Removal of Xylene from Waste Gases using Biotrickling Filters

Two identical laboratory‐scale biotrickling filters, filled with different ceramic materials, were operated in order to investigate the removal of xylene from a waste gas stream. The biotrickling filter columns were seeded with pure bacteria identified as Bacillus firmus, which can utilize xylene as the sole carbon and energy source. The purification performance of the biotrickling filters was examined for xylene inlet concentrations C_g ≤ 3000 mg/m³ at different gas flow rates of 0.2 m³/h, 0.6 m³/h, and 1 m³/h, which correspond to gas empty bed residence times (EBRTs) of 84.8 s, 28.3 s, and 17.0 s, respectively. Both biofilters displayed a removal efficiency of no less than 95 % with the inlet xylene less than 3000 mg/m³ at the EBRTs of 84.8 and 28.3 s. When EBRT decreased to 17.0 s, the biofilter filled with ceramic particle type 2 had a better performance. The flow rate of trickling liquid has little effect on the removal efficiencies of the two filters. In the case of uneven distribution of trickling liquid in the packing materials, the performance of the biofilter can be improved by increasing the nitrogen nutrient supplement. Biomass quantity decreases as the depth of packing material increases in both biofilters, but the biofilter filled with ceramic particle type 1 had more alive bacteria per unit mass of packing material than the other.     

Treatment of air polluted with high concentrations of toluene and xylene in a pilot-scale biofilter

Air biofiltration is now under active consideration for the removal of the volatile organic compounds from air polluted streams. In order to investigate the performance of this newly developed technology, a biofiltration pilot unit was operated for a continuous period of 8 months. The biofilter column was packed with commercially conditioned peat. At start-up, the filter bed was inoculated with four species of microorganisms. The resulting biofilter was fed with air contaminated with toluene, xylene or a mixture of toluene and xylene. The maximum elimination capacities attained were 165 g m⁻³ h⁻¹ for toluene, 66 g m⁻³ h⁻¹ for xylene and 115 g m⁻³ h⁻¹ for the mixture of toluene and xylene. These specific performances exceed the values published in the technical and commercial literature for similar processes. Xylene isomers were degraded in decreasing order of reactivity, m-xylene, p-xylene, o-xylene. In the case of air polluted with a toluene and xylene mixture, it was noticed that the metabolism of toluene biodegradation was inhibited by the presence of xylene. Characterization of the biofilm microbial populations after several weeks of operation showed that the dominant strains among the isolated culturable strains from the biofilm, even if different from the initially inoculated strains, had at least one physiological property favoring degradation of aromatic organic rings. The performance of the biofilter was found to be dependent on the temperature of the filter media and the pressure drop through the bed. Finally, a steady state mathematical model was tested in order to theoretically describe the experimental results. This model is used to illustrate the operating diffusion and reaction regimes at steady state for the case of each pollutant. © 1998 Society of Chemical Industry     

生物法处理苯、甲苯废气的工艺性能及动力学研究

研究了生物滴滤塔处理低质量浓度苯、甲苯混合废气的工艺性能及动力学模型拟合效果。在进气量600 L/h,循环液喷淋量20 L/h的操作条件下,生物滴滤塔对低质量浓度苯、甲苯混合气体有很好的去除效果,苯的去除率在65%左右,甲苯的去除率在93%左右。从生物反应器中分离筛选出1株能够降解苯、甲苯污染物的高效菌L4,通过Sherlock脂肪酸鉴定系统分析,匹配值SI为0.884,基本确定该菌株属于Bacillus.sp。采用吸附-生物膜理论进行动力学分析,与实验数据相比有良好的相关性,相关系数苯R2=0.999 5、甲苯R2=0.999 6。     

Treatment performance of volatile organic sulfide compounds by the immobilized microorganisms of B350 group in a biotrickling filter

BACKGROUND: In this work, the feasibility of biodegradation and the removal performance of sole and mixed odorous vapors, such as dimethyl disulfide (DMDS), methyl phenyl sulfide (MPS), and ethanethiol (EtSH) in an EtSH‐acclimated biotrickling filter seeded with commercially available B350 microorganisms, were investigated. RESULTS: Removal efficiencies (REs) for DMDS as a sole substrate were evaluated under different inlet concentrations and empty bed residence times (EBRT), 100% RE was achieved at concentration below 0.4 g m^?3 at EBRT 110 s. In addition, 100% RE was obtained for binary EtSH and DMDS (3:2) at the same EBRT. According to the Michaelis–Menten type kinetic equation, the maximum removal rates (V_max) were calculated as 28.7 and 13.9 g m^?3 h^?1 for DMDS and MPS as sole substrate, respectively, while V_max was 22.1 and 10.1 g m^?3 h^?1 for DMDS and MPS in the presence of EtSH and EtSH‐DMDS mixture, respectively. After 5 and 20 days starvation, the re‐acclimation times were only 2 and 8 days, respectively, for the binary system. An EtSH:DMDS:MPS (3:2:1) ternary mixture was removed efficiently by the rebooted system after starvation. CONCLUSION: The proposed system can be applied to cost‐effectively decompose a mixture of volatile organic sulfide compounds at pilot scale. Copyright © 2011 Society of Chemical Industry     

A trickling fibrous-bed bioreactor for biofiltration of benzene in air

A novel trickling fibrous-bed bioreactor was developed for biofiltration to remove pollutants present in contaminated air. Air containing benzene as the sole carbon source was effectively treated with a coculture of Pseudomonas putida and Pseudomonas fluorescens immobilized in the trickling biofilter, which was wetted with a liquid medium containing only inorganic mineral salts. When the inlet benzene concentration (C_gi) was 0·37 g m⁻³, the benzene removal efficiency in the biofilter was greater than 90% at an empty bed retention time (EBRT) of 8 min or a superficial air flow rate of 1·8 m³ m⁻² h⁻¹. In general, the removal efficiency decreased but the elimination capacity of the biofilter increased with increasing the inlet benzene concentration and the air (feed) flow rate. It was also found that the removal efficiency decreased but the elimination capacity increased with an increase in the loading capacity, which is equal to the inlet concentration divided by EBRT. The maximum elimination capacity achieved in this study was ∽11·5 g m⁻³ h⁻¹ when the inlet benzene concentration was 1·7 g m⁻³ and the superficial air flow rate was 3·62 m³ m⁻² h⁻¹. A simple mathematical model based on the first-order reaction kinetics was developed to simulate the biofiltration performance. The apparent first order parameter K_l in this model was found to be linearly related to the inlet benzene concentration (K_l=4·64−1·38 C_gi). The model can be used to predict the benzene removal efficiency and elimination capacity of the biofilter for benzene loading capacity up to ∽30 g m⁻³ h⁻¹. Using this model, the maximum elimination capacity for the biofilter was estimated to be 12·3 g m⁻³ h⁻¹, and the critical loading capacity was found to be 14 g m⁻³ h⁻¹. The biofilter had a fast response to process condition changes and was stable for long-term operation; no degeneration or clogging of the biofilter was encountered during the 3-month period studied. The biofilter also had a relatively low pressure drop of 750 Pa m⁻¹ at a high superficial air flow rate of 7·21 m³ m⁻² h⁻¹, indicating a good potential for further scale up for industrial applications. © 1998 Society of Chemical Industry     

Autotrophic deodorization of hydrogen sulfide in a biotrickling filter

The removal of hydrogen sulfide (H₂S) from airstreams was studied in a biotrickling filter (BTF) packed with plastic Pall rings operating with counter‐current flows of the air and liquid streams. Experiments were performed at different inlet H₂S concentrations, air and/or liquid volumetric flow rates, and sulfate concentrations in the recirculating liquid to check their effect on the performance of the BTF. Conversion of H₂S never dropped below 80% at the highest concentration and reached 100% at low concentrations. A maximum removal rate of 22.5 g H₂S m^?3 reactor h^?1 was observed with 100% removal efficiency. The shortest empty bed retention time studied at which complete H₂S removal was observed was around 11 s. Conversion of H₂S was found to slightly increase as the liquid flow rate decreased and as the air flow rate increased. Copyright © 2005 Society of Chemical Industry     

Optimum operating conditions for the removal of volatile organic compounds in a compost-packed biofilter

Biofiltration was performed for 101 days in a compost-packed biofilter (I.D. 5.0 cmxheight 62 cm) for the removal of nine volatile organic compounds (benzene, toluene,m-xylene,o-xylene, styrene, chloroform, trichloroethylene, isoprene, and dimethyl sulfide). Removal efficiency of the volatile organic compounds (VOCs) was dependent upon the column temperature, gas flow rate, and incoming concentrations of VOCs. At an empty bed residence time (EBRT) of 3 min and the incoming gas concentration of 66 g m^-3 overall removal and efficiency increased up to 92.1 and 86.4% at 25 °C and 45 °C, respectively. Upon further increase of the incoming gas concentration to 83 g m⁻³, the removal efficiency was 93.7% at 25 °C, but dropped to 73.1% at 45 °C. At incoming gas concentration of 92 g m^-3 and EBRT of 1.5 min, the removal efficiency at 25 °C (91.6%) was comparable to 32 °C (95.5%). However, for 1 min of EBRT removal efficiency was better (86.6%) at 32 °C as compared to at 25 °C (73.6%). The maximum removal rates of VOCs were 3,561, 4,196, and 1,150 g m^-3 h^-1 at 25, 32, and 45 °C, respectively. At an EBRT of 1.5 min and 32 °C the removal efficiency of individual component was highest for toluene (98.9%) andm-xylene (97.6%), and lowest for TCE (86.1%) and chloroform (89.4%). Aromatic compounds (benzene, toluene, and xylene) were removed by 97.1–98.9%. After 101 days of operation profiles of pH and moisture content from the top to the bottom of the column were 7.2–6.3 and 53.8–67.2%, respectively, at 32 °C column, and 67% of the incoming VOCs was removed in the first quarter of the column. After 36 days of operation the cell concentration increased 108-fold from its initial value at 25 °C, and reached a maximum of 1.08x108 cells·(g of dry compost)^-1.     

Removal of TEX vapours from air in a peat biofilter: influence of inlet concentration and inlet load

This paper presents the results of the study of the removal of toluene, ethylbenzene, and o‐xylene (TEX) by biofiltration using a commercial peat as filter‐bed material. Runs with a single organic compound in air, and with the mixture of TEX in air, were carried out for at least 55 days in laboratory‐scale reactors inoculated with a conditioned culture. The influence of organic compound inlet load and of gas flow rate on the biofilter's performance was studied, including relatively high values of pollutant inlet concentration (up to 4.3 gC m^?3 for ethylbenzene, 3.2 gC m^?3 for toluene, and 2.7 gC m^?3 for o‐xylene). Results obtained show maximum elimination capacities of 65 gC m^?3 h^?1 for o‐xylene, 90 gC m^?3 h^?1 for toluene, and 100 gC m^?3 h^?1 for ethylbenzene, and high removal efficiency (>90%) even for moderately elevated concentrations: 3.0, 2.5 and 1.8 gC m^?3 for ethylbenzene, toluene and o‐xylene, respectively. The behaviour of the TEX mixture was in good agreement with the results obtained for the runs in which only one organic compound was present. Ethylbenzene and toluene are degraded easier than o‐xylene, and inhibitory effects due to the presence of multiple substrates were not observed. Copyright © 2005 Society of Chemical Industry     

A three‐phase fluidized bed reactor in the combined anaerobic/aerobic treatment of wastewater

Aerobic degradation or polishing is an essential step in the combined anaerobic/aerobic treatment of wastewater. In this study, a type of porous glass beads was used for immobilization of microbial cells in a three‐phase aerobic fluidized bed reactor (AFBR) with an external liquid circulation. The effects of superficial gas and liquid velocities on bed expansion, solid and gas hold‐ups and specific oxygen mass transfer rate, k_La, were investigated. A tracer study showed that the mixing and flow pattern in the 8 dm³ reactor could be simulated by a non‐ideal model of two continuous stirred tank reactors (CSTRs) in series. By treating an effluent from an upflow anaerobic sludge blanket (UASB) digester, the distribution of suspended and immobilized biomass in the reactor as well as the kinetics of COD removal were determined. The specific oxygen mass transfer rate, k_La, at a superficial gas velocity of 0.7 cm s⁻¹ dropped by about 30% from 32 h⁻¹ in tap water to 22 h⁻¹ after a carrier load of 15% (v/v) was added. The measured k_La further dropped by about 20% to 18 h⁻¹ in the wastewater, a typical value of the bubbling fermenters with no stirring. Compared with the aerobic heterotrophs under optimum growth conditions, the microbes in this reactor which was fed with anaerobic effluent plus biomass behaved like oligotrophs and showed slow specific COD removal rates. This might be attributed to the presence of a significant amount of obligate anaerobes and facultative organisms in the aerobic reactor. This was confirmed by a relatively low intrinsic oxygen uptake rate of the microbial population in the reactor, 94 mg O₂ dm⁻³ h⁻¹ or 19 mg O₂g VS⁻¹ h⁻¹. © 1999 Society of Chemical Industry     

Removal of H2S using a new Ce(IV) redox mediator by a mediated electrochemical oxidation process

BACKGROUND: Hydrogen sulfide (H₂S) from industrial activities and anaerobic manure decomposition in commercial livestock animal operations is an offensive malodorous and toxic gas even in small concentrations, causing serious discomfort and health and social problems. The objective of this study was to employ for the first time a novel, attractive, low cost, environmentally benign mediated electrochemical oxidation (MEO) process with Ce(IV) as the redox catalyst for H₂S gas removal from an H₂S–air feed mixture. RESULTS: The influence of liquid flow rate (Q_L) from 2–4 L min^?1, gas flow rate (Q_G) from 30–70 L min^?1, H₂S concentration in the H₂S–air feed mixture from 5–15 ppm, and Ce(III) pre‐mediator concentration in the electrochemical cell from 0.1–1 mol L^?1 on H₂S removal efficiency were investigated. Both liquid and gas flow rates influenced the removal efficiencies, but in opposite directions. Nearly 98% H₂S removal was achieved when the concentration of Ce(IV) mediator ion in the flowing scrubbing liquid reached 0.08 mol L^?1. CONCLUSIONS: The new MEO method proved promising for H₂S removal, achieving high removal efficiency. Integration of the electrochemical cell with the scrubber set‐up ensured continuous regeneration of the mediator and its repeated reuse for H₂S removal, avoiding use of additional chemicals. Since the process works at room temperature and atmospheric pressure utilizing conventional transition metal oxide electrodes more commonly used in industrial applications, it is also safe and economical. Copyright © 2008 Society of Chemical Industry     

Simultaneous biofiltration of H<Subscript>2</Subscript>S,NH<Subscript>3</Subscript> and toluene using cork as a packing material

Simultaneous removal of ternary gases of NH₃, H₂S and toluene in a contaminated air stream was investigated over 185 days in a biofilter packed with cork as microbial support. Multi-microorganisms including Nitrosomonas and Nitrobactor for nitrogen removal, Thiobacillus thioparus (ATCC 23645) for H2S removal and Pseudomonas aeruginosa (ATCC 15692), Pseudomonas putida (ATCC 17484) and Pseudomonas putida (ATCC 23973) for toluene removal were used simultaneously. The empty bed residence time (EBRT) was 40–120 seconds and the inlet feed concentration was 50-180 ppmv for NH₃, 30–160 ppmv for H₂S and 40–130 ppmv for toluene, respectively. The observed removal efficiency was 45–100% for NH₃, 96–100% for H₂S, and 10–99% for toluene, respectively. Maximum elimination capacity was 5.5 g/m³/hr for NH₃, >20.4 g/m³/hr for H₂S and 4.5 g/m³/hr for toluene, respectively. During long-term operation, the removal efficiency of toluene gradually decreased, mainly due to depositions of elemental sulfur and ammonium sulfate on the cork surface. The results of microbial analysis showed that nearly the same population density was observed on the surfaces of cork chips collected at each sampling point. Kinetic model analyses showed that there were no particular evidences of interactions or inhibitions among the microorganisms.     

An attempt to compare the performance of bioscrubbers and biotrickling filters for degradation of ethyl acetate in gas streams

This study presents a comparison of the efficiency of a bioscrubber and a biotrickling filter (BTF) for the removal of ethyl acetate (EA) vapour from a waste gas stream, under the same operating conditions. The maximum EA elimination capacity achieved in the bioscrubber was 550 g m^?3 h^?1 with removal efficiency higher than 96%. For higher EA loadings the bioscrubber was oxygen limited, which caused incomplete EA biodegradation. When pure oxygen was fed to the bioscrubber at a rate of 0.02 L min^?1, the bioscrubber recovered and could treat higher EA loadings without any oxygen limitation. The BTF achieved EA elimination capacity of 600 g m^?3 h^?1 with removal efficiency higher than 97% and the dissolved oxygen concentration remained substantially higher than in the bioscrubber. However, severe channelling and blockage of the spray nozzle occurred due to the excessive biomass growth. Overall, the bioscrubber system was easier to operate and control than the BTF, while an enhancement of the oxygen mass transfer in the bioscrubber could potentially increase its performance by up to three times. Copyright © 2005 Society of Chemical Industry     

Design and performance of biofilters for the removal of alkylbenzene vapors

Three identical biofilters, run under the same conditions but inoculated with different mixed cultures, were fed a mixture of toluene, ethylbenzene, and o-xylene (TEX) gases. Inert porous perlite was used as support material, in contrast to the more conventional biofiltration systems where natural supports are used. Biodegradation started in all three biofilters a few hours after inoculation, without previous adaptation of the inocula to the toxic mixture. Despite acidification of the systems to pH values below 4·5, the elimination capacities reached were fully satisfactory. The best performing biofilter, in which bacteria were dominant, showed an elimination capacity of 70 g TEX m⁻³ h⁻¹ with a near complete removal of the mixture up to an influent concentration of 1200 mg TEX m⁻³ at a gas residence time of 57 s. Most of the ingoing carbon was recovered as carbon dioxide in the outgoing gas. In the other biofilters fungi dominated and performance was slightly worse. With single substrates, the elimination capacity was higher for toluene and ethylbenzene than for the TEX mixture, whereas o-xylene removal was slowest in all cases. Also when feeding the mixture to the biofilters, o-xylene was removed most slowly.     

Evaluation of Mass Transfer Coefficients in Biotrickling Filters: Experimental Determination and Comparison to Correlations

Overall mass transfer coefficients (K_Ga and K_La) were determined experimentally for four different‐nature packing materials used in gas‐phase biotrickling filters. A simple methodology based on overall mass balances and following a standard procedure allowed to calculate the mass transfer coefficients under different operating conditions corresponding to usual biotrickling filtration situations. Results showed an increase of mass transfer resistance when increasing the empty bed residence time (EBRT) of the reactor for all packing materials. Experimental results were fitted to existing and well‐accepted correlations used in conventional biofilter or biotrickling filter modeling. The comparison of experimental and theoretical data showed huge discrepancies. Simple correlations for the experimental data obtained in this study were also suggested.     

Removal of toluene from air streams using a gas–liquid–solid three‐phase airlift loop bioreactor containing immobilized cells

Toluene, a kind of volatile organic compound (VOC), is widely used as a solvent (paints and coatings, gums, resins, rubber) as well as a reagent (medicines, dyes, perfumes) and is one of the components of gasoline. Over the more recent decades, many studies have led to the development of biological methods to treat toluene. This paper presents the results of a study on the treatment of airborne toluene using a laboratory‐scale gas–liquid–solid three‐phase airlift loop bioreactor containing immobilized cells. Based on the optimum operating conditions such as the temperature of 28–30 °C, pH of 7.0–7.2, and an empty bed residence time (EBRT) of 39.6 s, a continuous bioprocess showed that this immobilized airlift loop bioreactor had a steady‐state performance within 15 days, the outlet concentrations of toluene were lower than the national emission standard in China (GB 16297‐1996), and the chemical oxygen demand and NH₄⁺‐N of the effluent also satisfied the primary discharge standard in China (GB 8978‐1996). In addition, this immobilized airlift loop bioreactor had a good ability to tolerate shock loads, while the maximum elimination capacity of toluene was 168 g m^?3 h^?1 which was higher than those not only in biofilters and biotrickling filters but also in the airlift bioreactor with free microorganisms. Copyright © 2005 Society of Chemical Industry     

Comparison of biological reactors (biofilter,biotrickling filter and modified RBC) for treating dichloromethane vapors

BACKGROUND: Bioreactors used for waste gas and odor treatment have gained acceptance in recent years to treat volatile organic compounds (VOCs). Different types of bioreactors (biofilter, biotrickling filter and rotating biological reactor) have been used for waste gas treatment. Most studies reported in the literature have used one of these systems to treat several types of inorganic and organic gases either individually or in mixtures. Each of these reactors has some advantages and some limitations. Though biodegradation is the main process for the removal of pollutants, the mechanisms of removal and the microbial communities may differ among these bioreactors. Consequently their performance or removal efficiency may also be different. RESULTS: At low loading rate (<35 g m^?3 h^?1), all three bioreactors showed comparable removal efficiencies and elimination capacity, but at higher loading rates, rotating biological contactors (RBC) showed a better performance with higher removal efficiency (40–50%) than both the biofilter and biotrickling filter (20–40%). The biofilter showed a sharp drop in removal efficiency and elimination capacity at high loading rates. CONCLUSIONS: The modified RBC had no clogging problems and no increase in pressure drop when compared with the other bioreactors. It can thus handle pollutant load for a longer period of time. This is the first study attempting to compare the performance of three different bioreactors for removal of the same VOC under different conditions. Copyright © 2010 Society of Chemical Industry     

Achieving 360 NL h−1 Hydrogen Production Rate Through 30‐Cell Solid Oxide Electrolysis Stack with LSCF–GDC Composite Oxygen Electrode

A 30‐cell solid oxide electrolysis (SOE) stack consisting of 30‐cell planar Ni–YSZ hydrogen electrode‐supported single cell with La_0.6Sr_0.4Co_0.2Fe_0.8O_3–δ–Ce_0.9Gd_0.1O_1.95 (LSCF–GDC) composite oxygen electrodes, interconnects, and sealing materials was tested at 750 °C in steam electrolysis mode for hydrogen production. The direction of gas flow in the stack was a cross‐flow configuration, and the stack configuration was designed to open gas flow channels at the air outlet. The electrolysis efficiency of the stack was higher than 100% at 90/10H₂O/H₂ ratio under <0.5 A cm⁻² current density. During hydrogen production, the stack was operated at 750 °C under 0.5 A cm⁻² constant current density for more than 500 h with 4.06% k h⁻¹ degradation rate. Up to 73% steam conversion rate and 91.6% current efficiency were obtained; the net hydrogen production rate reached as high as 361.4 NL h⁻¹. Our results suggested that the SOE stack that was designed with LSCF–GDC composite oxygen electrode could be used to conduct large‐scale hydrogen production.     

生物滴滤塔处理甲苯工艺过程的影响因素研究

采用陶粒为填料的生物滴滤塔降解甲苯,实验研究了浓度和气、液体流量对甲苯降解能力的影响,实验结果表明,随着气、液体流量的增大,净化效率降低。对影响气体进出口温差的因素和填料床内液膜温度分布的结果进行实测和分析发现：进口甲苯浓度和液体流量、气体进出口温差成正比,而与气体流量成反比。液膜在填料床内的温度分布是沿塔高先降低后升高。     

错流式生物滴滤塔净化含硫化氢废气的研究

利用错流式水平生物滴滤塔对H2S进行脱臭实验,采用城市生活污水处理厂曝气池污泥进行接种挂膜。结果显示,H2S最大进气浓度可达1400 mg/m3,最大的体积去除负荷为144 g/(m3填料.h),对应的生物膜去除负荷为34.5 mg/(g生物膜干重.h),系统有较高的净化H2S废气能力。     

Isolation and Characterization of Potent Strains for Metabolizing Paint VOCs from an Active Trickle‐bed Air Biofilter

In this study, seven strains of cells were isolated from a trickle‐bed air biofilter used for continuously treating paint of volatile organic compounds (VOCs) for six months. The morphology and biochemical study was conducted by streaking isolated mixed culture in solid agar slant media and the cell shapes were identified by using an electron microscope. It was found that this mixed culture was gram‐negative for seven different isolates. The isolated strains were grown on substrates including methyl ethyl ketone (MEK), toluene, n‐butyl acetate, and o‐xylene (MTBX), as the carbon and energy sources. Among the seven isolates, an AKM 02 strain had a high MTBX‐degrading activity and was identified as Shewanella putrefaciens by taxonomical analysis, biochemical tests and 16S rDNA gene analysis methods. All isolates grew in a pH range from 3.0–11.0 with an optimum range of 6.0–8.0. In addition, each of the isolates grew in the temperature range of 15–45 °C with an optimum range between 25–30 °C. The batch experiments were conducted at four different initial MTBX concentrations ranging from 100–1000 mg L^–1. S. putrefaciens was capable of completely degrading n‐butyl acetate, MEK and toluene at a concentration lower than 500 mg L^–1. When the initial concentration of n‐butyl acetate, MEK and toluene were 500 mg L^–1, S. putrefaciens could remove the n‐butyl acetate, MEK and toluene completely within 70, 98 and 110 h, respectively. However, for o‐xylene at concentration of 500 mg L^–1, incomplete degradation was observed with only 70 % of the o‐xylene degraded after 135 h. Collectively, the results indicate that the S. putrefaciens strain degrades MTBX at a faster rate, and this strain can be used effectively in trickle‐bed air biofilters for treating high strength mixtures of paint solvents.