Q. What is Activated Sludge process?

The term Activated Sludge is used to indicate the sludge which is obtained by settling sewage in presence of abundant oxygen. The Activated Sludge is biologically active and it contains a large number of aerobic bacteria and other micro organisms which have got an unusual property to oxidise organic matter.

Activated Sludge is mixed with raw or partially treated sewage. When Activated Sludge is mixed properly with sewage containing ample or sufficient quantity of oxygen, micro organisms present in Activated Sludge multiply rapidly as result of this.

a) Organic solids present in sewage are rapidly oxidised.

b) Suspended and colloidal matters coagulate and they from a readily settleable precipitate.

After such precipitate settles down the effluent which is obtained is clear and sparking. The effluent contains very low amount of organic matter. A portion of settled sludge is sent for recirculation and the remaining part is sent to sludge digestion tanks. The digested sludge is harmless.