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In oxidation pond , once BOD from the se...

In oxidation pond , once BOD from the sewage is reduced significantly, the 'flocs' are allowed to sediment and it is known as :

A

Activated sludge

B

Inactivated sludge

C

Primary sludge

D

Secondary sludge

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The correct Answer is:
To solve the question regarding the process that occurs in an oxidation pond after the biochemical oxygen demand (BOD) from sewage is significantly reduced and the flocs are allowed to sediment, follow these steps: ### Step-by-Step Solution: 1. **Understanding BOD**: - BOD stands for Biochemical Oxygen Demand. It is a measure of the amount of oxygen that microorganisms will consume while decomposing organic matter in water. - In an oxidation pond, the initial BOD is high due to the presence of organic matter in sewage. **Hint**: Remember that BOD indicates the level of organic pollution in water. 2. **Reduction of BOD**: - In the oxidation pond, bacteria and fungi break down the organic matter, which reduces the BOD. This process is essential for treating sewage effectively. - As the organic matter is degraded, the demand for oxygen decreases. **Hint**: Focus on the role of microorganisms in reducing organic matter and BOD. 3. **Formation of Flocs**: - During the treatment process, microorganisms aggregate to form clumps known as flocs. These flocs consist of bacteria and fungi that are involved in the degradation process. - The formation of flocs is crucial as they help in the sedimentation process. **Hint**: Flocs are important for the sedimentation process and consist of microbial aggregates. 4. **Sedimentation of Flocs**: - Once the BOD is significantly reduced, the flocs are allowed to settle or sediment at the bottom of the pond. - This sedimentation process helps in separating the treated water from the solid waste. **Hint**: Sedimentation is a key step in wastewater treatment to remove solids. 5. **Identification of the Process**: - The sedimented flocs in an oxidation pond are referred to as "activated sludge." This term is used because the sludge contains a high concentration of microorganisms that can be reused to treat more sewage. - While some may refer to it as secondary sludge, "activated sludge" is the more precise term in this context. **Hint**: The correct term for the sedimented flocs in this scenario is "activated sludge." ### Final Answer: The correct answer to the question is **activated sludge**.
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