Inlet H2S Concentration Research Articles

Energy efficiency in hydrogen sulfide removal by non-thermal plasma photolysis technique at atmospheric pressure

In this paper, a novel combined non-thermal plasma photolysis reactor was employed to decompose H2S in gas stream at atmospheric pressure. The filling gas pressure, applied voltage, and inlet H2S concentration were altered with the aim to improve the energy efficiency. High H2S removal efficiency could be achieved with sufficient but reasonable energy density deposited on gas stream. The energy consumption per molecule of destructed H2S, 26±1.5eV/molecule, was relatively low as compared with those values reported for plasma reactor operated at non-vacuum pressures and diluted condition. Furthermore, the H2S decomposition mechanism was proposed as direct electron attachment, radicals and excited species attack and photo-dissociation based on byproducts analysis by GC and IC. The results revealed the potential for energy efficient destruction of H2S by combined plasma photolysis process.

Hydrogen sulphide removal from biogas by an anoxic biotrickling filter packed with Pall rings

Hydrogen sulphide (H2S) is one of the most problematic contaminants in biogas. In this study, a biotrickling filter with a working volume of 2.4L and packed with polypropylene Pall rings was tested for its ability to remove H2S from biogas under anoxic conditions. The influence of the H2S inlet concentration, nitrate feeding regime (manual and controlled) and liquid flow rate on the elimination capacity of the biotrickling filter was studied. The results indicate that 99% of the H2S was removed for H2S inlet loads lower than 120gSm−3h−1 when using controlled nitrate feeding by ORP.

One-stage biotrickling filter for the removal of a mixture of volatile pollutants from air: Performance and microbial community analysis

The biodegradation of gas-phase mixtures of methanol, α-pinene and H2S was examined in a biotrickling filter (BTF), inoculated with a microbial consortium composed of an autotrophic H2S-degrading culture, and pure strains of Candida boidinii, Rhodococcus erythropolis, and Ophiostoma stenoceras. The inlet concentrations of methanol, α-pinene and H2S varied from 0.05 to 3.3 gm(-3), 0.05 to 2.7 gm(-3), and 0.01 to 1.4 gm(-3), respectively, at empty bed residence times (EBRT) of either 38 or 26s. The maximum elimination capacities (ECmax) of the BTF were 302, 175, and 191 gm(-3)h(-1), with 100%, 67%, and >99% removal of methanol, α-pinene and H2S, respectively. The presence of methanol showed an antagonistic removal pattern for α-pinene, but the opposite did not occur. For α-pinene, inlet loading rates (ILRs) >150 gα-pinenem(-3)h(-1) affected its own removal in the BTF. The presence of H2S did not show any declining effect on the removal of both methanol and α-pinene.

A comparative evaluation of dried activated sludge and mixed dried activated sludge with rice husk silica to remove hydrogen sulfide

The aim of this study was to investigate the effectiveness of dried activated sludge (DAS) and mixed dried activated sludge with rice husk silica (DAS & RHS) for removal of hydrogen sulfide (H2S). Two laboratory-scale filter columns (packed one litter) were operated. Both systems were operated under different conditions of two parameters, namely different inlet gas concentrations and different inlet flow rates. The DAS & RHS packed filter showed more than 99.96% removal efficiency (RE) with empty bed residence time (EBRT) of 45 to 90 s and 300 mg/L inlet concentration of H2S. However, the RE decreased to 96.87% with the EBRT of 30 s. In the same condition, the DAS packed filter showed 99.37% RE. Nonetheless, the RE was shown to have dropped to 82.09% with the EBRT of 30 s. The maximum elimination capacity (EC) was obtained in the DAS & RHS packed filter up to 52.32 g/m3h, with the RE of 96.87% and H2S mass loading rate of 54 g/m3h. The maximum EC in the DAS packed filter was obtained up to 44.33 g/m3h with the RE of 82.09% and the H2S mass loading rate of 54 g/m3h. After 53 days of operating time and 54 g/m3h of loading rates, the maximum pressure drop reached to 3.0 and 8.0 (mm H2O) for the DAS & RHS packed and DAS packed filters, respectively. Based on the findings of this study, the DAS & RHS could be considered as a more suitable packing material to remove H2S.

Hydrogen sulfide removal from livestock biogas by a farm-scale bio-filter desulfurization system

A farm-scale biogas desulfurization system was designed and tested for H2S removal efficiency from livestock biogas. This work assesses the H2S removal efficiency of a novel farm-scale biogas bio-desulfurization system (BBS) operated for 350 days on a 1,000-head pig farm. Experimental data demonstrated that suitable humidity and temperature can help sulfur-oxidizing bacteria to form active bio-films on the bio-carriers. The daily average removal rate increased to 879.16 from 337.75 g-H2S/d with an average inlet H2S concentration of 4,691 ± 1,532 mg/m(3) in biogas. Thus, the overall (0-350 days) average H2S removal efficiency exceeded 93%. The proposed BBS overcomes limitations of H2S in biogas when utilizing pig farm biogas for power generation and other applications.

Biotrickling filters for biogas sweetening: Oxygen transfer improvement for a reliable operation

An industrial-scale biotrickling filter for the removal of high concentrations of H2S is described in this work. The system has been operating at H2S inlet concentrations between 1000 and 3000ppmv at acidic conditions. A decrease of pH from 2.6 to 1.8 did not affect the biological activity inside the biofilter while reducing the water make-up consumption up to 75%. The current oxygen supply system, based on direct injection of air to the liquid phase, has demonstrated to be inefficient for a long-term operation leading to elemental sulfur accumulation in the packing material (i.e. promoting clogging episodes). The present study demonstrates it is possible to partially remove (40.3%) the deposited elemental sulfur by bio-oxidation when biogas is not fed. In normal operation conditions, the implementation of an aeration system based on jet-venturi devices has shown quite promising results in terms of oxygen transfer efficiency and robustness. Such improvement of oxygen transfer was translated in a better conversion of H2S to sulfate, which increased around 17%, prolonging the lifespan operation at low-pressure drop.

Performance study of biofilter developed to treat H2S from wastewater odour

Biofiltration is an efficient biotechnological process used for waste gas abatement in various industrial processes. It offers low operating and capital costs and produces minimal secondary waste streams. The objective of this study was to evaluate the performance of a pilot scale biofilter in terms of pollutants’ removal efficiencies and the bacterial dynamics under different inlet concentrations of H2S. The treatment of odourous pollutants by biofiltration was investigated at a municipal wastewater treatment plant (WWTP) (Charguia, Tunis, Tunisia). Sampling and analyses were conducted for 150days. Inlet H2S concentration recorded was between 200 and 1300mg H2S.m−3. Removal efficiencies reached 99% for the majority of the running time at an empty bed retention time (EBRT) of 60s. Heterotrophic bacteria were found to be the dominant microorganisms in the biofilter. The bacteria were identified as the members of the genus Bacillus, Pseudomonas and xanthomonadacea bacterium. The polymerase chain reaction-single stranded conformation polymorphism (PCR-SSCP) method showed that bacterial community profiles changed with the H2S inlet concentration. Our results indicated that the biofilter system, containing peat as the packing material, was proved able to remove H2S from the WWTP odourous pollutants.

Research on the Removal Results of Hydrogen Sulfide of the Treatment of Coal Gasification Wastewater Biogas in the Anaerobic Biotrickling Filter

The uncertainty of operating parameters hinders the practical application of the biological desulfurization. To solve this problem, this study which was conducted in room temperature, pH around seven conditions, investigated the effects of the operating parameters on the hydrogen sulfide (H2S) removal performance in the biotrickling filter, including inlet H2S concentration, inlet flow rate or gas retention time, inlet volume load and circulating liquid spraying flux. The results showed that, the inlet H2S concentration should be controlled within 800mg/m3, 650mg/m3, 400mg/m3, 300mg/m3 respectively while the inlet flow rate was 150L/h, 200L/h, 250L/h, 300L/h, at those conditions, the outlet H2S concentrations were lower than 8mg/m3 and the H2S removal efficiencies were more than 98%. The optimum gas retention time was 12.37s, corresponding to the inlet flow rate of 200L/h, at this time, even if the inlet H2S concentration as high as 700mg/m3, the removal efficiency could be still more than 98%, the outlet concentration of H2S was only 13.1mg/m3. The maximum inlet volume load was 130g/(m3•h), in this condition, the outlet concentration of H2S could be controlled below 12mg/m3, the removal efficiency could above 98.4%.

Pilot-scale chemical–biological system for efficient H2S removal from biogas

A pilot-scale chemical–biological process was performed efficiently to remove corrosive H2S from biogas. Consecutive 356-d livestock biogas purification was conducted at various H2S loading rates. The average inlet H2S concentration was 3542ppm, and a removal efficiency of 95% was achieved with gas retention time of 288s. This system showed robust performance during operation with stable parameters. Purified biogas with an average of 59% CH4 was collected for power production. Moreover, 28.3kWh of power was produced by using a 30kW biogas generator under 300LPM biogas flow rate. During the 30-d shut down test, the jarosite formation resulted in pH decrease and appearance of Leptospirillum sp. and Sulfobacillus sp. in the bioreactor. However, the cell density of the inoculated Acidithiobacillus ferrooxidans was maintained above 5×107CFU/g-AC during long-term operation. Thus, given the successful H2S elimination, the chemical–biological process is a feasible system for biogas purification.

Performance and Bacterial Community Diversity of a Full-Scale Biofilter Treating Leachate Odor in a Sanitary Landfill Site

Odors, such as the malodorous and toxic hydrogen sulfide (H2S), are released during leachate collection, storage, and treatment. A full-scale biofilter was applied to treat H2S emitted from a leachate equalization basin in a sanitary landfill site. The inlet concentration of H2S was 26.3–213.0 mg m−3. In steady state, total removal efficiency was over 90 % in summer and over 80 % in winter. The maximum elimination capacity achieved 9.1 g m−3 h−1 at a loading rate of 10.5 g m−3 h−1. The biofilter was effective at reducing H2S. Factors on the level of H2S inlet concentration and performance of the biofilter were investigated. The H2S inlet load and removal efficiency relied on ambient and biofilter temperature, respectively. The water containing rate and relative humidity presented seasonal variation, according to which the interval period of irrigation could be optimized. The main product of H2S degradation was sulfate, and sulfur also could be observed from the biofilter. Spatial and temporal shifts in bacterial community composition in the biofilter were determined by polymerase chain reaction-denaturing gradient gel electrophoresis followed by DNA sequence analysis. The present study revealed a correlation between biofilter performance and bacterial community structure, especially in a real application case.

Simplified Simulation Model of a Biotrickling Filter Used for the Removal of Hydrogen Sulfide From Biogas

Biogas produced by the anaerobic digestion of waste contains approximately 1000-1200 ppmv H2S, which is toxic and corrosive. It is necessary to remove H2S before using the biogas in further application. Biotrickling filters containing immobilized Thiobacillus sp. on inert packings are used extensively in the industries. The design equations for biotrickling filter are complex in nature. A simplified simulation model has been proposed where the complexity of solving the diffusion equation forming a boundary value problem has been avoided by utilizing an approximate general solution available in the literature for this class of problems. The simplified simulation model has been validated with the experimental data, with the analytical solutions available for limiting cases, and with the numerical solution. The results have been found in good agreement for air-H2S system. Further, the performance of an industrial biotrickling filter, designed to treat 10000 m3.day-1 biogas to reduce H2S concentration from 1200 ppmv to 100 ppmv, has been analyzed by studying the effect of packed bed height, inlet concentration of H2S, empty bed residence time of gas, biofilm thickness and packing size on its removal efficiency by using proposed simplified model.

Removal of H2S from gas stream using combined plasma photolysis technique at atmospheric pressure

In this paper, H2S in gas stream was successfully decomposed at atmospheric pressure by dielectric barrier discharge plasma and VUV–UV radiation from a combined plasma photolysis reactor (CDBD). In comparison with DBD, CDBD enhanced H2S removal efficiency significantly at the same applied voltage, inlet H2S concentration and gas residence time. H2S removal efficiency was determined as a function of Kr pressure, applied voltage, inlet H2S concentration, and gas residence time. H2S removal efficiency could reach as high as 93% at inlet H2S concentration of 27.1mgm−3, residence time of 0.4s, and applied voltage of 7.5kV. The main products were discerned as H2O and SO42- based on FTIR and IC analysis.

Monitoring and control of biogas desulphurization using oxidation reduction potential under denitrifiying conditions

AbstractBACKGROUND: Hydrogen sulphide (H2S) present in biogas can be oxidized to elemental sulphur (S0) or sulphate (SO42−) using nitrate and nitrite. Both nitrate and nitrite are normally available in most wastewater treatment plants and could be used to oxidize H2S depending on the molar loading ratio of wastewater and biogas. A control approach is required in order to minimize the fluctuations in inlet and outlet H2S concentrations in biogas, and the oxidation potential of the wastewater used.RESULTS: A control scheme has been developed for biogas desulphurization using oxidation reduction potential under industrial conditions. The redox potential was maintained at about + 50 to + 100 mV in the activated sludge plant to monitor the performance of the nitrification process. The redox potential in the bioscrubber was related to sulphide removal from biogas. More than 90% of the hydrogen sulphide was removed from the biogas.CONCLUSION: The oxidation reduction potential can be used as a key parameter for monitoring and controlling biogas cleaning. Fluctuations of the inlet H2S concentration in biogas can be compensated by manipulating the flowrates of wastewater used in order to achieve consistent and desired H2S concentrations in treated biogas. Copyright © 2011 Society of Chemical Industry

Removal of Hydrogen Sulfide Using a Compost-Based Biofilter

Hydrogen sulfide (H2S) is a malodorous gas which can cause nuisance and health effects to people who live and work in the contaminated air environment. Therefore, the main objective of this work was to study the removal of hydrogen sulfide (H2S) using a biofilter packed with mixture of compost, organic fertilizer, wood chips and municipal wastewater sludge at a ratio of 60:10:20:10 by weight. The experiment was carried out at hydrogen sulfide concentration of 5-200 ppmv and empty bed residence time (EBRT) of 60 seconds. The results indicated that completer H2S removal can be achieved at H2S inlet concentration of 200 ppmv. Elimination capacity of the biofilter reached as high as 24.38 gm−3 h−1.

Synthesize and Characterization of Rice Husk Silica to Remove the Hydrogen Sulfide through the Physical Filtration System

The main goal of this study was to synthesis and characterization of silica prepared from rice husk and its application to remove Hydrogen sulfide. Polyvinyl chloride filters with 50 cm in height and 7.5 cm in diameter have been used in this study. Rice husk silica (RHS) and regenerated rice husk silica (RRHS) were used as packing material in this work. System was studied at a constant empty bed residence time (EBRT) of 60 sec and different inlet concentration of H2S from 15 to 450 mg m-3. Brunauer-Emmett-Teller method showed rice husk silica has a very high surface area (226.3 m2 g-1) with median pore radius of 2.4 nm and mesoporous structure. The chemical composition analysis showed that the silica consisted of SiO2 up to 97.35%. The removal efficiency (RE) more than 98% were observed for both packed filters at a loading rate of 0.98 g H2S m-3 h-1 and 15 mg m-3 inlet concentrations of H2S. The maximum removal capacity of both packed filter were obtained 7.02 m-3 h-1 at a loading rate of 9.0 m-3 h-1 and 150 mg m-3 inlet concentration. The result from the analysis indicates that at a 1.0 L min-1 flow rate and different inlet concentration of H2S there is no significant difference between the RHS packed filter and the RRHS packed filter in the amount of removal efficiency and removal capacity (p<0.01). Also the result showed pressure drop was undetectable amount (zero) in both packed filter. The results of this study show the best performance of RHS and RRHS packed filters in low concentration of H2S.

Bacterial community analysis of a gas-phase biotrickling filter for biogas mimics desulfurization through the rRNA approach

The bacterial composition of a lab-scale biotrickling filter (BTF) treating high loads of H2S was investigated by the rRNA approach. Two 16S rRNA gene clone libraries were established 42 and 189 d after reactor startup, while fluorescent in-situ hybridization (FISH) with DNA probes was performed throughout 260d of reactor operation. Diversity, community structure and metamorphosis were studied from reactor startup to fully-established pseudo-steady state operation at near neutral pH and at an inlet H2S concentration of 2000 ppmv (load of 55.6g H2S m−3h−1). In addition, FISH was used for assessing the spatial distribution of sulfur-oxidizing bacteria (SOB) along the length of the reactor under pseudo-steady state operation. A major shift in the diversity of the community was observed with the operating time, from a well-diverse community at startup to pseudo-steady state operation with a majority of retrieved sequences affiliated to SOB of the sulfur cycle including Thiothrix spp., Thiobacillus spp., and Sulfurimonas denitrificans. Although aerobic species were predominant along the BTF, a vertical stratification was encountered, in which facultative anaerobes had a major relative abundance in the inlet part of the BTF, where the sulfide to oxygen ratio was higher. The observed changes were related to the trophic properties of the community, the DO concentration, the accumulation of elemental sulfur and the operation at neutral pH.

Development of a Biofilter with Tire-Derived Rubber Particle Media for Hydrogen Sulfide Odor Removal

The biofilter system containing tire-derived rubber particle (TDRP) filter media was utilized to treat the odorous gas contaminant, hydrogen sulfide, in consideration of the economic advantage of reusing discarded tire materials and the high potential of TDRP media for biofilm attachment. The pilot-scale system having 0.38 m3 of bed volume operated with synthetic hydrogen sulfide gas on continuous basis from a range of 0.34 to 1.15 m3/min. This bioreactor system achieved over 94% removal efficiency at 20–90 ppm of inlet H2S concentration while operating in 20–67 s of empty bed retention time, indicating that overall effective operation was performed at mass loading rates of H2S ranging from 19.6 to 28.5 g H2S/(m3 h). It was apparent by the effectiveness of the system’s performance that this system had the capability to effectively remove hydrogen sulfide with high efficiency over a range of concentrations. A maximum elimination capacity was not found for the biofilter during this study, which tested loading rates between 0 and 30 g H2S/(m3 h).

Performance of Biofilter for the Removal of Hydrogen Sulphide Odour

Laboratory scale experiments were performed to evaluate the feasibility of biofilters for the removal of H2 S from wastewater treatment plant waste air. The effects of changes in air flow rate and contaminant concentration on biofilter performance treating H 2 S odours were also assessed. Compost was used as media in biofilter. The study was carried out in six different phases, by increasing H2S concentrations gradually. In the first phase only humidified air was supplied to acclimatize and develop the biofilm, within the biofilter conditions. In the second phase, inlet H2S concentration was kept up to 10 ppm with the humidified air, H-2S removal efficiency was very high around 98%. It was concluded that the biofilter, used in the study, was more efficient (>95% removal efficiency) for low contaminant concentrations (up to 30 ppm). However, as the concentration of H2S was increased to 50 ppm the removal efficiency decreased to 85%. The study results showed that biofilter could withstand longer starvation period and required less time to recover to its full efficiency. The effect of operating parameter such as moisture content was also assessed. The study revealed that the compost biofilter may be successfully adopted for various industrial operations where a reduction in emissions of H2S is required..

Hydrogen sulphide removal in waste water treatment plant by compact oxidative scrubbing in Aquilair Plus™ process

Recently, the development of a high voidage contactor, named Aquilair Plus™, has demonstrated high efficiency for chemical scrubbing of hydrogen sulphide. Liquid and gas phases flow at co-current and high velocity, leading to a great dispersion of the liquid and then to an enhancement of the mass transfer rate by comparison with classical packed towers. This study focused on the results which obtained at semi-industrial scale with the Aquilair Plus™ process on a waste water treatment plant located in France. The scrubbing liquid consisted of a sodium hypochlorite alkaline solution. At once, pressure drop, H2S removal and reagents consumption were followed. The influence of the superficial gas velocity, liquid-to-gas mass ratio (L/G), pH, hypochlorite concentration of the scrubbing liquid and H2S inlet concentration was characterised. H2S removal percentages higher than 90% could be easily achieved with a moderate pressure drop (&amp;lt; 40 mbar). Both hydrodynamic and chemical conditions proved to influence performances. Reagents consumptions slightly higher than the predicted ones were measured.

Hydrogen Sulfide Removal in Biofilter: Evaluation of a New filter Material by Immobilization of Thiobacillus sp.

Different agricultural residue was evaluated as a biofilter material for the removal of Hydrogen sulfide (H2S) using Thiobacillus sp. A Combination of four different agricultural residues, viz., sugarcane bagasse, coconut coir pith, rice husk and saw dust were evaluated as biofilter material. From results, it was observed that filter material having composition of 2:4:2:2, 4:4:2:2 and 4:2:2:4 has resulted in retaining 70% moisture content at the end of 10 days. The biofilter was operated for 128 days in three phases by varying inlet H2S concentration from 321 to 2020 ppmv. Biofilter exhibited 100% removal efficiency (RE) at an inlet concentration of 570 ppmv, 99% RE at an inlet concentration of 1416 ppmv and 66% RE at a maximum inlet concentration of 2020 ppmv. The filter performance in terms of RE, dropped to 48% when the air was not humidified before sending to the filter, which has direct relation with the MC of the filter material. The RE recovered to 66% with recovery of moisture content (MC) to 57% upon subsequent re-introduction of the humidifier in to the circuit. The pH has dropped from 7.8 to 4.8 during the course of operation of the filter. H2S was effectively removed under different operating conditions using mixed agricultural residue as filter material. However humidification was most essential to maintain the required moisture content in the biofilter. SEM analysis has shown the good growth of Thiobacillus sp. in the filter bed and hence the new material proved to be good support for the immobilization of Thiobacillus sp.