Question

Describe how do 'flocs' and 'activated sludge' help in Sewage Treatment.  (3) 

CBSE Class XII Biology Question Paper 2017

Answer 1

Flocks are masses of bacteria associated with fungal filaments to form mesh like structure. It helps in aerobic decomposition as well as filament help in traping particles.

Activiated sludges is used as inoculum to produce flocks during secondary treatment. Process for treating sewage and in industrial waste water using air and a biolgical floc composed of bacteria and protozoa.