Inlet H2S Concentration Research Articles

Analysis and Assessment of H2S Sorption Capacity of the Selected Biofiltration Materials

Hydrogen sulfide known as one of the highly toxic chemical compounds existed in the raw biogas and needs to be eliminated before implementation at any industrial sector. Biofilter (a typical bioreactor) is a tool used to separate sulfide/sulfate from hydrogen by biofiltration method, which is known as the green technology. Packing material is the main component inside a laboratory-scale biofilter to undertake the desulfurization process of H2S. This study is dedicated to evaluating number of selected recyclable/waste organic, inorganic, and synthetic packing material’s rate of impact on amplifying purification progress of hydrogen sulfide from biogas, known as biofilters “removal efficiency (RE)”. Variable effective factors such as environmental and equipment conditions, consumed time (day), and inlet H2S concentration will be controlled throughout the measurements for all chosen packing materials. In the end, the best performed environment-friendly biofiltration material in terms of sorption capacity of H2S from the biogas will be announced.

High conversion of H2S to H2 and S via a robust microwave-induced discharge plasma

Direct conversion of H2S could achieve the co-production of hydrogen and sulfur, avoiding hydrogen waste in the traditional Claus process. Herein, we propose a robust SiC-mediated microwave-induced discharge plasma, achieving H2S conversion of 98.8% to H2 and S with the inlet H2S of 2% (volume concentration) at 600 W. We realize efficient excitation and stable maintenance of microwave plasma in the multimode cavity via optimizing large SiC particles at the waveguide port. In addition, the introduction of tungsten sheets enhances discharge plasma. The H2S conversion of 52.8% was realized for the high inlet H2S concentration (30%) at 600 W. In-situ optical emission spectroscopy reveals that atomic S and H are the key reactive intermediates in the overall H2S decomposition. Direct electron-H2S collision coupling excited Ar atom-H2S collision contributes to H2S direct conversion. This work paves a path to hydrogen production toward sustainable energy applications from the direct conversion and utilization of H2S.

Facile synthesis of cuprous chloride/copper chloride hydroxide composites for reactive removal of hydrogen sulfide at room temperature

In this work, a self-assembly method is developed to synthesize a series of cuprous chloride/copper chloride hydroxide composites (CCCCHs). The hydrogen sulfide (H2S) removal performances of these materials are investigated under the conditions of 25 °C, 1 atm and the inlet H2S concentration of 250 ppm in a gaseous N2 mixture with a flow rate of 40 mL min−1. It is demonstrated that the intermediate product of Cu by Fe reduction can react with CuCl2 to form cuprous chloride (CuCl). Then, CuCl2 and H2O are self-assembled on the surface of CuCl to generate the shell layer of copper chloride hydroxides (CCHs). When the molar ratio of CuCl2 to Fe is 4, the CCCCHs show the largest H2S adsorption capacity of 259.5 mg g−1 because CuCl core is almost covered by CCHs overlayers. Based on extensive results of XRD, SEM, TEM, EDS, XPS and FTIR analyses, the sulfidation reaction mechanism of CCCCHs can be revealed. When react with H2S, the CCHs surface is decomposed to generate CuCl2·2H2O and Cu2+ is reduced to Cu+, which is accompanied by the oxidation of H2S to form elemental sulfur and sulfate. During the decomposition process of CCHs, sulfidation reaction can penetrate deeply into the adsorbent particles, and the H2S treatment capacity of adsorbent is substantially improved.

Optimization of effecting parameters for flue gas desulfurization in a self‐priming venturi scrubber using response surface methodology

AbstractHydrogen sulfide (H2S), a highly poisonous and corrosive gas, is regarded as a hazardous air pollutant with significant effects on human health. Hence, reduction of hydrogen sulfide (H2S) gas from the atmosphere is very essential. In the present work, self‐priming venturi scrubber is employed to extract H2S gas from the air. Response surface methodology (RSM) with a central composite design (CCD) has been selected to investigate maximizing the H2S removal efficiency by optimizing the process variables. Experiments were carried out by altering the throat gas velocity, outer cylinder liquid level and inlet concentration of H2S. The analysis of variance (ANOVA) test showed that the parameters had a significant effect on the efficiency of H2S removal. A quadratic equation has been developed that accurately predicts the percentage of removal efficiency. The appropriateness of the generated model has been verified by the value of higher R2 resulting from the regression analysis. According to the observations, the velocity of throat gas has the highest effect on the H2S removal efficiency, whereas inlet H2S concentration has the least effect.

Digital twin-based optimization and demo-scale validation of absorption columns using sodium hydroxide/water mixtures for the purification of biogas streams subject to impurity fluctuations

This paper aims to validate a demo scale plant scrubber technology through experimental campaign and development of a digital twin. Thus, it is useful to evaluate the H2S absorption process in a biogas production plant for analysis and optimization purposes. The absorber unit removes H2S through the chemical absorption via sodium hydroxide (NaOH) as wet agent (30% w/w). The column treats 300 Nm3/h of biogas, whose inlet H2S concentration ranges from 1000 to 3000 ppm. Field measurements are conducted to investigate the H2S removal efficiency. An experimental dataset is collected, processed and used as input on Aspen PLUS suite to develop the digital twin.This model is helpful to generate a large dataset and simulate operating conditions different from the demo-scale plant. The process simulation is then exploited to perform a sensitivity analysis to figure out main variables influencing the H2S removal efficiency. Operating conditions such as H2S concentration, soda concentration and flowrate, temperature, and freshwater flowrate are perturbed in the sensitivity analysis. NaOH flowrate and its concentration are the variables with the biggest impact on the process. In detail, the highest efficiency performance was obtained using 50% NaOH solution with a flowrate higher than 8 kg/h.

Simultaneous removal of H2S and particulate matter by a multistage dual-flow sieve plate scrubber

In this work, an experimental study has been conducted in a newly designed and developed dual-flow scrubber with three sieve plates for simultaneous removal of hydrogen sulphide and particulate matter (fly-ash) from syngas produced in a gasifier as these impurities of syngas destroy and decrease the efficiency of the downstream processing equipment. The performance of the scrubber at different gas and liquid flow rates in the range of 16.59 × 10−4- 27.65 × 10−4 Nm3/s 20.649 × 10−6-48.183 × 10−6 m3/s has been observed for both the particulate matter and hydrogen sulphide removal along with the effect of inlet particulate loading (15 × 10−3- 25 × 10−3 kg/Nm3) and 100–300 ppm inlet H2S loading. The H2S removal efficiency in the dual-flow wet scrubber increased from 78.88% to 87.45% when the particulate matter loading was increased from zero to 25 × 10−3 kg/Nm3 at 300 ppm inlet H2S concentration for 48.183 × 10−6 m3/s liquid flow rate and 27.65 × 10−4 Nm3/s gas flow rate. The efficiency of the particulate matter is similar to that of the particulate scrubbing in absence of the H2S.

Evaluation of commercial moving bed media and sugarcane bagasse as packing material in biotrickling filter for hydrogen sulfide removal

This study compared two biotrickling filter packing materials for hydrogen sulfide removal. Inlet H2S concentrations and empty-bed retention time were tested on the two biotrickling filters. First reactor (BT1) had immobilized sulfur-oxidizing bacteria on commercial moving-bed media, whereas second reactor (BT2) had sulfur-oxidizing bacteria on sugarcane bagasse. The study found that BT1 performed best at 120 s empty-bed retention time, 422.39 g/m3·h hydrogen sulfide loading rate, resulted in 416 g/m3·h hydrogen sulfide elimination capacity. In contrast, BT2 performed best at 180 s empty-bed retention time, 278.77 g/m3·h hydrogen sulfide loading rate, and 273 g/m3·h elimination capacity was achieved. High-throughput sequencing showed Acidithobacillus spp. dominated the sulfur-oxidizing bacteria consortium. Sugarcane bagasse may receive less hydrogen sulfide loading than moving bed medium under optimal conditions, but its low cost and reasonable removal capacity of hydrogen sulfide -containing industrial gases in a biotrickling filter system make it an excellent alternative packing material.

Biodesulfurization of Consortia Immobilized on Oil Palm Frond Biochar in Biotrickling Filters under Anoxic Conditions

Biodesulfurization using biotrickling filters (BTFs) under anoxic conditions is a cost-effective method for biogas clean-up. To improve the performance of BTFs, the microbial consortia from the anaerobic pond of a swine farm (SW), the denitrification pond of a tuna factory (DN), and the UASB of the concentrated latex industry (LW) were immobilized on BTFs. In this study, the efficiency of BTFs immobilized with the microbial consortia for the reduction of H2S gas combined with the reduction of nitrate contained in wastewater was investigated. The results showed that H2S was completely removed at the inlet H2S concentration of 207.8–1476 ppmv with wastewater circulation under anoxic conditions. However, only the DN-BTF achieved H2S removal of 95.2% at an inlet concentration of 2500 ppmv. An increase in the N/S ratio (0.356–2.07 mol/mol) improved the H2S removal of the SW-BTF, LW-BTF, and DN-BTF but not the BTF-C. Moreover, the DN-BTF had the highest nitrate removal rate (71.1%) with an N/S ratio of 2.07 mol/mol. When oxygen was supplied in wastewater at DO = 3.60 ± 0.41 mg/L, sulfate was generated at a higher rate, but nitrite production was lower than at DO~0. After microbial community analysis, Proteobacteria were the main phyla involved in the biodesulfurization process.

Dynamic LCA of H2S adsorption from bio-syngas using mine residues

Hydrogen production from biomass and fuel cells is effective with respect to its small eco-burden and high energy efficiency. However, it is established that hydrogen sulfide (H2S) in gasified biomass (bio-syngas) can reduce the efficiency of fuel cells. To maintain high efficiency, H2S is removed by impurity adsorption. Although metal oxides are generally used as adsorbents, these can adsorb H2S only a single time, and the large amounts used represent an eco-burden. To overcome this problem, the use of mine waste (neutralized sediment) containing highly reactive iron was examined in a previous study, with H2S as an adsorbent to maintain a small eco-burden. It was found that its eco-burden is smaller than that of using metal oxides at 300°C. However, the authors treated the inlet H2S concentration, which affects sulfur capture capacity, as a constant, whereas the H2S concentration of biogas typically fluctuates dynamically between 50 and 1,200 ppmv. In addition, it is necessary to consider real situations from the perspective of a dynamic life cycle assessment. Consequently, it is necessary to determine the amounts of adsorbent used by considering changes in inlet H2S concentration. In this study, we investigated the relationship between changes in the inlet H2S concentration and sulfur capture capacity of neutralized sediment. The amounts used and eco-burden of neutralized sediment were calculated based on our experimental results, and on the basis of our findings, we established that the global warming potential of the proposed system at 300°0 was 70.7% smaller than that obtained using a metal oxide.

Modelling the removal efficiency of hydrogen sulfide from biogas in a biofilter using multiple linear regression and support vector machines

The main goal of this study is to create a statistical and intelligent model that can forecast the removal efficiency of hydrogen sulfide (H2S) in a fixed bed biofilter. The majority of conventional models employ mathematical principles that necessitate highly technical infrastructure, extremely detailed information on the biofiltration mechanism, and estimation of model input parameters. However, in this study, Multiple Linear Regression and Support Vector Machine methodology were used to reduce the reliance on experimental data. Experimental research was done to determine the effects of three factors on H2S removal efficiency, including the moisture content of the compost used as the biofilter bed, the empty bed residence time in the reactor, and the H2S concentration in the biogas stream input to the biofilter. Experimental findings demonstrated that the biofilter with a moisture content of 6%, and empty bed residence time of 60 s was capable of removing up to 75% of H2S from a biogas stream with H2S inlet concentration of 70 ppm(v). With a Coefficient of Determination between 0.98 and 0.99, the proposed models show excellent ability to predict the H2S removal efficiency. Compared to a Multiple Linear Regression based model, test results from a Support Vector Machine based model showed better agreement with experimental data.

Hydrogen sulfide removal from fermentative biohydrogen process: Effect of ZSM‐5 zeolite loading

AbstractThe production and consumption of biohydrogen is growing because it is a “green,” renewable energy that can be obtained in a relatively cost‐effective manner through anaerobic digestion. Biohydrogen produced from biomass is a viable source of renewable energy; nevertheless, the presence of highly toxic and corrosive hydrogen sulfide (H2S) in the process can hinder the quality of biohydrogen production and limit its application in energy conversion equipment. Consequently, the goal of the research was to assess the feasibility of using ZSM‐5 zeolite for H2S adsorption that function as activating agent to enhance biohydrogen quality under thermophilic conditions. The effect of ZMS‐5 Zeolite loading (0.2–1.0 g) on biohydrogen production via dark fermentation from mixed fruit waste (MFW) was investigated using anaerobic sludge from a sewage treatment plant. The pH of the broth mixture was adjusted to 6.0, anaerobic conditions were created by purging it with nitrogen gas, and the temperature of the fermentative biohydrogen process was maintained at 60°C. Meanwhile, the H2S adsorption test was run at ambient temperature with flow rates (100 ml/min) and an H2S inlet concentration of 10000 ppm. The results indicate that the Z + H2S exhibit spectral lines corresponding to the S‐H asymmetric stretching vibration of H2S at 2345.97 cm−1. The ideal adsorption capacity is at 0.8 g with yet, increasing the dosage amount of adsorbents, increases the time required for the adsorbent to achieve 90% saturation. The non‐linear curve fitting demonstrated that the adsorption kinetics of all dosages used followed those of the Avrami kinetic model. This approach of using ZSM‐5 zeolite for H2S removal provides an advantage in terms of minimizing environmental pollution and having great potential uses in industrial processes.

Resilience of hollow fibre membrane bioreactors for treating H2S under steady state and transient conditions

H2S removal performance by hollow fibre membrane bioreactors (HFMBs) was investigated for 271 days at ambient (20 ± 2 °C) temperature employing an inlet H2S concentrations up to 3600 ppmv and empty bed residence time (EBRT) of 187, 92 and 62 s. Different operating conditions including pH control (with or without), famine period, shock loads (4–72 h) and different biomass types (presence or absence of suspended biomass) were investigated. The H2S flux and mass-transfer coefficient were significantly higher for the biotic HFMBs (R1 and R2) compared to the abiotic control (R3) at all employed EBRTs. Significant differences in H2S removal efficiency (RE) and elimination capacity (EC) were noted for different inlet H2S concentrations, EBRTs, pH and biomass type. The HFMB achieved >99% RE at steady-state for biotic operation with an EC of 33.8, 30.0 and 30.9 g m−3 h−1 at an EBRT of 187, 92 and 62 s, respectively. Sulfate (92–93%) was the main sulfur species in the H2S bioconversion process. The HFMB showed a good resilience to shock loads and showed quick recovery (<24 h) after withdrawal of the shock loads. The HFMB had a critical loading rate of H2S about 135 g m−3 h−1 under transient-state.

Removal of hydrogen sulfide in biogas from wastewater treatment sludge by real-scale biotrickling filtration desulfurization process

Abstract The biological removal of hydrogen sulfide in biogas is an increasingly adopted alternative to conventional physicochemical processes because of its economic and environmental benefits. In this study, a real-scale biotrickling filtration (BTF) process packed with polypropylene carrier was used to investigate the removal of high concentrations of H2S in biogas from an anaerobic digester. The results show that H2S in biogas was entirely removed under different inlet concentrations of H2S from 2,923 to 4,400 ppmv, and the elimination capacity of H2S in the filter achieved about 52.71 g H2S/m3/h). In addition, the process efficiency was found to be independent of the inlet H2S concentration. The removal of high concentrations of H2S in biogas was accomplished by the BTF process with SOB (Acidithiobacillus thiooxidans), which is active in the acidic environment (pH 1.5–3.5). In addition, the process efficiency was found to be independent of the inlet H2S concentration. Consequently, a real-scale BTF process allowed the potential use of biogas and the recovery of elemental sulfur resources simultaneously.

H2S adsorption using ZnO modified Na-A zeolite and conditions optimization by Response Surface Methodology

Zinc oxide-impregnated Na-A zeolites were synthesized and used in sour gas treatment for hydrogen sulfide (H2S) removal. Response Surface Methodology (RSM) was used to study the effect adsorption variables, on the adsorbent adsorption capacity. Box– Behnken design of experiment was selected and quadratic regression was used to describe the relationship between the process variables and the adsorbent adsorption capacity. The effects of three process variables of A: reaction temperature (28, 64 and 100 °C), B: inlet H2S concentration (111, 142 and 200 ppm), and C: inlet flow rate (20,30 and 40 mL min–1) on the adsorbent adsorption capacity were investigated. ANOVA was used to analyzed the interaction between the process variables and response factor. The result showed that all studied factors are significant for H2S removal. Analysis of variance implied the selected model was fitted with the experimental data. The result indicates that up to 31.07 mg S/g adsorbent can be obtained at optimum conditions.

V2O5/TiO2 acting as both oxygen carrier and catalyst for chemical looping oxidation of H2S at a low temperature

Chemical looping oxidization of H2S at a low reaction temperature was investigated. A V2O5/TiO2 oxygen carrier produced by sol–gel method was employed, and experiments were performed in a fixed bed. Effects of reaction temperature (150-250℃), H2S inlet concentration (1000–4000 ppm) and cycles on H2S conversion behavior were investigated. X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) were used to characterize the oxygen carrier property. Finally, the S conversion pattern and role of oxygen carrier during the proposed chemical looping route were identified. Thermodynamic analysis and experimental results confirmed the proposed elementary sulfur production during reduction stage and a significant SO2 production during oxidization stage. Experimental results confirmed the proposed elementary sulfur production during reduction stage and a significant SO2 production during oxidization stage. At 150 ℃, the selectivity of SO2 during reduction stage is less than 5%, and the fraction of the converted H2S to S is higher than 95% in the present condition. XRD and XPS results supported that V5+(V2O5) was reduced to V4+(VO2) by the continuous feeding H2S. During oxidization stage, the V2O5/TiO2 material acted as both oxygen carrier and catalyst to produce SO2 for further H2SO4 production.

Model-based design and operation of biotrickling filters for foul air H2S removal at wastewater networks

Biotrickling filters (BTFs) are odour control technologies that utilise the action of sulfur oxidising bacteria to treat foul air contaminated with H2S. BTFs are complex systems where an immobilised biofilm is allowed to grow on a supportive solid media, while the foul air flows counter-currently with a stream of trickling liquid. In this work, a mechanistic model is developed, based on first principles where applicable, that describes the interphase mass transfer and biological oxidation kinetics. The model also focuses on the spatial discretisation of a BTF bed and describes the competition between sulfur oxidising bacteria (SOB) and aerobic heterotrophs growing within different niches of the bed. The model successfully produced concentration profiles over time and space of all relevant chemical and biological species within the bed. The model was then used to theoretically investigate the effect of design and operating parameters on the bed performance. It was found that the optimum liquid rate could vary significantly based on other factors such as bed size and inlet H2S concentrations but a typical value lies between 0.3 and 1.3 m/hr, with a larger bed and/or higher H2S loads requiring higher loading rates to achieve the same treatment levels. The model also predicted that bed shape has no significant impact on H2S removal, provided all other conditions are the same. The model successfully allowed for more detailed design of industrial BTF units in terms of both sizing and tuning of operational parameters.

Evaluation of continuous and intermittent trickling strategies for the removal of hydrogen sulfide in a biotrickling filter

Biotrickling filter (BTF) is a widely applied bioreactor for odour abatement in sewer networks. The trickling strategy is vital for maintaining a sound operation of BTF. This study employed a lab-scale BTF packed with granular activated carbon at a short empty bed residence time of 6 s and pH 1–2 to evaluate different trickling strategies, i.e., continuous trickling (different velocities) and intermittent trickling (different trickling intervals), in terms of the removal of hydrogen sulfide (H2S), bed pressure drop, H2S oxidation products and microbial community. The H2S removal performance decreased with the trickling velocity (∼3.6 m/h) in BTF. In addition, three intermittent trickling strategies, i.e., 10-min trickling per 24 h, 8 h, and 2 h, were investigated. The H2S elimination capacity deteriorated after about 2 weeks under both 10-min trickling per 24 h and 8 h. For both intermittent (10-min trickling per 2 h) and continuous trickling, the BTF exhibited nearly 100 % H2S removal for inlet H2S concentrations<100 ppmv, but intermittent BTF showed better removal performance than continuous trickling when inlet H2S increased to 120–190 ppmv. Furthermore, the bed pressure drops were 333 and 3888 Pa/m for non-trickling and trickling periods, respectively, which makes intermittent BTF save 83 % energy consumption of the blower compared with continuous tirckling. However, intermittent BTF exhibited transient H2S breakthrough (<1 ppmv) during trickling periods. Moreover, elemental sulfur and sulfate were major products of H2S oxidation and Acidithiobacillus was the dominant genus in both intermittent and continuous trickling BTF. A mathematical model was calibrated for the intermittent BTF and a sensitivity analysis was performed on the model. It shows mass transfer parameters determine the H2S removal. Overall, intermittent trickling strategy is promising for improving odour abatement performance and reducing the operating cost of the BTF.

Selective Catalytic Oxidation of Lean-H2S Gas Stream to Elemental Sulfur at Lower Temperature

Ceria-supported vanadium catalysts were studied for H2S removal via partial and selective oxidation reactions at low temperature. The catalysts were characterized by N2 adsorption at 77 K, Raman spectroscopy, X-ray diffraction techniques, and X-ray fluorescence analysis. X-ray diffraction and Raman analysis showed a good dispersion of the V-species on the support. A preliminary screening of these samples was performed at fixed temperature (T = 327 °C) and H2S inlet concentration (10 vol%) in order to study the catalytic performance in terms of H2S conversion and SO2 selectivity. For the catalyst that exhibited the higher removal efficiency of H2S (92%) together with a lower SO2 selectivity (4%), the influence of temperature (307–370 °C), contact time (0.6–1 s), and H2S inlet concentration (6–15 vol%) was investigated.

Adsorption of Hydrogen Sulfide at Low Temperatures Using an Industrial Molecular Sieve: An Experimental and Theoretical Study.

In the work presented herein, a joint experimental and theoretical approach has been carried out to obtain an insight into the desulfurization performance of an industrial molecular sieve (IMS), resembling a zeolitic structure with a morphology of cubic crystallites and a high surface area of 590 m2 g–1, with a view to removing H2S from biogas. The impact of temperature, H2S inlet concentration, gas matrix, and regeneration cycles on the desulfurization performance of the IMS was thoroughly probed. The adsorption equilibrium, sorption kinetics, and thermodynamics were also examined. Experimental results showed that the relationship between H2S uptake and temperature increase was inversely proportional. Higher H2S initial concentrations led to lower breakpoints. The presence of CO2 negatively affected the desulfurization performance. The IMS was fully regenerated after 15 adsorption/desorption cycles. Theoretical studies revealed that the Langmuir isotherm better described the sorption behavior, pore diffusion was the controlling step of the process (Bangham model), and that the activation energy was 42.7 kJ mol–1 (physisorption). Finally, the thermodynamic studies confirmed that physisorption predominated.

Effects of H2S Loading Rate on the Performance of Reactive Absorption with Electrochemical Oxidation

The odor released from environmental facilities is recognized as a major problem in environmental industries. In this study, reactive absorption, using an electrolyzed water solution (electrolyzed water scrubber, EWS), was developed to treat the odorous gases H2S and NH3, which are representative odorous substances. In addition, a numerical model composed of mass transfer coefficients and zero-order kinetic constants was established to predict the performance of EWS. The model was verified through experiments and data fittings. In the experiments, the concentration of H2S varied from 500 to 2000 ppm, while NH3 was fixed at 500 ppm. The results revealed that the H2S removal rate varied depending on the inlet H2S concentration, but no changes were observed for NH3. The numerical model appropriately described the experimental results to further predict the performance of EWS. The model prediction results for the shock loading of H2S indicated that a 100% removal rate can be achieved by increasing the current density to 70 mA cm−2 or higher. Finally, the EWS can be used to reduce the odor, owing to its flexible operation that responds to fluctuating loading rates.