Q. Identify the True or False statements about the sewage treatment plants.
I. The water is less polluted if BOD is high.
II. Flocs are formed by anaerobic bacteria with fungal filaments in mesh-like structures.
III. Activated sludge acts like an inoculum in activated sludge digesters.
IV. In activated sludge digesters, gases like methane, hydrogen sulphide and carbon dioxide are formed.

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Solution:

Water is more polluted if BOD is high as BOD denotes the amount of oxygen required to digest the organic matter present in sewage. Flocs are formed by aerobic bacteria. Activated sludge acts as inoculum in aeration tanks. In activated sludge digesters, gases methane, hydrogen sulphide and carbon dioxide are formed which is flammable and is called biogas.