KCET · BIOLOGY · STD 12 - 8. Microbes in Human Welfare
In sewage treatment, secondary treatment is considered highly significant, because
- A it increases the organic content of sewage
- B it helps to remove debris from the sewage
- C it reduces the BOD level of sewage
- D it helps in the production of biogas
Answer & Solution
Correct Answer
(C) it reduces the BOD level of sewage
Step-by-step Solution
Detailed explanation
(C) it reduces the BOD level of sewage,
The effluent from primary treatment flows into secondary treatment systems to remove suspended impurities. Sewage is usually very high in organic pollutants which deplete the oxygen levels of water in which it is released. Hence, to prevent this, the biochemical oxygen demand (BOD) levels of sewage have to be brought within the acceptable range before it is discharges into the environment. The secondary treatment of water involves biodegradation of such material containing large number of microoragnisms including bacteria that form a filamentous mesh-like filter and are called floc.
The effluent from primary treatment flows into secondary treatment systems to remove suspended impurities. Sewage is usually very high in organic pollutants which deplete the oxygen levels of water in which it is released. Hence, to prevent this, the biochemical oxygen demand (BOD) levels of sewage have to be brought within the acceptable range before it is discharges into the environment. The secondary treatment of water involves biodegradation of such material containing large number of microoragnisms including bacteria that form a filamentous mesh-like filter and are called floc.
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