The diagram above is that of a typical biogas plant. Explain the seQ uence of events occurring in a biogas plant. Identify a, b and c.

The sequences of events occurring in a biogas plant are:

(i) Hydrolysis: Through hydrolysis the complex organic molecules are broken down into simple sugars, amino acids and fatty acids.

(ii) Acidogenesis: In this step further breakdown of the remaining components by acidogenic (fermentative) bacteria takes place.

(iii) Acetogenesis: In this step simple molecule obtained by acidogenesis phase are further digested by acetogens, to produce largely acetic acid as well as carbon dioxide and hydrogen.

(iv) Methanogenesis: In this step methanogens utilize the intermediate products of the previous stages and convert them into methane, carbon dioxide and water.

The parts of biogas plant:

The part labelled (a) is sludge

The part labelled (b) is a gas holder, and

The part labelled (c) is inlet to feed slurry