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METHANOGENS AND BIOGAS

u cla genomics. METHANOGENS AND BIOGAS. Methanogens. Methanogens are bacteria that produce methane gas They can be used as sources of biogas gas This would be a renewable source of energy. © 2008 Paul Billiet ODWS. Ecology. Methanogens require anaerobic conditions

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METHANOGENS AND BIOGAS

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  1. ucla genomics METHANOGENS AND BIOGAS

  2. Methanogens • Methanogens are bacteria that produce methane gas • They can be used as sources of biogas gas • This would be a renewable source of energy © 2008 Paul Billiet ODWS

  3. Ecology • Methanogens require anaerobic conditions • In the digestive systems of herbivores, marshes or lake bottoms. • Many require warm conditions to work best. • They are associated with a source of organicmatter(e.g. plant remains or sewage) and with heterotrophic bacteria • The heterotrophs break down this organic matter to release compounds such as ethanoic acid (aka acetic acid or vinegar) and hydrogen • The ethanoate ions are a substrate for the methanogens © 2008 Paul Billiet ODWS

  4. Classification • Methanogens belong to the Archaea group of the Prokaryotes • Examples Methanococcus jannaschiiMethanobacterium thermoautotrophicum The prokaryote kingdom has been split into several further kingdoms (e.g. Archaea and Eubacteria) based on the genetics and biochemistry of microbes © 2008 Paul Billiet ODWS

  5. Biochemistry • Methanogens are chemoautotrophs • Methanogens use a number of different ways to produce methane Using ethanoate (acetate) that may be derived from the decomposition of cellulose: CH3COO+ + H- CH4 + CO2 +36 kJ mol-1 Or using hydrogen and carbon dioxide produced by the decomposers: 4 H2 + CO2 CH4 + 2 H2O +130.4 kJ mol-1 © 2008 Paul Billiet ODWS

  6. BEA Dithmarschen Biogas production • From the decomposition of wastes in farming sewage treatment • A bi-product of the cleaning up of waste water • Biogas consists of about 40% CO2 and 60% CH4 © 2008 Paul Billiet ODWS

  7. Requirements • a fermenter, which is supplied with an innoculum of bacteria (methanogens and decomposers) • anaerobic conditions • an optimum temperature of 35°C • an optimum pH of 6.5 to 8This needs to be monitored as the decomposers produce acids and they work faster than the methanogens consume the acids • organic waste (biomass) e.g. sewage, wood pulp © 2008 Paul Billiet ODWS

  8. DAF Shiga Pref. Methanogens and the greenhouse effect • Half of the methane produced by methanogens is used up as an energy source by other bacteria • Half is lost to the atmosphere (600 M tonnes y-1) where it acts as an important greenhouse gas • As more land is converted to rice paddy fields and pasture for grazing animals more methane will be produced © 2008 Paul Billiet ODWS

  9. Warming up the brew • As global warming progresses the permafrost with thaw in the regions covered by tundra • Tundra contains extensive reserves of frozen peat • As the peat warms and melts, it will provide a source of material for methanogens © 2008 Paul Billiet ODWS

  10. UNEP The knock on effect • The amount of methane release into the atmosphere will accelerate. • This in turn will drive global warming even further • Peatlands form 20-30% of organic C in N. Hemisphere © 2008 Paul Billiet ODWS

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