Biochemical Oxygen Demand (BOD) may not be a good index for pollution for water bodies receiving effluents from

Options

A. Domestic sewage
B. Dairy industry
C. Petroleum industry
D. Sugar industry

Answer

### Step-by-Step Solution:

1. **Understanding BOD**:
- Biochemical Oxygen Demand (BOD) is a measure of the amount of oxygen that microorganisms will consume while decomposing organic matter in water. A higher BOD indicates a higher level of organic pollution.

2. **Identifying the Context**:
- The question asks about the effectiveness of BOD as an index for pollution in water bodies that receive effluents from various sources.

3. **Analyzing the Options**:
- **Domestic Sewage**: This typically contains biodegradable organic matter, which would increase BOD levels, indicating pollution.
- **Dairy Industry**: Similar to domestic sewage, the effluents from the dairy industry also contain biodegradable substances, leading to a high BOD.
- **Petroleum Industry**: Effluents from this industry primarily consist of non-biodegradable substances. Since BOD measures the oxygen demand for the degradation of organic matter, the presence of non-biodegradable substances means that BOD levels would not accurately reflect pollution levels.
- **Sugar Industry**: This industry also produces biodegradable waste, which would contribute to a higher BOD.

4. **Conclusion**:
- Since BOD is a measure of the oxygen demand for the degradation of organic matter, it is not a good index for pollution in water bodies receiving effluents from the petroleum industry, as these effluents do not significantly contribute to BOD due to their non-biodegradable nature.

5. **Final Answer**:
- The correct answer is **C) Petroleum Industry**.