Question

In the treatment of waste water discharge, which treatment stage involves biological treatment?

• A. Primary treatment
• B. Secondary treatment
• C. Tertiary treatment
• D. Reservoir osmosis stage

Answer 1

Answer: (B)

Secondary treatment

Secondary treatment involves biological treatment of the waste water discharge. It involves the removal of dissolved and colloidal compounds by oxidation. It is usually done through microorganisms for removal of organic compounds. The three methods involved in secondary treatment are:

(i) Biofiltration

(ii) Aeration/activated sludge process

(iii) Oxidation ponds.

So, the correct answer is 'Secondary treatment'