A stirred-tank reactor is usally cylindrical or with a curved base to

Options

A. give a large surface area
B. facilitate the mixing of the reactor content
C. avoid the mixing of the reactor contents
D. increase the oxygen transfer area

Answer

### Step-by-Step Solution:

1. **Understanding the Structure of a Stirred-Tank Reactor**: A stirred-tank reactor is typically designed in a cylindrical shape or with a curved base. This design is crucial for the effective mixing of the contents within the reactor.

2. **Reason for the Cylindrical Shape**: The cylindrical shape allows for a large volume of culture to be accommodated. This is important because many biological processes require a significant amount of space for the growth of microorganisms or cells.

3. **Importance of Mixing**: The primary function of a stirred-tank reactor is to facilitate mixing. Mixing is essential for ensuring that nutrients, oxygen, and other necessary components are evenly distributed throughout the culture. This enhances the overall efficiency of the biological process taking place.

4. **Oxygen Transfer**: One of the critical factors in a bioreactor is the transfer of oxygen to the culture. The design of the reactor, being cylindrical or curved, aids in increasing the oxygen transfer area. This is vital for aerobic processes where oxygen is a key requirement for the growth of microorganisms.

5. **Circulation Pattern**: The internal configuration of the reactor is designed to create an effective circulation pattern. This circulation pattern helps in maintaining uniform conditions throughout the reactor, which is essential for optimal growth and productivity.

6. **Conclusion**: Therefore, the primary reason a stirred-tank reactor is usually cylindrical or has a curved base is to **increase the oxygen transfer area**, which is crucial for the efficiency of the biological processes occurring within the reactor.