What happens to activated sludge?

Options

A. It is generally released into natural water bodies like rivers and streams
B. It is completely pumped back inito aeration tank to serve as inoculum
C. The major part of the sludge is plumped into large tanks called anaerobic sludge digesters
D. It undergoes sequential filtration

Answer

**Step-by-Step Solution:**

1. **Understanding Activated Sludge**: Activated sludge is a mixture of microorganisms and organic matter that is produced during the sewage treatment process, particularly after primary and secondary treatments.

2. **Aeration Tank Process**: The activated sludge is sent to an aeration tank where it is continuously aerated. This means that oxygen is supplied to the sludge, which is crucial for the next steps.

3. **Aerobic Digestion**: In the presence of oxygen, the microorganisms in the activated sludge undergo aerobic digestion. This process allows them to break down the organic matter present in the sludge.

4. **Utilization of Stored Material**: The microorganisms utilize the stored materials in their bodies for energy, leading to a reduction in the biological matter.

5. **Oxidation of Organic Matter**: As the microorganisms digest the sludge, the organic matter is oxidized. This process results in the production of carbon dioxide, water, and ammonia.

6. **Conversion of Ammonia**: The ammonia produced during the digestion process is further converted into nitrates as the digestion continues.

7. **Final Outcome**: The major part of the activated sludge is then pumped into a large tank known as the aerobic sludge digester, where it undergoes further treatment.

8. **Conclusion**: The activated sludge does not get released into natural water bodies but is instead processed further in the aerobic sludge digester.

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