Question 29
What is biomass? Explain the principle and working of a biogas plant using a labelled schematic diagram.
Biomass: The materials in the bodies of plants and animals are called biomass. These materials act as fuels. It includes wastes from tree and grass crops forestry agricultural and urban wastes. The excreta of living organisms and their bodies contribute to biomass.
Biomass is produced by the anaerobic degradation of animal wastes like cow-dung (or plant waste) in the presence of water. This degradation is carried out by anaerobic micro-organisms called anaerobic bacteria in the presence of water but in the absence of oxygen.
Slurry of cow-dung and water is made in the mixing tank. This slurry flows into the digester having no oxygen. Anaerobic micro-organisms decompose or breakdown complex compounds of the cow-dung slurry. It takes a few days for the decomposition process to be completed and generated bio-gas. The biogas is stored in the gas tank above the digester from which they are drawn through pipes for use.