The residue left after methane production from cattle dung is

Options

A. burnt
B. buried in land fills
C. used an manure
D. used in civil construction

Answer

C

Explanation

The raw material for biogas production is excreta (dung) of cattle. The biogas planr consists of a concrete tank (10-15 feet deep) in which bio-wastes are collected and a slurry of dung is fed. A floating cover is placed over the slurry, which keeps on rising as the gas is produced in the tank dur to the microbial activity. Methanobacterium in the dung act on the bio-wastes to produce bio-gas. the gas produced in supplied to nearly houses by an oulet. Through another outlet, the spent slurry is removed to be used as manure.