Question

The domestic sewage in large cities

• A. has a high BOD as it contains both aerobic and bacteria
• B. is processed by aerobic and then anaerobic bacteria in the secondary treatment in Sewage Treatment Plants (STPs)
• C. when treated in STPs does not really require the aeration step as the sewage contains adequate oxygen
• D. has very high amounts of suspended solids and dissolved salts

Answer 1

Answer: (B)

Sewage is wastewater having food residue, animals and human excreta, detergents, discharges from commercial and industrial establishments. The domestic sewage is processed first by aerobic and then by anaerobic bacteria in Secondary Treatment Plants (STPs).