Describe the steps involved in obtaining biogas and explain what is meant by anaerobic decomposition.

(N/A) The process of obtaining biogas involves the following steps:
$1$. $A$ slurry of animal dung (e.g.,cow dung) and water is prepared in a mixing tank.
$2$. This slurry is fed into a digester,which is a sealed,underground tank made of bricks.
$3$. Inside the digester,anaerobic microorganisms break down the complex organic compounds present in the biomass.
$4$. This process occurs in the absence of oxygen and produces gases like methane $(CH_4)$,carbon dioxide $(CO_2)$,hydrogen $(H_2)$,and hydrogen sulphide $(H_2S)$.
$5$. The resulting mixture,known as biogas,is collected and supplied to consumers through pipes.
Anaerobic decomposition is the process where microorganisms (anaerobic bacteria) decompose complex organic matter such as carbohydrates,proteins,and fats present in animal and plant wastes into simpler substances like methane gas,in the presence of water but in the complete absence of oxygen.