Biotechnol Bioeng, 2004 Jan 5, 85(1), 68 - 77 Toluene removal from waste air using a flat composite membrane bioreactor; Jacobs P et al.; In this report, gaseous toluene biodegradation results in a flat composite membrane reactor inoculated with Pseudomonas putida TVA8 are presented . Preliminary abiotic experiments showed that transport of toluene through the membrane was linearly and negatively correlated with the gas residence time (tau) . During a 339-day biofiltration experiment, the influence of gas residence time (2-24 sec) and mass loading rate (B(v); 10-483 g x m(-3) h(-1)) on the toluene elimination capacity was investigated . A maximum elimination capacity (EC(max)) of 397 g x m(-3) h(-1) was achieved at tau = 24 sec and B(v) = 473 g x m(-3) h(-1) . Expressed per unit membrane area, the EC(m,max) was 0.793 g x m(-2) h(-1), which is five times higher than results obtained with other membrane bioreactor experiments in the same range of loading rates . At low gas residence times, reactor performance was limited by mass transfer . Toluene concentration profiles along the membrane were measured for several biotic and abiotic conditions . For inlet concentrations (C(in)) up to 1 g x m(-3), more than 90% was eliminated at 15 cm from the reactor inlet . For C(in) > 1.65 g x m(-3), longer membranes are necessary to obtain these high removal efficiencies . J Nephrol, 2003 Jul-Aug, 16(4), 572 - 9 Cost analysis of blood purification in intensive care units: continuous versus intermittent hemodiafiltration; Vitale C et al.; BACKGROUND: We implemented a program for continuous renal replacement therapies (CRRT) in intensive care units (ICU) based on the cooperative work of dialysis and ICU personnel . Our aim was to report the main details of this program and compare its cost with that of intermittent hemodiafiltration (IHDF) . METHODS: The study referred to 181 ICU patients with renal failure . We considered the costs of both technical devices and assisting personnel . CRRT was performed as continuous veno-venous hemodiafiltration (CVVHDF) (24 hr daily); dialysis and ICU nurses shared surveillance . Only dialysis nurses performed IHDF (as acetate-free biofiltration, 4 hr daily) in the ICU . RESULTS: The daily cost of CRRT was Euro 276.70; of which 79% was for devices and 21% was for human resources . Nurse surveillance required 141 min per day, ICU nurses supplied 55% (77 min) and dialysis nurses 45% (64 min) . On average, CRRT surveillance required less than 1 min/nurse/hr for both dialysis and ICU nurses . The daily cost of 4-hr IHDF sessions of was Euro 247.83, of which 44% was for technical devices and 56% was for human resources . CONCLUSIONS: The cooperation between dialysis and ICUs improved the use of human resources and allowed us to supply CRRT to all critically ill patients with acute renal failure . The expenditure for CRRT was 12% higher than that for IHDF, due to the cost of technical devices. Bioresour Technol, 2004 Apr, 92(2), 143 - 9 Aerobic degradation of the azo dye acid red 151 in a sequencing batch biofilter; Buitron G et al.; The azo dye acid red 151 (AR151) was aerobically biodegraded in a sequencing batch biofilter packed with a porous volcanic rock . AR151 was used as the sole source of carbon and energy for acclimated microorganisms . Acclimation was followed using the degradation time and the oxygen uptake rate . A maximal oxygen uptake rate of 0.5 mg O(2)/(lmin) was obtained . Mineralization studies showed that 73% (as carbon) of the initial azo dye was transformed to CO(2) by the consortia . A maximal substrate degradation rate of 247 mg AR151/(l(reactor)d) was obtained . Color removal was up to 99% using an initial concentration of 50 mg AR151/l . Anaerobic tests suggested that in the interior of the porous material, anaerobic biotransformations can occur, contributing from 14% to 16% of the decoloration of the azo dye. Water Sci Technol, 2003, 48(8), 89 - 96 Biomass accumulation patterns for removing volatile organic compounds in rotating drum biofilters; Yang C et al.; A rotating drum biofilter (RDB) with multi-layered foam media was developed for the improvement of current biofiltration technology . The biofilter was used to investigate the effects of organic loadings and influent volatile organic compound (VOC) concentrations on VOC removal efficiency and biomass accumulation . These effects were evaluated using diethyl ether and toluene separately as model VOCs at an empty bed contact time (EBCT) of 30 s . When the toluene loading increased from 2.0 to 4.0 and 8.0 kgCOD m(-3) day(-1), toluene removal efficiency of the biofilter decreased from over 99% to 78% and 74%, respectively . The biomass distribution was found to be more even within the medium when removing toluene than when removing diethyl ether . Higher organic loading also resulted in the more even distribution of the biomass . The ratios of biomass accumulation rates in the medium of the outermost, middle and innermost layers ranged from 1:0.11:0.02 when removing diethyl ether at 2.0 kgCOD m(-3) day(-1) to 1:0.69:0.51 when removing toluene at 8.0 kgCOD m(-3) day(-1) . Review of these ratios revealed three biomass accumulation patterns: surface pattern, in-depth pattern and shallow pattern . Different patterns represent different removal mechanisms in the biofiltration process . Improved biofilter design and operation should be based on the biomass accumulation pattern. Water Res, 2004 Jan, 38(2), 404 - 13 Hydrodynamic behaviour and comparison of technologies for the removal of excess biomass in gas-phase biofilters; Mendoza JA et al.; The hydrodynamic behaviour of a biofilter fed toluene and packed with an inert carrier was evaluated on start-up and after long-term operation, using both methane and styrene as tracers in Residence Time Distribution experiments . Results indicated some deviation from ideal plug flow behaviour after 2-year operation . It was also observed that the retention time of VOCs gradually increased with time and was significantly longer than the average residence time of the bulk gas phase . Non-ideal hydrodynamic behaviour in packed beds may be due to excess biomass accumulation and affects both reactor modeling and performance . Therefore, several methods were studied for the removal of biomass after long-term biofilter operation: filling with water and draining, backwashing, and air sparging . Several flow rates and temperatures (20-60 degrees C) were applied using either water or different chemicals (NaOH, NaOCl, HTAB) in aqueous solution . Usually, higher flow rates and higher temperatures allowed the removal of more biomass, but the efficiency of biomass removal was highly dependent on the pressure drop reached before the treatment . The filling/draining method was the least efficient for biomass removal, although the treatment did basically not generate any biological inhibition . The efficiency of backwashing and air sparging was relatively similar and was more effective when adding chemicals . However, treatments with chemicals resulted in a significant decrease of the biofilter's performance immediately after applying the treatment, needing periods of several days to recover the original performance . The effect of manually mixing the packing material was also evaluated in duplicate experiments . Quite large amounts of biomass were removed but disruption of the filter bed was observed . Batch assays were performed simultaneously in order to support and quantify the observed inhibitory effects of the different chemicals and temperatures used during the treatments. Biodegradation, 2003 Dec, 14(6), 415 - 21 Addressing biofilter limitations: a two-phase partitioning bioreactor process for the treatment of benzene and toluene contaminated gas streams; Davidson CT et al.; A two-phase partitioning bioreactor (TPPB) achieved simultaneous and continuous removal and degradation of benzene and toluene from an air stream . The aqueous- organic system utilized n-hexadecane as the organic phase, and the organism Alcaligenes xylosoxidans Y234 in the aqueous phase to achieve the degradation of benzene and toluene . The system, which operates as a well-mixed dispersion and is therefore resistant to substrate surges, was first shown to be capable of utilizing toluene while operating at a loading capacity of 235 g m(-3) h(-1) with an elimination capacity of 233 g m(-3) h(-1) . It was also determined that to characterize TPPB performance in terms of elimination capacity the definition of elimination capacity must be extended to include the cell mass present, a readily controllable variable given the nature of the system . Based on this criterion, it was estimated that for a cell concentration of 1 g l(-1) present in the TPPB, the potential maximum toluene elimination capacity is 1290 g m(-3) h(-1) which is substantially higher than any toluene elimination capacity achieved by biofilters at a high removal efficiency . If no other factor were to limit the system, elimination capacities could be many times higher still, and are dependent on maintaining desired cell concentrations above 1 g l(-1) . The TPPB was then operated at nominal loading capacities of 63 g m(-3) h(-1) (benzene) and 51 g m(-3) h(-1) (toluene) at a removal efficiency greater than 99% to demonstrated the applicability of this system in dealing with two chemical species simultaneously . TPPB systems therefore have been shown to be effective at removing gaseous organic contaminants at high removal efficiencies while also possessing desirable operating features, such as providing and maintaining high cell concentrations throughout the reactor, and a capacity to effectively deal with high contaminant loadings. Appl Microbiol Biotechnol, 2004 Jun, 64(6), 855 - 61 Epub 2003 Dec 10. Mesophilic and thermophilic BTEX substrate interactions for a toluene-acclimatized biofilter; Strauss JM et al.; Benzene, toluene, ethylbenzene and xylene (BTEX) substrate interactions for a mesophilic (25 degrees C) and thermophilic (50 degrees C) toluene-acclimatized composted pine bark biofilter were investigated . Toluene, benzene, ethylbenzene, o-xylene, m-xylene and p-xylene removal efficiencies, both individually and in paired mixtures with toluene (1:1 ratio), were determined at a total loading rate of 18.1 g m(-3) h(-1) and retention time ranges of 0.5-3.0 min and 0.6-3.8 min for mesophilic and thermophilic biofilters, respectively . Overall, toluene degradation rates under mesophilic conditions were superior to degradation rates of individual BEX compounds . With the exception of p-xylene, higher removal efficiencies were achieved for individual BEX compounds compared to toluene under thermophilic conditions . Overall BEX compound degradation under mesophilic conditions was ranked as ethylbenzene >benzene > o-xylene > m-xylene > p-xylene . Under thermophilic conditions overall BEX compound degradation was ranked as benzene > o-xylene >ethylbenzene > m-xylene > p-xylene . With the exception of o-xylene, the presence of toluene in paired mixtures with BEX compounds resulted in enhanced removal efficiencies of BEX compounds, under both mesophilic and thermophilic conditions . A substrate interaction index was calculated to compare removal efficiencies at a retention time of 0.8 min (50 s) . A reduction in toluene removal efficiencies (negative interaction) in the presence of individual BEX compounds was observed under mesophilic conditions, while enhanced toluene removal efficiency was achieved in the presence of other BEX compounds, with the exception of p-xylene under thermophilic conditions. Microbiol Mol Biol Rev, 2003 Dec, 67(4), 503 - 49 Recent advances in petroleum microbiology; Van Hamme JD et al.; Recent advances in molecular biology have extended our understanding of the metabolic processes related to microbial transformation of petroleum hydrocarbons . The physiological responses of microorganisms to the presence of hydrocarbons, including cell surface alterations and adaptive mechanisms for uptake and efflux of these substrates, have been characterized . New molecular techniques have enhanced our ability to investigate the dynamics of microbial communities in petroleum-impacted ecosystems . By establishing conditions which maximize rates and extents of microbial growth, hydrocarbon access, and transformation, highly accelerated and bioreactor-based petroleum waste degradation processes have been implemented . Biofilters capable of removing and biodegrading volatile petroleum contaminants in air streams with short substrate-microbe contact times (<60 s) are being used effectively . Microbes are being injected into partially spent petroleum reservoirs to enhance oil recovery . However, these microbial processes have not exhibited consistent and effective performance, primarily because of our inability to control conditions in the subsurface environment . Microbes may be exploited to break stable oilfield emulsions to produce pipeline quality oil . There is interest in replacing physical oil desulfurization processes with biodesulfurization methods through promotion of selective sulfur removal without degradation of associated carbon moieties . However, since microbes require an environment containing some water, a two-phase oil-water system must be established to optimize contact between the microbes and the hydrocarbon, and such an emulsion is not easily created with viscous crude oil . This challenge may be circumvented by application of the technology to more refined gasoline and diesel substrates, where aqueous-hydrocarbon emulsions are more easily generated . Molecular approaches are being used to broaden the substrate specificity and increase the rates and extents of desulfurization . Bacterial processes are being commercialized for removal of H(2)S and sulfoxides from petrochemical waste streams . Microbes also have potential for use in removal of nitrogen from crude oil leading to reduced nitric oxide emissions provided that technical problems similar to those experienced in biodesulfurization can be solved . Enzymes are being exploited to produce added-value products from petroleum substrates, and bacterial biosensors are being used to analyze petroleum-contaminated environments. J Air Waste Manag Assoc, 2003 Nov, 53(11), 1373 - 83 Biofiltration of cyclic air emissions of alpha-pinene at low and high frequencies; Dirk-Faitakis C et al.; Biofiltration of periodically fluctuating concentrations of an alpha-pinene-laden waste gas was investigated to treat both high-frequency and low-frequency fluctuations . The effects of periodic concentration fluctuations on biofilter performance were measured . Controlled variables of periodic operation included cycle period and amplitude . The cycle period ranged from 10 min to 6 days, with the inlet alpha-pinene concentration fluctuating between 0 and 100 parts per million volume . At high-frequency concentration cycling (i.e., on the order of minutes), both cyclic and constant concentration biofilters maintained similar long-term performance with an average removal efficiency of 77% at an averaged loading rate of 29 g alpha-pinene/m3 bed/hr . A first approximation suggests kinetics that are time-independent, indicating that steady-state data can be used to predict transient behavior at this time scale . Cyclic biofilter operation with a cycle period of 24 hr (with equal on/off time) was achievable for biofilters without a significant loss in performance . At longer time scales, cyclic biofilter performance decreased at the restart of the ON cycle . The recovery time to previous levels of performance increased with increasing cycle period; the recovery time was less than 1 hr for a cycle period of 24 hr and between 6 and 8 hr for a cycle period of 6 days. Water Sci Technol, 2003, 48(6), 311 - 8 Combined anaerobic-aerobic treatment of landfill leachates under mesophilic, submesophilic and psychrophilic conditions; Kalyuzhnyi S et al.; As a first step of treatment of landfill leachates (total COD--1,430-3,810 mg/l, total nitrogen 90-162 mg/l), a performance of laboratory UASB reactors has been investigated under mesophilic (30 degrees C), sub-mesophilic (20 degrees C) and psychrophilic (10 degrees C) conditions . Under hydraulic retention times (HRT) of around 7 h, when the average organic loading rates (OLR) were around 5 g COD/l/day, the total COD removal accounted for 81% (on the average) with the effluent concentrations close to anaerobic biodegradability limit (0.25 g COD/l) for mesophilic and sub-mesophilic regimes . The psychrophilic treatment conducted under the average HRT of 8 h and the average OLR of 4.22 g COD/l/day showed a total COD removal of 47% producing the effluents (0.75 g COD/l) more suitable for subsequent biological nitrogen removal . All three anaerobic regimes used for leachate treatment were quite efficient for elimination of heavy metals (Fe, Zn, Cu, Pb, Cd) by concomitant precipitation in the form of insoluble sulphides inside the sludge bed . The application of aerobic/anoxic biofilter as a sole polishing step for psychrophilic anaerobic effluents was acceptable for elimination of biodegradable COD and nitrogen approaching the current standards for direct discharge of treated wastewater. Biotechnol Lett, 2003 Oct, 25(20), 1757 - 61 Development and operation of a trickling biofilter system for continuous treatment of gas-phase trichloroethylene; Lee EY et al.; A parallel trickling biofilter (TBF) system that consists of two TBFs units in parallel, one for biodegradation of trichloroethylene (TCE) and the other for reactivation of an inactivated biofilm, was developed and operated for continuous treatment of gas-phase TCE by Burkholderia cepacia G4 . For inlet loadings below 8.6 mg TCE l(-1) d(-1) complete removal of TCE was achieved . The maximal TCE elimination capacity was 17 mg l(-1) d(-1). J Air Waste Manag Assoc, 2003 Oct, 53(10), 1248 - 55 Biofiltration of trichloroethylene-contaminated air: a pilot study; Lackey LW et al.; This project demonstrated the biofiltration of a trichloroethylene (TCE)-contaminated airstream generated by air stripping groundwater obtained from several wells located at the Anniston Army Depot, Anniston, AL . The effects of several critical process variables were investigated to evaluate technical and economic feasibility, define operating limits and preferred operating conditions, and develop design information for a full-scale biofilter system . Long-term operation of the demonstration biofilter system was conducted to evaluate the performance and reliability of the system under variable weather conditions . Propane was used as the primary substrate necessary to induce the production of a nonspecific oxygenase . Results indicated that the process scheme used to introduce propane into the biofiltration system had a significant impact on the observed TCE removal efficiency . TCE degradation rates were dependent on the inlet contaminant concentration as well as on the loading rate . No microbial inhibition was observed at inlet TCE concentrations as high as 87 parts per million on a volume basis. Bioresour Technol, 2004 Jan, 91(2), 145 - 52 A dispersion modelling approach to determining the odour impact of intensive pig production units in Ireland; Sheridan BA et al.; It is becoming more common now to use atmospheric dispersion models to predict where odour nuisance is likely to occur near pig units . An odour threshold concentration of 1 OuE m(-3) is the level at which an odour is detectable by 50% of screened panellists . A new odour annoyance criterion (C(98,1-h) (98%-ile, 1-h average odour concentration) < or = 4.3 OuE m(-3)) was developed in this study and compared to the Environmental Protection Agency (EPA) (Ireland) recommendation (C(98,1-h)< or = 6 OuE m(-3)) using the ISCST3 model with data from three meteorological stations . Abatement techniques such as exhaust vent modification, feed manipulation, and biofiltration were assessed . Based on current limits (C(98,1-h)< or = 6 OuE m(-3)) for existing facilities, predicted setback distances can be up to 780 m for a 1000-sow unit, depending on which meteorological data set is used . However, if using the suggested odour impact criterion in this research (C(98,1-h)< or = 4.3 OuE m(-3)), setback distances could reach a maximum of 1000 m . Biofilters on second stage weaning and finishing pig buildings offer the greatest single reduction (up to 650 m) in odour impact . When combined with feed manipulation and increased exhaust air velocity, the figure can be as high as 920 m . Due to the critical requirement for local meteorological data, it is recommended that a meteorological station be installed on large pig units to facilitate more accurate predictions . Site measurements of odour emissions should be made in each case because emissions are influenced by a range of local factors including feed, manure management, building design and operation. Water Environ Res, 2003 Sep-Oct, 75(5), 444 - 54 Odor and volatile organic compound removal from wastewater treatment plant headworks ventilation air using a biofilter; Converse BM et al.; Laboratory-scale experiments and field studies were performed to evaluate the feasibility of biofilters for sequential removal of hydrogen sulfide and volatile organic compounds (VOCs) from wastewater treatment plant waste air . The biofilter was designed for spatially separated removal of pollutants to mitigate the effects of acid production resulting from hydrogen sulfide oxidation . The inlet section of the upflow units was designated for hydrogen sulfide removal and the second section was designated for VOC removal . Complete removal of hydrogen sulfide (H2S) and methyl tert-butyl ether (MTBE) was accomplished at loading rates of 8.3 g H2S/(m3 x h) (15-second empty bed retention time {EBRT}) and 33 g MTBE/(m3 x h) (60-second EBRT), respectively . In field studies performed at the Hyperion Treatment Plant in Los Angeles, California, excellent removal of hydrogen sulfide, moderate removal of nonchlorinated VOCs such as toluene and benzene, and poor removal of chlorinated VOCs were observed in treating the headworks waste air . During spiking experiments on the headworks waste air, the percentage removals were similar to the unspiked removals when nonchlorinated VOCs were spiked; however, feeding high concentrations of chlorinated VOCs reduced the removal percentages for all VOCs . Thus, biofilters offer a distinct advantage over chemical scrubbers currently used at publicly owned treatment works in that they not only remove odor and hydrogen sulfide efficiently at low cost, but also reduce overall toxicity by partially removing VOCs and avoiding the use of hazardous chemicals. Chemosphere, 2004 Jan, 54(3), 243 - 54 Evaluation of dispersion methods for enumeration of microorganisms from peat and activated carbon biofilters treating volatile organic compounds; Khammar N et al.; To enumerate microorganisms having colonized biofilters treating volatile organic compounds, it is necessary firstly to evaluate dispersion methods . Crushing, shaking and sonication were then tested for the removal of microflora from biofilters packing materials (peat and activated carbon) . Continuous or discontinuous procedures, and addition of glass beads had no effect on the number of microorganisms removed from peat particles . The duration of treatment also had no effect for shaking and crushing, but the number of microorganisms after 60 min of treatment with ultrasound was significantly higher than that obtained after 0.5 min . The comparison between these methods showed that crushing was the most efficient for the removal of microorganisms from both peat and activated carbon . The comparison between three chemical dispersion agents showed that 1% Na-pyrophosphate was less efficient, compared with 200 mM phosphate buffer or 1% Na-hexametaphosphate . To optimize the cultivation of microorganisms, three different agar media were compared . Tryptic soy agar tenfold diluted (TSA 1/10) was the most suitable medium for the culture of microflora from a peat biofilter . For the activated carbon biofilter, there was no significant difference between Luria Bertoni, TSA 1/10, and plate count agar . The optimized extraction and enumeration protocols were used to perform a quantitative characterization of microbial populations in an operating laboratory activated carbon biofilter and in two parallel peat biofilters. J Environ Sci (China), 2003 Sep, 15(5), 691 - 6 Biodegradation of methanol vapor in a biofilter; Arulneyam D et al.; Volatile organic compounds (VOCs) are a new class of air pollutants posing threat to the environment . Newer technologies are being developed for their control among which biofiltration seem to be most attractive . Biofiltration of methanol vapor from air stream was evaluated in this study . Experimental investigations were conducted on a laboratory scale biofilter, containing mixture of compost and polystyrene inert particles as the filter materials . Mixed consortium of activated sludge was used as an inoculum . The continuous performance of biofilter for methanol removal was monitored for different concentrations and flow rates . The removal efficiencies decreased at higher concentrations and higher gas flow rates . A maximum elimination capacity of 85 g/(m3 x h) was achieved . The response of biofilter to upset loading operation showed that the biofilm in the biofilters was quite stable and quickly adapted to adverse operational conditions. Water Sci Technol, 2003, 48(4), 209 - 12 Microbiological removal of hydrogen sulfide from biogas by means of a separate biofilter system: experience with technical operation; Schieder D et al.; The "BIO-Sulfex" biofilter of ATZ-EVUS removes hydrogen sulfide from biogas in a biological way . Hydrogen sulfide causes massive problems during power generation from biogas in a power plant, e.g . corrosion of engines and heat exchangers, and thus causes frequent and therefore expensive engine oil changes . The BIO-Sulfex module is placed between the digester and the power-plant and warrants a cost-effective, reliable and fully biological desulfurization . In the cleaned gas concentrations of less than 100 ppm can be achieved . Power-plant manufacturers usually demand less than 500 or less than 200 ppm . At present, several plants with biogas flow rates between 20 and 350 m3/h are in operation. J Environ Sci Health A Tox Hazard Subst Environ Eng, 2003, 38(10), 2077 - 88 Pharmaceutical wastewater treatment using an anaerobic/aerobic sequencing batch biofilter; Buitron G et al.; The performance of a sequencing batch biofilter integrating anaerobic/aerobic conditions in one tank to treat a pharmaceutical wastewater effluent was studied . A pilot reactor, packed with a porous volcanic stone (puzzolane) was used in the study . The reactor operated as a sequencing batch biofilter, SBB, with reaction times varying for the anaerobic stage from 8 to 24 h and for the aerobic one from 4 to 12 h . The volume of exchange was from 16 to 88% . The pharmaceutical wastewater contained organic chemicals including phenols and o-nitroaniline, a concentration of organic matter that varied from 28,400 to 72,200 mg/L (as total COD), 280 to 605 mg N-NH4/L . and 430 to 650 mg SST/L . In order to acclimatize the microorganisms to the industrial wastewater, the organic load was increased stepwise from 1 to 7.7 kg COD/m3/d . The adequate time was obtained when the removal efficiency of COD reached 80%, or more . Maximal removal loads, associated to high removal efficiencies (95-97% as COD), varied from 4.6 to 5.7 kg COD/m3/d . Under these conditions color removal was 80% as Pt-Co units . Microtox analysis was performed to the wastewater and to the anaerobic and aerobic stages . It was observed that the aerobic stage was the responsible for wastewater detoxification . Results showed that the anaerobic/aerobic SBB was able to treat efficiently initial concentrations of the raw effluent up to 28,400 mg COD/L. Environ Sci Technol, 2003 Sep 15, 37(18), 4299 - 303 Biofiltration at composting facilities: effectiveness for bioaerosol control; Sanchez-Monedero MA et al.; Biofiltration was evaluated as a method to control the airborne microorganisms released at composting facilities . Seven commercial composting plants were selected for this study because of their different operating conditions and biofilter designs . In all plants, the biofilters were originally designed for odor control . The concentrations of both Aspergillus fumigatus and mesophilic bacteria were measured in the air stream before and after passing through the biofilters and compared with the background concentrations in the surrounding area . Results showed that biofiltration achieved an average reduction greater than 90% and 39% in the concentrations of A . fumigatus and mesophilic bacteria, respectively . In all the plants, the airborne A . fumigatus concentration after the biofilter was lower than 1.2 x 10(3) cfu m(-3), independent of the inlet concentration, whereas the mesophilic bacteria concentration was dependent on the inlet concentration . The different behaviors of the two microorganism groups were thought to be due to the different aerodynamic characteristics of the particles that affected the capture by impact in the biofilter bed . The fungus, whose spores had a maximum of diameter size distribution between 2.1 and 3.3 microm, were more effectively captured in the biofilter than the bacteria, which had diameters mainly between 1.1 and 2.1 microm. Environ Sci Technol, 2003 Sep 15, 37(18), 4228 - 34 Dimethyl sulfide removal from synthetic waste gas using a flat poly(dimethylsiloxane)-coated composite membrane bioreactor; De Bo I et al.; The reduction of volatile organic sulfur emissions should be completely as they cause odor nuisance, even when they are emitted in very small amounts . In general, biofilters are applied for odor reduction, but their operational control is limited . A new biotechnique for the treatment of complex emissions is the use of membranes integrated within bioreactors (MBRs) . In this study, the reactor performance of MBRs for removal of dimethyl sulfide (DMS) as a model compound is presented . Composite membranes with a poly(dimethylsiloxane) (PDMS)-coating layer were used . The MBRs were inoculated with the sulfur-degrading culture Hyphomicrobium VS or a suspension of Hyphomicrobium VS, ammonium-oxidizing bacteria (AOB), and nitrite-oxidizing bacteria (NOB) to colonize the PDMS-coating layer . Although inoculation with AOB and NOB might give rise to competition for space on the membrane, their presence in the MBRs appeared to be positive as they co-oxidize DMS . Dimethyl sulfide elimination depended on the inoculum type, DMS inlet concentration, gas residence time, and membrane polymer . For equal loading rates, the elimination capacity (EC) increased at larger gas residence times and inlet concentrations . The maximum EC obtained with the MBRs was 4.8 kg of DMS x m(-3) x d(-1) . This value is higher than any reported figure for biofilters and biotrickling filters. Appl Biochem Biotechnol, 2003 Sep, 110(3), 125 - 36 Biofiltration of 1,1,1-trichloroethane by a trickle-bed air biofilter; Lu C et al.; The performance of a trickle-bed air biofilter (TBAB) in the removal of 1,1,1-trichloroethane (TCLE) was evaluated in concentrations varying from 0.025 to 0.049 g/m3 and at empty-bed residence time (EBRT) varying from 20 to 90 s . Nearly complete TCLE removal could be achieved for influent carbon loading between 0.98 and 5.88 g/m3 h . The TBAB appeared efficient for controlling TCLE emission under low-carbon-loading conditions . Carbon recoveries higher than 95% were achieved, demonstrating the accuracy of results . The carbon mass rate of the liquid effluent was approximately two orders of magnitude less than that of the effluent CO2, indicating that dissolved TCLE and its derivatives in leachate were present in negligible amounts in the TBAB. J Biotechnol, 2003 Oct 9, 105(1-2), 83 - 94 Biofiltration of waste gases containing both ethyl acetate and toluene using different combinations of bacterial cultures; Hwang SC et al.; To investigate the microbial degradation of ethyl acetate and toluene mixtures in biofiltration, three strains were selected, identified and studied in a shake-flask culture, and finally inoculated into biofilters . These strains, namely AC6, TO3 and B5, can degrade different substrates at a different rate . The results showed that competitive inhibition from substrate and microbial community would affect the toluene degradation efficiency . Owing to substrate competition, the toluene degradation efficiency of strain B5 would decrease in the presence of high concentration of ethyl acetate . However, the addition of strain AC6 would alleviate such inhibition because it could remove ethyl acetate rapidly . Microbial community competition from strain AC6 or B5 would impede the toluene degradation efficiency of strain TO3 unless a large amount of strain TO3 was inoculated . In biofiltration, strain B5 would be a better choice for inoculation into biofilters than strains AC6 and TO3, as it would grow rapidly under a low concentration of ethyl acetate. Water Res, 2003 Nov, 37(18), 4497 - 505 Nitrogen utilization in a vapor-phase biofilter; Song J et al.; The effect of media nitrogen levels on biofilter performance was investigated in a lab-scale biofilter treating toluene and p-xylene . Nitrogen utilization rates and the quantity of nitrogen recycled to meet microbial demand in the biofilm were estimated using a nitrogen balance approach . Experimental data imply that overall biofilter performance was a strong function of normalized nitrogen levels in the synthetic media . The biodegradation of p-xylene was found to be more sensitive to media nitrogen levels than was the degradation of toluene . However, increasing the nitrogen supply improved both toluene (>99%) and p-xylene removal efficiencies (>90%) . Nitrogen balance calculations indicate that substantial recycling of nitrogen occurred in the biofilm even under nitrogen-rich conditions . The fraction of nitrogen demand met by recycling nitrogen increased when the external supply of nitrogen was terminated, and the biofilm became nitrogen limited . However, to avoid severe nitrogen limitation conditions, an external nitrogen source must be provided to sustain high pollutant removals in the biofilter. Bioprocess Biosyst Eng, 2002 Apr, 25(1), 61 - 7 Epub 2002 Mar 16. Removal of acrylonitrile and styrene mixtures from waste gases by a trickle-bed air biofilter; Lu C et al.; The trickle-bed air biofilter (TBAB) performance for treating acrylonitrile (AN) and styrene (SR) mixtures was evaluated under different influent carbon loadings . In the pseudo steady state conditions, the elimination capacities of AN and SR increased but the removal efficiencies decreased with increased influent carbon loading . The removal efficiencies of AN were higher than those of SR, indicating that AN is a preferred substrate in the ANSR waste gas . More than 80% removal efficiencies were achieved with influent carbon loadings of AN and SR below 28 and 22 g/m(3)/h, respectively . The TBAB appears to be efficient for controlling ANSR emission with low to medium carbon loadings, and the effectiveness could be maintained over 175 days of laboratory operation . The elimination capacities of AN and SR for a pure volatile organic compound (VOC) feed were higher than those for a mixed VOC feed and the differences increased with increased influent VOC loading. J Environ Sci (China), 2003 Jul, 15(4), 494 - 9 Phosphorus limitation in biofiltration for drinking water treatment; Yu X et al.; Bacterial growth potential (BGP) method and two parallel pilot-scale biofilters were used to investigate phosphorus limitation and its effect on the removal of organic matters in biofiltration for drinking water treatment . Addition of phosphorus can substantially increase the BGPs of the samples . Its effect was equivalent to that of addition of a mixture of various inorganic nutrients including phosphorus . The biofilter with phosphate added into its influent performed a higher biological stability of the effluent and a higher COD(Mn) removal than the control filter . These results suggested that phosphorus was the limiting nutrient in the biofiltration and the removal efficiency of organic matters could be improved by adding phosphate into the influent. Waste Manag, 2003, 23(7), 609 - 19 Kinetics of microbial landfill methane oxidation in biofilters; Gebert J et al.; A methane oxidizing biofilter system fitted to the passive venting system of a harbor sludge landfill in Germany was characterized with respect to the the methanotrophic population, methane oxidizing capacity, and reaction kinetics . Methanotrophic cell counts stabilized on a high level with 1.3 x 10(8) to 7.1 x 10(9) cells g dw(-1) about one year after first biofilter operation, and a maximum of 1.2 x 10(11) cells g dw(-1) . Potential methane oxidizing activity varied between 5.3 and 10.7 microg h(-1) g dw(-1) . Cell numbers correlated well with methane oxidation activities . Extrapolation of potential activities gave methane removal rates between 35 and 109 g CH4 h(-1) m(-3), calculated for 30 degrees C . Optimum temperature was 38 degrees C for freshly sampled biofilter material and 22 degrees C for a methanotrophic enrichment culture grown at 10 degrees C incubation temperature . Substrate kinetics revealed the presence of a low-affinity methane oxidizing community with a high Vmax of 1.78 micromol CH4 h(-1) g ww(-1) and a high K(M) of 15.1 microM . K(MO2) for methane oxidation was 58 microM . No substantial methane oxidizing activity was detected below 1.7-2.6 vol.-% O2 in the gaseous phase . Methane deprivation led to a decrease in methane oxidation activity within 5-9 weeks but could still be detected after 25 weeks of substrate deprivation and was fully restored within 3 weeks of continuous methane supply . Very high salt loads are leached from the novel biofilter material, expanded clay, yielding electric conductivity values of up to 15 mS cm(-1) in the leachate . Values > 6 mS cm(-1) were shown to depress methane consumption . Water retention characteristics of the material proved to be favourable for methane oxidizing systems with a gas permeable volume of 78% of bulk volume at field capacity water content . Correspondingly, no influence of water content on methane oxidation activity could be detected at water contents between 2.5 and 20 vol.-%. Waste Manag, 2003, 23(7), 573 - 80 Microbial oxidation of methane from old landfills in biofilters; Streese J et al.; Landfill gas emissions are among the largest sources of the greenhouse gas methane . For this reason, the possibilities of microbial methane degradation in biofilters were investigated . Different filter materials were tested in two experimental plants, a bench-scale plant (total filter volume 51 l) and a pilot plant (total filter volume 4 m3) . Three months after the beginning of the experiment, very high degradation rates of up to 63 g CH4/(m3h) were observed in the bench-scale plant at mean methane concentrations of 2.5% v/v and with fine-grained compost as biofilter material . However, the degradation rates of the compost biofilter decreased in the fifth month of the experiment, probably due to the accumulation of exopolymeric substances formed by the microorganisms . A mixture of compost, peat, and wood fibers showed stable and satisfactory degradation rates around 20 g/(m3h) at mean concentrations of 3% v/v over a period of one year . In this material, the wood fibers served as a structural material and prevented clogging of the biofilter . Extrapolation of the experimental data indicates that biofilters for methane oxidation have to be at least 100 times the volume of biofilters for odor control to obtain the same cleaning efficiency per unit volume flow of feed gas. Arch Environ Contam Toxicol, 2003 Jul, 45(1), 1 - 10 Use of a coupled biological system to treat a chemically complex air stream; Manninen MR et al.; The use of biological systems to remove contaminants from waste streams has been well documented . However, when dealing with complex waste streams, the use of one biological treatment system may not be the best alternative . When treating a complex waste stream, the use of "treatment trains" or "coupled systems" may be advantageous compared with any single biological technology . This article demonstrated that a coupled system was effective in biodegrading a chemically complex mixture of volatile organic compounds (VOCs) . A bench-scale system consisting of a liquid bioreactor and a biofilter was used for the biodegradation of acetone, methanol, methyl ethyl ketone, naphthalene, alpha-pinene, and toluene . The bioreactor contained an inert solid support that immobilized a microbial population . The biofiltration portion of the system utilized the same microbial inoculum but employed Douglas fir bark as its solid support . Successful biodegradation of the complex VOC mixture was accomplished with this coupled system with an average VOC removal efficiency of 96% and VOC loading rates as high as 79 g/m3/h for inlet concentrations of > 8,000 ppmv . At elevated flow rates the liquid reactor demonstrated limited removal of some compounds, such as alpha-pinene and toluene, while maintaining excellent removal of other compounds, such as methanol and acetone . The biofilter portion of the system proved very successful in degrading the remaining toluene and alpha-pinene, thus complementing the removal from the bioreactor . This study demonstrates that coupled biological systems may be utilized for a chemically complex VOC-laden air stream that previously may not have been considered for biological treatment. J Air Waste Manag Assoc, 2003 Aug, 53(8), 1011 - 21 Changes in physical properties of a compost biofilter treating hydrogen sulfide; Morgan-Sagastume JM et al.; A technique is presented that can be used to estimate the changes in physical structure in a natural biofilter packing medium, such as compost, over time . The technique applies information from tracer studies, grain size distribution, and pressure drop analysis to a model that estimates the number of channels, average channel diameter, number of particles, and specific surface area of the medium . Important operational factors, such as moisture content, pressure drop, and sulfate accumulation also were evaluated both in a conventionally operated biofilter and in one operated with periodic compost mixing . In the conventionally operated laboratory-scale compost biofilter, hydrogen sulfide (H2S) removal efficiency decreased from 100% to approximately 90% over 206 days of operation . In a similar system, operated with compost mixing, the H2S removal efficiency was maintained near 100% . Variations in media moisture conditions and specific surface area can explain the results observed in this study . Under conventional operation, drying near the inlet disintegrated the compost particles, producing a large number of particles and flow channels and increasing the specific surface area . At the top of the column, where moisture was added, particle size increased and specific surface area decreased . In the column with media mixing, moisture content, particle size, and specific surface area remained homogeneous. Environ Technol, 2003 Jul, 24(7), 797 - 807 Pressure drop and gas distribution in compost based biofilters: medium mixing and composition effects; Morgan-Sagastume JM et al.; The pressure drop and gas distribution in four different filter media for compost biofilters were studied as a function of three superficial loading rates of moist air and by carrying out the filter medium homogenization by mixing . The filter media used were compost, compost with cane bagasse, lava rock and aerobic sludge previously dried to 60% of water content . The pressure drop increased when lava rock and cane bagasse were used as bulking agents . The same trend was observed when water was added to the filter medium . Pressure drop tended to decrease with time as flow channels were formed inthe filter media . Tracer studies were carried out to quantify the gas distribution and the effect of channel formation . For the biofilters submitted to an airflow of 10, 40 and 70 l min(-1), an average normalized time of 0.96, 0.89 and 0.82, respectively were obtained . The results showed that channel formation was increased as the superficial loading rate was also increased . An operational practice that this work proposes and evaluates to improve gas distribution and medium moisture control is to carry out intermittent medium mixing . The medium moisture and void volume achieved under mixing condition were around 50% and 0.40, respectively with an average constant pressure drop of 11, 45 and 78 cm of water m(-1) for air velocities of 75, 300 and 525 m h(-1). Waste Manag, 2003, 23(5), 403 - 9 Assessment of the environmental impact of management measures for the biodegradable fraction of municipal solid waste in São Paulo City; Mendes MR et al.; There is increasing concern about landfilling of biodegradable wastes . Therefore, biological treatment processes such as composting and biogasification have been considered as alternative strategies for managing those wastes . In this work, life cycle assessment was employed to compare the environmental impacts of landfilling, composting, and biological treatment of municipal solid waste in Sao Paulo City, Brazil . Energy consumption, recovered resources, and emissions to air and water were quantified and analyzed in terms of their potential contribution to global warming, acidification, and nutrient enrichment impact . The results demonstrated that processes that require high levels of energy consumption, such as wastewater treatment, play an important role in the outcome of environmental impact potentials . It was found that the landfilling of all waste is generally the worst strategy from an environmental point of view . However, significant reductions in the resulting impacts can be accomplished through biogasification and composting of the biodegradable fraction . Regarding composting, the application of a biofilter for gas treatment reduced significantly the gaseous emissions. Environ Technol, 2003 Jun, 24(6), 745 - 54 Greenhouse gas emissions from mechanical and biological waste treatment of municipal waste; Clemens J et al.; The mechanical and biological waste treatment (MBT) is an increasingly important technology for the treatment of municipal solid waste (MSW) before landfilling . This process includes composting of the material with intensive aeration in order to minimize the organic fraction that may induce methane and leachate emissions after landfilling . The exhaust air is treated by biofilters to remove odorous and volatile organic compounds . The emission of direct and indirect greenhouse gases, namely methane (CH4), carbon dioxide (CO2), ammonia (NH3), nitric (NO) and nitrous oxide (N2O) was studied in four existing treatment plants . All gases except NO were emitted from the composting material . The emission factors were 12 to 185 kg ton(-1) substrate for CO2, 6-12 x 10(3) g ton(-1) substrate for CH4, 1.44 to 378 g ton(-1) substrate for N2O and 18-1150 g ton(-1) for NH3 . In general, emission factors increased with increasing treatment time . The biofilters had no net effect on CH4, but removed 13-89% of the NH3 . For CO2 the biofilters were a small, for N2O a major and for NO the exclusive source . Approximately 26% of the NH3-N that was removed in the biofilter was transformed into N2O when NH3 was the exclusive nitrogen source . Assuming that all municipal waste was treated by MBT, the emissions would account for 0.3 to 5% of the N2O and for 0.1 to 3% of the CH4 emissions in Germany, respectively . Optimising aeration and removing NH3 before the exhaust gas enters the biofilter could lead to reduced greenhouse gas emissions. Water Sci Technol, 2003, 47(10), 55 - 9 Anaerobic treatment of textile dyeing wastewater; Stern SR et al.; Aerobic treatment commonly applied to textile wastewater results in good or even excellent removal of organic load . This is not, however, accompanied by an equally good removal of colour . Traditional or advanced chemical methods of decolourisation are costly and not always reliable in justifying an interest in microbial decolourisation . Among several processes anaerobic methods seem most promising . In this paper, the results of a study conducted in two pilot-scale plants comprising anaerobic fixed bed biofilters of 15 L and 5 m3 operating as continuous reactors are presented, along with evaluation of the microbial kinetics . As is shown the process proved efficient in a long-term study with no stability problems of the biofilters . The six-month performance of the pilot plant confirmed also that the pre-treated wastewater could be applied in the operation of dyeing . For the majority of the colours applied in the factory no problems were encountered when the dyeing baths were prepared by substituting 90% of fresh water to the effluent treated by a sequence of activated sludge processes: anaerobic-aerobic. Lett Appl Microbiol, 2003, 37(1), 7 - 11 Degradation of the main components of cellulose-paint thinner by the mould Scopulariopsis brevicaulis cultured on rice hulls; Alba J et al.; AIMS: Biodegradation of the main components of the cellulose-paint thinner (toluene, acetone, isopropanol and xylenes) by Scopulariopsis brevicaulis, isolated from a thinner biodegradation microbial consortium was investigated . METHODS AND RESULTS: Our results showed that 90% of S . brevicaulis conidia survived after 4 weeks in a cellulose-paint thinner saturated atmosphere . The mould was able to grow under these environmental conditions with a low development of conidia . The biodegradation potential of S . brevicaulis was established with and without support material (rice hulls) . Biodegradation without support was very limited, <10% for all the components quantified . There was notable thinner biodegradation when the fungus was grown on rice hulls . CONCLUSIONS: Our results suggest the potential use of fungi in biofiltration systems employed in biodegradation of the main components of the cellulose-paint thinner . SIGNIFICANCE AND IMPACT OF THE STUDY: This is the first report of volatile organic compounds biodegradation by this fungal species. Environ Technol, 2003 May, 24(5), 605 - 14 Determination of the hydraulic residence time in a trickling biofilter filled with organic matter; Garzon-Zuniga MA et al.; Biofiltration process using peat as media has been shown to be efficient for the treatment of agroindustrial, chemical and municipal effluents . However, determining the hydraulic retention time of this process is difficult due to many factors . Generally tracer techniques are used, but they measure the molecular retention time instead of the hydraulic retention time; and depending on the case, the results can be wrong . In order to contribute to solving this problem, the objective of this research was to find a trustworthy and adequate technique to determine the hydraulic retention time for a process using a very adsorbent filter bed material (peat) . An overview of the hydraulic behaviour of a peat bed filter related to their particular structural composition is presented . Then, based on these characteristics, two different techniques to determine the hydraulic retention time were developed and tested . The first, an indirect modified tracing technique and, the second, a direct one which determines the volume of liquid in treatment into the filter bed through the establishment of a relation between the volume of porosity and the volume of empty spaces (or not occupied by liquid) into the filter bed . The results obtained showed that the proposed techniques gave similar results and proved adequate. Environ Technol, 2003 May, 24(5), 531 - 44 Sequencing batch biofilter operation for treatment of methyl ethyl ketone (MEK) contaminated air; Li C et al.; Biofiltration is increasingly used as a method for decontaminating gas streams containing low concentrations of biodegradable volatile organic compounds . In typical biofilter installation control is quite passive and is often restricted to adjustment of the medium's moisture content or nutrient supply . Although inexpensive, such operation limits implementation of engineering decisions that could improve performance during normal operation orallow effective handling of the short-term variations in the waste stream typical of industrial operations . This paper describes how sequencing batch operation can be applied to biofilters designed and operated as controlled, unsteady-state, periodic processes for the destruction of gas-phase contaminants . In the studies described herein, the impact of sequencing batch operation was assessed in a methylethyl ketone degrading biofilter over a 130-day period . The biofilter was packed with a polyurethane foam medium that contained activated carbon . Methyl ethyl ketone and carbon dioxide concentrations were monitored during both normal steady loading conditions and short-term, unsteady-state transient loading conditions (i.e., shock loading) . A gas stream containing 106 ppm, methyl ethyl ketone was used for normal loading studies, and several model shock loads consisting of 530 ppm, methyl ethyl ketone for a duration of one hour were used to assess system response to transient loads . Data are presented which clearly demonstrate that sequencing batch operation can be successfully applied to biofilters treating methyl ethyl ketone contaminated air streams . Such operation can increase an operator's ability to minimize contaminant emission during transient periods of elevated contaminant loading. Biodegradation, 2003, 14(1), 9 - 18 Biofiltration of isopropyl alcohol by a trickle-bed air biofilter; Chang K et al.; The performance of trickle-bed air biofilter (TBAB) for the removal of isopropyl alcohol (IPA) was evaluated in concentrations varying from 100 to 500 ppmv and at empty-bed residence time (EBRT) varying from 20 to 90 s . Nearly complete IPA removal could be achieved for influent carbon loading between 6 and 88 g/m3 x h . The TBAB appears efficient for controlling IPA emission under low-to-high carbon loading conditions . Carbon recoveries of 95-99% were achieved demonstrating the accuracy of results . Applicable operating conditions of TBAB for controlling IPA emission were suggested. Biotechnol Bioeng, 2003 Aug 20, 83(4), 479 - 88 Biofiltration of a mixture of volatile organic compounds on granular activated carbon; Aizpuru A et al.; The performance of a biofilter packed with Active Carbon (AC) was evaluated . The effluent (alcohol, ketones, esters, aromatic and chlorinated compounds) treated was a representative mixture of most common industrial emissions . To achieve a better knowledge of multicomponent adsorption mechanisms, and to underline the interest of inoculating AC, a control abiotic humidified filter had been operated in the same conditions as the biofilter . For a load of 110 g VOC m(-3) AC h(-1), after 55 days of operation, the removal efficiency was higher in the biotic than in the abiotic filter (85% vs 55%, respectively) . Moreover, in the biofilter, at steady state, the elimination of all compounds was almost complete except for chlorinated compounds and p-xylene (removal efficiency of 25% and 64%, respectively) . The microbial colonization of AC involved a decrease of the adsorption sites accessibility and enhanced the treatment of VOCs (volatile organic compounds) having a lower affinity for activated carbon . Moreover, while aromatic compounds and MIBK were eliminated along the overall height of the biofilter, pollutants with reduced affinity for AC, such as methanol, acetone, and halogenated compounds were only treated on the second half of the reactor . Thus, the affinity for activated carbon was an important parameter controlling the biodegradation process . Nevertheless, the use of AC as packing material in biofilters treating complex mixtures of VOCs is limited . Actually, similar removal efficiency could be reached, in the same conditions, for a biofilter packed with granular peat . Furthermore, for the biofilter packed with AC, the column height necessary to remove biodegradable compounds, with reduced affinity for the support, was important . Exp Appl Acarol, 2002, 27(4), 265 - 76 Mite growth on fungus under various environmental conditions and its potential application to biofilters; Woertz JR et al.; The effects of relative humidity, temperature, pH and vapor-phase toluene concentration on Tyrophagus putrescentiae growth on Cladophialophora sp . were tested in controlled environmental chambers . It was observed that the mites were able to reproduce readily at relative humidities between 90% and 97% as well as on porous perlite support material pre-soaked in nutrient media of pH 2.5, 4 and 7 . Also, the presence of toluene at gas-phase concentrations of 500 to 2000 mg m(-3) was found to be non-toxic to the mites . The mites, however, were unable to maintain a large population when the temperature was maintained at 14 degrees C, and overpopulation of the living space led to declines in mite population over time . Overall, it was found to be relatively simple to cultivate mites that may be used for fungal biomass control measures in biofilter applications. Appl Biochem Biotechnol, 2003 Apr-Jun, 109(1-3), 181 - 95 Removal of chemical oxygen demand, nitrogen, and heavy metals using a sequenced anaerobic-aerobic treatment of landfill leachates at 10-30 degrees C; Kalyuzhnyi S et al.; As a first step of treatment of landfill leachates (total chemical oxygen demand {COD}: 1.43-3.81 g/L; total nitrogen: 90-162 mg/L), performance of laboratory upflow anaerobic sludge bed reactors was investigated under mesophilic (30 degrees C), submesophilic (20 degrees C), and psychrophilic (10 degrees C) conditions . Under hydraulic retention times (HRTs) of about 0.3 d, when the average organic loading rates (OLRs) were about 5 g of COD/(L.d), the total COD removal accounted for 81% (on average) with the effluent concentrations close to the anaerobic biodegradability limit (0.25 g of COD/L) for mesophilic and submesophilic regimes . The psychrophilic treatment conducted under an average HRT of 0.34 d and an average OLR of 4.22 g of COD/(L.d) showed a total COD removal of 47%, giving effluents (0.75 g of COD/L) more suitable for subsequent biologic nitrogen removal . All three anaerobic regimes used for leachate treatment were quite efficient for elimination of heavy metals (Fe, Zn, Cu, Pb, Cd) by concomitant precipitation in the form of insoluble sulfides inside the sludge bed . The application of aerobic/ anoxic biofilter as a sole polishing step for psychrophilic anaerobic effluents was acceptable for elimination of biodegradable COD and nitrogen approaching the current standards for direct discharge of treated wastewater. Appl Biochem Biotechnol, 2003 Apr-Jun, 109(1-3), 77 - 94 Sustainable treatment and reuse of diluted pig manure streams in Russia: from laboratory trials to full-scale implementation; Kalyuzhnyi S et al.; This article summarizes the results obtained during the laboratory and pilot development of integrated biologic and physicochemical treatment and reuse of diluted pig manure streams . The application of a straw filter was an effective means to separate the solid and liquid fractions of raw wastewater and resulted in the removal of a significant part of the dry matter, total nitrogen, and phosphorus (65, 27, and 32%, respectively) . From the filtrate generated, 60-80% of the total chemical oxygen demand (COD) was removed in an upflow anaerobic sludge bed reactor operating at 15-30 degrees C . Ammonia was efficiently eliminated (>99%) from the anaerobic effluents using Ural laumantite as an ion exchanger . However, the nitrogen-content of the zeolite was too low to consider this method of ammonia removal economically feasible . The phosphate precipitation block, consisting of stripper of CO2 and fluidized-bed crystallizator, was able to decrease the concentration of soluble phosphate in the anaerobic effluents up to 7-15 mg of phosphate/L . The application of aerobic/anoxic biofilter as a sole polishing step was acceptable from an aesthetic point of view (the effluents were transparent and almost colorless and odorless) and elimination of biochemical oxygen demand (the resting COD was hardly biodegradable) . However, the effluent nutrient concentrations (especially nitrogen) were far from the current standards for direct discharge of treated wastewater . We discuss the approaches for further improvement of effluent quality . Finally, we provide an outline of a full-scale system that partially implements the laboratory- and pilotscale results obtained. Nat Mater, 2003 Jun, 2(6), 386 - 90 Dextran templating for the synthesis of metallic and metal oxide sponges; Walsh D et al.; Silver or gold-containing porous frameworks have been used extensively in catalysis, electrochemistry, heat dissipation and biofiltration . These materials are often prepared by thermal reduction of metal-ion-impregnated porous insoluble supports (such as alumina and pumice), and have surface areas of about 1 m(2) g(-1), which is typically higher than that obtained for pure metal powders or foils prepared electrolytically or by infiltration and thermal decomposition of insoluble cellulose supports . Starch gels have been used in association with zeolite nanoparticles to produce porous inorganic materials with structural hierarchy, but the use of soft sacrificial templates in the synthesis of metallic sponges has not been investigated . Here we demonstrate that self-supporting macroporous frameworks of silver, gold and copper oxide, as well as composites of silver/copper oxide or silver/titania can be routinely prepared by heating metal-salt-containing pastes of the polysaccharide, dextran, to temperatures between 500 and 900 degrees C . Magnetic sponges were similarly prepared by replacing the metal salt precursor with preformed iron oxide (magnetite) nanoparticles . The use of dextran as a sacrificial template for the fabrication of metallic and metal oxide sponges should have significant benefits over existing technologies because the method is facile, inexpensive, environmentally benign, and amenable to scale-up and processing. Biomed Environ Sci, 2003 Mar, 16(1), 29 - 39 Improving removal efficiency of organic matters by adding phosphorus in drinking water biofiltration treatment; Yu X et al.; OBJECTIVE: To investigate phosphorus limitation and its effect on the removal efficiency of organic matters in drinking water biological treatment . METHODS: Bacterial growth potential (BGP) method and a pair of parallel pilot-scale biofilters were used for the two objectives, respectively . RESULTS: The addition of phosphorus could substantially increase the BGPs of the water samples and the effect was stronger than that of the addition of carbon . When nothing was added into the influents, both CODMn removals of the parallel biofilters (BF1 and BF2) were about 15% . When phosphate was added into its influent, BF1 performed a CODMn removal, 6.02 percentage points higher than the control filter (BF2) and its effluent had a higher biological stability . When the addition dose was < 20 micrograms.L-1, no phosphorus pollution would occur and there was a good linear relationship between the microbial utilization of phosphorus and the removal efficiency of organic matters . CONCLUSIONS: Phosphorus was a limiting nutrient and its limitation was stronger than that of carbon . The addition of phosphate was a practical way to improve the removal efficiency of organic matters in drinking water biological treatment. Appl Microbiol Biotechnol, 2003 May, 61(4), 366 - 73 Epub 2003 Feb 20. Pseudomonas putida as the dominant toluene-degrading bacterial species during air decontamination by biofiltration; Roy S et al.; The microbial communities established in three laboratory-scale compost matrix biofilters fed with toluene were characterized . The biofilters were operated for 7 weeks at inlet concentrations of toluene ranging over 250-500 ppm with daily irrigation, using a nutrient solution containing variable concentrations of nitrogen, supplied as urea, and other inorganic salts . The indigenous microflora of the compost included toluene-degrading species, making inoculation unnecessary . The numerically predominant toluene-degrading strains were isolated from the most diluted positive wells of most-probable-number counts on mineral medium with toluene as sole carbon source and identified by rRNA 16S gene sequencing . On the basis of sequence similarity, all the isolated strains were assigned to the species Pseudomonas putida, although some variations were observed in their respective sequences . It is concluded that the mode of biofilter operation including a daily supply of non-carbon nutrients created an environment favoring the constant numerical predominance of this fast-growing toluene-degrading species. Appl Microbiol Biotechnol, 2003 Aug, 62(2-3), 297 - 301 Epub 2003 May 13. The treatment of gaseous benzene by two-phase partitioning bioreactors: a high performance alternative to the use of biofilters; Davidson CT et al.; A 2-l (1-l working volume) two-phase partitioning bioreactor (TPPB) was used as an integrated scrubber/bioreactor in which the removal and destruction of benzene from a gas stream was achieved by the reactor's organic/aqueous liquid contents . The organic solvent used to trap benzene was n-hexadecane, and degradation of benzene was achieved in the aqueous phase using the bacterium Alcaligenes xylosoxidans Y234 . A gas stream with a benzene concentration of 340 mg l(-1) at a flow rate of 0.414 l h(-1) was delivered to the system at a loading capacity of 140 g m(-3) h(-1), and an elimination capacity of 133 g m(-3 )h(-1) was achieved (the volume in this term is the total liquid volume of the TPPB) . This elimination capacity is between 3 and 13 times greater than any benzene elimination achieved by biofiltration, a competing biological air treatment strategy . It was also determined that the evaluation of TPPB performance in terms of elimination capacity should include the cell mass present in the system, as this is a readily controllable quantity . A specific benzene utilization rate of 0.57 g benzene (g cells)(-1) h(-1) was experimentally determined in a bioreactor with a cell concentration that varied dynamically between 0.2 and 1 g l(-1) . If it assumed that this specific benzene utilization rate (0.57 g g(-1) h(-1)) is independent of cell concentration, then a TPPB operated at high cell concentrations could potentially achieve elimination capacities several hundred times greater than those obtained with biofilters. Biotechnol Bioeng, 2003 Jul 5, 83(1), 29 - 38 Macrokinetic and quantitative microbial investigation on a bench-scale biofilter treating styrene-polluted gaseous streams; Zilli M et al.; We performed a macrokinetic and quantitative microbial investigation of a continuously operating bench-scale biofilter treating styrene-polluted gases . The device was filled with a mixture of peat and glass beads as packing medium and inoculated with the styrene-oxidizing strain, Rhodococcus rhodochrous AL NCIMB 13259 . The experimental data of styrene and microbial concentrations, obtained at different biofilter heights, were used to evaluate the pollutant concentration profiles as well as the influence of styrene loading on biomass distribution along the packing medium . Styrene and biomass concentration profiles permitted detection of a linear relationship between the amount of biomass grown in a given section of the biofilter and that of pollutant removed, regardless of the operating conditions tested . Biomass development in the bed appeared to: depend linearly on pollutant concentration at an inlet styrene concentration of <0.10 g m(-3) in the gaseous stream; achieve a maximum value (7 . 10(7) colony forming units per gram of packing material) within a wide styrene concentration range (0.10 to 1.0 g m(-3)); and fall sharply beyond this inhibition threshold . The process followed zeroth-order macrokinetics with respect to styrene concentration, which is consistent with zeroth-order microkinetics with either fully active or not fully active biofilm . The maximal volumetric styrene removal rate was found to be 63 g m(packing material) (-3) h(-1) for an influent pollutant concentration of 0.80 g m(-3) and a superficial gas velocity of 245 m h(-1) . Appl Environ Microbiol, 2003 May, 69(5), 2616 - 23 Naturally occurring bacteria similar to the methyl tert-butyl ether (MTBE)-degrading strain PM1 are present in MTBE-contaminated groundwater; Hristova K et al.; Methyl tert-butyl ether (MTBE) is a widespread groundwater contaminant that does not respond well to conventional treatment technologies . Growing evidence indicates that microbial communities indigenous to groundwater can degrade MTBE under aerobic and anaerobic conditions . Although pure cultures of microorganisms able to degrade or cometabolize MTBE have been reported, to date the specific organisms responsible for MTBE degradation in various field studies have not be identified . We report that DNA sequences almost identical (99% homology) to those of strain PM1, originally isolated from a biofilter in southern California, are naturally occurring in an MTBE-polluted aquifer in Vandenberg Air Force Base (VAFB), Lompoc, California . Cell densities of native PM1 (measured by TaqMan quantitative PCR) in VAFB groundwater samples ranged from below the detection limit (in anaerobic sites) to 10(3) to 10(4) cells/ml (in oxygen-amended sites) . In groundwater from anaerobic or aerobic sites incubated in microcosms spiked with 10 microg of MTBE/liter, densities of native PM1 increased to approximately 10(5) cells/ml . Native PM1 densities also increased during incubation of VAFB sediments during MTBE degradation . In controlled field plots amended with oxygen, artificially increasing the MTBE concentration was followed by an increase in the in situ native PM1 cell density . This is the first reported relationship between in situ MTBE biodegradation and densities of MTBE-degrading bacteria by quantitative molecular methods. Chemosphere, 2003 Jul, 52(1), 161 - 73 In situ cadmium reclamation by freshwater bivalve Lamellidens marginalis from an industrial pollutant-fed river canal; Das S et al.; The biofilter potential of the freshwater bivalve, Lamellidens marginalis was examined in cage experiments conducted in a river canal (Ichhapore, 24-Parganas, West Bengal, India) receiving industrial effluents from steel and metal factories as well as from an ordinance factory . Cadmium is one of the major contaminants in this river canal . Lamellidens collected from pollution free natural ponds, were sorted into three size groups (large: 59+/-3.2 g, 10+/-2.3 cm; medium: 30+/-2 g, 6+/-1.7 cm and small: 13+/-1.5 g, 4+/-1.2 cm) were held in cages at three different sites along a cadmium concentration gradient . Concentrations of cadmium were measured from water, sediment and different tissues of Lamellidens at weekly intervals using atomic absorption spectrophotometric methods . Cadmium uptake by Lamellidens in all media were highly concentration dependent in both summer and winter months . For all three size groups, cadmium uptake was maximum in the gills at the beginning of experiment, and liver at the later phase . Cadmium uptake was maximum in the small bivalves and minimum in the large bivalves groups . Cadmium uptake was 11-67% higher during summer than during the monsoon season for all tissues and size groups . Estimation of concentration factor revealed that tissues were saturated with cadmium during the 13-14th week after Lamellidens introduction during summer, but remained unsaturated during the monsoon season . It is concluded that Lamellidens might be considered as an efficient biofilter for reclamation of aquatic environment having sub-lethal concentrations of cadmium. J Ind Microbiol Biotechnol, 2003 Mar, 30(3), 168 - 74 Epub 2003 Feb 26. Biofiltration eliminates nuisance chemical odors from industrial air streams; Shareefdeen Z et al.; This paper focuses on recent developments of biofiltration technology used in treating nuisance chemical odors from industrial and municipal air streams . In the biofiltration process, odorous chemical constituents in the air are first transported to biofilms by diffusion, solubilization and adsorption processes . Bacteria within the biofilms oxidize odor constituents into harmless and odorless products . Through successful laboratory and pilot research on biofiltration of odorous air-stream constituents, numerous commercial biofilters have been designed and installed across North America . In this paper, case studies related to biofiltration of air emissions from meat rendering plants, municipal wastewater treatment applications, and printed circuit board production are discussed to demonstrate the robustness of this technology in eliminating a wide variety of compounds. Huan Jing Ke Xue, 2003 Jan, 24(1), 57 - 62 {Phosphorus as a limiting nutrient in drinking water biological treatment}; Yu X et al.; Bacterial Growth Potential (BGP) method was used to investigate the limiting effect of phosphorus in the biological process for drinking water treatment in a water plant in Huai River basin . BGP was increased by 54% when 50 micrograms.L-1 KH2PO4-P was added to the raw water, while addition of other inorganic nutrients had no significant difference from the addition of phosphorus . The effect of addition of 20 mg.L-1 C6H12O6 to raw water was not so strong as that of 50 micrograms.L-1 KH2PO4-P . The CODMn removal rate of the biological filter was 7.5 percentiles higher than the control one and carbon was the main limiting nutrient in its effluent when phosphorus was added to the raw water, while phosphorus was the main limiting nutrient in the effluent of the control filter . These results suggest that phosphorus was a limiting nutrient and had a stronger limiting effect than carbon on the biological process in this plant thus the removal efficiency of the organic matters could be increased by adding phosphorus to the influent. Environ Technol, 2003 Mar, 24(3), 265 - 75 Effects of packing material on the biofiltration of benzene, toluene and xylene vapours; Ortiz I et al.; Biofiltration was used to eliminate volatile organic compounds from air streams in bench-scale reactors inoculated with an adapted consortium . Organic and inert supports were tested on 100 days of operation . The supports were: peat, vermiculite, a mixture of vermiculite and activated carbon, tree bark and, porous glass Rashig rings . A mixture of benzene, toluene and xylene vapors with a load of 200 gC m(-3) h(-1) was fed to the biofilters with an empty bed residence time of 60 s . Removal efficiencies higher than 95% were obtained with the mixture of vermiculite and activated carbon, 85% for peat and bark, 80% for vermiculite and 65% for the Rashig rings . In all cases, drying problems in beds were observed after several days of operation . Water addition with or without nutrients was required to maintain and increase the performance of biofilters . In steady state operation, experiments at loads ranging from 50 to 400 gC m(-3) h(-1) were carried out and a maximum elimination capacity of 260 gC m(-3) h(-1) was obtained for vermiculite-activated carbon support . The three xylene isomers were degraded . Observations of the supports surface by scanning electronic microscopy at the end of the biofiltration experiment showed abundant growth of fungi, which were not in the inoculum, had colonized the biofilter. Tunis Med, 2002 Aug, 80(8), 473 - 84 {Clinical evaluation of acetate-free biofiltration at 84 0/00 in patients with chronic renal insufficiency}; Hmida J et al.; We report in this study the outcome of chronically hemodialysed patients with a new technique: Acetate free biofiltration 84@1000 . This study is divided into two steps: during the first period we studied the hemodynamic stability of the technique in patients hemodynamically unstable under bicarbonate hemodialysis . During the second period we compared the hemodynamic effects and the quality of dialysis in these patients with other patients under bicarbonate hemodialysis . We obtained less hypotensive episodes, a better correction of acidosis, a better tolerance of the technique and comfort of the patient with the new technique, the quality of dialysis was the same with both techniques . We recommend the use of acetate free biofiltration 84@1000 whenever the patients are hemodynamicallyunstable with bicarbonate hemodialysis. Meded Rijksuniv Gent Fak Landbouwkd Toegep Biol Wet, 2002, 67(2), 117 - 28 Effects of addition of straw, chitin and manure to new or recycled biofilters on their pesticides retention and degradation properties; Genot P et al.; Pollution of surface and groundwater by pesticides is an increasing problem that needs to be addressed by the authorities as well as by the farmers themselves . Nowadays, some researchers are considering the numerous small spillages at the farm sites as a relevant entry route to be taken into account for predicting surface and groundwater pollution . In order to tackle this problem, several solutions exist for limiting the disposal of pesticide wastes into the environment . One such system is biopurification of farm wastes by biobed, biofilter or phytobac . In this study, the results of pesticides retention by biofilters under outdoor conditions are presented . The biofilters were filled with a mixture of a soil + peat constituent (25% by volume for each of them) and the rest (50%) with straw or with composted manure ot with chitin (in this later case at the rate of 5 g chitin per liter of substrate) . The soil + peat constituent was made either of a material already challenged by pesticides (= recycled biofilters) or of untreated material (new biofilters) . Selected pesticides (atrazine, carbofuran, chloridazon, chlortoluron, cyanazine, isoproturon and lenacil) were applied onto biofilters and the eluates were collected and analyzed . Two successive injections of pesticides into the biofilters were conducted . After the first pesticides application, the recycled biofilters made of soil + peat previously treated with pesticides had better retention and degradation rates than the new biofilters . Adding manure also improved these properties of biofilters . Columns made of unchallenged soil + peat and straw (new biofilters) were the least satisfactory: up to 25% of carbofuran were lost . Biofilters made of unchallenged soil + peat and chitin retained the least lenacil . Atrazine was the most retained by biofilters (either new or recycled) with added chitin . Cyanazine was almost absent in the percolates of all biofilters . After the second application of carbofuran and isoproturon, all biofilters improved to the point where (with the exception the new biofilters made of chitin) they retained the totality of the pesticides. Bioresour Technol, 2003 Sep, 89(2), 199 - 205 Biofiltration of n-butyric acid for the control of odour; Sheridan BA et al.; Odour control from pig production facilities is a significant concern due to increased public awareness and the development of more stringent legislation to control production . Although many technologies exist, biofiltration is still the most attractive due to its low maintenance and operating costs . One of the key odour components, n-butyric acid, was selected for a laboratory scale biofilter study . It was examined as a sole carbon substrate in order to investigate the effectiveness of biofiltration in reducing n-butyric acid concentration under different operating conditions using a moist enriched woodchip medium . Three superficial gas velocities; 38.2, 76.4, and 114.6 m x h(-1) were tested for n-butyric acid concentrations ranging from 0.13 to 3.1 g {n-butyric acid} m(-3) {air} . For superficial gas velocities 38.2, 76.4, and 114.6 m x h(-1), maximum elimination capacities (100% removal) of 148, 113 and 34.4 g x m(3) x h(-1), respectively, were achieved . Upon investigation of effective bed height, true elimination capacities (100% removal) of 230, 233 and 103 g x m(-3) x h(-1), respectively, were achieved at these superficial gas velocities . Averaged pressure drops for superficial gas velocities 38.2, 76.4, and 114.6 m x h(-1) were 30, 78 and 120 Pa, respectively . It was concluded that biofiltration is a viable technology for the removal of n-butyric acid from waste exhaust air, but near 100% removal efficiency is required due to the low odour detection threshold for this gaseous compound. Water Res, 2003 Feb, 37(3), 525 - 32 Biofouling reduction in recirculating cooling systems through biofiltration of process water; Meesters KP et al.; Biofouling is a serious problem in industrial recirculating cooling systems . It damages equipment, through biocorrosion, and causes clogging and increased energy consumption, through decreased heat transfer . In this research a fixed-bed biofilter was developed which removed assimilable organic carbon (AOC) from process water, thus limiting the major substrate for the growth of biofouling . The biofilter was tested in a laboratory model recirculating cooling water system, including a heat exchanger and a cooling tower . A second identical model system without a biofilter served as a reference . Both installations were challenged with organic carbon (sucrose and yeast extract) to provoke biofouling . The biofilter improved the quality of the recirculating cooling water by reducing the AOC content, the ATP concentration, bacterial numbers (30-40 fold) and the turbidity (OD660) . The process of biofouling in the heat exchangers, the process water pipelines and the cooling towers, was monitored by protein increase, heat transfer resistance, and chlorine demanded for maintenance . This revealed that biofouling was lower in the system with the biofilter compared to the reference installation . It was concluded that AOC removal through biofiltration provides an attractive, environmental-friendly means to reduce biofouling in industrial cooling systems. Klin Lab Diagn, 2003 Feb, (2), 23 - 4, 33-7 {The functional role of arterial intima . Endogenous and exogenous pathogens and specificity of atheromatosis as an inflammation}; Titov VN; We believe that the intima is a biological filter accountable for arresting the endogenous and exogenous pathogens, which activate the biological function of inflammation, and for preventing the access of pathogens into the internal-space intercellular pool . The below described biological reactions occur in the arterial intima: trans-cytosis of pathogens by endothelial cells onto the intima surface; sorption of pathogens into the filter proteoglycan matrix; destruction of the matrix by macrophage metalloproteinases; desorption of pathogens with matrix elements by resident macrophages through squewenjer-receptor endocytosis; proteolysis of pathogens in lysosomes; retroendocytosis of non-hydrolyzed components of pathogens into the intercellular medium; and a recovery of the integrity of proteoglycan matrix by the smooth-muscle cells . Sorption and desorption of pathogens (i.e . modified low-density lipoproteins who carry the essential polyene fat acids to cells) by resident macrophages (from the filter) under the conditions of the blockade of apoB-100-receptoral endocytosis predetermine the specificity of atheromatosis as an inflammation. J Ind Microbiol Biotechnol, 2003 May, 30(5), 260 - 70 Epub 2003 Apr 03. Accelerated biodegradation of petroleum hydrocarbon waste; Ward O et al.; Conventional landfarming approaches to bioremediation of refinery and other petroleum sludges are not acceptable environmentally and are banned in most North American jurisdictions . While initial bioreactor-based systems for treatment of these sludges required batch-cycle process-times of 1-3 months, an accelerated process has now been developed which can be completed in 10-12 days . In this process, up to 99% of total petroleum hydrocarbons are degraded and the sludges are converted from hazardous to non-hazardous according to the United States EPA's toxicity characteristic leachate procedure criteria . Understanding and exploiting mechanisms to improve hydrocarbon accession to the degrading microorganisms was a key development component of the process . Contrasting physiological mechanisms were observed for different component organisms of the mixed culture with respect to their associations with the hydrocarbon substrate; and the beneficial effects of using surfactants were demonstrated . The mixed culture used in the process exhibited a capacity for high-rate degradation of volatile organic carbons and the potential use of the culture as a liquid biofilter was demonstrated . The culture was also effective as an inoculant for the bioaugmentation of total petroleum hydrocarbon-contaminated soil and as a de-emulsifier of oilfield emulsions and could transform some other environmental contaminants which are not predominant components of crude oil. Environ Sci Technol, 2003 Mar 1, 37(5), 985 - 92 Effect of drying on biofilter performance: modeling and experimental approach; Morales M et al.; The moisture content of biofilter media is a key parameter for its adequate performance . Control of moisture requires a better understanding of the drying of the support due to changes in inlet air temperature and relative humidity and from metabolic heat production by pollutant oxidation . A dynamic one-dimensional model was developed to describe drying and its effect on biofilter performance . Mass and energy balances were established on an elementary representative volume . The biological reaction term incorporated temperature, water content, and pollutant concentration effects . The model describes the variations in pollutant concentration, air relative humidity, temperature, and water content of the media . It predicts (1) water evaporation from the packing material as a consequence of metabolic heat generation and variations of the relative humidity of the inlet air stream, and (2) the resulting decrease in biofilter performance . The model was validated with biofiltration experiments treating gaseous toluene using peat as support . Various ranges of inlet air relative humidity, temperature, air velocity, and inlet pollutant concentration were assayed. Appl Biochem Biotechnol, 2003 Mar, 104(3), 199 - 214 Mass transfer and benzene removal from air using latex rubber tubing and a hollow-fiber membrane module; Fitch M et al.; A dense-phase latex rubber tube and a polyporous propylene hollow-fiber membrane module (HFMM) were investigated for control of benzene-contaminated gas streams . The abiotic mass flux observed through the latex tube was 3.9 13 mg/(min.m(2)) for 150 ppm of benzene at various gas and liquid flow rates, while a 100-fold lower mass flux was observed in the HFMM . After seeding with an aromatic-degrading culture enriched from activated sludge, the observed removal was 80% of 150 ppm, corresponding to a mass flux of 45 mg/(min.m(2)) . The observed mass flux through the HFMM during biofiltration also rose, to 0.4 mg/(min.m(2)) . Because the HFMM had a 50-fold higher surface area than the latex tube, the observed benzene removal was 99.8% . Compared to conventional biofilters, the two reactors had modest elimination capacities, 2.5 18 g/(m(3).h) in the latex tube membrane bioreactor and 4.8 58 g/(m(3).h) in the HFMM . Although the HFMM had a higher elimination capacity, the gas-phase pressure drop was much greater. Braz J Biol, 2002 Nov, 62(4A), 713 - 23 Epub 2003 Feb 11. Utilization of macrophyte biofilter in effluent from aquaculture: I . Floating plant; Sipauba-Tavares LH et al.; The objective of this work was to manufacture a low-cost biofilter, made of floating macrophyte (Eichhornia crassipes) . Limnological studies were conducted 7 days after the macrophytes were placed in the biofilter, and continued over a period of 30 consecutive days . During rainy and dry seasons, and high production period, samples were taken three times a week . The lowest levels of nitrogen compounds were observed in the July/August period, which corresponded to lower fish production and low supply rattion in the culture ponds . During the experimental period, pH values ranged from acid to alkaline and did not oscillate with higher average values during April/May . Alkalinity and bicarbonate dominance in the medium were directly affected by pH . With respect to associated micro-fauna, among phyto-plankton Chlorophyta was the dominant group and among zooplankton, Rotifera . It is recommended that during production peaks, the aquatic plants should be replaced by small buds every 10 days. Water Sci Technol, 2003, 47(3), 147 - 50 Inactivation of Salmonella spp . from secondary and tertiary effluents by UV irradiation; Keller R et al.; The aim of this study was to verify the efficiency of UV irradiation in the inactivation of Salmonella spp . in treated wastewater with different levels of turbidity and exposed to increasing doses of UV irradiation . Experiments were carried out in a batch reactor and in a real scale reactor . Salmonellae obtained from clinical samples were seeded into autoclaved wastewater collected from a wastewater treatment plant (WWTP) comprising an association of a UASB reactor followed by three submerged aerated biofilters (BAF) and one tertiary filter . The results showed that salmonellae were not inactivated in effluents from the UASB reactor indicating that the presence of suspended solids was an important obstacle to UV penetration in bacteria . However, UV irradiation was efficient in inactivating Salmonella of effluents from aerated secondary and tertiary biofilm reactors. Bioresour Technol, 2003 Jul, 88(3), 259 - 63 Characterization of five agricultural by-products as potential biofilter carriers; Ramirez-Lopez E et al.; Biofiltration is the most commonly used biological gas treatment technology and is extensively used for the treatment of polluted air with gas flow rates of up to 2 x 10(5) m(3)/h . It involves a filter bed of organic matter serving both as carrier for microorganisms and as nutrient supplier . Polluted gas passes through the filter bed and is cleaned by biological activity . Biofiltration is not being developed in Latin America as in the USA, Canada or Europe; the main reason probably being the absence of specific technology and of potential organic carriers locally available . Five different agriculture by-products available in Latin America: peanut shells, rice husk, coconut shells, cane bagasse and maize stubble, were chemically, physically and structurally characterized for their potential use as biofilter carrier . It was found that peanut shells could be used as biofilter carrier and therefore would have potential biological application. J Environ Sci Health B, 2003 Jan, 38(1), 89 - 101 Bench-scale biofilter for removing ammonia from poultry house exhaust; Shah SB et al.; A bench-scale biofilter was evaluated for removing ammonia (NH3) from poultry house exhaust . The biofilter system was equipped with a compost filter to remove NH3 and calcium oxide (CaO) filter to remove carbon dioxide (CO2) . Removal of NH3 and CO2 from poultry house exhaust could allow treated air with residual heat to be recirculated back into the poultry house to conserve energy during winter months . Apart from its use as a plant nutrient, NH3 removal from poultry house exhaust could lessen the adverse environmental impacts of NH3 emissions . Ammonia and CO2 were measured daily with gas detector tubes while temperatures in the poultry pen and compost filter were monitored to evaluate the thermal impact of the biofilter on treated air . During the first 37 days of the 54-day study, exhaust air from 33 birds housed in a pen was treated in the biofilter; for the final 17 days, NH3-laden exhaust, obtained by applying urea to the empty pen was treated in the biofilter . The biofilter system provided near-complete attenuation of a maximum short-term NH3 concentration of 73 ppm . During the last 17 days, with a mean influent NH3 concentration of 26 ppm, the biofilter provided 97% attenuation . The CaO filter was effective in attenuating CO2 . Compared with a biofilter sized only for NH3 removal, an oversized biofilter would be required to provide supplemental heat to the treated air through exothermic biochemical reactions in the compost . The biofilter could conserve energy in poultry production and capture NH3 for use as plant nutrient . Based on this study, a house for 27,000 broilers would require a compost filter with a volume of approximately 34 m3. Environ Microbiol, 2003 Mar, 5(3), 183 - 201 Microbial community and physicochemical analysis of an industrial waste gas biofilter and design of 16S rRNA-targeting oligonucleotide probes; Friedrich U et al.; A study was conducted to investigate the microbial community structure, the physicochemical properties, and the relationships between these parameters of a full-scale industrial biofilter used for waste gas abatement in an animal-rendering plant . Fluorescence in situ hybridization (FISH) was successfully combined with digital image analysis to study the composition of the microbial community . Several new nucleic acid probes were designed and established based on published 16S rDNA sequences and on ones retrieved from the biomass of the biofilter under investigation . Bacterial detection rates varied greatly over time and filterbed depth between 27.2% and 88.1% relative to DAPI counts . Overall, members of the Betaproteobacteria followed by Actinobacteria, Alphaproteobacteria, Cytophaga-Flavobacteria, Firmicutes and Gammaproteobacteria were the most abundant groups . Among the groups below phylum level, members of the Alcaligenes/Bordetella lineage were on average the most abundant group accounting for up to 8.5% of DAPI-stained cells . Whereas the community composition generally showed no vertical gradient, the lower 50 cm of the biofilter proved to be the most active part for the degradation of aldehydes such as 2- and 3-methylbutanal, 2-methylpropanal, and hexanal . This zone of the filterbed being operated in up-flow direction degraded about 80% of these compounds . Dimethyldisulphide was the most common reduced sulphur compound . Statistical analysis of microbial versus waste gas parameters generally revealed only weak or non-significant correlations between the two . Possible explanations for this finding are discussed. Adv Space Res, 2003, 31(1), 201 - 10 The "C.E.B.A.S . MINI-MODULE": a self-sustaining closed aquatic ecosystem for spaceflight experimentation; Blum V et al.; The C.E.B.A.S . MINI-MODULE is the miniaturized space flight version of the Closed Equilibrated Biological Aquatic System (C.E.B.A.S.) . It fits into a large middeck locker tray and is scheduled to be flown in the STS 85 and in the NEUROLAB missions . Its volume is about 9 liters and it consists of two animal tanks, a plant cultivator, and a bacteria filter in a monolithic design . An external sensor unit is connected to a data acquisition/control unit . The system integrates its own biological life support . The CO2 exhaled by the consumers (fishes, snails, microorganisms) is assimilated by water plants (Ceratophyllum demersum) which provide them with oxygen . The products of biomass degradation and excretion (mainly ammonia ions) are converted by bacteria into nitrite and nitrate . The latter is taken up by the plants as a nitrogen source together with other ions like phosphate . The plants convert light energy into chemical energy and their illumination is regulated via the oxygen concentration in the water by the control unit . In ground laboratory tests the system exhibited biological stability up to three month . The buffer capacity of the biological filter system is high enough to eliminate the degradation products of about one half of the dead animal biomass as shown in a "crash test" . A test series using the laboratory model of the flight hardware demonstrated the biological stability and technical reliability with mission-identical loading and test duration . A comprehensive biological research program is established for the C.E.B.A.S . MINI-MODULE in which five German and three U.S.-American universities as well as the Russian Academy of Sciences are involved . c2002 Published by Elsevier Science Ltd on behalf of COSPAR. J Air Waste Manag Assoc, 2003 Jan, 53(1), 92 - 101 Removal of ammonia by biofilters: a study with flow-modified system and kinetics; Choi JH et al.; The characteristics of ammonia removal by two types of biofilter (a standard biofilter with vertical gas flow and a modified biofilter with horizontal gas flow) were investigated . A mixture of organic materials such as compost, bark, and peat was used as the biofilter media based on the small-scale column test for media selection . Complete removal capacity, defined as the maximum inlet load of ammonia that was completely removed, was obtained . The modified biofilter showed complete removal up to 1.0 g N/kg dry material/day . However, the removal capacity of the standard biofilter started to deviate from complete removal around 0.4 g N/kg dry material/day, indicating that the modified biofilter system has higher removal efficiency than the standard upflow one . In kinetic analysis of the biological removal of ammonia in each biofilter system, the maximum removal rate, Vm, was 0.93 g N/kg dry material/day and the saturation constant, Ks, was 32.55 ppm in the standard biofilter . On the other hand, the values of Vm and Ks were 1.66 g N/kg dry material/day and 74.25 ppm, respectively, in the modified biofilter system. Huan Jing Ke Xue, 2002 Sep, 23(5), 13 - 8 {Use of biological activated carbon to degrade benzene and toluene in a biofilter}; Li G et al.; The biodegradation of toluene and benzene in a biofilter using cylindrical activated carbon as the filler materials was studied . For total mass loading lower than 350 g/(h.m3), retention time ranging from 15 s to 90 s the biofilter proved to be highly efficient in biodegradation of toluene and benzene, their removal capacity were 120 and 150 g/(h.m3) respectively and toluene was more easily degraded than benzene . The CO2 produced increased with the degradation of benzene and toluene, but the experimental value was lower than the theoretical value . The observation of biotic community demonstrated that the microbes consisted of bacillus, spore bacillus and fungi, of them spore bacillus was dominant . According to basic theories of mass-transfer, adsorption and biodegradation process, mathematical model of removal of VOCs by biofiltration was established and verified. Water Sci Technol, 2002, 46(11-12), 51 - 6 Biological treatment characteristics of benzene and toluene in a biofilter packed with cylindrical activated carbon; Li GW et al.; The biodegradation of toluene and benzene in a biofilter using cylindrical activated carbon as the filler materials was studied . Three gas low rates, i.e . 0.25, 0.50 and 0.75 m3/h, corresponding to empty bed gas residence of 75, 37.5 and 25 s, respectively, and total organic load lower than 400 g/m3 x h were tested . The biofilter proved to be highly efficient in biodegradation of toluene and benzene, and toluene was more easily degraded than benzene . When each inlet load was lower than 150 g/m3 x h, removal rate increased with inlet load and reached a maximum, which was 150 and 120 g/m(-3) x h for toluene and benzene, respectively . For inlet load higher than the maximum removal capacity conditions, the removal rate decreased with inlet load . Carbon dioxide concentration profile through the biofilter revealed that the mass ratios of carbon dioxide produced to the toluene and benzene removed were 2.15 g(CO2)/g(toluene) and 1.67 g(CO2)/g(benzene), which furthermore, confirmed the biodegradation performance in biofilter . The observation of biotic community demonstrated that the microbes consisted of bacillus, spore bacillus and fungi, of which the spore bacillus was dominant. Environ Pollut, 2003, 121(2), 181 - 7 Biofiltration of gasoline vapor by compost media; Namkoong W et al.; Gasoline vapor was treated using a compost biofilter operated in upflow mode over 4 months . The gas velocity was 6 m/h, yielding an empty bed retention time (EBRT) of 10 min . Benzene, toluene, ethylbenzene and xylene (BTEX) and total petroleum hydrocarbon (TPH) removal efficiencies remained fairly stable approximately 15 days after biofilter start-up . The average removal efficiencies of TPH and BTEX were 80 and 85%, respectively, during 4 months of stable operation . Biodegradation portions of the treated TPH and BTEX were 60 and 64%, respectively . When the influent concentration of TPH was less than 7800 mg TPH/m3, approximately 50% of TPH in the gas stream was removed in the lower half of the biofilter . When the influent concentration of BTEX was less than 720 mg BTEX/m3, over 75% of BTEX in the gas stream was removed in the lower half of the biofilter . Benzene removal efficiency was the lowest among BTEX . A pressure drop could not be detected over a 1-m bed height at a gas velocity of 6 m/h after approximately 4 months of operation . Results demonstrated that BTEX in gasoline vapor could be treated effectively using a compost biofilter. Waste Manag Res, 2002 Oct, 20(5), 434 - 44 The effect of various environmental and design parameters on methane oxidation in a model biofilter; Park S et al.; Methane from landfills built with RCRA (Resource Conservation and Recovery Act) covers is frequently vented directly to the atmosphere . Alternatively, landfill gasses could be vented through a layer of soil that could serve as a biofilter to oxidize CH4 to carbon dioxide and water . Properly designed soil biofilters may reduce atmospheric CH4 emissions from landfills and help reduce the accumulation of greenhouse gasses in the atmosphere . This study was conducted to investigate the performance of a lab-scale model biofilter system using soil as the filterbed medium in packed columns to measure the effect of a variety of environmental and design factors on the CH4 oxidation capacity of a soil biofilter . Biofilter performance was tested under a variety of environmental and design conditions . The optimum soil moisture content for CH4 oxidation in a loamy sand was 13% by weight . Addition of NO3-N did not affect the CH4 oxidation rate . Soil depths of 30 cm and 60 cm were equally efficient in CH4 oxidation . When the CH4 loading rate was decreased, the percentage of CH4 oxidized increased . The maximum CH4 oxidation rate was 27.2 mol m(-2) d(-1) under optimum conditions. J Environ Qual, 2002 Nov-Dec, 31(6), 1782 - 8 Hydrogen sulfide effects on ammonia removal by a biofilter seeded with earthworm casts; Lee EY et al.; Ammonia (NH3) removal efficencies were evaluated when hydrogen sulfide (H2S) and NH3 in binary mixture gases were supplied to a ceramic biofilter seeded with earthworm (Lumbricus terrestris) casts . The effect of inlet H2S concentration and space velocity (SV) on the removal of NH3 was investigated after the acclimation of the biofilter with NH3 gas . When NH3 was singly supplied to the biofilter, NH3 removal was maintained at almost 100% until inlet NH3 concentration was increased up to 600 microL L(-1) and SV up to 330 h(-1), at which the elimination capacity of NH3 was 148 g N m(-3) h(-1) . When H2S was supplied simultaneously, however, the accumulation of toxic sulfide ions showed dual effects on NH3 removal efficiencies . First, no effects were observed at inlet H2S loading below 60 g S m(-3) h(-1); however, inhibition by H2S at higher loading was observed above 60 g S m(-3) h(-1) . The point at which loading achieved a maximum of more than 99% NH3 removal efficiency was 139 g N m(-3) h(-1), when inlet H2S concentration was held under 100 microL L(-1), but it dropped to 76 and 30 g N m(-3) h(-1) when the inlet H2S concentration increased to 220 and 460 microL L(-1), respectively . The critical points of inlet H2S loading that guaranteed over 99% NH3 removal were determined as 100, 100, 60, and 40 g S m(-3) h(-1) at inlet NH3 concentrations of 100, 200, 400, and 600 microL L(-1), respectively . Inlet NH3 loading had synergic effects of increasing the inhibition of inlet H2S loading on the NH3 removability of the biofilter. J Air Waste Manag Assoc, 2002 Nov, 52(11), 1288 - 97 1-Butanol removal from a contaminated airstream under continuous and diurnal loading conditions; Fitch MW et al.; A polysulfone microporous membrane module was investigated for control of 1-butanol-contaminated gas streams . A diurnal loading condition, using two different butanol concentrations, was used to simulate start-up and stop conditions associated with shift work . The membrane module was also used to remove 1-butanol from air under continuous loading conditions in a bioreactor . The reactors were seeded with a mixed bacterial consortium capable of butanol biodegradation . Biokinetic parameters for butanol utilization were determined for the culture to be a maximum specific utilization rate (k) equal to 4.3 d(-1) and a half saturation constant (Ks) equal to 8.9 mg L(-1) . A biofilter running only with diurnal loading conditions giving a "40-hr work-week" had an average 1-butanol removal rate of 29% (111 ppm, 74 gm(-3) hr(-1)) from a 350-ppm influent at the end of an 8-hr operational day . End-of-day removal varied between 4 and 67% during the operational period . With continuous steady-state operation followed by placement on a diurnal loading schedule and influent butanol concentrations increased to 700 ppm, butanol removal averaged 38% (269 ppm, 145 gm-3 hr(-1)) . Under continuous loading, steady-state conditions, 1-butanol removal from the airstream was greater than 99% (200 ppm, 73 gm-3 hr(-1)) . These results suggest that the bioreactor can be operated on a diurnal schedule or 40-hr week operational schedule without any decline in performance. Water Res, 2003 Jan, 37(1), 206 - 14 The sensitivity of fixed-bed biological perchlorate removal to changes in operating conditions and water quality characteristics; Brown JC et al.; Flow rate, electron donor addition, and biomass control were evaluated in order to optimize perchlorate (ClO4-) removal from drinking water using biologically active carbon (BAC) filtration . Influent dissolved oxygen (DO) was lowered from ambient conditions to approximately 2.5 mg/L for all experiments using a nitrogen sparge . When influent nitrate concentration was 0-2.0 mg/L, 1.6-2.8 mg/L as carbon of acetate or ethanol was required to achieve and sustain the complete removal of 50 microg/L perchlorate in a BAC filter . Most or all of the exogenous acetate and ethanol was removed during biofiltration . When a 72-h electron donor feed failure was simulated, a maximum perchlorate breakthrough of 18 microg/L was observed and, once electron donor was reapplied, 9 days were required to reestablish complete perchlorate removal . During a 24-h electron donor feed failure simulation, the maximum effluent perchlorate concentration detected was 6.7 microg/L . Within 24 h of reactivating the electron donor, the filter regained its capacity to consistently remove 50 microg/L perchlorate to below detection . Although biomass growth diminished the filter's ability to consistently remove perchlorate, a cleaning procedure immediately restored stable, complete perchlorate removal . This cleaning procedure was required approximately every 50 days (4800 bed volumes) when influent DO concentration was 2.5 mg/L . Empty-bed contact time (EBCT) experiments showed that 80% perchlorate removal was achieved using a 5-min EBCT, and complete perchlorate removal was observed for an EBCT of 9 min . It was also demonstrated that BAC filtration consistently removed perchlorate to below detection for influent perchlorate concentrations ranging from 10 to 300 microg/L, influent sulfate concentrations between 0 and 220 mg/L, influent pH values of 6.5-9.0, and operating temperatures of 5-22 degrees C. Environ Microbiol, 2002 Nov, 4(11), 721 - 34 High bacterial diversity of a waste gas-degrading community in