Editing Methanogen (section)

== Biotechnological application ==

=== Wastewater treatment ===
Methanogens are widely used in anaerobic digestors to treat wastewater as well as aqueous organic pollutants. Industries have selected methanogens for their ability to perform [[biomethanation]] during wastewater decomposition thereby rendering the process sustainable and cost-effective.<ref>Appels, Lise; et al. (2008). "Principles and potential of the anaerobic digestion of waste-activated sludge" Progress in Energy and Combustion Science. 34 (6): 755–781. doi: 10.1016/j.pecs.2008.06.002</ref>

Bio-decomposition in the anaerobic digester involves a four-staged cooperative action performed by different microorganisms.<ref>Christensen, Thomas H; et al. (2010). "Anaerobic Digestion: Process" Solid Waste Technology & Management, Volume 1 & 2. doi: 10.1002/9780470666883.ch372</ref> The first stage is the hydrolysis of insoluble polymerized organic matter by anaerobes such as Streptococcus and Enterobacterium.<ref>Shah, Fayyaz Ali, et al. (2014). "Microbial Ecology of Anaerobic Digesters: The Key Players of Anaerobiosis" ScientificWorldJournal. 3852369 (1). doi:10.1155/2014/183752</ref> In the second stage, acidogens break down dissolved organic pollutants in wastewater to [[fatty acids]]. In the third stage, acetogens convert fatty acids to [[acetates]]. In the final stage, methanogens metabolize acetates to gaseous [[methane]]. The byproduct methane leaves the aqueous layer and serves as an energy source to power wastewater-processing within the digestor, thus generating a self-sustaining mechanism.<ref>{{cite journal | last1 = Lettinga | first1 = G | year = 1995 | title = Anaerobic Digestion and Wastewater Treatment Systems | journal = Antonie van Leeuwenhoek | volume = 67 | issue = 1| pages = 3–28 | doi = 10.1007/bf00872193 | pmid = 7741528 | s2cid = 9415571 }}</ref>

Methanogens also effectively decrease the concentration of organic matter in wastewater run-off.<ref name="doi_10.1016/j.procbio.2010.05.017"/> For instance, [[agricultural wastewater]], highly rich in organic material, has been a major cause of aquatic ecosystem degradation. The chemical imbalances can lead to severe ramifications such as [[eutrophication]]. Through anaerobic digestion, the purification of wastewater can prevent unexpected blooms in water systems as well as trap [[methanogenesis]] within digesters. This allocates biomethane for energy production and prevents a potent greenhouse gas, methane, from being released into the atmosphere.{{cn|date=March 2025}}

The organic components of wastewater vary vastly. Chemical structures of the organic matter select for specific methanogens to perform anaerobic digestion. An example is the members of ''[[Methanosaeta]]'' genus dominate the digestion of palm oil mill effluent (POME) and brewery waste.<ref name="doi_10.1016/j.procbio.2010.05.017"/> Modernizing wastewater treatment systems to incorporate higher diversity of microorganisms to decrease organic content in treatment is under active research in the field of microbiological and chemical engineering.<ref>Marihiro, Takashi., Sekiguchi, Yuji. (2007). "Microbial communities in anaerobic digestion processes for waste and wastewater treatment: a microbiological update" Current Opinion in Biotechnology. 18 (3): 273–278. doi: 10.1016/j.copbio.2007.04.003</ref> Current new generations of Staged Multi-Phase Anaerobic reactors and Upflow Sludge Bed reactor systems are designed to have innovated features to counter high loading wastewater input, extreme temperature conditions, and possible inhibitory compounds.<ref>{{cite journal|doi=10.1016/S0273-1223(97)00222-9|title=Advanced anaerobic wastewater treatment in the near future|journal=Water Science and Technology|volume=35|issue=10|year=1997}}</ref>