Social & Preventive Medicine Aerobic digestion of sludge takes place in – a) Trickling filterb) Broad irrigationc) Activated sludged) Septic tank A a B bc C ac D b 💡 Explanation Aerobic digestion of sludge takes place in – a) Trickling filterb) Broad irrigationc) Activated sludged) Septic tank ✓ Correct Answer: C. ac