Effect of Organic Carbon on Tertiary Denitrification of the Secondary Effluent in Biofilters Packed with Suspended Carriers

Denitrifying biokinetics in biofilters packed with suspended carriers were evaluated under different empty bed residence times (EBRT) with ethanol or acetate as the electron donor. The two denitrifying biofilters removed nitrate (NO₃^––N) effectively after only 3–4 days operation. At EBRT of 30; 15 and 7.5 min, the NO₃^––N removal percentage was 84; 72 and 59% in the ethanol biofilter, and was 89; 70 and 62% in the acetate biofilter, respectively. With the influent NO₃^––N loading rate ranged from 0.4 to 1.8 g/(m²·d), the NO₃^––N removal loading rate increased with increasing influent NO₃^––N loading rates, and the system was substrate limited. While when the influent nitrate loading rate was above 3 g/(m²·d), the system was biomass limited. The half-order coefficients were 0.162; 0.175 and 0.274 (mg/L)^1/2/min for the ethanol biofilter with the influent NO₃^––N concentration of 7.3–7.7 mg/L, and were 0.107; 0.165 and 0.303 (mg/L)^1/2/min for the acetate biofilter with the influent NO₃^––N concentration of 6.8–8.0 mg/L. Denitrification efficiency varied slightly during the backwashing cycle, and the effect of backwashing on the effluent turbidity was relatively large, especially for the biofilter with ethanol as the organic carbon.     

Effect of gas empty bed contact time on performances of various types of rotating drum biofilters for removal of VOCs

The effects of gas empty bed contact time (EBCT), biofilter configuration, and types of volatile organic compounds (VOCs) were evaluated to assess the performance of rotating drum biofilters (RDBs), especially at low EBCT values. Three types of pilot-scale RDBs, a single-layer RDB, a multi-layer RDB, and a hybrid RDB, were examined at various gas EBCTs but at a constant VOC loading rate. Diethyl ether, toluene, and hexane were used separately as model VOC. When EBCT increased from 5.0 to 60s at a constant VOC loading rate of 2.0kgCOD/(m(3)day), ether removal efficiency increased from 73.1% to 97.6%, from 81.6% to 99.9%, and from 84.0% to 99.9% for the single-layer RDB, the multi-layer RDB, and the hybrid RDB, respectively, and toluene removal efficiency increased from 76.4% to 99.9% and from 84.8% to 99.9% for the multi-layer RDB and the hybrid RDB, respectively. When hexane was used as the model VOC at a constant loading rate of 0.25kgCOD/(m(3)day), hexane removal efficiency increased from 31.1% to 57.0% and from 29.5% to 50.0% for the multi-layer RDB and hybrid RDB, respectively. The single-layer, multi-layer, and hybrid RDBs exhibited, respectively, the lowest, middle, and highest removal efficiencies, when operated under similar operational loading conditions. Hexane exhibited the lowest removal efficiency, while diethyl ether displayed the highest removal efficiency. The data collected at the various EBCT values correlated reasonably well with a saturation model. The sensitivity of removal efficiency to EBCT varied significantly with EBCT values, VOC properties, and biofilter configurations. Process selection and design for RDB processes should consider these factors.     

Effect of nitrogen limitation on performance of toluene degrading biofilters

The literature reports conflicting observations regarding the need for nutrient addition to biofilters treating contaminated gases. Such conflicts are often based on quasi-steady-state performance data collected on biofilters operated under continuous loading conditions. In the studies described herein, the impact of nitrogen limitations on two toluene-fed biofilters was assessed over a 97-day period. The biofilters were packed with polyurethane foam medium and contained different initial levels of nitrate-nitrogen. Toluene and CO2 concentration profiles were monitored during both normal steady loading conditions and short-term, unsteady-state transient loading conditions (e.g., shock loads). Packing medium samples were periodically removed and analyzed to quantify changes in nitrate-nitrogen content over time. Data are presented which show that over long-time periods (several months), nutrient-induced kinetic limitations diminished biofilter performance during transient, unsteady-state conditions even when performance during normal steady loading was not adversely affected. Elemental analysis of biomass removed from the biofilters support nitrate-nitrogen and CO2 concentration profile data and clearly illustrate how kinetically limited biofilters fail during shock loads even when there is an overall stoichiometric excess of nutrients.     

Hydrodynamic behaviour and comparison of technologies for the removal of excess biomass in gas-phase biofilters

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.     

Non-steady state simulation of BOM removal in drinking water biofilters: applications and full-scale validation

A biofilter model called "BIOFILT" was used to simulate the removal of biodegradable organic matter (BOM) in full-scale biofilters subjected to a wide range of operating conditions. Parameters that were varied included BOM composition, water temperature (3.0-22.5 degrees C), and biomass removal during backwashing (0-100%). Results from biofilter simulations suggest a strong dependence of BOM removal on BOM composition. BOM with a greater diffusivity or with faster degradation kinetics was removed to a greater extent and also contributed to shorter biofilter start-up times. In addition, in simulations involving mixtures of BOM (i.e. readily degradable and slowly degradable components), the presence of readily degradable substrate significantly enhanced the removal of slowly degradable material primarily due to the ability to maintain greater biomass levels in the biofilters. Declines in pseudo-steady state BOM removal were observed as temperature was decreased from 22.5 to 3 degrees C and the magnitude of the change was significantly affected by BOM composition. However, significant removals of BOM are possible at low temperatures (3-6 degrees C). Concerning the impact of backwashing on biofilter performance, BOM removal was not affected by backwash resulting in biomass removals of 60% or less. This suggests that periodic backwashing should not significantly impact biofilter performance as observed biomass removals from full-scale biofilters were negligible. In general, the simulation results were in good qualitative and quantitative agreement with experimental results obtained from full-scale biofilters.     

生物滤塔处理含三甲胺气体的研究

研究了分别填充堆肥和污泥的生物滤塔对含三甲胺气体的处理能力.结果表明,两种生物滤塔均能有效处理含三甲胺的气体,对三甲胺的去除率几乎达到了100%,三甲胺被生物降解并生成氨.堆肥生物滤塔各段填料中的硝态氮含量随时间的延长呈显著提高的趋势,但pH值出现下降,说明其中发生了氨的硝化作用.而在污泥生物滤塔中,随着氨的积累则各填料层的pH值迅速升高,并且没有观察到亚硝态氮以及硝态氮含量的增加,因此其不具备进一步降解氨的能力.     

Performance of a fungal biofilter treating gas-phase solvent mixtures during intermittent loading

Biological treatment processes used to remove and degrade volatile organic compounds (VOCs) from contaminated gases emitted by industrial operations or waste treatment processes are almost always subjected to transient loading conditions because of the inherently unsteady-state nature of contaminant generating processes. In the study presented here, a laboratory-scale biofilter populated by a mixed culture of fungi was used to study the transient response to various periods of no contaminant loading in a system treating a model waste gas stream containing a mixture of commonly used solvents. The biofilter, packed with cubed polyurethane foam media and operated with an empty bed residence time of 15s, was supplied with a four-component mixture of n-butyl acetate, methyl ethyl ketone, methyl propyl ketone, and toluene at target influent concentrations of 124, 50.5, 174, and 44.6 mg/m(3), respectively. This corresponds to a total VOC loading rate of 94.3g/(m(3)h). Biofilter performance was evaluated over a 94-day period for three loading conditions intended to simulate processes generating contaminated gases only during daytime operation, daytime operation with weekend shutdown periods, and with long term (9-day) shutdown. Results indicate that fungal biofilters can be an effective alternative to conventional abatement technologies for treating solvent contaminated off-gases even under discontinuous loading conditions.     

The effect of biofilter loading rate on the removal of organic ozonation by-products

The effect of biofilter loading rate on the removal of organic ozonation by-products (OBPs) was studied in three biofilters used for the pretreatment of drinking water. One of the biofilters contained plastic biofilm media (KMT) and the two others contained expanded clay aggregates (Filtralite). Tests were carried out with ozonated humic water at several OBP concentration levels using empty bed contact times (EBCTs) from 6.2 to 48 min. The sum of aldehyde (formaldehyde, acetaldehyde, glyoxal and methyl glyoxal) and acetone concentrations ranged from 21 to 77 μg l⁻¹ in the ozonated water. The total ketoacid (glyoxylic, pyruvic, and ketomalonic acids) concentrations varied from 92 to 521 μg l⁻¹. The results were modelled using a first-order model including parameter for minimum substrate concentration (S_min). The OBPs showed different sensitivities to decreasing EBCT. Formaldehyde and pyruvic acid had the highest specific removal rates and their removal was little affected by increased loading rate. Ketomalonic acid had the lowest specific removal rate and its removal efficiency was reduced most with decreasing EBCT. The other studied OBPs had specific removal rates close to each other. The ketoacids had higher S_min concentrations than aldehydes and the S_min concentrations were influenced by the influent OBP concentrations. The biofilter media did not have a significant effect on OBP removal efficiency. Generally, over 80% removal efficiency was obtained for OBPs at EBCTs over 20 min. The significance of OBP concentrations close to S_min for the biological stability of drinking water needs to be determined.     

Advancing post-anoxic denitrification for biological nutrient removal

The objective of this research was to advance a fundamental understanding of a unique post-anoxic denitrification process for achieving biological nutrient removal (BNR), with an emphasis on elucidating the impacts of surface oxygen transfer (SOT), variable process loadings, and bioreactor operational conditions on nitrogen and phosphorus removal. Two sequencing batch reactors (SBRs) were operated in an anaerobic/aerobic/anoxic mode for over 250 days and fed real municipal wastewater. One SBR was operated with a headspace open to the atmosphere, while the other had a covered liquid surface to prevent surface oxygen transfer. Process performance was assessed for mixed volatile fatty acid (VFA) and acetate-dominated substrate, as well as daily/seasonal variance in influent phosphorus and ammonia loadings. Results demonstrated that post-anoxic BNR can achieve near-complete (>99%) inorganic nitrogen and phosphorus removal, with soluble effluent concentrations less than 1.0 mgN L⁻¹ and 0.14 mgP L⁻¹. Observed specific denitrification rates were in excess of typical endogenous values and exhibited a linear dependence on the glycogen concentration in the biomass. Preventing SOT improved nitrogen removal but had little impact on phosphorus removal under normal loading conditions. However, during periods of low influent ammonia, the covered reactor maintained phosphorus removal performance and showed a greater relative abundance of polyphosphate accumulating organisms (PAOs) as evidenced by quantitative real-time PCR (qPCR). While GAOs were detected in both reactors under all operational conditions, BNR performance was not adversely impacted. Finally, secondary phosphorus release during the post-anoxic period was minimal and only occurred if nitrate/nitrite were depleted post-anoxically.     

Development of biomass in a drinking water granular active carbon (GAC) filter

Indigenous bacteria are essential for the performance of drinking water biofilters, yet this biological component remains poorly characterized. In the present study we followed biofilm formation and development in a granular activated carbon (GAC) filter on pilot-scale during the first six months of operation. GAC particles were sampled from four different depths (10, 45, 80 and 115 cm) and attached biomass was measured with adenosine tri-phosphate (ATP) analysis. The attached biomass accumulated rapidly on the GAC particles throughout all levels in the filter during the first 90 days of operation and maintained a steady state afterward. Vertical gradients of biomass density and growth rates were observed during start-up and also in steady state. During steady state, biomass concentrations ranged between 0.8-1.83 x 10⁻⁶ g ATP/g GAC in the filter, and 22% of the influent dissolved organic carbon (DOC) was removed. Concomitant biomass production was about 1.8 × 10¹² cells/m²h, which represents a yield of 1.26 × 10⁶ cells/μg. The bacteria assimilated only about 3% of the removed carbon as biomass. At one point during the operational period, a natural 5-fold increase in the influent phytoplankton concentration occurred. As a result, influent assimilable organic carbon concentrations increased and suspended bacteria in the filter effluent increased 3-fold as the direct consequence of increased growth in the biofilter. This study shows that the combination of different analytical methods allows detailed quantification of the microbiological activity in drinking water biofilters.     

固定化微生物强化生物滤池处理硝基苯和苯胺废水

利用复合微生物菌群BCP35,对自制的大孔功能化载体FPU进行微生物的固定化,并与厌氧生物滤池和好氧生物滤池联用处理含高浓度硝基苯和苯胺的废水,研究了固定化微生物强化生物滤池处理污染物的运行效果、硝基苯和苯胺的降解特征,比较了固定化微生物和游离态微生物的除污性能,同时分析了载体上微生物的状态和生物量.结果表明,固定化微生物强化生物滤池工艺对硝基苯、苯胺具有很好的去除效果,对硝基苯和苯胺的降解率可分别达到99.8%和99.9%;同时生物滤池还对污染物浓度变化具有较强的抗冲击负荷能力;与游离态微生物相比,固定化微生物在去除COD、硝基苯、苯胺等方面更具优势;生物滤池内的微生物浓度较高,可达到38g/L.     

Modeling of trihalomethane cometabolism in nitrifying biofilters

The computer program AQUASIM was used to model biofilter experiments seeded with Lake Austin, Texas mixed-culture nitrifiers. These biofilters degraded four trihalomethanes (THMs) (trichloromethane (TCM) or chloroform, bromodichloromethane (BDCM), dibromochloromethane (DBCM), tribromomethane (TBM) or bromoform) commonly found in treated drinking water. Apparent steady-state data from the biofilter experiments and supporting batch experiments were used to estimate kinetic parameters for TCM, DBCM and ammonia degradation. Subsequently, the model was verified against other experimental biofilter data. To allow for full-scale simulations, BDCM and TBM rate constants were estimated using data from batch kinetic studies. Finally, the model was used to simulate full-scale filter performance under different filter surface loading rates and THM speciation seen in practice. Overall, total THM removals ranged from 16% to 54% in these simulations with influent total THM concentrations of 75-82microg/L, which illustrates the potential of THM cometabolism to have a significant impact on treated water quality.     

地下水曝气修复一维土柱试验集总参数分析

目前挥发与半挥发性有机物(VOCs/SVOCs)地下水曝气修复机理描述主要包括集总参数模型和多相流模型两类,但这些模型相对复杂,不适于实用化设计与评价。基于曝气过程气液两相间污染物传质双区理论和试验条件,对已有一维集总参数模型进行简化,得到一个以液相表示的集总参数方程。然后通过不同粒径饱和砂土中甲基叔丁基醚(MTBE, methyl tert-butyl ether)地下水曝气修复一维土柱试验,确定了不同曝气流量条件下的液相集总参数。试验结果表明,液相集总参数与砂土的性质及曝气流量密切相关。最后,利用获得的集总参数对不同深度处曝气修复过程污染物浓度变化进行了预测。结果表明,简化处理后的模型可以预测及评价高进气流量条件下地下水曝气修复过程及效果,具有一定实用性。     

Influence of detachment on substrate removal and microbial ecology in a heterotrophic/autotrophic biofilm

Competition between heterotrophic bacteria oxidizing organic substrate and autotrophic nitrifying bacteria in a biofilm was evaluated. The biofilm was grown in a tubular reactor under different shear and organic substrate loading conditions. The reactor was initially operated without organic substrate in the influent until stable ammonia oxidation rates of 2.1 g N/(m² d) were achieved. A rapid increase of fluid shear in the tubular reactor on day 156 resulted in biofilm sloughing, reducing the biofilm thickness from 330 to 190 μm. This sloughing event did not have a significant effect on ammonia oxidation rates. The addition of acetate to the influent of the reactor resulted in decreased ammonia oxidation rates (1.8 g N/(m² d)) for low influent acetate concentrations (17 mg COD/L) and the breakdown of nitrification at high influent acetate concentrations (55 mg COD/L). Rapidly increasing fluid shear triggered biofilm sloughing in some cases—but maintaining constant shear did not prevent sloughing events from occurring. With the addition of acetate to the influent of the reactor, the biofilm thickness increased up to 1350 μm and individual sloughing events removed up to 50% of the biofilm. Biofilm sloughing had no significant influence on organic substrate removal or ammonia oxidation. During 325 days of reactor operation, ammonia was oxidized only to nitrite; no nitrate production was observed. This lack of nitrite oxidation was confirmed by fluorescent in situ hybridization (FISH) analysis, which detected betaproteobacterial ammonia oxidizers but not nitrite oxidizers. Mathematical modeling correctly predicted breakdown of nitrification at high influent acetate concentrations. Model predictions deviated systematically from experimental results, however, for the case of low influent acetate concentrations.     

Laboratory modelling of manganese biofiltration using biofilms of Leptothrix discophora

Laboratory biofilters (pilot-scale, 20 l and laboratory-scale, 5l) were constructed in order to model the bioaccumulation of manganese (Mn) under flow conditions similar to those occurring in biofilters at groundwater treatment sites. The biofilters were operated as monocultures of Leptothrix discophora, the predominant organism in mature Mn oxidising biofilms. Biologically mediated Mn bioaccumulation was successfully modelled in both filter systems. The data obtained showed that in the small-scale biofilter, the Mn concentrations that gave the highest rate of Mn bioaccumulation, shortest maturation time, highest optical density (biomass) and growth rate were between 2000 and 3000 microg x l(-1). The non-problematic scale-up of the process from the laboratory-scale to the pilot-scale biofilter model suggests that Mn biofilters may be 'seeded' with laboratory grown cultures of L. discophora. By initially operating the biofilter as a re-circulating batch culture, with an initial Mn concentration of approximately 2500 microg x l(-1), it is hoped to reduce the filter maturation time from months to days.     

The biofiltration of indoor air: implications for air quality

An alternative method of maintaining indoor air quality may be through the biofiltration of air recirculating within the structure rather than the traditional approach of ventilation. This approach is currently being investigated. Prior to its acceptance for dealing with volatile organic compounds (VOCs) and CO2, efforts were made to determine whether the incorporation of this amount of biomass into the indoor space can have an (negative) impact on indoor air quality. A relatively large ecologically complex biofilter composed of a ca. 10 m2 bioscrubber, 30 m2 of plantings and a 3,500 litre aquarium were established in a 160 m2 'airtight' room in a recently constructed office building in downtown Toronto. This space maintained ca. 0.2 air changes per hour (ACH) compared to the 15 to 20 ACH (with a 30% refresh rate) of other spaces in the same building. Air quality parameters of concern were total VOCs (TVOCs), formaldehyde and aerial spore counts. TVOC and formaldehyde levels in the biofilter room were the same or significantly less than other spaces in the building despite a much slower refresh rate. Aerial spore levels were slightly higher than other indoor spaces but were well within reported values for 'healthy' indoor spaces. Levels appeared to be dependent on horticultural management practices within the space. Most genera of fungal spores present were common indoors and the other genera were associated with living or dead plant material or soil. From these results, the incorporation of a large amount of biomass associated with indoor biofilters does not in itself lower indoor air quality.     

贝壳填料曝气生物滤池的硝化特性研究

贝壳粗糙的表面及其合有的大量碳酸钙，可作为生物膜的载体及硝化反应的碱度来源。以海产弃物贝壳为生物膜载体，通过改变进水氨氮浓度及pH值，考察了贝壳填料曝气生物滤池的硝化脱氮规律。结果表明：对于氨氮〈120mg／L的原水，贝壳溶解提供的碱度能够满足硝化反应的需要，因此硝化反应进行得比较完全，对氨氮的去除率不受进水氨氮浓度的影响，可达90％以上；而当进水氨氮浓度达240mg／L时，因贝壳溶解提供的碱度不能完全满足硝化反应之所需，硝化反应将停滞，但对氨氮的去除率仍可达65％左右。此外，进水pH值对贝壳填料曝气生物滤池去除氨氮的效果及出水pH值基本没有影响。     

Treatment of a colored groundwater by ozone-biofiltration: pilot studies and modeling interpretation

Pilot studies investigated the fates of color, dissolved organic carbon (DOC), and biodegradable organic matter (BOM) by the tandem of ozone plus biofiltration for treating a source water having significant color (50 cu) and DOC (3.2 mg/l). Transferred ozone doses were from 1.0 to 1.8 g O3/g C. Rapid biofilters used sand, anthracite, or granular activated carbon as media with empty-bed contact time (EBCT) up to 9 min. The pilot studies demonstrated that ozonation plus biofiltration removed most color and substantial DOC, and increasing the transferred ozone dose enhanced the removals. For the highest ozone dose, removals were as high as 90% for color and 38% for DOC. While most of the color removal took place during ozonation, most DOC removal occurred in the biofilters, particularly when the ozone dose was high. Compared to sand and anthracite biofilters, the GAC biofilter gave the best performance for color and DOC removal, but some of this enhanced performance was caused by adsorption, since the GAC was virgin at the beginning of the pilot studies. Backwashing events had no noticeable impact of the performance of the biofilters. The Transient-State, Multiple-Species Biofilm Model (TSMSBM) was used to interpret the experimental results. Model simulations show that soluble microbial products, which comprised a significant part of the effluent BOM, offset the removal of original BOM, a factor that kept the removal of DOC relatively constant over the range of EBCTs of 3.5-9 min. Although improved biofilm retention, represented by a small detachment rate, allowed more total biofilm accumulation and greater removal of original BOM, it also caused more release of soluble microbial products and the build up of inert biomass in the biofilm. Backwashing had little impact on biofilter performance, because it did not remove more than 25% of the biofilm under any condition simulated.     

滤料粒径对地下水中铁、锰、氨氮、浊度去除效果的影响

滤料粒径是生物滤池设计的一个重要参数。采用滤料粒径分别为0. 8~1. 0、3~4、8~10 mm的3根成熟生物滤柱处理地下水,考察滤料粒径对铁、锰、氨氮、浊度去除效果的影响。结果表明,1^#、2^#、3^#滤柱出水的总铁平均浓度分别为0. 020、0. 037、0. 078 mg/L,锰平均浓度分别为0. 003 0、0. 005 1、0. 006 7 mg/L,氨氮平均浓度分别为0. 022、0. 030、0. 050 mg/L,浊度均值分别为0. 28、0. 69、1. 32 NTU,除3^#滤柱出水浊度不达标外,其余指标均满足国家标准。随着滤料粒径的增大,铁、锰、氨氮的沿程浓度明显升高,去除区域向下延伸,浊度主要在0~0. 4 m滤层被去除。     

Biological treatment of H(2)S using pellet activated carbon as a carrier of microorganisms in a biofilter

Biological treatment is an emerging technology for treating off-gases from wastewater treatment plants. The most commonly reported odourous compound in off-gases is hydrogen sulfide (H(2)S), which has a very low odor threshold. This study aims to evaluate the feasibility of using a biological activated carbon as a novel packing material, to achieve a performance-enhanced biofiltration processes in treating H(2)S through an optimum balance and combination of the adsorption capacity with the biodegradation of H(2)S by the bacteria immobilized on the material. The biofilm was mostly developed through culturing the bacteria in the presence of carbon pellets in mineral media. Scanning electron microscopy (SEM) was used to identify the biofilm development on carbon surface. Two identical laboratory scale biofilters, one was operated with biological activated carbon (BAC) and another with virgin carbon without bacteria immobilization. Various concentrations of H(2)S (up to 125 ppmv) were used to determine the optimum column performance. A rapid startup (a few days) was observed for H(2)S removal in the biofilter. At a volumetric loading of 1600 m(3)m(-3)h(-1) (at 87 ppmv H(2)S inlet concentration), elimination capacity of the BAC (181 gH(2)Sm(-3)h(-1)) at removal efficiency (RE) of 94% was achieved. If the inlet concentration was kept at below 30 ppmv, high H(2)S removal (over 99%) was achieved at a gas retention time (GRT) as low as 2s, a value, which is shorter than most previously reported for biofilter operations. The bacteria population in the acidic biofilter demonstrated capacity for removal of H(2)S in a broad pH range (pH 1-7). There are experimental evidences showing that the spent BAC could be re-used as packing material in a biofilter based on BAC. Overall, the results indicated that an unprecedented performance could be achieved by using BAC as the supporting media for H(2)S biofiltration.