Question

During secondary treatment of primary effluent, how does significant decrease in BOD occur?

Answer 1

The amount of dissolved oxygen needed (i.e. demanded) by aerobic biological organisms to break down organic material present in a given water sample at certain temperature over a specific time period. During the secondary treatment of primary effluents, the BOD level decreases because useful microbes consume a major part of the organic matter. Reduction in the organic matter leads to lowering of BOD.