Methanogenesis is the process used by microorganisms to produce methane (CH4). The reason it is so important and of interest to many is that methane is the major contributor to greenhouse gas emissions. It is a highly potent greenhouse gas.
The source of methane is mostly fugitive release from agricultural production and organic waste (Kapoor et al., 2020). The situation of releasing methane from decaying animal and plant matter has occurred for millennia. The gas was removed by natural processes and formed a balanced system (Nisbet et al., 2020).
The issue however has been increased industrialization and intensive agriculture which has outpaced those natural processes that removed excess methane. There is now an elevated atmospheric concentration of methane.
The global warming effect of methane is 25 times higher than that of carbon dioxide (CO2) (McCauley et al., 2020).
Collecting methane from any biogenic source is now a valuable fuel and a renewable source of raw chemicals for the organic chemicals industry.
When oxygen is absent, a variety of microorganisms break down organic materials to produce a mixture of CH4 and CO2. This is called biogas. The microorganisms producing biogas are mainly hydrolytic and fermentative bacteria, acetogens, and methanogens.
Anaerobic digestion is an industrial system that converts organic waste to biogenic methane which is then used for further purposes (Kapoor et al., 2020, Nguyen & Lee, 2021). Whilst biogas is highly useful, small amounts or traces of hydrogen sulphide (H2S) contaminate and spoil the performance of this gas.
Biogas is used directly for household heating and cooking, for generating electricity and for producing biomethane. Biomethane is used as a transport fuel, as a natural gas replacement or feedstock to the chemical industry (Nguyen et al., 2021). It’s especially valuable in developing countries with or without the presence of H2S. To be truly useful, hydrogen sulphide needs to be removed from biogas.
References
Kapoor, R., Ghosh, P., Kumar, M., Sengupta, S., Gupta, A., Kumar, S. S., … & Pant, D. (2020). Valorization of agricultural waste for biogas based circular economy in India: A research outlook. Bioresource Technology, 304, 123036 (Article)
McCauley, J. I., Labeeuw, L., Jaramillo-Madrid, A. C., Nguyen, L. N., Nghiem, L. D., Chaves, A. V., & Ralph, P. J. (2020). Management of enteric methanogenesis in ruminants by algal-derived feed additives. Current Pollution Reports, 6, pp. 188-205.
Nisbet, E. G., Fisher, R. E., Lowry, D., France, J. L., Allen, G., Bakkaloglu, S., … & Zazzeri, G. (2020). Methane mitigation: methods to reduce emissions, on the path to the Paris agreement. Reviews of Geophysics, 58(1), e2019RG000675.
Nguyen, A. D., & Lee, E. Y. (2021). Engineered methanotrophy: a sustainable solution for methane-based industrial biomanufacturing. Trends in Biotechnology, 39(4), pp. 381-396.
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