In the sewage treatment, bacterial flocs are allowed to sediment in a setting tank. This sediment is called as

Options

A. inactivated sludge
B. activated sludge
C. primary sludge
D. secondary sluge

Explanation

**Step-by-Step Solution:**

1. **Understanding Sewage Treatment Process:**
- Sewage treatment involves multiple steps to purify wastewater. The main stages include preliminary, primary, secondary, and sometimes tertiary treatments.

2. **Preliminary Treatment:**
- In this stage, large solids and debris are removed from the sewage. This step prepares the sewage for further treatment.

3. **Primary Treatment:**
- During primary treatment, sewage is allowed to settle in a tank, where solids settle down to form a sludge. This sludge is referred to as "primary sludge."

4. **Secondary Treatment:**
- In this stage, the remaining wastewater undergoes biological treatment. Bacteria are introduced to break down organic matter. The bacteria form flocs, which are clusters of microorganisms.

5. **Sedimentation in Secondary Treatment:**
- After the biological treatment, the bacterial flocs are allowed to settle in a setting tank. The sediment formed from this process is crucial for further treatment.

6. **Identifying the Sediment:**
- The sediment that results from the settling of bacterial flocs during secondary treatment is known as "activated sludge." This is because it contains a high concentration of bacteria that are actively involved in the breakdown of organic material.

7. **Conclusion:**
- Therefore, the correct answer to the question is "activated sludge."

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