Read the given passage and answer the following question.\ Disposal of untreated sewage into the ri

Question

Read the given passage and answer the following question.\ Disposal of untreated sewage into the river or freshwater pond causes huge water pollution. Four water samples from different sources (A, B, C, D) are collected and tested for BOD value in a lab to assess their quality. The BOD values are presented in the given table. Water samples are collected from primary effluent, secondary effluent, untreated sewage and river water. Study the given table.\ In which of the following samples, vigorous growth of useful aerobic microbes into flocs-occurs?\

Professor PC Thomas Classes · Answer

(c) : The primary effluent is passed into large aeration tanks where it is constantly agitated mechanically and air is pumped into it. This allows vigorous growth of useful aerobic microbes into flocs (masses of bacteria associated with fungal filaments to form mesh like structures).