Question

Read the following statements and select the correct statement.

• A. The dough, which is used for making foods such as dosa and idli, is fermented by yeast.
• B. Statin is used as an immuno-suppressive agent in organ transplant patients.
• C. Some microbes produce chemical substances that can kill or retard the growth of all (disease-causing) microbes.
• D. The flocs, a mesh like structure formed by the association of masses of bacteria with fungal filaments, reduces BOD.

Answer 1

Answer: (D)

During secondary treatment, constant agitation and aeration allows vigorous growth of useful aerobic microbes into flocs (masses of bacteria associated with fungal filaments to form mesh like structures) in the aeration tank. While growing, these microbes consume the major part of the organic matter in the effluent. This significantly reduces the BOD (biochemical oxygen demand) of the effluent.