with the collaboration of Iranian Society of Mechanical Engineers (ISME)

Document Type : Research Article


1 PhD Student of Agricultural Mechanization, Department of Biosystems Engineering, Faculty of Agriculture, Ferdowsi University of Mashhad, Mashhad, Iran

2 Department of Biosystems Engineering, Faculty of Agriculture, Ferdowsi University of Mashhad, Mashhad, Iran

3 Department of Chemical Engineering, Faculty of Engineering, Ferdowsi University of Mashhad, Mashhad, Iran


Anaerobic bacteria break down organic materials like animal manure, household trash, plant wastes, and sewage sludge during the anaerobic digestion process of biological materials and produce biogas. One of the main issues in using biogas is hydrogen sulfide (H2S), which can corrode pipelines and engines in concentrations between 50 and 10,000 ppm. One method for removing H2S from biogas with minimal investment and operation costs is biofiltration. Whether organic or inorganic, the biofilter's bed filling materials must adhere to certain standards including high contact surface area, high permeability, and high absorption. In this study, biochar and compost were used as bed particles in the biofilter to study the removal of H2S from the biogas flow in the lab. Afterward, kinetic modeling was used to describe the removal process numerically.
Material and Methods
To remove H2S from the biogas, a lab-sized biofilter was constructed. Biochar and compost were employed separately as the material for the biofilter bed. Because of its high absorption capacity and porosity, biochar is a good choice for substrate and packed beds in biofilters. The biochar pieces used were broken into 10 mm long cylindrical pieces with a diameter of 5 mm. Compost was used as substrate particles because it contains nutrients for microorganisms. Compost granules with an average length of 7.5 mm and 3 mm in diameter were used in this study. For the biofilter reactor, each of these substrates was put inside a cylinder with a diameter of 6 cm and a height of 60 cm. The biofilter's bottom is where the biogas enters, and its top is where it exits. During the experiment, biogas flowed at a rate of 72 liters per hour. Mathematical modeling was used to conduct kinetic studies of the process to better comprehend and generalize the results. This method involves feeding the biofilter column with biogas that contains H2S while the biofilm is present on the surface of the biofilter bed particles. The bacteria in the biofilm change the gaseous H2S into the harmless substance sulfur and store it in their cells. The assumptions that form the foundation of the mathematical models are: the H2S concentration is uniform throughout the gas flow, the gas flow is constant, and the column's temperature is constant at a specific height.
Results and Discussion
In the beginning, biochar was used as a substrate in the biofilter to test its effectiveness, and the results obtained for removing H2S from the biogas were acceptable. H2S concentration in biogas was significantly reduced using biochar beds. It dropped from 300 ppm and 200 ppm to 50 ppm where the greatest H2S concentration reduction was achieved. The level of Methane in the biogas was not significantly impacted by the biofilter. This is regarded as a significant outcome when taking into account the goal which is producing biogas with a high concentration of methane. The H2S elimination effectiveness was 94% with the biochar bed and biogas input with 185 ppm H2S concentration. The removal efficiency reached 76% with the compost bed and input concentration of 70 ppm. Using mathematical models, the simulation was carried out by modifying the model's parameters until the predicted results closely matched the experimental data. It may be concluded that the suggested mathematical model is sufficient for the quantitative description of H2S removal from biogas utilizing biofilm in light of how closely the calculation results matched the experimental data. The only model parameter that was changed to make the model results almost identical to the experimental data was the value of the maximum specific growth rate (μmax) which has the greatest influence on the model results. The value of μmax for the biochar bed was calculated as 0.0000650 s-1 and for the compost bed at 70 ppm and 35 ppm concentrations as 0.0000071 s-1 and 0.0000035 s-1, respectively.
The primary objective of this study is to examine the removal of H2S from biogas using readily available and natural substrates. According to the findings, at a height of 60 cm, H2S concentration in biochar and compost beds decreased from 185 ppm to 11 ppm (removal efficiency: 94%) and from 70 ppm to 17 ppm (removal efficiency: 76%), respectively. The mathematical models that were created can quantify the H2S elimination process, and the μmax values in biochar and compost were calculated as 0.0000650 s-1 and 0.0000052 s-1, respectively.
The authors would also like to thank UNESCO for providing some of the instruments used in this study under grant number No. 18-419 RG, funded by the World Academy of Sciences (TWAS).


Main Subjects

©2023 The author(s). This article is licensed under Creative Commons Attribution 4.0 International License (CC BY 4.0), which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source.

Allegue, L. B., & Hinge, J. (2014). Biogas upgrading Evaluation of methods for H2S removal. Danish Technological Institute, 31(December), pp.1-31.
Al Mamun, M. R., & Torii, S. (2015). Removal of hydrogen sulfide (H2S) from biogas using zero-valent iron. Journal of Clean Energy Technologies3(6), 428-432. https://doi.org/10.7763/jocet.2015.v3.236
Amini, A., Ebrahimi-Nik, M. A., Abbaspour-Fard, M. H., & Rohani, A. (2021). Preparation of charcoal pellets from grape pruning wastes and study of some of its characteristics. Faculty of Agriculture. Ferdowsi University of Mashhad. (in Persian with English abstract)
Amini, H. R., & Reinhart, D. R. (2011). Regional prediction of long-term landfill gas to energy potential. Waste Management31(9-10), 2020-2026. https://doi.org/10.1016/j.wasman.2011.05.010
Bird, R. B., Stewart, W. E., & Lightfoot, E. N. (2007). Other mechanisms for mass transport. Transport Phenomena, John Wiley & Sons, Inc.
Boumnijel, I., Amor, H. B., Chekir, H., & Hajji, N. (2016). Hydrogen sulphide removal from the effluents of a phosphoric acid production unit by absorption into chlorinated seawater under alkaline conditions. Comptes Rendus Chimie19(4), 517-524. https://doi.org/10.1016/j.crci.2015.10.010
Chung, Y. C., Huang, C., & Tseng, C. P. (1996). Microbial oxidation of hydrogen sulfide with biofilter. Journal of Environmental Science & Health Part A31(6), 1263-1278. https://doi.org/10.1080/10934529609376423
Das, J., Rene, E. R., Dupont, C., Dufourny, A., Blin, J., & van Hullebusch, E. D. (2019). Performance of a compost and biochar packed biofilter for gas-phase hydrogen sulfide removal. Bioresource Technology273, 581-591. https://doi.org/10.1016/j.biortech.2018.11.052
Delhoménie, M. C., & Heitz, M. (2005). Biofiltration of air: a review. Critical reviews in biotechnology25(1-2), 53-72. https://doi.org/10.1080/07388550590935814
Devinny, J. S., Deshusses, M. A., & Webster, T. S. (2017). Biofiltration for air pollution control. CRC press.
Elias, A., Barona, A., Arreguy, A., Rios, J., Aranguiz, I., & Penas, J. (2002). Evaluation of a packing material for the biodegradation of H2S and product analysis. Process Biochemistry37(8), 813-820. https://doi.org/10.1016/S0032-9592(01)00287-4
Fischer, M. E. (2010). Biogas purification: H2S removal using biofiltration (Master's thesis, University of Waterloo). http://hdl.handle.net/10012/5458
Heijnen, J. J., & Kleerebezem, R. (1999). Bioenergetics of microbial growth. Encyclopedia of bioprocess technology: Fermentation, Biocatalysis, and Bioseparation1, 267-291.
Jiang, X., & Tay, J. H. (2011). Removal mechanisms of H2S using exhausted carbon in biofiltration. Journal of Hazardous Materials185(2-3), 1543-1549. https://doi.org/10.1016/j.jhazmat.2010.10.085
Lestari, R. A., Sediawan, W. B., Syamsiah, S., & Teixeira, J. A. (2016). Hydrogen sulfide removal from biogas using a salak fruit seeds packed bed reactor with sulfur oxidizing bacteria as biofilm. Journal of Environmental Chemical Engineering4(2), 2370-2377. https://doi.org/10.1016/j.jece.2016.04.014
Lien, C. C., Lin, J. L., & Ting, C. H. (2014). Water scrubbing for removal of hydrogen sulfide (H2S) inbiogas from hog farms. Journal of Agricultural Chemistry and Environment3(02), 1-6. http://dx.doi.org/10.4236/jacen.2014.32B001
Marzouk, S. A., Al-Marzouqi, M. H., Teramoto, M., Abdullatif, N., & Ismail, Z. M. (2012). Simultaneous removal of CO2 and H2S from pressurized CO2–H2S–CH4 gas mixture using hollow fiber membrane contactors. Separation and Purification Technology86, 88-97. https://doi.org/10.1016/j.seppur.2011.10.024
Monod, J. (1949). The growth of bacterial cultures. Annual Review of Microbiology3(1), 371-394. https://doi.org/10.1146/annurev.mi.03.100149.002103
Namini, M. T., Heydarian, S. M., Bonakdarpour, B., & Farjah, A. (2008). Removal of H2S from synthetic waste gas streams using a biotrickling filter. Iranian Journal of Chemical Engineering, 5(3), 40-51.
Neill, C., & Gignoux, J. (2006). Soil organic matter decomposition driven by microbial growth: a simple model for a complex network of interactions. Soil Biology and Biochemistry38(4), 803-811. https://doi.org/10.1016/j.soilbio.2005.07.007
Pipatmanomai, S., Kaewluan, S., & Vitidsant, T. (2009). Economic assessment of biogas-to-electricity generation system with H2S removal by activated carbon in small pig farm. Applied Energy86(5), 669-674. https://doi.org/10.1016/j.apenergy.2008.07.007
Poloncarzova, M., Vejrazka, J., Vesely, V., & Izak, P. (2011). Effective Purification of Biogas by a Condensing‐Liquid Membrane. Angewandte Chemie International Edition50(3), 669 671. https://doi.org/10.1002/anie.201004821
Rattanapan, C., Boonsawang, P., & Kantachote, D. (2009). Removal of H2S in down-flow GAC biofiltration using sulfide oxidizing bacteria from concentrated latex wastewater. Bioresource Technology100(1), 125-130. https://doi.org/10.1016/j.biortech.2008.05.049
Rene, E. R., López, M. E., Kim, J. H., & Park, H. S. (2013). Back propagation neural network model for predicting the performance of immobilized cell biofilters handling gas-phase hydrogen sulphide and ammonia. BioMed Research International2013. https://doi.org/10.1155/2013/463401
Salehi, R., & Lestari, R. A. S. (2021). Predicting the performance of a desulfurizing bio-filter using an artificial neural network (ANN) model. Environmental Engineering Research, 26(6). https://doi.org/10.4491/eer.2020.462
Sreekrishnan, T. R., Kohli, S., & Rana, V. (2004). Enhancement of biogas production from solid substrates using different techniques––a review. Bioresource Technology95(1), 1-10. https://doi.org/10.1016/j.biortech.2004.02.010
Syed, M., Soreanu, G., Falletta, P., & Béland, M. (2006). Removal of hydrogen sulfide from gas streams using biological processes a review. Canadian Biosystems Engineering48, 2.
Taheri, M., Mohebbi, A., Hashemipour, H., & Rashidi, A. M. (2016). Simultaneous absorption of carbon dioxide (CO2) and hydrogen sulfide (H2S) from CO2–H2S–CH4 gas mixture using amine-based nanofluids in a wetted wall column. Journal of Natural Gas Science and Engineering28, 410-417. https://doi.org/10.1016/j.jngse.2015.12.014
Xie, L., Zhu, J., Ramirez, M., & Jiang, C. (2021). CFD-single particle modeling and simulation of the removal of H2S in a packed-bed bioreactor. Journal of Environmental Chemical Engineering, 9(4), 105692. https://doi.org/10.1016/j.jece.2021.105692
Xu, X., Chen, C., Lee, D. J., Wang, A., Guo, W., Zhou, X., ... & Chang, J. S. (2013). Sulfate-reduction, sulfide-oxidation and elemental sulfur bioreduction process: modeling and experimental validation. Bioresource Technology147, 202-211. https://doi.org/10.1016/j.biortech.2013.07.113