Name the solid waste extracted during sewage treatment.

Answer

**Step-by-Step Solution:**

1. **Understanding Sewage Treatment**: Sewage treatment involves the process of removing contaminants from wastewater, which includes both industrial and municipal waste.

2. **Identifying the By-products**: During the sewage treatment process, various by-products are generated. One of these by-products is solid waste.

3. **Naming the Solid Waste**: The solid waste that is extracted during the sewage treatment process is specifically known as "sludge."

4. **Defining Sludge**: Sludge is characterized as a wet or muddy mixture that consists of the solid materials that settle out from the wastewater during treatment.

5. **Conclusion**: Therefore, the solid waste extracted during sewage treatment is called sludge.

**Final Answer**: The solid waste extracted during sewage treatment is called **sludge**.

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