Operational and microbiological aspects of a bioaugmented two-stage biotrickling filter removing hydrogen sulfide and dimethyl sulfide

Hydrogen sulfide degradation characteristics of Bordetella sp. Sulf-8 in a biotrickling filter

The applicability of Bordetella sp. Sulf-8 to degrade Hydrogen Sulfide (H(2)S) gas in a biotrickling system was investigated. The isolate is a heterotrophic gram-negative, catalase- and oxidase-positive, rod-shaped bacterium which can metabolize thiosulfate or sulfide into sulfate. The mesophilic Bordetella sp. Sulf-8 can grow within a wide pH range using yeast as carbon source, with or without the presence of sulfur. In batch experiments, kinetic constants such as maximum specific growth rate (μ (max) = 0.12 1/h), saturation constant (K (S) = 0.017 g/L), and specific sulfur removal rate (88 mg S/g cells h) were obtained. In biotrickling experiments removal efficiencies were satisfactory, but the system performance was observed to be more influenced by empty bed residence time than by H(2)S feed gas concentration. Critical and maximum elimination capacities were 78.0 and 94.5 g H(2)S/m(3) day, respectively. Macrokinetic analysis of the biotrickling system revealed maximum H(2)S removal rate V (max) = 15.97 g S/kg media-day and half saturation constant K (S') = 12.45 ppm(v).

Process of simultaneous hydrogen sulfide removal from biogas and nitrogen removal from swine wastewater

The feasibility of a new flowchart describing simultaneous hydrogen sulfide removal from biogas and nitrogen removal from wastewater was investigated. It took 30 days for the reactor inoculated with aerobic sludge to attain a removal rate of 60% for H(2)S and NO(x)-N simultaneously. It took 34 and 48 days to attain the same removal rate for the reactor without inoculated sludge and the reactor inoculated with anaerobic sludge respectively. The reactor without inoculated sludge still operated successfully, despite requiring a slightly longer startup time. The packing material was capable of enhancing the removal efficiency of reactors. Based on the concentration of NO(x)-N and H(2)S in the effluent, the loading rate and the ability of the system to resist shock loading, the performance of the reactor filled with hollow plastic balls was greater than that of the reactor filled with elastic packing and the reactor filled with Pall rings.

Dimethyl sulphide degradation using immobilized Thiobacillus thioparus in a biotrickling filter

Gaseous dimethyl sulphide (DMS) was eliminated in a biotrickling filter with Thiobacillus thioparus grown in polyurethane foam cubes as carrier material. The temperature, pH and empty bed residence time of the gas were maintained at 30 degrees C, 7.0 and 40 s, respectively. In the first 45 days, DMS loads of around 2.0 gDMS m(-3) h(-1) were fed to the BTF to adapt T. thioparus to DMS consumption, attaining close to 100% removal efficiency (RE) on day 46, and the maximum elimination capacity (EC) was 4.0 gDMS m(-3) h(-1) with a RE of 77%. The overall performance was enhanced by adding a nitrogen-enriched (9x) medium but was negatively affected by high superficial liquid velocity (8.18 m h(-1)) and high pH (>7.5). Sulphate concentrations (up to 10 g L(-1)) showed no effect. The system supported shock loads up to 58 gDMS m(-3) h(-1) with increased elimination. With nitrogen-enriched medium and a pH of 7.0 it was possible to increase the EC of DMS up to a maximum of around 23 gDMS m(-3) h(-1) with 65% RE.

Two-stage gas-phase bioreactor for the combined removal of hydrogen sulphide, methanol and alpha-pinene

Biological treatment systems have emerged as cost-effective and eco-friendly techniques for treating waste gases from process industries at moderately high gas flow rates and low pollutant concentrations. In this study, we have assessed the performance of a two-stage bioreactor, namely a biotrickling filter packed with pall rings (BTF, 1st stage) and a perlite + pall ring mixed biofilter (BF, 2nd stage) operated in series, for handling a complex mixture of hydrogen sulphide (H2S), methanol (CH3OH) and alpha-pinene (C10H16). It has been reported that the presence of H2S can reduce the biofiltration efficiency of volatile organic compounds (VOCs) when both are present in the gas mixture. Hydrogen sulphide and methanol were removed in the first stage BTF, previously inoculated with H2S-adapted populations and a culture containing Candida boidinii, an acid-tolerant yeast, whereas, in the second stage, alpha-pinene was removed predominantly by the fungus Ophiostoma stenoceras. Experiments were conducted in five different phases, corresponding to inlet loading rates varying between 2.1 and 93.5 g m(-3) h(-1) for H2S, 55.3 and 1260.2 g m(-3) h(-1) for methanol, and 2.8 and 161.1 g m(-3) h(-1) for alpha-pinene. Empty bed residence times were varied between 83.4 and 10 s in the first stage and 146.4 and 17.6 s in the second stage. The BTF, working at a pH as low as 2.7 as a result of H2S degradation, removed most of the H2S and methanol but only very little alpha-pinene. On the other hand, the BF, at a pH around 6.0, removed the rest of the H2S, the non-degraded methanol and most of the alpha-pinene vapours. Attempts were originally made to remove the three pollutants in a single acidophilic bioreactor, but the Ophiostoma strain was hardly active at pH <4. The maximum elimination capacities (ECs) reached by the two-stage bioreactor for individual pollutants were 894.4 g m(-3) h(-1) for methanol, 45.1 g m(-3) h(-1) for H2S and 138.1 g m(-3) h(-1) for alpha-pinene. The results from this study showed the potential effectiveness of a two-stage bioreactor for treating H2S together with two hydrophilic and hydrophobic VOCs that are typically emitted from wood industries.

Removal of hydrogen sulfide by immobilized Thiobacillus thioparus in a biotrickling filter packed with polyurethane foam

In the work described here, a biotrickling filter with Thiobacillus thioparus (ATCC 23645) immobilized on polyurethane foam is proposed for the removal of hydrogen sulfide contained in air. The effect of surface velocity of the recirculation medium (5.9-1.2 m/h), sulfate concentration inhibition (3.0-10.7 g/L), pH (6.0-8.2), empty bed residence time (EBRT) (150-11 s) for constant loads of 11.5 and 2.9 g S/m(3)/h, and pressure drop of the system were investigated. The total amount of biomass immobilized on the carrier was 8.2+/-1.3x10(10) cells/g. The optimal values of the operating variables were: pH between 7.0 and 7.5, surface velocity of 5.9 m/h and sulfate concentration below 5 g/L. The critical EC value was 14.9 g S/m(3)/h (removal efficiency of 99.8%) and the EC(max) was 55.0 g S/m(3)/h (removal efficiency of 79.8%) for an EBRT of 150 s. For loads of 2.89+/-0.05 and 11.5+/-0.1 g S/m(3)/h, the removal efficiency was higher than 99% for an EBRT over 90 s.

Removal of dichloromethane from waste gases in one- and two-liquid-phase stirred tank bioreactors and biotrickling filters

The removal of dichloromethane (DCM) from polluted air was studied both in biotrickling filters and in continuous stirred tank bioreactors, using either a single-liquid aqueous phase or a combination of an aqueous-organic liquid phase. The presence of the organic phase, i.e. silicone oil, at a volume ratio of 10% of the liquid phase, increased the maximum EC by about 25% in the BTF, reaching 200 gm(3)/h, and by as much as 300% in the CSTB, reaching 350 gm(3)/h. Based on data of chloride release in the aqueous phase and carbon dioxide production in the gas phase, complete dechlorination and mineralization of the pollutant could be confirmed. When applying shock loads, a more stable behaviour was observed in the presence of the organic phase. Generally, the completely mixed reactors were also more stable than the plug-flow biotrickling filters, irrespective of the presence of the organic phase. The use of molecular techniques allowed showing that the originally inoculated DCM-degrading Hyphomicrobium strains remained present, although not dominant, after long-term bioreactor operation. Different new bacterial populations did also appear in the systems, some of which were unable to degrade DCM.

Biofiltration of trimethylamine, dimethylamine, and methylamine by immobilized Paracoccus sp. CP2 and Arthrobacter sp. CP1

A biofilter using granular activated carbon with immobilized Paracoccus sp. CP2 was applied to the elimination of 10-250 ppm of trimethylamine (TMA), dimethylamine (DMA), and methylamine (MA). The results indicated that the system effectively treated MA (>93%), DMA (>90%), and TMA (>85%) under high loading conditions, and the maximum degradation rates were 1.4, 1.2, and 0.9g-Nkg(-1) GAC d(-1). Among the three different amines treated, TMA was the most difficult to degrade and resulted in ammonia accumulation. Further study on TMA removal showed that the optimal pH was near neutral (6.0-8.0). The supply of high glucose (>0.1%) inhibited TMA removal, maybe due to substrate competition. However, complete TMA degradation was achieved under the co-immobilization of Paracoccus sp. CP2 and Arthrobacter sp. CP1 ( approximately 96%). Metabolite analysis results demonstrated that the metabolite NH(4)(+) concentrations decreased by a relatively small 27% while the metabolite NO(2)(-) apparently increased by heterotrophic nitrification of Arthrobacter sp. CP1 in the co-immobilization biofilter.

Microbial populations analysis and field application of biofilter for the removal of volatile-sulfur compounds from swine wastewater treatment system

A biofilter packed with granular activated carbon (GAC) was applied to eliminate volatile-sulfur compounds (VSC) emitted from solid-liquid separation tank in swine wastewater treatment system. Hydrogen sulfide, methanethiol, dimethyl disulfide, and dimethyl sulfide were effectively reduced to 96-100% at gas residence times of 13-30s. Elemental sulfur and sulfate are their primary oxidation metabolites. Regarding odor, an average of 86% reduction was achieved at short residence time (13s). In addition, bioaerosol emissions could also be effectively reduced by 90% with the biofilter. Advantages of the system include low moisture demand, low pressure drop, and high biofilm stability. Further characterization of bacterial populations of the activated carbon samples using the fluorescent in situ hybridization (FISH) technique revealed that Pseudomonas sp. remained the predominant community (56-70%) after long-term evaluation of 415 days.

Developing a biofilm of sulfur oxidizing bacteria, starting-up and operating a bioscrubber treating H2S

Development of an acclimatized SOB biofilm, startup and performance of a fixed bed bioscrubber packed with corrugated tube parts as a media having high specific surface area was investigated. Bioscrubber was a cylindrical Plexiglas air-and water-tight column with 10 L in working bed volume. Sludge from a tannery wastewater treatment plant was used as a seed for SOB separation, acclimation and enrichment. Enriched acclimatized SOB were applied as inoculum for biofilm development, which was carried out by recirculating the prepared microbial suspension through the bed. Thickness of the developed biofilm was 56 microm in which active acidophilic autotrophic H2S oxidizing bacteria were completely predominated. Activity measurements showed highest biodegradation rate of biofilm at liquid pH around 3. Due to employing an efficient specialized biofilm, startup period of the reactor was quite short and H2S removal efficiency just 12 h after starting up reached above of 92% and increased to 96% at day 3 of starting up while inlet H2S concentration gradually was increased to around 30 ppm. At the end of start up pH of the recycle liquid was modified to the optimal value of 3 +/- 0.5 in which biofilm demonstrated the highest activity in terms of OUR after which removal efficiency increased around 3% while other operating conditions were consistent. Furthermore, performance of the bioscrubber was evaluated at various inlet H2S concentrations ranging from 30 to 150 ppm(v). It was indicated that the inlet H2S concentrations in studied range did not affect the performance of the bioscrubber so that the removal efficiency of H2S was greater than 99.4% at all concentrations. These observations suggested that the development of an efficient specialized SOB biofilm on a media with high specific surface area will decrease the startup course and achieve high removal efficiency in the bioscrubber treating H2S. In addition, operation in acidic recycle liquid will overcome use of alkaline to adjust the pH, which reduce the operation cost of the control system.

Performance and microbial analysis of defined and non-defined inocula for the removal of dimethyl sulfide in a biotrickling filter

The performance and microbial communities of three differently inoculated biotrickling filters removing dimethyl sulfide (DMS) were compared. The biotrickling filters were inoculated with Thiobacillus thioparus TK-m (THIO), sludge (HANDS) and sludge + T. thioparus TK-m + Hyphomicrobium VS (HANDS++), respectively. The criteria investigated were length of the start-up period, the maximum elimination capacity, and the effects of intermittent loading rates, low pH, peak loading and very low loading rate on the DMS removal efficiency. The HANDS++ reactor exhibited the best performance considering all treatments. HANDS performed almost equally well as HANDS++, except during the determination of the EC(max), while THIO was generally the least efficient. During stable DMS loading at concentrations of 20 ppmv or lower, all reactors exhibited similar and high removal efficiencies (>99%). Denaturing gradient gel electrophoresis (DGGE) analysis showed the establishment of T. thioparus in the biofilm of all reactors, but not of Hyphomicrobium VS. Quantitative monitoring of the introduced bacterial strains was performed with a newly developed real-time PCR protocol. Initially, the inoculated strains were exclusively found in the reactors in which they were added. Afterwards, however, both strains developed in the biofilm of all three reactors, although T. thioparus attained higher cell densities than Hyphomicrobium. The presence of T. thioparus in THIO was related with the DMS loading rates that were applied, in the sense that intermittent DMS loading and very low DMS loading rates (0.5 ppmv) induced a decrease in gene copy numbers. Real-time PCR and DGGE both gave consistent results regarding the presence of Hyphomicrobium VS and Thiobacillus thioparus TK-m in the reactors. Only real-time PCR could be used to detect bacteria comprising of less than 1.4% of the total bacterial community ( approximately 10(5) copies ring(-1)).

H2S degradation is reflected by both the activity and composition of the microbial community in a compost biofilter

In this study, 16S rRNA- and rDNA-based denaturing gradient gel electrophoresis (DGGE) were used to study the temporal and spatial evolution of the microbial communities in a compost biofilter removing H(2)S and in a control biofilter without H(2)S loading. During the first 81 days of the experiment, the H(2)S removal efficiencies always exceeded 93% at loading rates between 4.1 and 30 g m(-3) h(-1). Afterwards, the H(2)S removal efficiency decreased to values between 44 and 71%. RNA-based DGGE analysis showed that H(2)S loading to the biofilter increased the stability of the active microbial community but decreased the activity-based diversity and evenness. The most intense band in both the RNA- and DNA-based DGGE patterns of the H(2)S-degrading biofilter represented the sulfur oxidizing bacterium Thiobacillus thioparus. This suggested that T. thioparus constituted a major part of the bacterial community and was an important primary degrader in the H(2)S-degrading biofilter. The decreasing H(2)S removal efficiencies near the end of the experiment were not accompanied by a substantial change of the DGGE patterns. Therefore, the decreased H(2)S removal was probably not caused by a failing microbiology but rather by a decrease of the mass transfer of substrates after agglutination of the compost particles.