a large number of different influencing parameters . As the preservation of aerobic conditions in the reed bed is the crucial prerequisite for a high nitrification performance and for the avoidance of clogging, the ORP thus offers the possibility of immediate operation control. Water Sci Technol, 2003, 48(5), 135 - 42 Nitrous oxide, dinitrogen and methane emission in a subsurface flow constructed wetland; Mander U et al.; N2O, N2 and CH4 fluxes were measured from a horizontal subsurface flow (HSSF) constructed wetland (CW) for wastewater treatment in Estonia . The closed chamber method was used in the field and the He-O method (intact soil core analyses) in the lab throughout the period from October 2001 to June 2002 . The average flux of N2O-N, N2-N and CH4-C from various microsites ranged from 0.1 to 59, 4.1 to 1,458 and -0.04 to 2,094 mg m(-2) d(-1), respectively . A significantly higher flux of N2O was found in chambers installed above the inlet pipes, while the methane flux was higher in the inlet part of the bed with wetter conditions . The groundwater table significantly correlates with gas emission rates of all the gases studied; N2 emission was enhanced by higher temperature of wastewater . PO4(3-) and NH4+ content significantly enhanced, and NO2- and NO3- content inhibited, both N2O and CH4 fluxes . NH4+ showed a negative correlation with N2 flux . Nitrification and denitrification are the main processes of the N removal in the CW covering 42.9% . The specific global warming potential was highest in the wet bed and lowest in the dry bed with lowered water table (32 and 9 g CO2 pe(-1) d(-1), respectively). Mikrobiol Z, 2003 Jul-Aug, 65(4), 37 - 42 {The effect of bacterium inoculation on the yield of pure and mixed corn with soya on leached chernozems}; Rybak VK; The use of biopreparations resulted in the increase of green mass within 64-126 c/ha when field experiments were carried out with joint and mixed crops of corn with soya in conditions of the Polyssya leached chernozems . An advantage of 8-23 c/ha was achieved when growing their mixtures . The average crop of green mass for the years of investigations was within 530-894 c/ha . Bacterial fertilizers and soya activate microbiological process of nitrogen cycle, increasing the number of nitrifiers and denitrifiers in the rhizosphere of plants . Thus these factors improve the nitrogen nutrition of cultures in the mixed crops . There is an interaction between plants of corn-soya phytocenosis which has the metabolic-competition character that guarantees better employment of biopreparations and fertilizers, genetic properties of plants and natural resources. J Bacteriol, 2003 Dec, 185(23), 6809 - 14 Chemolithoorganotrophic growth of Nitrosomonas europaea on fructose; Hommes NG et al.; The nitrifying bacterium Nitrosomonas europaea can obtain all its carbon for growth from CO(2) and all its energy and reductant for growth from the oxidation of NH(3) and is considered an obligate chemolithoautotroph . Previous studies have shown that N . europaea can utilize limited amounts of certain organic compounds, including amino acids, pyruvate, and acetate, although no organic compound has been reported to support the growth of N . europaea . The recently completed genomic sequence of N . europaea revealed a potential permease for fructose . With this in mind, we tested if N . europaea could utilize fructose and other compounds as carbon sources to support growth . Cultures were incubated in the presence of fructose or other organic compounds in sealed bottles purged of CO(2) . In these cultures, addition of either fructose or pyruvate as the sole carbon source resulted in a two- to threefold increase in optical density and protein content in 3 to 4 days . Studies with {(14)C}fructose showed that >90% of the carbon incorporated by the cells during growth was derived from fructose . Cultures containing mannose, glucose, glycerol, mannitol, citrate, or acetate showed little or no growth . N . europaea was not able to grow with fructose as an energy source, although the presence of fructose did provide an energy benefit to the cells . These results show that N . europaea can be grown in CO(2)-free medium by using fructose and pyruvate as carbon sources and may now be considered a facultative chemolithoorganotroph. Rapid Commun Mass Spectrom, 2003, 17(22), 2550 - 6 Dual isotope and isotopomer ratios of N2O emitted from a temperate grassland soil after fertiliser application; Bol R et al.; The N2O and N2 fluxes emitted from a temperate UK grassland soil after fertiliser application (equivalent to 25 and 75 kg N ha(-1)) were simultaneously measured, using a new automated soil incubation system, which replaces soil atmosphere (N2 dominated) with a He+O2 mixture . Dual isotope and isotopomer ratios of the emitted N2O were also determined . Total N2O and N2 fluxes were significantly lower (P<0.001) in the control (0 kg N) than in the 25 and 75 kg N treatments . The total N2O flux was significantly higher (P<0.001) in the 75 kg N than in the 25 kg N treatment . The general patterns of N2O and N2 fluxes were similar for both fertiliser treatments . The total gaseous N loss in the control treatment was nearly all N2, whereas in the fertiliser treatment more N2O than N2 was emitted from the soil . The ratio N2O/N2 fluxes as measured during the experiment suggested three phases in N2O production, in phase 1 nitrification>denitrification, in phase 2 denitrification>nitrification, and in phase 3 denitrification (and total denitrification)>>nitrification . Dual delta15N and delta18O isotope and isotopomer (delta15Nalpha and delta15Nbeta) value ratios of emitted N2O also pointed towards an increasing dominance of the production of N2O by denitrification and total denitrification . The site preference value from the soil-emitted N2O was lower than the troposphere value . This confirmed that the enhanced troposphere N2O site preference could result from back injection of N2O from the stratosphere . The measurements of N2O/N2 flux ratio and the isotopic content of emitted N2O pointed, independently, to similar temporal trends in N2O production processes after fertiliser application to grassland soil . This confirmed that both measurements are suitable diagnostic tools to study the N2O production process in soils . Water Res, 2003 Dec, 37(20), 4965 - 73 Characterization of nitrifying granules produced in an aerobic upflow fluidized bed reactor; Tsuneda S et al.; Since nitrification is the rate-determining step in the biological nitrogen removal from wastewater, many research studies have been conducted on the immobilization of nitrifying bacteria . In this research, granulation of nitrifying bacteria in an aerobic upflow fluidized bed (AUFB) reactor in a nitrification process for inorganic wastewater containing 500 g/m(3) of NH(4)(+)-N was investigated . It was observed that spherical, pseudocubic and elliptical granules with a diameter of 346 microm were produced at the bottom of the reactor after 300 days . Denaturing gradient gel electrophoresis analysis revealed that Nitrosomonas-like bacteria were the dominant ammonia-oxidizing species in the granules . Many colonies of Nitrosomonas-like bacteria were found in the outer part of the granules based on the spatial distribution analysis by fluorescence in situ hybridization . By stepwise reduction of the hydraulic retention time, the ammonia removal rate of the AUFB reactor containing these nitrifying granules finally reached 1.5 kg-N/m(3)/day . Results suggested that the use of granules realizes the retention of a large amount of nitrifying bacteria in the reactor, which guarantees a highly efficient nitrification. Appl Environ Microbiol, 2003 Nov, 69(11), 6875 - 87 The isotope array, a new tool that employs substrate-mediated labeling of rRNA for determination of microbial community structure and function; Adamczyk J et al.; A new microarray method, the isotope array approach, for identifying microorganisms which consume a (14)C-labeled substrate within complex microbial communities was developed . Experiments were performed with a small microarray consisting of oligonucleotide probes targeting the 16S rRNA of ammonia-oxidizing bacteria (AOB) . Total RNA was extracted from a pure culture of Nitrosomonas eutropha grown in the presence of {(14)C}bicarbonate . After fluorescence labeling of the RNA and microarray hybridization, scanning of all probe spots for fluorescence and radioactivity revealed that specific signals were obtained and that the incorporation of (14)C into rRNA could be detected unambiguously . Subsequently, we were able to demonstrate the suitability of the isotope array approach for monitoring community composition and CO(2) fixation activity of AOB in two nitrifying activated-sludge samples which were incubated with {(14)C}bicarbonate for up to 26 h . AOB community structure in the activated-sludge samples, as predicted by the microarray hybridization pattern, was confirmed by quantitative fluorescence in situ hybridization (FISH) and comparative amoA sequence analyses . CO(2) fixation activities of the AOB populations within the complex activated-sludge communities were detectable on the microarray by (14)C incorporation and were confirmed independently by combining FISH and microautoradiography . AOB rRNA from activated sludge incubated with radioactive bicarbonate in the presence of allylthiourea as an inhibitor of AOB activity showed no incorporation of (14)C and thus was not detectable on the radioactivity scans of the microarray . These results suggest that the isotope array can be used in a PCR-independent manner to exploit the high parallelism and discriminatory power of microarrays for the direct identification of microorganisms which consume a specific substrate in the environment. Water Environ Res, 2003 Sep-Oct, 75(5), 422 - 33 Pilot-scale evaluation of separate-stage nitrification using an attached-growth, moving-bed media process; Zimmerman RA et al.; Submerged attached-growth processes, both fixed and moving bed, are becoming more popular . These processes may or may not be used in combination with suspended-growth treatment . The objective of this project was to evaluate a tertiary attached-growth, moving-bed media nitrification system based on the ammonia-nitrogen removal rates and effluent concentrations that could be achieved . A pilot-scale system for nitrification of secondary municipal wastewater effluent was operated for 142 days . The minimum aeration requirements for media mixing provided sufficient dissolved oxygen . The generation of biological solids from nitrification was insignificant . Design effluent ammonia-nitrogen concentrations (<6 mg/L) were achieved at influent loading rates greater than design (1.18 g ammonia-nitrogen/{m2 x d}) coincident with detention times shorter than design conditions (4 hours) . Empirical relationships for the ammonia-nitrogen removal rate and effluent concentration as a function of influent ammonia-nitrogen loading were developed . Detention time is believed to be an important parameter affecting these relationships. Environ Toxicol Chem, 2003 Nov, 22(11), 2592 - 8 Comparison of toxicity of zinc for soil microbial processes between laboratory-contamined and polluted field soils; Smolders E et al.; Soil microbial processes are readily disturbed by added zinc (Zn) in laboratory ecotoxicity tests . This study compares Zn toxicity between freshly spiked soils and soils that have been contaminated with Zn in the field . Soils were sampled in three transects (< 80 m) toward galvanized electricity transmission towers (pylons) . The soil total Zn concentrations gradually increased in each transect from background values (25-82 mg Zn/kg) to elevated Zn concentrations near the pylon (226-595 mg Zn/kg) . Soil samples taken at the furthest distance from the Zn source were spiked with ZnCl2 to a range of total Zn concentrations similar to those in the transect . Nitrification, respiration, and N-mineralization rates were significantly reduced by added Zn in laboratory-spiked soils and were 9 to 95% (mean 32%) of the control values at largest doses depending on soil type and the microbial process . In contrast, these processes were either unaffected by soil Zn (p > 0.05) or increased significantly with soil Zn concentrations in the transect soils . These increases could not be explained by soil pH or % soil organic carbon . Leaching soils after spiking significantly lowered the toxic effects of Zn on nitrification or on substrate-induced respiration . The soil solution Zn concentrations of field soils were always smaller than in spiked soils at equivalent total Zn . Highest soil solution Zn concentrations were always lower than the soil-solution EC50s of spiked soils . It is concluded that there is a large discrepancy in microbial responses to elevated Zn between spiked soils (unleached) and field-contaminated soils and there is a need to explain this discrepancy in terms of Zn availability, adaptation processes, and additional soil factors controlling the microbial processes. Water Res, 2003 Nov, 37(19), 4781 - 91 Membrane bioreactor for the drinking water treatment of polluted surface water supplies; Li XY et al.; A laboratory membrane bioreactor (MBR) using a submerged polyethylene hollow-fibre membrane module with a pore size of 0.4 microm and a total surface area of 0.2 m2 was used for treating a raw water supply slightly polluted by domestic sewage . The feeding influent had a total organic carbon (TOC) level of 3-5 mg/L and an ammonia nitrogen (NH(3)-N) concentration of 3-4 mg/L . The MBR ran continuously for more than 500 days, with a hydraulic retention time (HRT) as short as 1h or less . Sufficient organic degradation and complete nitrification were achieved in the MBR effluent, which normally had a TOC of less than 2 mg/L and a NH(3)-N of lower than 0.2 mg/L . The process was also highly effective for eliminating conventional water impurities, as demonstrated by decreases in turbidity from 4.50+/-1.11 to 0.08+/-0.03 NTU, in total coliforms from 10(5)/mL to less than 5/mL and in UV(254) absorbance from 0.098+/-0.019 to 0.036+/-0.007 cm(-1) . With the MBR treatment, the 3-day trihalomethane formation potential (THMFP) was significantly reduced from 239.5+/-43.8 to 60.4+/-23.1 microg/L . The initial chlorine demand for disinfection decreased from 22.3+/-5.1 to 0.5+/-0 . 1mg/L . The biostability of the effluent improved considerably as the assimilable organic carbon (AOC) decreased from 134.5+/-52.7 to 25.3+/-19.9 microg/L . All of these water quality parameters show the superior quality of the MBR-treated water, which was comparable to or even better than the local tap water . Molecular size distribution analysis and the hydrophobic characterisation of the MBR effluent, in comparison to the filtered liquor from the bioreactor, suggest that the MBR had an enhanced filtration mechanism . A sludge layer on the membrane surface could have functioned as an additional barrier to the passage of typical THM precursors, such as large organic molecules and hydrophobic compounds . These results indicate that the MBR with a short HRT could be developed as an effective biological water treatment process to address the urgent need of many developing countries that are plagued by the serious contamination of surface water resources. Water Res, 2003 Nov, 37(19), 4587 - 94 Comparison of ammonia volatilisation rates in algae and duckweed-based waste stabilisation ponds treating domestic wastewater; Zimmo OR et al.; Quantification of ammonia volatilisation from wastewater stabilisation ponds is important in order to understand its significance for overall nitrogen removal in these widely applied low-cost treatment systems . Ammonia volatilisation rates were measured in pilot plant facilities consisting of one line of four algae-based ponds in series and a parallel line of four ponds with a floating mat of duckweed (Lemna gibba) . Ammonia volatilisation was assessed during a period of one and a half years . The method applied is accurate, convenient and is proposed for analysis of a wide range of gasses emitted from stabilisation ponds and possibly other aquatic systems . The ammonia volatilisation rates in algae-based ponds (ABPs) were higher than in duckweed-based ponds (DBPs) . This can be explained by the lower values of NH(3) in DBPs due to shading and lower pH values, since the volatilisation rate highly correlated with free ammonia concentration (NH(3)) in pond water . The duckweed cover appeared not to provide a physical barrier for volatilisation of unionised ammonia, because whenever NH(3) concentrations were equal in ABP and DBP also the volatilisation rates were equal . Volatilisation was in the range of 7.2-37.4 mg-Nm(-2)d(-1) and 6.4 -31.5 mg-Nm(-2)d(-1) in the ABPs and DBPs, respectively . Average influent and effluent ammonium nitrogen measurements showed that the ammonia volatilisation during the study period in any system did not exceed 1.5% of total ammonium nitrogen removal . Therefore this study confirmed results from simultaneous experimental work in our laboratory indicating that nitrification/denitrification, rather than ammonia volatilisation, is the most important mechanism for N removal in ABPs and DBPs. J Environ Sci (China), 2003 Sep, 15(5), 669 - 73 Temperature effect on aerobic denitrification and nitrification; Xie SG et al.; Nitrogen loss without organic removal in biofilter was observed and its possible reason was explained . A lower hydraulic loading could improve aerobic denitrification rate . Aerobic denitrification was seriously affected by low temperature(below 10 degrees C) . However, nitrification rate remained high when the temperature dropped from 15 degrees C to 5 degrees C . It seemed the autotrophic biofilm in BAF could alleviate the adverse effect of low temperature. J Environ Sci (China), 2003 Sep, 15(5), 607 - 10 Inhibition of nitrification in soil by metal diethyldithiocarbamates; Arora A et al.; Nitrification acts as a key process in determining fertilizer use efficiency by crops as well as nitrogen losses from soils . Metal dithiocarbamates in addition to their pesticidal properties can also inhibit biological oxidation of ammonium(nitrification) in soil . Metal {M = V(III), Cr(III), Mn(II), Fe(III), Ni(II), Cu(II), Zn(II) and Co(II)} diethyldithiocarbamates (DEDTC) were synthesized by the reaction of sodium diethyldithiocarbamate with metal chloride in dichloromethane/water mixture . These metal diethyldithiocarbamates were screened for their ability to inhibit nitrification at different concentrations( 10 microg/g soil, 50 microg/g soil and 100 microg/g soil) . With increasing concentration of the complex, capacity to retard nitrification increased but the extent of increase varied for different metals . At 100 microg/g soil, different complexes showed nitrification inhibition from 22.36% to 46.45% . Among the diethyldithiocarbamates tested, Zn(DEDTC)2 proved to be the most effective nitrification inhibitor at 100 microg/g soil . Manganese, iron and chromium diethyldithiocarbamates also proved to be effective nitrification inhibitors than the others at 100 microg/g soil . The order of percent nitrification inhibition in soil by metal diethyldithiocarbamates was: Zn(II) > Mn(II) > Fe(III) > Cr(III) > V(III) > Co(II) > Ni(II) > Cu(II). Huan Jing Ke Xue, 2003 Jul, 24(4), 94 - 8 {Cultivation of aerobic granular sludge for simultaneous nitrification and denitrification in SBR system}; Yang Q et al.; The cultivation of aerobic granular sludge used for nitrogen removal in Sequencing Batch Reactor (SBR) fed with a synthetic municipal wastewater was investigated . The results showed that the aerobic granular sludge with the high activity of simultaneous nitrification and denitrification, could form in the reactor by controlling the addition of carbon source, and the removal rates of COD and NH3-N reached 74.0%-92.8% and 82.3%-98.5%, respectively, in the reactor . The granular formed was averagely 0.5-1.0 mm in diameter, and the Mixed Liquid Suspended Solids (MLSS) and the Sludge Volumetric Index (SVI) in the reactor were above 4.5 g/L and above 32.5, respectively . Compared with the normal aerobic activated sludge process, the system with aerobic granular sludge had a higher concentration of effective biomass and a much stronger ability of nitrogen removal. FEMS Microbiol Rev, 2003 Oct, 27(4), 481 - 92 New concepts of microbial treatment processes for the nitrogen removal in wastewater; Schmidt I et al.; Many countries strive to reduce the emissions of nitrogen compounds (ammonia, nitrate, NOx) to the surface waters and the atmosphere . Since mainstream domestic wastewater treatment systems are usually already overloaded with ammonia, a dedicated nitrogen removal from concentrated secondary or industrial wastewaters is often more cost-effective than the disposal of such wastes to domestic wastewater treatment . The cost-effectiveness of separate treatment has increased dramatically in the past few years, since several processes for the biological removal of ammonia from concentrated waste streams have become available . Here, we review those processes that make use of new concepts in microbiology: partial nitrification, nitrifier denitrification and anaerobic ammonia oxidation (the anammox process) . These processes target the removal of ammonia from gases, and ammonium-bicarbonate from concentrated wastewaters (i.e . sludge liquor and landfill leachate) . The review addresses the microbiology, its consequences for their application, the current status regarding application, and the future developments. Biotechnol Adv, 2000 May, 18(3), 219 - 32 Production of nitrogen oxide and dinitrogen oxide by autotrophic nitrifiers; Colliver BB et al.; Autotrophic nitrifiers have been shown to produce nitrogen oxide and dinitrogen oxide under oxic conditions . Dinitrogen oxide is produced mainly during nitrite reduction (i.e . aerobic denitrification) whereas nitrogen oxide is produced during both aerobic denitrification and as a result of chemodenitrification . Oxygen is the single most influential environmental factor affecting the production of nitrogen and dinitrogen oxides; a decrease in oxygen can result in a several-fold increase in nitrogen oxide and dinitrogen oxide production . Emission of nitrogen oxide and dinitrogen oxide from wastewater treatment plants and fertilized soils is well documented; however, only recently have the contributions from such environments to the global nitrogen and dinitrogen oxide budget been considered. J Environ Qual, 2003 Sep-Oct, 32(5), 1895 - 904 Particulates, not plants, dominate nitrogen processing in a septage-treating aerated pond system; Hamersley MR et al.; In pond and wetland systems for wastewater treatment, plants are often thought to enhance the removal of ammonium and nitrogen through the activities of root-associated bacteria . In this study, we examined the role of plant roots in an aerated pond system with floating plants designed to treat high-strength septage wastewater . We performed both laboratory and full-scale experiments to test the effect of different plant root to septage ratios on nitrification and denitrification, and measured the abundances of nitrifying bacteria associated with roots and septage particulates . Root-associated nitrifying bacteria did not play a significant role in ammonium and total nitrogen removal . Investigations of nitrifier populations showed that only 10% were associated with water hyacinth {Eichhornia crassipes (Mart.) Solms} roots (at standard facility plant densities equivalent to 2.2 wet g roots L(-1) septage); instead, nitrifiers were found almost entirely (90%) associated with suspended septage particulates . The role of root-associated nitrifiers in nitrification was examined in laboratory batch experiments where high plant root concentrations (7.4 wet g L(-1), representing a 38% net increase in total nitrifier populations over plant-free controls) yielded a corresponding increase (55%) in the non-substrate-limited nitrification rate (V(max)) . However, within the full-scale septage-treating pond system, nitrification and denitrification rates remained unchanged when plant root concentrations were increased to 7.1 g roots L(-1) (achieved by increasing the surface area available for plants while maintaining the same tank volume) . Under normal facility operating conditions, nitrification was limited by ammonium concentration, not nitrifier availability . Maximizing plant root concentrations was found to be an inefficient mechanism for increasing nitrification in organic particulate-rich wastewaters such as septage. J Environ Sci Health A Tox Hazard Subst Environ Eng, 2003, 38(11), 2633 - 41 Anaerobic-aerobic sewage treatment using the combination UASB-SBR activated sludge; Guimaraes P et al.; The performance of a pilot scale sewage treatment system composed of an upflow anaerobic sludge blanket (UASB) digester and a sequencing batch activated sludge reactor (SBR) is described . The system constitutes a simple, economic, and compact treatment option and is able to produce consistently a final effluent quality that is equal or better than that of a conventional activated sludge plant . The entire treatment system had a retention time of only 9h and an average operational temperature of 25 degrees C . Due to the efficient anaerobic pre treatment the aerobic sludge production was low and could easily be accommodated for stabilisation in the UASB reactor . The system exhibited excellent operational stability with full nitrification for aerobic sludge ages longer than 9 days . At shorter sludge ages there was excessive wash out of sludge particles and the sludge mass could not be maintained in the SBR reactor . Sludge settleability was good throughout the experimental investigation period of one year . The reduction of the reactor volume and oxygen consumption was more than 50% compared to conventional activated sludge . The anaerobic excess sludge had a high concentration and good stability so that its dewatering and final disposal was a relatively minor problem. Appl Environ Microbiol, 2003 Oct, 69(10), 5974 - 82 Community composition and functioning of denitrifying bacteria from adjacent meadow and forest soils; Rich JJ et al.; We investigated communities of denitrifying bacteria from adjacent meadow and forest soils . Our objectives were to explore spatial gradients in denitrifier communities from meadow to forest, examine whether community composition was related to ecological properties (such as vegetation type and process rates), and determine phylogenetic relationships among denitrifiers . nosZ, a key gene in the denitrification pathway for nitrous oxide reductase, served as a marker for denitrifying bacteria . Denitrifying enzyme activity (DEA) was measured as a proxy for function . Other variables, such as nitrification potential and soil C/N ratio, were also measured . Soil samples were taken along transects that spanned meadow-forest boundaries at two sites in the H . J . Andrews Experimental Forest in the Western Cascade Mountains of Oregon . Results indicated strong functional and structural community differences between the meadow and forest soils . Levels of DEA were an order of magnitude higher in the meadow soils . Denitrifying community composition was related to process rates and vegetation type as determined on the basis of multivariate analyses of nosZ terminal restriction fragment length polymorphism profiles . Denitrifier communities formed distinct groups according to vegetation type and site . Screening 225 nosZ clones yielded 47 unique denitrifying genotypes; the most dominant genotype occurred 31 times, and half the genotypes occurred once . Several dominant and less-dominant denitrifying genotypes were more characteristic of either meadow or forest soils . The majority of nosZ fragments sequenced from meadow or forest soils were most similar to nosZ from the Rhizobiaceae group in alpha-Proteobacteria species . Denitrifying community composition, as well as environmental factors, may contribute to the variability of denitrification rates in these systems. Appl Environ Microbiol, 2003 Oct, 69(10), 5950 - 6 Comparing denitrification estimates for a Texas estuary by using acetylene inhibition and membrane inlet mass spectrometry; Bernot MJ et al.; Characterizing denitrification rates in aquatic ecosystems is essential to understanding how systems may respond to increased nutrient loading . Thus, it is important to ensure the precision and accuracy of the methods employed for measuring denitrification rates . The acetylene (C2H2) inhibition method is a simple technique for estimating denitrification . However, potential problems, such as inhibition of nitrification and incomplete inhibition of nitrous oxide reduction, may influence rate estimates . Recently, membrane inlet mass spectrometry (MIMS) has been used to measure denitrification in aquatic systems . Comparable results were obtained with MIMS and C2H2 inhibition methods when chloramphenicol was added to C2H2 inhibition assay mixtures to inhibit new synthesis of denitrifying enzymes . Dissolved-oxygen profiles indicated that surface layers of sediment cores subjected to the MIMS flowthrough incubation remained oxic whereas cores incubated using the C2H2 inhibition methods did not . Analysis of the microbial assemblages before and after incubations indicated significant changes in the sediment surface populations during the long flowthrough incubation for MIMS analysis but not during the shorter incubation used for the C2H2 inhibition method . However, bacterial community changes were also small in MIMS cores at the oxygen transition zone where denitrification occurs . The C2H2 inhibition method with chloramphenicol addition, conducted over short incubation intervals, provides a cost-effective method for estimating denitrification, and rate estimates are comparable to those obtained by the MIMS method. J Environ Sci Health A Tox Hazard Subst Environ Eng, 2003, 38(10), 2317 - 28 Upgrading of a small overloaded activated sludge plant using a MBBR system; Andreottola G et al.; The aim of this research was the application of a biofilm system for the upgrading of a full-scale overloaded activated sludge MWWTP using the MBBR (Moving Bed Biofilm Reactor) technology . The choice of this fixed biomass system appeared appropriate because it offers several advantages including good potential in nitrification process, easiness of management and above all, the possibility to use the existing tank with very few modifications . MBBR system counts only few full-scale plants in Italy at the moment, thus a pilot-scale experimentation was preliminarily carried out . The acquired parameters were used for the fullscale MWWTP upgrading . The upgrading of the activated sludge reactor in the MBBR system has given (1) a relevant increase in the flowrate treated up to 60%; (2) a good efficiency in organic carbon removal and nitrification, equal to 88% and 90% respectively, with HRTs of 5.5-7 h; (3) the overcoming of the hydraulic overload of the secondary settler, applying a lamellar settler . It was observed a good correlation between the results obtained at pilot-scale and those observed in the full-scale plant. J Environ Sci Health A Tox Hazard Subst Environ Eng, 2003, 38(10), 2179 - 89 Novel phased isolation ditch system for enhanced nutrient removal and its optimal operating strategy; Hong KH et al.; Phased isolation ditch system with intrachannel clarifier is a simplified novel oxidation ditch system enhancing simultaneous removal of biological nitrogen and phosphorus in municipal wastewater . The system employs two ditches with intra-clarifier, and eliminates external final clarifier, additional preanaerobic reactor, and recycle of sludge and nitrified effluent . Separation of anoxic, anaerobic, and aerobic phases can be accomplished by alternating flow and intermittent aeration . Its pilot-scale system operated at HRTs of 10-21 h, SRTs of 15-41 days, and a cycle times of 2-8 h showed removals of BOD, TN, and TP in the range of mixed liquor temperature above 10 degrees C as high as 88-97, 70-84, and 65-90%, respectively . As the SRTs became longer, the effluent TN decreased dramatically, whereas the effluent TP increased . Higher nitrogen removal was accomplished at shorter cycle times, while better phosphorus removal was achieved in longer cycle times . Optimal system operating strategies maximizing the performance and satisfying both the best nitrogen and phosphorus removals included HRTs ranged 10-14 h, SRTs ranged 25-30 days, and a cycle time of 4 h at the mixed liquor temperature above 10 degrees C . Thus, complete phase separation in a cycle maximizing phosphorus release and uptake as well as nitrification and denitrification was accomplished by scheduling of alternating flow and intermittent aeration in the simplified process scheme . Especially, temporal phase separation for phosphorus release without additional anaerobic reactor was successfully accomplished during anaerobic period without any nitrate interference and carbon-limiting. J Environ Sci Health A Tox Hazard Subst Environ Eng, 2003, 38(10), 2157 - 67 Nitrification-denitrification of opto-electronic industrial wastewater by anoxic/aerobic process; Chen TK et al.; This research focused on the biological treatment of high-strength organic nitrogen wastewater, and presented the results from the nitrification and denitrification of an actual industrial wastewater using anoxic/aerobic process . The opto-electronic industrial wastewater often contains a significant quantity of organic nitrogen compounds and has a ratio over 95% in organic nitrogen (Org-N) to total nitrogen (T-N) . In this study, a 2-stage anoxic/aerobic process was established and evaluated the efficiency of wastewater treatment . Raw wastewater from an actual TFT-LCD manufacturing plant was obtained as the sample for looking into the feasibility of opto-electronic industrial wastewater treatment . After toxicity identification evaluation (TIE) test of raw wastewater . the inhibition was related to organic nitrogen (TMAH, MEA) and unionized ammonia (free ammonia, NH3) with high pH . Therefore, pH control is important for biological treatment of high-strength organic nitrogen industrial wastewater . Besides . hydraulic retention time (HRT) and mixed liquor recycled rate (MLR) were controlled independently to distinguish between the effects of these two factors . Under suitable HRT ( > 1.7 d) and mixed liquor recycled rate (< 4Q), effluent of NH4-N . NO3-N + NO2-N, and COD can fall below 20 mg/L, 30 mg/L, and 80 mg/L . The anoxic/aerobic process removed 92-98% of the carbon source, and approximately 80% of TKN, 70% of T-N. J Environ Sci Health A Tox Hazard Subst Environ Eng, 2003, 38(10), 2147 - 56 Combined carbonaceous removal and nitrification with biological aerated filters; Belgiorno V et al.; This paper describes the use of a submerged biological aerated filter (BAFs), on a pilot plant scale, in the secondary nitrification of low strength domestic wastewater . The results, obtained throughout three months of tests, confirmed the ability of BAFs to obtain simultaneous carbonaceous removal and nitrification . In fact, alter a start-up period of 5 weeks, a remarkable steady state condition in the removal of suspended solids (TSS), chemical oxygen demand (COD) and nitrification was reached . For a hydraulic loading rate of 1.6 m3 m(-2) h(-1), the mean efficiency of the process in the removal of TSS and COD was 85% and 83% respectively . Mean concentrations in the influent flow of around 114 mg(TSS)/L and 140 mg(COD)/L were reduced to average values of below 17 mg(TSS)/L and 25 mg(COD)/L . Secondary nitrification was achieved with a mean efficiency of 85% for a mean volumetric loads of 0.45 kg(N-Namm) m(-3) d(-1) (25 degrees C) . Through an intensive activity of nitrification, in the steady state condition, mean influent concentrations of around 12 mg(N-Namm)/L were reduced to average values of below 2 mg(N-Namm)/L . The removal loading rate increased linearly with the applied loading rate for volumetric loads of up to 0.7 kg(N-Namm) m(-3) d(-1) . The nitrification was not sensitive to the applied COD loads because of the low level of carbon substrate. J Environ Sci Health A Tox Hazard Subst Environ Eng, 2003, 38(10), 1997 - 2007 Molecular analysis of microbial communities in nitrification and denitrification reactors treating high ammonia leachate; Calli B et al.; Molecular analysis of microbial populations in two bench-scale nitrification and denitrification reactors fed with high ammonia landfill leachate was conducted in this study by using DGGE, cloning, and FISH techniques in addition to classical efficiency control parameters . Nitrification tank was operated with a computer-controlled alkalinity dosing system to supply the alkalinity intermittently as consumed on the basis of on-line pH monitoring . By keeping the pH at 7.0 with this system, 99% nitrification efficiency and rates of about 0.14-0.18 mgNH4+-N/mgVSSday were obtained . Meanwhile, as ammonia oxidizing bacteria Nitrosomonas and Nitrosococcus mobilis-like cells and as nitrite oxidizing bacteria Nitrobacter-related cells were intensively indicated . Moreover, some aerobic denitrifiers as Thauera species were also identified . After the termination of pH adjustment in the preceding anaerobic reactors, nitrification tank was loaded with more biodegradable COD as a result of reduced COD removal in anaerobic reactors . Microbial diversity was immediately affected from this alteration and heterotrophic carbonaceous bacteria and aerobic denitrifiers have dominated . To provide the former high efficiencies, retention time has increased from 24 to 48 h and a second pump dosing HCl was included to the automatic control system . Subsequent to these precautions, numbers of ammonia (Nso190) and nitrite oxidizing bacteria (NIT3) were comparatively increased . In denitrification system, about 98% denitrification efficiencies were obtained at 2000 mg/L NOx-N concentrations if sodium acetate was supplied as carbon source . Meanwhile, with 20 gVSS/l biomass concentration, denitrification rates of about 1.34 mgNOx-N/mgVSSday were obtained . All sludge samples have represented similar DGGE patterns and Paraccoccus-related species were identified as dominant denitrifying bacteria. Environ Sci Technol, 2003 Sep 15, 37(18), 4021 - 6 Fate of estrogens in a municipal sewage treatment plant; Andersen H et al.; The fate of the highly potent endocrine disrupters estrone (E1), 17beta-estradiol (E2), and 17alpha-ethinylestradiol (EE2) was investigated in mechanical and biological sewage treatment as well as in sewage-sludge treatment at a municipal German sewage treatment plant (STP) . The main outcome of the study was that a common municipal STP with an activated sludge system for nitrification and denitrification including sludge recirculation can appreciably eliminate natural and synthetic estrogens . As a consequence, the endocrine effects of biota in the receiving waters should be significantly reduced . All estrogen concentrations decreased gradually along the treatment train . In the STP effluent, the steroid estrogen concentrations were always below the quantification limit of 1 ng/L . The elimination efficiency of the natural estrogens (E1 and E2) exceeded 98%, and EE2 was reduced by more than 90% . The natural estrogens were largely degraded biologically in the denitrifying and aerated nitrifying tanks of the activated sludge system, whereas EE2 was only degraded in the nitrifying tank . Only about 5% of the estrogens are sorbed onto digested sewage sludge . It is very likely that conjugates (glucuronides and sulfates) of the estrogens were cleaved into the parent compounds mainly in the first denitrification tank. Water Sci Technol, 2003, 48(3), 73 - 9 Evaluation of sequencing batch reactor (SBR) and sequencing batch biofilm reactor (SBBR) for biological nutrient removal from simulated wastewater containing glucose as carbon source; Kumar BM et al.; In general, conventional activated sludge (ASP) or enhanced biological phosphorus removing (EBPR) sludge has been used as seed culture for developing EBPR sludge and the time reported for development varies from months to year . In the present study cow-dung has been used as seed culture and EBPR sludge was developed within 36 days . The developed EBPR sludge has been used to evaluate the performance of sequential batch reactor (SBR) and sequential batch biofilm reactors (SBBR) for simultaneous nitrogen and phosphorus removal from synthetic wastewater containing glucose as carbon source . Three reactors were operated, SBR-1 containing only suspended biomass, SBBR-2 and SBBR-3 containing 5% and 10% polyurethane foam (PUF) media respectively along with suspended biomass . In all the reactors phosphorus removal was nearly the same and was more than 80% . In all the three reactors greater than 90% nitrification was achieved . Nitrogen removal in SBR-1 was 48% and in SBBR-2 and SBBR-3 it was more than 62% . On line monitoring of oxidation-reduction potential (ORP), pH and phosphorus during a cycle indicated that ORP and pH can be useful for real time control and optimization of the process. Water Sci Technol, 2003, 48(3), 31 - 8 Calorimetric assessment of activity in WWTP biomass; Daverio E; A heat flux bench-scale calorimeter (Bio-RC1) has been used to assess the metabolic activity of microbial populations involved in wastewater treatment biological processes under aerobic, anoxic and anaerobic conditions . Under strictly aerobic conditions, a linear correlation was observed between oxygen uptake rate and heat flux for heterotrophic and nitrifying bacterial populations . Using the same calorimetric approach and the same apparatus, toxicity and biodegradability of a pesticides factory wastewater were investigated . The activity of heterotrophic and nitrifying aerobic communities was monitored considering both oxygen consumption and heat dissipation, whereas, under anoxic conditions, calorimetric data were compared to the traditional NUR (nitrate uptake rate) test . Heterotrophic activity was found to be 52% inhibited after toxic wastewater exposure under both aerobic and anoxic conditions and 30% inhibition was observed on autotrophic ammonia oxidation . Additionally, calorimetric measurements have been successfully applied to investigate anaerobic digestion . The thermal response of a mesophilic granular sludge to repetitive glucose pulses has been evaluated and a toxicity test has been performed by exposing the biomass to increasing concentrations of formaldehyde. Water Sci Technol, 2003, 48(3), 17 - 24 A comparitive study of ammonia-oxidizing bacteria in lab-scale industrial wastewater treatment reactors; Rowan AK et al.; The diversity and community structure of the beta-proteobacterial ammonia oxidising bacteria (AOB) in a range of different lab-scale industrial wastewater treatment reactors were compared . Three of the reactors treat waste from mixed domestic and industrial sources whereas the other reactor treats waste solely of industrial origin . PCR with AOB selective primers was combined with denaturing gradient ge electrophoresis to allow comparative analysis of the dominant AOB populations and the phylogenetic affiliation of the dominant AOB was determined by cloning and sequencing or direct sequencing of bands excised from DGGE gels . Different AOB were found within and between different reactors . All AOB sequences identified were grouped within the genus Nitrosomonas . Within the lab-scale reactors there appeared to be selection for a low diversity of AOB and predominance of a single AOB population . Furthermore, the industrial input in both effluents apparently selected for salt tolerant AOB, most closely related to Nitrosococcus mobilis and Nitrosomonas halophila. Biotechnol Lett, 2003 Sep, 25(17), 1469 - 71 Ammonia removal from freshwater using nitrifying bacteria enriched from a seawater aquaculture pond; Shan H et al.; Intensively cultured fish stock when fed protein-rich feeds typically excrete high concentrations of total ammoniacal-nitrogen (TAN) into the water column which can have adverse effects on productivity, and upon the environment when aquaculture water is discharged . An immobilized culture of nitrifying bacteria isolated from prawn pond water and known to effectively remove TAN from saline water was tested for its ability to remove TAN from freshwater . The culture was readily adaptable to non-saline conditions and maintained TAN at less than 0.25 mg l(-1), even with a daily addition of 3.2 to 4.2 mg TAN l(-1) per d . The use of the immobilized culture of nitrifying bacteria represents an innovative and economical in situ treatment technology for removal of TAN in both saline and freshwater. J Biotechnol, 2003 Oct 9, 105(1-2), 71 - 82 Characterization and evaluation of aerobic granules in sequencing batch reactor; Jang A et al.; In order to investigate the aerobic granules cultured under alternating aerobic and anoxic conditions, a sequencing batch reactor (SBR) was operated without the presence of a carrier material . Nitrification and denitrification occurred alternately in the SBR operation, with an increased nitrification efficiency of up to 97% and a high chemical oxygen demand (COD) removal efficiency of up to 95% . It was observed that physical characteristics of granule play an important role in the performance of the SBR process . Light microscopy was used to observe the time dependent development of the granules in the SBR . Based on the microscopic observations, some floc-like sludges remained in the form of a mixture with granules for 30 days of operation . Even though various granule sizes had been formed in the reactor after 50 days, the granule sizes were primarily from 1 +/- 0.35 to 1.3 +/- 0.45 mm, rarely exceeding 2 mm . The granules were analyzed by a combination of microelectrodes and fluorescent in situ hybridization (FISH), which provides more detailed information on what happens inside the granules . Based on their results, ammonia oxidizing bacteria (AOB) existed primarily in the upper and middle layers of the granule . Assuming a first-order reaction for nitrification, most of the nitrification is likely to occur from the surface to 300 microm into the granular thickness. J Biotechnol, 2003 Oct 9, 105(1-2), 33 - 40 In situ PCR for visualizing distribution of a functional gene "amoA" in a biofilm regardless of activity; Hoshino T et al.; In this study, ammonia-oxidizing bacteria present in biofilms resulting from a nitrifying reactor were detected by both a conventional FISH technique and an original in situ PCR technique . Both techniques showed that ammonia-oxidizing bacteria were found near the surface of the biofilms . However, after the biofilm had been exposed to 2 weeks of ammonia starvation, ammonia-oxidizing bacteria present in the biofilm could not be detected by fluorescence in situ hybridization (FISH) because they did not have sufficient copies of rRNA . In contrast, ammonia-oxidizing bacteria could be detected by in situ PCR with strong signal . It was thus demonstrated that a cell possessing a specific functional gene is detectable by in situ PCR regardless of its activity. Water Res, 2003 Nov, 37(18), 4343 - 50 COD and nitrogen removal by biofilms growing on gas permeable membranes; Semmens MJ et al.; A bioreactor was constructed and used to treat a synthetic wastewater containing ammonium acetate and trace nutrients for about 190 days . The reactor was aerated by means of bundles of gas-permeable hollow-fiber membranes that were installed in the reactor . The membranes provided a specific surface area of 422 m(2)/m(3) and the external surface of the membranes rapidly became covered in an active biofilm . The membrane bundles were agitated by an internal gas recycle . The gas bubbles in the water encouraged fiber-fiber contact and were intended to control biofilm growth . Chemical oxygen demand (COD) removals in