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 a sewage treatment plant, we will analyze each of the provided statements step by step.

### Step-by-Step Solution:

1. **Understanding the Aeration Tank**:
- The aeration tank is a crucial component of the sewage treatment process, specifically during the secondary treatment phase. It is where microorganisms break down organic matter in the sewage.

2. **Analyzing the Statements**:
- **Statement 1**: "In this tank, microbes consume the major part of the organic matter."
- This statement is **correct**. The primary function of the aeration tank is to allow microbes to decompose organic matter present in the sewage.

- **Statement 2**: "Flocks contain the aerobic fungal and anaerobic bacteria."
- This statement is **incorrect**. Flocks in the aeration tank primarily consist of aerobic bacteria, not anaerobic bacteria. Aerobic bacteria require oxygen for their metabolic processes, which is the condition maintained in the aeration tank.

- **Statement 3**: "The BOD will reduce significantly."
- This statement is **correct**. The biological oxygen demand (BOD) is reduced as aerobic bacteria consume organic matter and oxygen, leading to a decrease in BOD levels.

- **Statement 4**: "The primary effluent is constantly agitated mechanically and air is pumped into it."
- This statement is **correct**. The aeration tank involves mechanical agitation and the introduction of air to maintain aerobic conditions for the bacteria.

3. **Conclusion**:
- The only incorrect statement regarding the aeration tank of the sewage treatment plant is **Statement 2**.

### Final Answer:
The incorrect statement with respect to the aeration tank of the sewage treatment plant is: **"Flocks contain the aerobic fungal and anaerobic bacteria."**

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