Select the colloidal material in domestic sewage

Options

A. Sand, Silt and Clay
B. Fecal matter, Bacteria, cloth and paper fibres
C. Nitrate, ammonia, phosphate
D. Garbage

Answer

**Step-by-Step Solution:**

1. **Understanding Domestic Sewage**: Domestic sewage is wastewater generated from households, which includes various impurities that make it unfit for human use.

2. **Identifying Impurities in Domestic Sewage**: Domestic sewage contains three main types of impurities:
- Suspended solids
- Colloidal materials
- Dissolved materials

3. **Classifying the Types of Impurities**:
- **Suspended Solids**: These include materials like sand, silt, and clay, which do not dissolve in water and can settle at the bottom.
- **Colloidal Materials**: These are tiny particles that remain suspended in water and do not settle out easily. In domestic sewage, colloidal materials include:
- Fecal matter
- Bacteria
- Cloth and paper fibers
- **Dissolved Materials**: These are substances that dissolve completely in water, such as nitrates, ammonia, and phosphates.

4. **Selecting the Colloidal Material**: From the options provided, the colloidal materials present in domestic sewage are fecal matter, bacteria, cloth, and paper fibers.

5. **Conclusion**: Therefore, the correct answer to the question "Select the colloidal material in domestic sewage" is **Fecal Matter, Bacteria, Cloth, and Paper Fibers**.

---