Question

Draw a labelled diagram of floating gas holder type biogas plant and describe it's working. Mention any two advantage of using animal dung for making biogas over using it as a fuel in the form of dried dung cakes.

Answer 1

Biogas plant has a dome-shaped digestor in which cow dung is kept. It is completely isolated and thus does not have oxygen in them. In this anaerobic conditions, methanogens (methane producing bacteria) perform their function & produces methane (CH₄) by digesting the cow dung. Along with methane, carbon-dioxide (CO₂), hydrogen sulphide (H₂S) is also produced. These gases so produced is recovered from the gas outlet while the remaining slurry can be used as fertilizer.