Editing Microorganism (section)

===Water treatment===
{{Further |Drinking water#Water quality}}
[[File:WWTP Antwerpen-Zuid.jpg|thumb|[[Wastewater treatment]] treatment plants rely largely on microorganisms to [[oxidise]] organic matter.]]

These depend for their ability to clean up water contaminated with organic material on microorganisms that can respire dissolved substances. Respiration may be aerobic, with a well-oxygenated filter bed such as a [[slow sand filter]].<ref>{{Cite book| title=Biology of Wastewater Treatment | author=Gray, N. F. | publisher=Imperial College Press | year=2004 | page=1164 | isbn=978-1-86094-332-4}}</ref> [[Anaerobic digestion]] by [[methanogen]]s generate useful [[methane]] gas as a by-product.<ref>{{cite journal| doi=10.1016/j.procbio.2010.05.017 | volume=45 | issue=8 | title=Importance of the methanogenic archaea populations in anaerobic wastewater treatments | year=2010 | journal=Process Biochemistry | pages=1214–1225 | last1 = Tabatabaei | first1 = Meisam| url=http://psasir.upm.edu.my/id/eprint/15129/1/Importance%20of%20the%20methanogenic%20archaea%20populations%20in%20anaerobic%20wastewater%20treatments.pdf }}</ref>