Question

Which one of the following statements is correct with respect to Biochemical Oxygen Demand(BOD)?A. Secondary treatment of effluent decreases the BOD B. Secondary treatment of effluent increases the BOD C. Secondary treatment of effluent does not change the BOD D. Secondary treatment of effluent first increases and then decreases the BOD

Answer 1

Answer: A. is correct

Explanation: In secondary treatment microbes consume the major part of organic matter while growing in the effluent. This consumption significantly decreases BOD.