GATE 2026 ES – Question 20
Match processes P Activated sludge, Q Anaerobic filter, R Trickling filter, S Anaerobic digestion with (i) anaerobic suspended growth,(ii) anaerobic attached growth,(iii) aerobic suspended growth,(iv) aerobic attached growth. Options list P, Q, R, S.
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Correct answer: (B) iii, ii, iv, i
Explanation
Activated sludge maintains aerobic organisms as suspended flocs: iii. An anaerobic filter retains an attached anaerobic biofilm: ii. A trickling filter supports an aerobic biofilm on packing: iv. Anaerobic digestion conventionally uses suspended anaerobic biomass: i. Thus P–iii, Q–ii, R–iv, S–i, which is **B**.