The GATE Grind

GATE 2026 CE (CE1) – Question 44

Water and Waste Water Quality and Treatment · Sewerage system design and quantity of domestic wastewater · 2 marks · Multiple choice

The average sewage from a city is 90 million litres per day and the average 5-day Biochemical Oxygen Demand (BOD$_5$) is 300 mg/l. Average standard BOD$_5$ of the domestic sewage is 0.08 kg/day/person. The population equivalent of the city is

  1. 337500
  2. 216000
  3. 270000
  4. 168750

Practise this question in The GATE Grind →

Show answer and explanation

Correct answer: (A) 337500

Explanation

The daily BOD load is $90 \times 10^6\ \text{L/d} \times 300\ \text{mg/L} = 27{,}000$ kg/day. The population equivalent is $\frac{27000}{0.08} = 337{,}500$.