Question

It is possible to estimate the amount of biodegradable organic matter in sewage water by measuring Biochemical Oxygen Demand (BOD). Can you explain how?

Answer 1

Part 1: Definition of BOD
Biochemical oxygen demand (BOD) is the amount of dissolved oxygen required by aerobic bacteria to oxidise the organic matter present in the sample water at a specific period of time and temperature.

Part 2: Significance

• If the BOD levels in a water sample is more than the limit, the organic matter present is more indicating more pollution.
• If BOD levels are less, the pollution levels are less.

Part 3: Estimation of sewage organic matter by BOD
BOD can be estimated using two main methods:-

• Dilution method
• Manometric method