Question

The dried spent slurry obtained after the production of biogas is an excellent
A. Fuel
B. Pesticide
C. Manure
D. None of these

Answer 1

Biogas is a mixture of flammable gases mainly consisting of methane and carbon dioxide produced from the anaerobic fermentation of organic material such as agricultural waste, municipal waste, sewage, etc.

Complete answer:
Biogas production is a form of fermentation where certain microorganisms convert organic matter into flammable gases such as methane under anaerobic conditions. This is produced from biological waste mainly consisting of agricultural waste, animal waste, manure, municipal waste, food waste, etc.
-In India, this is called gobar gas, as it is mainly produced from animal waste and manure obtained from cow dung. Cow dung is rich in a specific form of microorganisms called methanogenic bacteria. From the name, we can identify that these organisms are responsible for the production of methane.
-Biogas is a form of sustainable energy that can be produced from waste. It is also an effective method of waste management. Many countries are currently employing the use of biogas for several applications but mainly in the production of electricity and fuel for transport.
-As the gas is used as fuel, the spent slurry is used as manure or fertilizer. The bacteria have digested all the organic matter into simple molecules which can be used as manure where the plant is capable of readily taking the digested simple biomolecules.

Therefore, the correct option is C.

Note: Gobar gas gets its name in India from gow meaning cow, as cow dung is the frequently used raw material to produce this gas. Since it has a high methane content, it is a flammable gas, but also has significant carbon dioxide content which makes it less efficient when compared to other sources of flammable gases. The gas obtained is used as fuel and the by-product is used as manure.