Question

Explain the principle and working of a biogas plant.

Answer 1

Hint: The principle of a biogas plant is, the anaerobic fermentation of the biomass (organic matter) in presence of water. The working of a biogas plant is, the biomass is mixed with water and then is decomposed by the anaerobic bacteria into the products like gasses (methane, hydrogen, carbon dioxide) and the other side products (manure, fertilizers).

Complete step by step answer:
The principle of a biogas plant: The principle of a biogas plant is to produce the gasses like methane and other side products like carbon dioxide, etc by decomposing (breaking down the complex substances into the simple/basic substances) the biomass (the organic matter - the natural substances obtained from the plants and animals, such as the cow dung, the vegetable waste) in the absence of air (the anaerobic fermentation) and presence of the water.
The schematic diagram representing the bio-gas plant is as follows.

The working of a biogas plant: Consider the above diagram while going through the below-working steps of the biogas plant.
The inlet of the biogas plant is the mixing tank. In this mixing tank, the biomass is mixed with the water to form a slurry. A slurry is a composition of the water and the cow dung (biomass). The mixing tank is also called the slurry region. Then, this slurry enters the digester.
The digester (air-tight chamber) is an area with the absence of the oxygen (basically an anaerobic region) and the presence of microorganisms (the anaerobic bacteria). These bacteria are capable of decomposing the substances in absence of oxygen.
Thus, these microorganisms in the digester, decompose the biomass, that is, breaks down the complex substance into basic substances like methane, hydrogen, carbon dioxide, hydrogen sulfide. These gasses produced are stored in the gas tank and wherever required, these gases are taken out through the gas outlet.
The other side products, other than the gas, produced during the decomposition of the biomass are substances like manure and the fertilizers.

Note:
The microorganisms present in the digester are capable of decomposing the substance in the absence of air, thus, they are also called as the anaerobic bacteria. This biogas produced in a biogas plant has many commercial and household applications, like, this biogas can be used as a fuel, even as a kitchen gas, in gas engines.