Question

Why is aerobic degradation more important than anaerobic degradation for the treatment of large volumes of waste waters rich in organic matter? Discuss.

Accepted Answer

The aerobic and anaerobic degradation of wastewater takes place in the secondary treatment tank of the sewage treatment system. The secondary treatment is also called biological treatment. Here the primary effluent is taken into the aeration tank. A large number of aerobic, heterotrophic bacteria grow in this aeration tank helps in the degradation of organic matter and these bacteria later forms flocs. These are the masses of bacteria held together by the fungal filament to form a mesh-like structure.

The microbes while growing, consume the major part of organic matter in the effluent. It decreases the biochemical oxygen demand (BOD) i.e. the amount of oxygen required by microorganisms to oxidise all the organic matter present in the effluent at a certain temperature over a specific time period. Higher the organic content, the higher would be the BOD and similarly lower the organic content, lower would be the BOD.

When the BOD decreases at a significant level, the effluent is passed into the settling tank. The effluent from the secondary treatment plant is generally released into natural water bodies like rivers and streams. The major part of the organic sludge is digested by the aerobic degradation of the wastewater which reduces the BOD at a significant level. Thus, aerobic degradation is more important for the treatment of wastewater.

NCERT Solutions for Chapter: Microbes in Human Welfare, Exercise 4: LONG ANSWER QUESTIONS

NCERT Biology Solutions for Exercise - NCERT Solutions for Chapter: Microbes in Human Welfare, Exercise 4: LONG ANSWER QUESTIONS

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