Question 3

Which of the following is/are products of wastewater treatment?
(a) Biogas
(b) Sludge
(c) Both biogas and sludge
(d) Aerator

The answer is option (c).

Biogas and sludge both are the products of wastewater treatment. In wastewater treatment plant, the wastewater is passed through screens and then is allowed to settle down in a large tank. Semi-solids such as faeces that settle down during wastewater treatment are called sludge. This sludge is removed using a skimmer and then is transferred to a tank where it is decomposed by anaerobic bacteria to produce biogas. The biogas produced in the process can be used as fuel or can be used to produce electricity.