Table 3: Typical reactions carried out by methanogens during anaerobic process [11].

Reaction carried out by methanogens

Hydrogen: 4H2 + CO2 CH4 + 2H2O
Acetate: CH3COOH CH4 + CO2
Formate: 4HCOOH CH4 + CO2 + 2H2O
Methanol 4CH3OH 3CH4 + CO2 + 2H2O
Carbon monoxide: 4CO + 2H2O CH4 + 3H2CO3
Trimethylamine: 4(CH3)3N + 6H2O 9CH4 + 3CO2 + 4NH3
Dimethylamine: 2(CH3)2NH + 2H2O 3CH4 + CO2 + 2NH3
Methylamine: 4(CH3)NH2 + 2H2O 3CH4 + CO2 + 4NH3
Methyl mercaptans: 2(CH3)2S + 3H2O 3CH4 + CO2 + H2S
Metals: 4Me0 + 8H+ + CO2 4Me++ + CH4 + 2H2O