Aerobic digestion of sludge takes place in -
Trickling filter
Broad irrigation
Activated sludge
Septic tank
Park's textbook of preventive and social medicine 23rd edition. *The effluent from the primary sedimentation tank still contains a propoion of organic matter in solution or colloidal state and numerous living organisms.it is subjected to fuher treatment by filter method activated sludge process.
Environment and health