Question

(a)Why is air passed through wastewater during wastewater treatment?
(b) How are impurities filtered during wastewater treatment?

Answer 1

(a) Aeration is a part of secondary treatment, in which, the air is pumped so that aerobic bacteria can grow and consume remaining human waste, food. The amount of oxygen in water is increased during this process. Chlorine is added after aeration to sterilize the filtered and aerated water. This process is known as chlorination.

(b) Impurities that do not get settled are removed by the filter. Fine sand and gravel are used respectively in the upper and lower portions of the filter unit.