● `color{Violet}"Biogas"` is a `color{Violet}"mixture of gases"` (containing predominantly `color{Violet}"methane"`) produced by the microbial activity and which may be used as `color{Violet}"fuel"`.

● We have learnt that microbes produce different types of `color{Violet}"gaseous end-products"` during growth and metabolism.

● The type of the gas produced depends upon the `color{Violet}"microbes"` and the `color{Violet}"organic substrates"` they utilise.

● In the examples cited in relation to `color{Violet}"fermentation"` of dough, cheese making and production of beverages, the `color{Violet}"main gas"` produced was `CO_2`.

● However, certain bacteria, which grow an `color{Violet}"aerobically"` on `color{Violet}"cellulosic material"`, produce large amount of `color{Violet}"methane"` along with `CO_2` and `H_2`.

● These bacteria are collectively called `color{Violet}"methanogens"`, and one such common bacterium is `color{Violet}"𝘔𝘦𝘵𝘩𝘢𝘯𝘰𝘣𝘢𝘤𝘵𝘦𝘳𝘪𝘶𝘮"`.

● These bacteria are commonly found in the `color{Violet}"anaerobic sludge"` during `color{Violet}"sewage treatment"`.

● These bacteria are also present in the `color{Violet}"rumen"` (a part of `color{Violet}"stomach"`) of cattle.

● A lot of `color{Violet}"cellulosic material"` present in the food of cattle is also present in the `color{Violet}"rumen"`.

● In rumen, these bacteria help in the `color{Violet}"breakdown of cellulose"` and play an important role in the `color{Violet}"nutrition of cattle"`.

● Thus, the `color{Violet}"excreta"` (dung) of cattle, commonly called `color{Violet}"gobar"`, is rich in these bacteria.

● `color{Violet}"Dung"` can be used for `color{Violet}"generation of biogas"`, commonly called `color{Violet}"gobar gas"`.

● The `color{Violet}"biogas plant"` consists of a `color{Violet}"concrete tank"` (10-15 feet deep) in which bio-wastes are collected and a `color{Violet}"slurry of dung"` is fed.

● A `color{Violet}"floating cover"` is placed over the slurry, which keeps on `color{Violet}"rising"` as the gas is produced in the tank due to the `color{Violet}"microbial activity"`.

● The biogas plant has an `color{Violet}"outlet"`, which is connected to a pipe to `color{Violet}"supply biogas"` to nearby houses.

● The `color{Violet}"spent slurry"` is removed through another `color{Violet}"outlet"` and may be used as `color{Violet}"fertiliser"`.

● `color{Violet}"Cattle dung"` is available in large quantities in `color{Violet}"rural areas"` where cattle are used for a `color{Violet}"variety of purposes"`.

● So biogas plants are more after build in `color{Violet}"rural areas"`.

● The biogas thus produced is used for `color{Violet}"cooking and lighting"`.

● The `color{Violet}"technology of biogas"` production was developed in `color{Violet}"India"` mainly due to the efforts of `color{Violet}"Indian Agricultural Research Institute"` (IARI) and `color{Violet}"Khadi and Village Industries Commission"` (KVIC).