What are ‘flocs’? State their role in effluent treatment and their ultimate fate in sewage treatment tank.

Explanation

Flocs: It is the masses of bacteria associated with fungal filaments to form mesh like structure.
Effluent treatment: The treated sewage effluent is subjected to chemical treatment for disinfection before releasing it into natural water bodies like rivers and streams.
Sewage treatment: The BOD of sewage or waste water is reduced significantly. The effluent is then passed into a settling tank where the bacterial ‘flocs’ are allowed to sediment. It is called activated sludge.