H2S Removal Efficiency Research Articles

Removal of hydrogen sulfide using a photocatalytic livestock biogas desulfurizer

The objective of this study was to develop a simple operating photocatalytic biogas desulfurizing reactor (PDR) using sol-gel preparation assay in coordination with biogas absorption chiller. Hydrogen sulfide in biogas can be oxidized to SO2 by photocatalytic oxidation of TiO2-coated carriers with UV irradiation. This PDR method is the lowest maintenance cost and simple operation for small biogas consumption users water than packed scrubber or granular ferric oxide filter. Experimental results showed that H2S removal efficiency by the first PDR was 99.1 ± 1.1, 92.9 ± 2.9, 88.2 ± 3.6, 84.1 ± 2.3, and 82.7 ± 9.4% under biogas flow rate at 1, 2, 3, 4, and 5 L/min, respectively. Removal efficiency of H2S at biogas flow rate at 1 L/min was significantly different from the other biogas flow rate sets (P < 0.05). Experimental results showed that total H2S removal efficiency for all biogas flow sets was more than 99% by the dry PDR. Thus, this implies that the photocatalytic reactor can be applied to remove H2S from biogas. The successful development of the PDR can help to promote utilization efficiency of livestock biogas and reduce livestock’s greenhouse gas emissions.

Enhancing the removal of H2S from biogas through refluxing of outlet gas in biological bubble-column

Biological bubble-column (BBC) is beneficial for elemental sulfur recycle from H2S, but it’s difficult to remove high concentration of H2S in biogas efficiently due to the mass transfer limitation of H2S from gas to liquid. In this study, a novel method with refluxing outlet gas in BBC was investigated. The results showed that gas reflux greatly enhanced the removal of high concentration of H2S (about 5000 ppmv) from biogas. The removal efficiency of H2S was 88.0 ± 4.1% with the reflux ratio at 1.0, which was higher than those without gas reflux (58.4 ± 1.0%), when the inlet H2S loading was 143.1 ± 4.5 g/(m3·h). Moreover, the removal capacity of H2S improved significantly with the increase of the reflux ratios from 1.0 to 4.0 and achieved the maximum at 271.8 ± 2.4 g/(m3·h). This might mainly be attributed to longer residence time and enhanced the mass transfer of O2 and H2S from gas to liquid through gas reflux.

Application and regeneration of honeycomb-type catalysts for the selective catalytic oxidation of H2S to sulfur from landfill gas

In this research, selective catalytic oxidation was applied to remove high-concentration hydrogen sulfide in landfill gas. The removal efficiency of H2S was the best with V/TiO2 catalyst produced by wet impregnation among. The optimum vanadium content was 10 %. In addition, selective conversion to elemental sulfur and generation of SO2 could be controlled by adjusting O2/H2S ratio. The larger the cell per square inch that affected the performance of the honeycomb-type catalyst, the greater the removal efficiency of H2S according to increase in specific surface area. An analysis of long-term performance of the honeycomb-type catalyst with landfill gas including CH4 and CO2 revealed that more than 90 % of H2S was removed. In addition, the performance of the catalyst could be recovered by thermal regeneration. Considering that the performance of a catalyst can be recovered for durability and regeneration, V/TiO2 coated honeycomb-type catalyst can be used in the actual process.

Resilient performance of an anoxic biotrickling filter for hydrogen sulphide removal from a biogas mimic: Steady, transient state and neural network evaluation

Biological hydrogen sulphide (H2S) removal from a biogas mimic (pH = ∼7.0) was tested for 189 days in an anoxic biotrickling filter (BTF) inoculated with a pure culture of Paracoccus versutus strain MAL 1HM19. The BTF was packed with polyurethane foam cubes and operated in both fed-batch and continuous modes. The H2S inlet concentration to the BTF was varied between ∼100 and ∼500 ppmv during steady-state tests, and thereafter to ∼1000, ∼2000, ∼3000 and ∼4000 ppmv during shock-load (i.e. transient state) tests. The H2S removal efficiency (RE) ranged between 17 and 100% depending on the operational mode of the BTF and the presence of acetate as a carbon source. The maximum elimination capacity (ECmax) of the BTF reached 113.5 (±6.4) g S/m3 h with 97% RE during H2S shock-load experiments at ∼4000 ppmv which showed the robustness and resilient capacity of BTF for the large fluctuations of H2S concentrations. The results from polymerase chain reaction denaturing gradient gel electrophoresis (PCR–DGGE) revealed that P. versutus remained dominant throughout the 189 days of BTF operation which can imply the crucial role of this bacterium to remove H2S and upgrade to clean biogas. The analysis using artificial neural networks (ANNs) predicted the H2S and NO3−-N REs and SO42− production in the anoxic BTF. Consequently, this study revealed that a BTF can be used to treat H2S contamination of biogas under anoxic conditions.

Design of a bioaugmented multistage biofilter for accelerated municipal wastewater treatment and deactivation of pathogenic microorganisms

Biological treatment of municipal wastewater for reuse in irrigation is highly required, especially with the current global financial and water shortage crises. Bioaugmentation is a simple and cost-effective technology which could be a useful tool in alleviating this challenge. Thus, this study aimed to enhance the biological treatment of municipal wastewater using a bioaugmented substance supplemented in a three-stages bio-filter consisting of a sedimentation step followed by gravel biofiltration and then sand biofiltration at a laboratory scale. Also, a toxicity assay, the antimicrobial effect of the bioaugmented substance against pathogenic microorganisms, and identification of the synergistic effect of the bacterial consortium involved in the bioaugmented substance were studied. The bioaugmented substance was nontoxic and had an antimicrobial effect against the tested potentially pathogenic microorganisms (Escherichia coli, Pseudomonas aeruginosa, Listeria monocytogenes, Staphylococcus aureus, and Candida albicans). The minimum effective concentration of the bioaugmented substance for organic, inorganic and microbial pollutants removal from high strength wastewater was 2.5 ppm with a contact time of 6–8 h. The removal efficiencies of H2S, COD, BOD5, total solids (TS), total dissolved solids, total suspended solids, ammonia, nitrate, phosphorus, and oil and grease reached 85, 93.4, 83.5, 37, 49.2, 93.4, 100, 55.7, 76.6 and 76.6%, respectively in the treated effluent after sand biofiltration. The physicochemical parameters of the treated wastewater effluent were below the Egyptian recommended limits (Law 84/1984) for use in irrigation. However, COD and BOD values were 90.33 and 38.46 mgO2/L, respectively, and were still above the regulations (COD ≤60 and BOD ≤20). The high fecal coliforms count in the wastewater influent (8.4 × 108 MPN-index/100 mL) were 95.1% removed after the sedimentation stage, and 99.99% removal was achieved after gravel and sand biofiltration. Thus, this study successfully designed a bioaugmented multistage biofiltration system for the effective removal of pollutants from wastewater, especially in resource-limited areas.

Single-/triple-stage biotrickling filter treating a H2S-rich biogas stream: Statistical analysis of the effect of empty bed retention time and liquid recirculation velocity

ABSTRACTBiogas containing H2S has limited use in electricity and heat production as H2S can be corrosive to metal equipment. Bio-filtration has proved to be a suitable technology for biogas desulfurization because of economical and environmental benefits over physicochemical techniques. In the present study, a response surface methodology using 32 full factorial design was employed to determine the effects of two operating parameters, namely empty bed retention time (EBRT: 100–180 sec) and liquid recirculation velocity (LRV: 2.4–7.1 m3 m−2 h−1) on H2S removal efficiency (%) in single-stage and triple-stage bio-trickling filters (SBTF and TBTF) treating an H2S-rich biogas. Quadratic model was found to be the best predictive model for H2S removal efficiency. The results indicated that H2S removal efficiency was significantly influenced by the synergistic effect of linear terms of EBRT and LRV with a greater effect associated with EBRT. However, the quadratic term of LRV had an antagonistic effect. The quadratic term of EBRT and cross-product term between EBRT and LRV did not exhibit a significant effect on H2S removal efficiency. The predicted values from the established models showed a close agreement with the experimental data with the coefficient of determination (R2) of 0.99 for H2S removal efficiency in both SBTF and TBTF. Response analysis demonstrated that the performance of TBTF was superior compared to SBTF.Implications: Bio-trickling filter technology has gained a lot of attention for biogas desulfurization because it is economically and environmentally superior over chemical methods. Empty bed retention time (EBRT) and liquid recirculation velocity (LRV) are crucial variables influencing the performance of bio-trickling filters. In this work, the authors established a model that can properly predict H2S removal efficiency in a single/triple bio-trickling filter (SBTF and TBTF) treating H2S-rich biogas with regard to the individual and interaction effects between EBRT and LRV. Analysis with the help of response surface methodology indicated that TBTF was more efficient compared to SBTF for H2S removal.

A novel multi-phase treatment scheme for odorous rubber effluent

ABSTRACT Despite the great profits of rubber latex production, its preliminary processing releases a large amount of wastewater into the water bodies from several processing steps. This rubber effluent is rich in total Kjeldahl nitrogen (TKN), total dissolved solids (TDS), biological oxygen demand (BOD) and chemical oxygen demand (COD). Therefore, the study addressed a liquid phase treatment of the effluent using an Upflow Anaerobic Sludge Blanket (UASB) reactor followed by coagu-flocculation and aeration. In addition, the gas phase (containing odorous hydrogen sulphide of 10–12% by volume) from the UASB reactor was sent to a caustic scrubber where the H2S removal efficiency of 63 ± 5% was achieved. This integrated multi-phase treatment scheme proved to be an effective approach by reducing TKN, TDS, BOD and COD by 68–87%, 61–69%, 81–84% and 81–87% respectively in the final effluent.

Dissolved hydrogen sulfide removal from anaerobic bioreactor permeate by modified direct contact membrane distillation

Hydrogen sulfide (H2S) is a volatile, toxic and malodorous compound, which presence causes corrosion, damages to the environment, health and safety problems. Thus, the removal of H2S present in wastewaters is important, especially in the context of wastewater reclamation. In this work, a modified direct contact membrane distillation (M-DCMD) process with receiving NaOH solution in permeate side, flowing in counter-current mode, was evaluated for accelerating dissolved H2S removal from a two-stage anaerobic membrane bioreactor (2S-AnMBR) treating vinasse, rich in organic matter and sulfate. The H2S concentration in the 2S-AnMBR permeate was 166 ± 15 mg L−1. The effect of pH and temperature and the interference of the organic and inorganic compounds on the H2S removal were investigated. The results demonstrated the application potential of a M-DCMD process for the H2S removal from permeate of a 2S-AnMBR treating vinasse. The DCMD process is favored at lower pH values, where all the sulfide species are present as H2S. High temperature can be used to increase the M-DCMD process performance, mainly in neutral pH, and so, to reduce the chemicals demand. The highest removal efficiency of H2S was achieved at pH 4.2 and temperature of 44 °C, referring to the optimal condition, after 20 min. Repeated H2S removal tests of the 2S-AnMBR effluent caused a decrease of 23% of the mass transfer coefficient likely attributed to membrane fouling. Tests were also carried out by inverting the flow configuration, i.e., lumen-side feed and shell-side feed. The more effective contact of hot feed and membrane in the lumen-side feed, favored by the flow conditions as the larger contact area, resulted in a higher permeate flux.

Simultaneous removal of hydrogen sulfide and ammonia using a combined system with absorption and electrochemical oxidation

Hydrogen sulfide (H2S) and ammonia (NH3), common impurities in biogas, need to be removed before utilizing it. In this study, a combined system, which consisted of an absorption column and an electrochemical oxidation reactor, was tested to simultaneously remove these impurities. The effects of the current density and the chemical loading rate on the system performance were investigated. Firstly, the mass transfer coefficients for the absorption column were determined at various gas flow rates. More mass of NH3 was transferred, compared with that of H2S, because of its higher solubility. In the electro-oxidation reactor, reactive chlorine species (RCSs) were generated and oxidized both H2S and NH3; however, NH3 started to degrade only after H2S was completely eliminated. At a current density of 400 A/m2, the current efficiencies of H2S and NH3 were 23.1% and 5.9%, respectively. In the combined system, the removal efficiency of H2S was closely related to the mass ratio of the H2S transferred and the RCSs generated. The removal efficiency of H2S was greater than 99% when the ratio was less than 1. The mass transfer potential and the oxidation kinetics should be balanced to improve the system performance for the simultaneous removal of H2S and NH3.

Desulfurization of Biogas from a Closed Landfill under Acidic Conditions Deploying an Iron-Redox Biological Process

Desulfurization processes play an important role in the use of biogas in the emerging market of renewable energy. In this study, an iron-redox biological process was evaluated at bench scale and pilot scale to remove hydrogen sulfide (H2S) from biogas. The pilot scale system performance was assessed with real biogas emitted from a closed landfill to determine the desulfurization capacity under outdoor conditions. The system consisted of an Absorption Bubble Column (ABC) and a Biotrickling Filter (BTF) with useful volumes of 3 L and 47 L, respectively. An acidophilic mineral-oxidizing bacterial consortium immobilized in polyurethane foam was utilized to regenerate Fe(III) ion, which in turn accomplished the continuous H2S removal from inlet biogas. The H2S removal efficiencies were higher than 99.5% when H2S inlet concentrations were 120–250 ppmv, yielding a treated biogas with H2S &lt; 2 ppmv. The ferrous iron oxidation rate (0.31 g·L−1·h−1) attained when the system was operating in natural air convection mode showed that the BTF can operate without pumping air. A brief analysis of the system and the economic aspects are briefly analyzed.

Simultaneous removal of hydrogen sulfide and volatile organic sulfur compounds in off-gas mixture from a wastewater treatment plant using a two-stage bio-trickling filter system

Simultaneous removal of hydrogen sulfide (H2S) and volatile organic sulfur compounds (VOSCs) in off-gas mixture from a wastewater treatment plant (WWTP) is difficult due to the occasional inhibitory effects of H2S on VOSC degradation. In this study, a two-stage bio-trickling filter (BTF) system was developed to treat off-gas mixture from a real WWTP facility. At an empty bed retention time of 40 s, removal efficiencies of H2S, methanethiol, dimethyl sulfide, and dimethyl disulfide were 90.1, 88.4, 85.8, and 61.8%, respectively. Furthermore, the effect of lifting load shock on system performance was investigated and results indicated that removal ofboth H2S and VOSCs was slightly affected. Illumina Miseq sequencing revealed that the microbial community of first-stage BTF contained high abundance of H2S-affinity genera including Acidithiobacillus (51.43%), Metallibacterium (25.35%), and Thionomas (8.08%). Analysis of mechanism demonstrated that first stage of BTF removed 86.1% of H2S, mitigating the suppression on VOSC degradation in second stage of BTF. Overall, the two-stage BTF system, an innovative bioprocess, can simultaneously remove H2S and VOSC.

Использование спеченного сорбента для удаления сероводорода из отходящего промышленного газа при грануляции металлургических шлаков

Authors suggest removing hydrogen sulfide from the hot industrial gas at temperatures 200-300 °C and its subsequent interaction with Fe2O3. For this purpose the following sorbents have been proposed: a mixture of iron oxide and fly ash; iron oxide and pumice; different samples of red mud (bauxite treatment residues containing iron oxide). To prevent dusting and loss of absorbing capacity, the sorbents were shaped into porous granules with other metallic oxides. Materials utilized in the study were obtained the following way: mixing of Fe2O3 with fly ash; sintering of the mixture with red mud. The blend contains aluminum oxide and silica, which can act as matrix shapers, alkali oxides and fluxing agents that reduce the temperature during metal sintering. After the samples had been saturated with sulfur, they were positioned in a venting reservoir, where under the temperature 600-700 °C desorption to the initial state occurred by means of passing an air flow through the sorbent layer. In the process of this operation, sulfur dioxide was released and reactive metal oxides re-emerged. Desorption also generated a small amount of elemental sulfur and sulfuric acid. Absorbing capacity was assessed at higher temperatures, efficiency of H2S removal reached 95-99.9 %. Proposed technology of air cleaning is recommended to use in metallurgic processes with elevated atmospheric pollution, e.g. granulation of melted blast-furnace slag.

Desulfurization of Offshore Natural Gas by Chelated Iron Solution in a HiGee Reactor: A Feasibility Study

Applying a HiGee reactor for H2S removal with solid sulfur generation by a chelated iron solution offers an economical way to exploit offshore natural gas. However, the high H2S removal efficiency ...

Biofiltration performance and kinetic study of hydrogen sulfide removal from a real source.

Biofiltration is one of the most accepted technologies in odor control in wastewater facilities. A biofilter system consists of a bed of organic material providing both as the carrier for the active microorganisms and as nutrient supply. This study was aimed to evaluate and model a biofilter performance operated under real conditions of odor emission from a wastewater pump station located in Khorramabad, Iran. The media was a mixture of compost and wood chips with a weight ratio of 5:1. The treatment performance of the biofilter was assessed during a 90-day operation period and the gathered data were utilized to develop and determine the best fit kinetic model based on Michaelis-Menten and Ottengraf models. The best fit model was used in the analysis of scenarios defined based on inlet H2S loading fluctuations. Also, the effectiveness of the main parameters in biofilter performance was evaluated using a dimensionless sensitivity coefficient. The best fit model was found the Ottengraf zero-order type limited by diffusion based on the values of R-square (0.98) and mean square error (MSE) (0.002). The results demonstrated a high H2S removal efficiency of about 98% in an EBRT (empty bed residence time) of 60s. despite high fluctuations of inlet concentration under real conditions. The system was able to meet the effluent standard limit of 10ppm even if the inlet H2S loading increases up to two times the base level. According to the results of the defined sensitivity coefficient, the system performance was more sensitive to the inlet concentration than EBRT with a ratio of 1.4. In addition to the acceptable efficiencies of biofilter in odor removal, the results proved the worth of using a kinetic model in forecasting the system performance which is a useful tool in the design and operation of such systems.

Transient-state operation of an anoxic biotrickling filter for H2S removal.

The application of an anoxic biotrickling filter (BTF) for H2S removal from contaminated gas streams is a promising technology for simultaneous H2S and NO3- removal. Three transient-state conditions, i.e. different liquid flow rates, wet-dry bed operations and H2S shock loads, were applied to a laboratory-scale anoxic BTF. In addition, bioaugmentation of the BTF with a H2S removing-strain, Paracoccus MAL 1HM19, to enhance the biomass stability was investigated. Liquid flow rates (120, 60 and 30 L d-1) affected the pH and NO3- removal efficiency (RE) in the liquid phase. Wet-dry bed operations at 2-2 h and 24-24 h reduced the H2S elimination capacity (EC) by 60-80%, while the operations at 1-1 h and 12-12 h had a lower effect on the BTF performance. When the BTF was subjected to H2S shock loads by instantly increasing the gas flow rate (from 60 to 200 L h-1) and H2S inlet concentration (from 112 (± 15) to 947 (± 151) ppmv), the BTF still showed a good H2S RE (>93%, EC of 37.8 g S m-3 h-1). Bioaugmentation with Paracoccus MAL 1HM19 enhanced the oxidation of the accumulated S0 to sulfate in the anoxic BTF.

Hydrogen sulfide removal from biogas in biotrickling filter system inoculated with Paracoccus pantotrophus

Biogas generated from anaerobic digestion can be employed as fuel in either industrial boilers or electric generators. The presence of a trace amount of hydrogen sulfide (H2S) in the biogas can severely impact on the biogas applications. Biotrickling filter (BF) inoculated with a pure strain of sulfide oxidizing bacterium, Paracoccus pantotrophus NTV02 was used to remove H2S from the biogas in the present work. P. pantotrophus was successfully immobilized on plastic packing media in BF after 228 h inoculation. H2S containing biogas and liquid media was subsequently fed into BF under countercurrent direction with fixed inlet gas flowrate and liquid media recirculation rate at 0.5 LPM (120 s EBRT) and 3.6 L/h. H2S in the biogas was varied in the range of 100–2,000 ppmv. BF achieved H2S removal efficiency at 98.3–99.7% at its inlet concentration ranges of 300–1,500 ppmv of H2S. The removal efficiency (99.5%) little declined as H2S inlet reached 2,000 ppmv. The maximum of elimination capacity was 82.98 g H2S/m3·h at the loading rate of 83.58 g H2S/m3·h.

Technical and economic investigation of chemical scrubber and bio-filtration in removal of H2S and NH3 from wastewater treatment plant

A detailed techno-economic comparison of a chemical scrubber (CS) and a bio-filter (BF) was conducted over a 45-day time period at a municipal wastewater treatment plant (WWTP), Yazd city. The assessment of emissions quantity indicated that odor emissions from the Yazd WWPT mainly consist of hydrogen sulfide (H2S) and ammonia (NH3). It was also found that odor gaseous loading changes corresponding to water consumption pattern in society (R2 = 0.922) for H2S and (R2 = 0.978) for NH3. The highest level of 25 and 3 ppm for H2S and NH3, respectively were detected at specific times during the day. The BF system was continuously supplied with Yazd WWPT's off-gas treatment while the CS was only examined at the times during the day when the gas emissions are at the highest level. The removal efficiency of NH3 and H2S were found to be affected by their respective loading rate. Additionally, among the various oxidants examined in the CS, the NaOCl solution showed the best results in terms of removal efficiency and compatibility. The experiment revealed almost complete removal of NH3 while the H2S removal efficiency remained above 95% for both systems regardless of the operating conditions. This study clearly demonstrates the effectiveness of both systems in treating actual waste gases containing H2S and NH3. By comparing the gas loading rate of both systems and considering limitations of the BF system, the CS seems to be more efficient applicable odor control technology from a technical viewpoint. From the economic viewpoint, comparisons revealed that chemical usage and operating expenses were costly parts of the CS and the BF, respectively. The economic indexes of 1.58 €.m−3. h−1 and 2.57 €.m−3. h−1 were obtained for the BF and CS, respectively, reflecting cost-effectiveness of the BF system.

Synthesis and modification of Zeolitic Imidazolate Framework (ZIF-8) nanoparticles as highly efficient adsorbent for H2S and CO2 removal from natural gas

In this work, synthesis and modification of some ZIF-8 nanoparticles in different functionalization media using ethylenediamine (ED) were investigated for H2S and CO2 efficient removal form synthetic natural gas mixture. Characterization of the prepared ZIF-8 nanoparticles was performed using X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), dynamic light scattering (DLS), and N2 adsorption/desorption analysis. XRD and FTIR analysis of the ZIF-8 nanoparticles before and after H2S adsorption revealed that their structure does not considerably change. CO2 and H2S removal efficiencies of the nanoparticles were evaluated at 25 °C and their Co-adsorption performance was also measured in static and dynamic modes at 25 °C and 0–13 bar. The unmodified ZIF-8 nanoparticles (WS-ZIF-8) adsorption capacities for CH4, CO2 (20 bar and 25 °C) and H2S (10 bar and 25 °C) were found as 4.4, 10.8, 18.8 mmol/g, respectively. Those for modified ZIF-8 nanoparticles (ED-ZIF-8) increased by 15%, 22% and 3 times, respectively. Mixed gas H2S adsorption of ED-ZIF-8 nanoparticles measurements up to 3 mol. % H2S approved their improved acid gases removal efficiencies and also structural stability confirmed by XRD analysis. The unmodified ZIF-8 nanoparticles breakthrough times for H2S and CO2 adsorbed from mixed gas of CH4 / CO2 / H2S /He as 88.8 / 7.3 / 3 / 1 mol. % at 25 °C and 2 bar were found as ˜ 190 and 308 s, respectively, while those for modified ZIF-8 nanoparticles considerably improved ˜ 400 and 531 s, respectively.

Evaluation of Semi-Continuous Pit Manure Recharge System Performance on Mitigation of Ammonia and Hydrogen Sulfide Emissions from a Swine Finishing Barn

In this research, for the first time, we present the evaluation of a semi-continuous pit manure recharge system on the mitigation of ammonia (NH3) and hydrogen sulfide (H2S) emissions from a swine finisher barn. The pit recharge system is practiced on many swine farms in the Republic of Korea, primarily for improving air quality in the barn. It consists of an integrated waste management system where the fraction of stored manure is pumped out (10× of the daily production of manure, 3× a day); solids are separated and composted, while the aerobically treated liquid fraction is then returned to the pit. We compared emissions from two 240-pig rooms, one equipped with a pit recharge system, and the other operating a conventional slurry pit under the slatted floor. Mean reduction of NH3 and H2S emissions were 49 ± 6% and 82 ± 7%, respectively, over 14 days of measurements. The removal efficiency of H2S was higher than NH3, likely because the pH of aerobically treated liquid manure remained slightly above 8. More work is warranted to assess the N balance in this system and the emissions of odor and greenhouse gasses (GHGs). It is also expected that it will be possible to control the NH3 and H2S removal rates by controlling the nitrification level of the liquid manure in the aerobic treatment system.

Anoxic biodesulfurization using biogas digestion slurry in biotrickling filters

In this study, an alternative technology for using chemically produced nitrate/nitrite as an electron acceptor for biogas anoxic desulfurization was developed. The method was validated through the investigation of the impacts of loading rate, trickling liquid velocity, empty bed residence time, liquid height/filler height ratio and restart on H2S removal efficiency in biotrickling filters packed with polyurethane foam (BTF B) and multi-surface hollow spheres (BTF C). The results of this study showed that the best desulfurization efficiency was obtained at a liquid height/filler height ratio of 1/3, rather than at 1/2 or 1/6. In a 122-day experiment, the maximum elimination capacity of 81.29 gH2S m−3h−1 was achieved under a H2S removal efficiency of 94.5%. In addition, the fastest restart process required only 8 days after 25 days of shutdown. High throughput sequencing results indicated that the microbial community structure was more stable below the liquid level than above the liquid level. The genus Sulfurimonas in BTF C was positively correlated with the loading rate (R2 = 0.99, P < 0.01), but the significance of the correlation was lower in BTF B (R2 = 0.76, P < 0.05). In general, the outcomes affirmed that utilizing biogas digestion slurry after nitrification (provided low-cost electron acceptor) could realize a stable and efficient desulfurization efficiency of biogas.