Question

The given figure is a picture of a biogas plant. Briefly explain how biogas is generated.

Answer 1

Biogas is generated through the anaerobic degradation of animal and plant wastes in the presence of water. It involves the breakdown of organic matter by bacteria in the absence of oxygen, a process called anaerobic fermentation. The raw materials like cattle dung and water are mixed and fed into an underground digester tank through an inlet pipe. Inside the digester tank, bacteria ferment the organic waste, producing a gas mixture primarily composed of methane along with carbon dioxide, hydrogen, and hydrogen sulphide. This gas is collected in a floating gas-holder above the digester tank.

The leftover residue, called spent slurry, is discharged through an outlet pipe and is rich in nutrients which can be used as fertilizer. The biogas produced can be used for cooking, lighting, and pumping water. The system efficiently converts organic waste into a useful energy source and nutrient-rich manure, benefiting both energy needs and agriculture.