Select the incorrect statement with respect to aeration tank of the sewage treatment plant.

Options

A. In this tank microbes consume the major part of organic matter.
B. Flocs contain aerobic fungal and anaerobic bacteria.
C. BOD will reduce significantly.
D. The primary effluent is constantly agitate mechanically and air is pumped into it.

Answer

To solve the question regarding the incorrect statement about the aeration tank of the sewage treatment plant, we will analyze the statements provided and identify which one is incorrect.

### Step-by-Step Solution:

1. **Understanding the Aeration Tank Function**:
- The aeration tank is part of the secondary treatment in sewage treatment plants where biological treatment occurs.
- It is designed to promote the growth of microorganisms that consume organic matter in the sewage.

2. **Analyzing the Statements**:
- **Statement 1**: "In this tank, microbes consume organic matter, major part, it is not the whole part, but most of the high BOD which is occurring due to this."
- This statement is correct. Microbes in the aeration tank do consume organic matter, which reduces the biochemical oxygen demand (BOD).

- **Statement 2**: "Aerobic fungus and anaerobic bacteria are found in flocs."
- This statement is incorrect. The microorganisms in flocs are primarily aerobic bacteria and fungi. Anaerobic bacteria are not typically present in the aeration tank as it operates under aerobic conditions.

- **Statement 3**: "BOD is reduced."
- This statement is correct. The activity of the microorganisms in the aeration tank leads to a reduction in BOD.

- **Statement 4**: "Primary effluent is mechanically agitated and air-pumped."
- This statement is also correct. The primary effluent, which is the sewage after primary treatment, is agitated and aerated in the aeration tank to enhance microbial activity.

3. **Identifying the Incorrect Statement**:
- After analyzing all the statements, it is clear that the incorrect statement is **Statement 2**, which claims that anaerobic bacteria are found in the flocs of the aeration tank. This is incorrect because the conditions in the aeration tank are aerobic, and thus, anaerobic bacteria would not thrive there.

### Conclusion:
The incorrect statement with respect to the aeration tank of the sewage treatment plant is: **"Aerobic fungus and anaerobic bacteria are found in flocs."**

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