Which of the following organisms produce biogas from sludge in the digester tank of a wastewater treatment plant ?

Options

A. anaerobic bacteria
B. fungi
C. aerobic bacteria
D. protozoa

Answer

To answer the question about which organisms produce biogas from sludge in the digester tank of a wastewater treatment plant, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding the Digester Tank**:
- The digester tank is a crucial component of a wastewater treatment plant where sludge (solid waste) is processed.

2. **Identifying the Types of Bacteria**:
- In the digester tank, there are different types of bacteria present. These include aerobic bacteria and anaerobic bacteria.
- Aerobic bacteria require oxygen to survive, while anaerobic bacteria do not.

3. **Role of Anaerobic Bacteria**:
- Anaerobic bacteria are responsible for breaking down organic matter in the absence of oxygen.
- They digest the organic substances found in the sludge, such as bacteria, fungi, and other organic materials.

4. **Production of Biogas**:
- During the digestion process, anaerobic bacteria produce biogas as a byproduct.
- This biogas is primarily composed of methane (60-70%), along with other gases like hydrogen sulfide and carbon dioxide.

5. **Conclusion**:
- Therefore, the organisms that produce biogas from sludge in the digester tank are anaerobic bacteria.

### Final Answer:
The correct answer is **anaerobic bacteria**.

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