GATE Water and Wastewater Treatment and Management: Sewage Collection and Treatment – Previous Year Questions

10 GATE previous year questions on Sewage Collection and Treatment (Water and Wastewater Treatment and Management, Environmental Science and Engineering) with answers and explanations, from every paper.

GATE 2021 ES Q42 (2 marks, Multiple choice) – An STP treats20000 m³/day with 200 mg/L suspended solids. Primary clarification removes60% into sludge containing5 wt% solids, density1000 kg/m³. Find…
GATE 2021 ES Q60 (2 marks, Numerical answer) – A 10 MLD activated-sludge plant receives primary-treated sewage BOD₅140 mg/L into a 1500 m³ aeration tank. MLVSS3000 mg/L;effluent BOD₅5 mg/L. Find…
GATE 2022 ES Q62 (2 marks, Numerical answer) – A 10 MLD aerobic plant operates at 80% capacity. Inlet/outlet BOD100/30 mg/L;observed biomass yield .5 g VSS/g BOD. Find sludge production in kg/day,…
GATE 2024 ES Q17 (1 mark, Multiple choice) – Crown corrosion in reinforced-concrete sewers is caused by
GATE 2024 ES Q28 (1 mark, Multiple select) – Which settling classifications are correct?
GATE 2024 ES Q53 (2 marks, Numerical answer) – An activated-sludge plant treats1 MLD soluble BOD from 200 to 20 mg/L. Observed biomass yield is .35 kg/kg BOD removed. Find daily biomass generation…
GATE 2025 ES Q39 (2 marks, Multiple choice) – The ASP diagram labels flow Q, substrate S, microorganisms X, and aeration volume V. Subscripts 0,r, w, e, i denote influent, recycle, waste,…
GATE 2026 ES Q20 (1 mark, Multiple choice) – Match processes P Activated sludge, Q Anaerobic filter, R Trickling filter, S Anaerobic digestion with (i) anaerobic suspended growth,(ii) anaerobic…
GATE 2026 ES Q29 (1 mark, Multiple select) – Which processes primarily remove organic matter in sludge? Select all that apply.
GATE 2026 ES Q58 (2 marks, Numerical answer) – An activated-sludge plant has influent flow .150\,m3/s,soluble influent and effluent BOD 5 of 84 and 11 mg/L, mean cell residence time 5 days, yield…