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Microbes in Human Welfare — BIOLOGY STD 12 Science — Question

Gujarat BoardEnglish MediumSTD 12 ScienceBIOLOGYMicrobes in Human Welfare2 Marks
Question
During the secondary treatment of the primary effluent how does the significant decrease in BOD occur?
OR
During the secondary treatment of the primary effluent how does the significant decrease in BOD occur?
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Answer

During secondary treatment of primary effluents, vigorous growth of useful aerobic microbes into flocs occur when it is agitated mechanically and air is pumped into it in a large aeration tank. These microbes while growing consume major part of the organic matter in the effluent. This significantly reduces BOD.
  • Useful aerobic microbes grow rapidly and form flocs.
  • Flocs are masses of bacteria associated with fungal filaments to form mesh-like structures.
  • The growing microbes consume organic matter and thus reduce the biochemical oxygen demand (BOD).

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