What are the three major kinds or impurities in domestic wastewater?

Explanation

To answer the question about the three major kinds of impurities in domestic wastewater, we can break it down into clear steps:

### Step-by-Step Solution:

1. **Identify the Types of Impurities**: The first step is to understand what impurities are typically found in domestic wastewater. Domestic wastewater is primarily generated from household activities and contains various contaminants.

2. **Dissolved Salts**: The first major kind of impurity is dissolved salts. This includes:
- **Nitrates**: These are nutrients that can come from fertilizers and human waste.
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