Question

What is the key difference between primary and secondary sewage treatment?

Answer 1

Primary sewage treatment involves the removal of large and floating particles such as leaves, plastic, polythenes and other oily substances while secondary treatment is removal of fine and suspended dissolved matter.

Sedimentation and Filteration is used in primary sewage treatment while aerobic and anaerobic biological units are used in secondary sewage treatment.

Primary sewage treatment is physical method of treatment while secondary treatment is biological treatment.

Primary treatment takes less time and it is simple while secondary treatment is complex and takes longer time to complete the treatment.