Question

Explain how microbes are useful in pollution control and also in production of alternative source of energy.

Accepted Answer

Non-renewable sources of energy are obtained from fossil fuels and crude petrol. Another important source of energy is biogas. It is a complex mixture of gases such as methane ( $60 %$ ), carbon dioxide ( $30 %$ ), nitrogen ( $7 %$ ), hydrogen ( $5 %$ ), oxygen ( $0.01 %$ ). Biogas is inflammable gas produced by bacteria in the intestine of ruminant cattle and natural wetlands by anaerobic digestion of complex organic molecules. The methane producing bacteria are known as the methanogenic bacteria and process of methane production is called methanogenesis.

In India, biogas is popularly known as gobar gas. The cattle population in our rural areas is maximum, the biogas is produced from their excreta called cow dung or gobar. Economically, viable biogas is produced in large vessels called bioreactors.

The anaerobic digestion of complex organic molecule is achieved in three steps. In the first step, cellulose, fat and proteins contained in the waste products are made soluble. In the second step, such products of low molecular weight are converted into organic acids mainly acetate by microbial action and in the third step, acetate by methanogenic bacteria converted to methane and carbon dioxide.

In recent years, biogas is also obtained from municipal sewage, agricultural an urban wastes. The biogas in Asia is mainly used in cooking and lighting purposes. There are many other uses of biogas such as its use in internal combustion engines to power pumps and electric generators. The sludge is used as biofertilizer. By this extent of environmental population is reduced and demand for energy is met.

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