Domestic sewage is a ________ pollutant.

Answer

**Step-by-Step Text Solution:**

1. **Understanding Domestic Sewage**: Domestic sewage refers to wastewater that is generated from households. It includes water from sinks, toilets, showers, and washing machines.

2. **Source of Pollution**: Domestic sewage is a significant source of pollution, particularly for water bodies. It introduces various impurities into the water, making it unfit for consumption.

3. **Composition of Domestic Sewage**: The sewage contains approximately 0.1% impurities. These impurities can be categorized into three main types:
- **Suspended Solids**: This includes materials like sand, clay, and other particulate matter.
- **Colloidal Materials**: This includes organic matter such as fecal matter and other biodegradable materials.
- **Dissolved Materials**: This includes chemicals such as nitrates, phosphates, and ammonia.

4. **Biodegradability**: The impurities found in domestic sewage are primarily biodegradable. This means they can be broken down by microorganisms, such as bacteria and fungi, which can utilize these organic materials for their growth.

5. **Conclusion**: Given that domestic sewage contains biodegradable impurities that can be decomposed by microorganisms, it can be classified as a **biodegradable pollutant**.

**Final Answer**: Domestic sewage is a **biodegradable** pollutant.

---