Review the key concepts, formulae, and examples before starting your quiz.
🔑Concepts
Biogas is a mixture of gases (containing predominantly methane) produced by the microbial activity and which may be used as fuel.
The type of gas produced depends upon the microbes and the organic substrates they utilize. Certain bacteria, which grow anaerobically on cellulosic material, produce large amounts of methane () along with and .
These bacteria are collectively called methanogens, and one such common bacterium is Methanobacterium.
Methanogens are commonly found in the anaerobic sludge during sewage treatment and are also present in the rumen (a part of the stomach) of cattle.
Cattle dung (gobar) is rich in these bacteria; hence, dung can be used for the generation of biogas, commonly called gobar gas.
The biogas plant consists of a concrete tank ( feet deep) in which bio-wastes are collected and a slurry of dung is fed.
A floating cover is placed over the slurry, which keeps on rising as the gas is produced in the tank due to microbial activity.
The technology of biogas production was developed in India mainly due to the efforts of Indian Agricultural Research Institute (IARI) and Khadi and Village Industries Commission (KVIC).
📐Formulae
💡Examples
Problem 1:
Why is the excreta of cattle used for the generation of biogas?
Solution:
Cattle dung is used because it contains a high concentration of Methanobacterium and cellulosic material.
Explanation:
Cattle consume a lot of cellulosic material in their diet. This cellulose is broken down in the rumen by methanogenic bacteria. Since these bacteria and undigested cellulose are excreted in the dung, it serves as an ideal substrate for biogas production.
Problem 2:
Identify the components of a biogas plant and their functions.
Solution:
- Digester (anaerobic fermentation), 2. Charge pit (mixing slurry), 3. Gas holder (collecting , ), 4. Sludge outlet (removing spent slurry).
Explanation:
The digester is where the actual microbial action takes place. The floating gas holder rises as is generated, providing a visual indication of gas production and pressure.