Question

Biogas production from waste biomass with the help of methanogenic bacteria is a
A. One-step process
B. Two-step process
C. Three-step process
D. Multi-step process

Answer 1

Hint:- Biogas is a mixture of gases that are produced as a result of the breakdown of organic matter. It occurs in the absence of oxygen i.e. in anaerobic condition. Biogas can be produced from raw materials like plant material, agricultural waste, manure.

Complete step-by-step solution:-
The raw material used for biogas production is crushed and made into smaller pieces. Then water is added to it to convert it into a slurry. This will help in easy digestion of the materials. Biogas production is mediated by microorganisms such as-methanogens. Certain microorganisms need slight warmer conditions for their action hence it is heated to about 37 degrees. The slurry will be acted by the microorganisms in a large biogas tank. It takes 3 weeks for anaerobic digestion of slurry.
After the production of biogas, purification is done to remove the impurities and carbon dioxide. Production of biogas by anaerobic process involves 4 steps. They include- hydrolysis, acidogenesis, acetogenesis, and methanogenesis. In the first step, the complex compounds are hydrolyzed into smaller units. In acidogenesis, these simpler components are converted into organic acids. The acetogenesis involves the production of acetic acid by using the oxygen present and creates an anaerobic condition for methane production. In methanogenesis, methanogens are involved in the production of methane gas and carbon dioxide.
So, the correct answer is option D.

Note:-
Biogas mainly contains methane and carbon dioxide with a percentage of 45 to 75 percent and 25 to 50 percent respectively. They also contain water vapor and nitrogen gas in a low amount. There are many uses of biogas they include- can be directly used as fuel, it can also be used to generate electricity.