Biogas is a fuel gas made from biomass such as faeces, food waste, grass and straw etc. during the anaerobic fermentation process.
Biogas contains about 55% - 70% methane (CH4), and some carbon dioxide, some water, some hydrogen some carbon monoxide and some hydrogen sulfide (H2S).
The heat value of biogas is 5142 Kcal/m3
Conditions needed for biogas production are:
1- Strict absence of Oxygen.
2- Temperature between 8 – 65 Deg. C. Higher the temperature the more active methane bacteria, and the higher biogas production.
3- Neutral or slightly Alkaline environment, a pH value between 6.8 and 7.5
For a 10 m3 biogas plant to keep a 5 m3/d biogas production, 150 kg cow dung or 110 kg pig dung is needed daily.
The liquid from biogas plant can be recycled.
Biogas residue are good organic fertilizers.
Raw material needed to produce 1 cubic meter biogas:
Pig Manure 4 kg dry = 22.23 kg fresh
Cow Manure 5.26 kg dry = 30.96 kg fresh
Chicken Manure 4 kg dry = 13.34 kg fresh
Human Manure 3.33 kg dry = 16.67 kg fresh
Biogas System (Power Point)