Question

This is chiefly produced by the activity of an anaerobic bacteria on sewage
(a) Laughing gas
(b) Propane
(c) Mustard gas
(d) Marsh gas

Answer 1

Hint:
Another name for this gas is methane. It is produced naturally in marshes. It is produced due to the anaerobic decomposition of dead vegetation and animal waste. It is also known to stimulate methane production in aquatic muds and uses acetate, methanol, and trimethylamine as substrates for methane production.

Complete step by step answer:
Once the BOD sewage or wastewater is decreased a lot, the leftover is sent to a settling tank. In the settling tank, bacterial flocs are sedimented. These bacterial flocs are referred to as activated sludge. And some activated sludge is passed into the aeration tank. There it works as an inoculum. And all the sludge that is left is sent to anaerobic sludge digesters. The bacteria that grow anaerobically digest fungi and bacteria in the sludge. Biogas is produced while this digestion takes place and is produced by bacteria. The activity of anaerobic bacteria on sewage produces biogas, commonly called gobar gas or marsh gas. The major component of biogas is methane. It also includes other gases like carbon dioxide, hydrogen, nitrogen, oxygen, and hydrogen sulfide

Option ‘D’ is correct

Note:
Large amounts of methane, hydrogen and carbon dioxide are produced by bacteria that grow anaerobically on cellulosic material. Methanogens are those bacteria that produce methane gas. These are mostly found in anaerobic sludge during sewage treatment.