BOD level in fresh water should not exceed beyond:

Options

A. 5 ppm
B. 10 ppm
C. 25 ppm
D. 50 ppm

Answer

**Step-by-Step Solution:**

1. **Understanding BOD**: BOD stands for Biochemical Oxygen Demand. It measures the amount of oxygen that microorganisms will consume while decomposing organic matter in water.

2. **Significance of BOD Levels**: The level of BOD indicates the degree of pollution in water. Higher BOD values suggest a higher presence of organic matter, which means the water is heavily polluted.

3. **BOD Levels in Freshwater**: Generally, freshwater should have a low BOD level to support aquatic life. A BOD level of 1 to 2 parts per million (ppm) is considered clean.

4. **Identifying the Threshold**: It is important to determine the maximum BOD level that freshwater should not exceed. If BOD levels exceed this threshold, it can lead to a depletion of dissolved oxygen (DO) in the water.

5. **Impact of High BOD**: When BOD levels are high, the oxygen required for the decomposition of organic matter is taken from the water, leaving insufficient oxygen for aquatic organisms, which can lead to their death.

6. **Conclusion**: Based on the information, the BOD level in freshwater should not exceed 5 ppm. Therefore, the correct answer is option A: 5 ppm.

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