Select non-biodegradable industrial waste

Options

A. Waste from cotton mills
B. Waste from paper mills
C. Fly ash from
D. Waste from food processsing units

Answer

To solve the question of selecting non-biodegradable industrial waste, we will analyze each option provided:

1. **Waste from Cotton Mills**:
- Cotton mill waste typically consists of cotton fibers, which are organic materials. Since they can decompose naturally, this waste is considered biodegradable.

2. **Waste from Paper Mills**:
- Paper mill waste primarily consists of wood fibers and other organic materials. These materials can also break down over time, making this waste biodegradable as well.

3. **Fly Ash**:
- Fly ash is a byproduct of burning finely ground coal in power plants. It is a very fine powdery material composed mostly of silica and other inorganic compounds. Fly ash does not decompose naturally and remains in the environment for a long time, making it non-biodegradable.

4. **Waste from Food Processing Units**:
- Waste from food processing units includes organic materials such as fruits, vegetables, and other food scraps. These materials can decompose naturally, classifying this waste as biodegradable.

Based on this analysis, the only non-biodegradable industrial waste among the options is **Fly Ash**.

### Final Answer:
**Fly Ash** is the non-biodegradable industrial waste.