Question

The purpose of biological treatment of waste-water is to

• A. Reduce BOD
• B. Increase BOD
• C. Reduce sedimentation
• D. Increase sedimentation

Answer 1

The correct option is A Reduce BOD

Decomposition of organic matter by microbes require oxygen. The degree of impurity of water due to organic matter is measured in terms of Biological Oxygen Demand (BOD). BOD is the oxygen required by microorganisms to metabolise organic wastes in the water. Biological treatment of wastewater will reduce the organic impurities or an organic load of polluted water, thus curtail the level of BOD.

So, the correct answer is option A.