Question

Which of the following conditions are required during the production of biogas?
A. Absence of carbon
B. Presence of oxygen
C. Presence of carbon
D. Absence of oxygen

Answer 1

The biogas is the mixture of various gases along with methane that is produced by the activity of the microbes. Biogas is mainly used as fuel. Moreover, the microbes producing the biogas are known as the methanogen bacteria.

Complete answer: The biogas is produced by the activity of the various microbes. The microbes produce various kinds of gases and end-products during their growth and metabolic processes. These microbes are methanogen bacteria. And methanogens are obligate anaerobic bacteria. Methanogen bacteria cannot survive in aerobic conditions.
These bacteria grow on cellulose anaerobically and produce large amounts of methane gas along with hydrogen and carbon dioxide. These bacteria are commonly found in the anaerobic sludge tanks of the sewage treatment plants. The sludge tanks are the concrete tanks in which the bio-wastes are collected and a slurry of the dung is fed. Apart from that, the methanogen bacteria are found in the rumen of the cattle. Therefore, they are also found in their dung or gobar. This dung helps in the production of gobar gas or biogas. Since it contains methanogen thus an anaerobic environment is maintained for their action.
Thus, based on the above information we can conclude that the absence of oxygen is required during the production of biogas.

Hence, the correct answer is an option (D).

Note: The biogas is a highly inflammable and non-polluting fuel. The calorific value of biogas at fifty percent methane content is 4429 $kcal/{m^3}$. The biogas consists of fifty to seventy percent methane, thirty to forty percent carbon dioxide, and ten percent other gases like hydrogen, hydrogen sulfide, etc.