Aerobic digestion of sludge takes place in -: (A) Trickling filter, (B) Broad irrigation, (C) Activated sludge, (D) Septic tank
Answer is A. 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.