CBSE Class 12-science Answered

Biogas is a mixture of gases produced from decomposable organic matter by the activity of various anaerobic bacteria that can be used as a fuel.

Mechanism of biogas production:

1. The biogas plant tank is fed with a mixture of dung or waste materials from kitchen and night soil along with water.

2. The biogas tank is covered with a floating lid which keeps on rising as the gas is produced in the slurry due to the microbial activity of methanogens like Methanobacterium.

3. Methanogens grow anaerobically on cellulosic material in cowdung to produce a large amount of methane, CO₂ and H₂.

4. The biogas plant has an outlet, which is connected to a pipe to supply biogas. The leftover slurry is removed through another outlet and is used as fertiliser.

5. Biogas is used as a fuel for heating and cooking, lighting, power for irrigation and other purposes as an alternative for firewood, kerosene, electricity and LPG. It is considered as an ecofriendly and pollution free source of energy.