List the events that reduce the biological oxygen demand (Bod) of a promary effluent during sewage treatment .

Explanation

**Step-by-Step Solution:**

1. **Understanding Biological Oxygen Demand (BOD):**
- Biological Oxygen Demand (BOD) refers to the amount of oxygen that bacteria will consume while decomposing organic matter in water. A higher BOD indicates a higher level of organic pollution, which means more oxygen is required for bacterial decomposition.

2. **Introduction of Primary Effluent:**
- The primary effluent, which is the untreated sewage, is the starting point in sewage treatment. It contains a significant amount of organic matter that contributes to its BOD.

...