Question

Why is the liquid effluent from the primary sewage treatment step passed on for secondary treatment?

• A. To kill all the microbes
• B. To digest all the nutrients using microbes
• C. To filter out the toxic waste
• D. To remove organic solvents from it

Answer 1

The correct option is B To digest all the nutrients using microbes

The liquid effluent from the primary sewage treatment step is rich in organic nutrients. This effluent cannot be allowed to be dumped into any water bodies as it will increase its BOD causing a lot of harm. Thus, microbes are used to act upon the effluent. These microbes digest all the nutrients and then the remaining effluent is passed on to the nearby water body safely.