The Four Stages Of Biogenesis Of Methane

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3.1 Biogenesis of methane In anaerobic digestion there are four stages: hydrolysis, acidification, acetogenesis and methane production (Sagagi et al; 2009; Rai 2004).
Different microorganisms play a significant role in each stage ofthe processes. Therefore, intervention and follow up in all the stages is essential for enhanced and optimum methane production.
3.1.1 Enzymatic hydrolysis
Enzymatic hydrolysis is the process where the fats, starches and proteins contained in cellulosic biomass are broken down into simple compounds (Rai, 2004).
Polymers are transformed into soluble monomers through enzymatic hydrolysis. These monomers become substrates for the microorganisms in the second
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Along with them, microbes belonging to the genera like Enterobacterium, Acetobacterium and Eubacterium also carry out the process of fermentation (Schnurer and Jarvis, 2010).
3.1.3 Acetogenesis
Simple molecules created through the acidogenesis phase are further digested by acetogens to produce largely acetic acid as well as carbon dioxide and hydrogen (Buswell and Sollo , 1948). Acetogen are the vital link between hydrolysis, acidogenesis and the methanogenesis in anaerobic digestion. Acetogenesis
Provides the two main substrates for the last step in the methanogenic conversion oforganic material, namelyhydrogen and acetate. Both the acidogenesis andacetogenesis produce the methanogenic substrates, acetate, H2and CO2 (Chynoweth and Isaacson, 1987). n(C6H12O6) →n(CH3COOH) ……………..Acetogensis process
Clostridiums, and Syntrobacter are examples of genera in which there are numerous organisms that can perform acetogenesis in syntrophy with an organism that uses hydrogen gas (McInerney et al. 2008).
3.1.4 Methane formation
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For the former case, methane bacteria (methanogens) work best at a temperature of 35-38 °C and fall in gas production starts at 20 °C and stops at a temperature of 10 to 13 °C (Velsen et al. (1979); Dahlman and Forst (2001); Rai 2004)). In this connection, there are two significant temperature zones in anaerobic digestion and two types of microorganisms that should be considered, mesophilic and thermophilic. The optimum mesophilic temperature lies at about 35 °C, while the thermophilic temperature is around 55 °C. Most of the sewage digestion tanks are heated at 35 °C so as to reduce the time required for digestion and minimize the capacity of the tanks (Velsen et al., 1979; Rai

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