The domestic sewage in large cities

has a high BOD as it contains both aerobic and anaerobic bacteria

is processed by aerobic and then anaerobic bacteria in the secondary treatment is Sewage Treatment Plants (STPs)

When treated in STPs does not really require the aeration step as the sewage contains adequate adequate oxygen

has very high amounts of suspended solids and dissolved salts

Solution

is processed by aerobic and then anaerobic bacteria in the secondary treatment is Sewage Treatment Plants (STPs)

Sewage is waste water having food residue, animal 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 in Sewage Treatment Plant (STPs).