The residue left after methane production from cattle dung is

Options

A. burnt
B. buried in land fills
C. used as manure
D. used in civil construction

Answer

To solve the question regarding the residue left after methane production from cattle dung, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Biogas Production**:
- Biogas is produced through the anaerobic digestion of organic matter, such as cattle dung. This process involves microorganisms breaking down the organic material in the absence of oxygen.

2. **Composition of Biogas**:
- The biogas produced primarily consists of 50 to 70 percent methane (CH4) and 30 to 40 percent carbon dioxide (CO2), along with trace amounts of nitrogen and hydrogen sulfide.

3. **Residue After Biogas Production**:
- After the anaerobic digestion process, there is a residue left behind. This residue is the undigested material that did not convert into biogas.

4. **Characteristics of the Residue**:
- The residue is rich in minerals and contains components like lignin and cellulose. These characteristics make it valuable.

5. **Uses of the Residue**:
- The residue can be utilized in various ways: it can be burnt, buried in landfills, used as manure, or even used in civil construction. However, its rich nutrient content makes it particularly suitable for agricultural use.

6. **Conclusion**:
- Therefore, the residue left after methane production from cattle dung is primarily used as manure.

### Final Answer:
The residue left after methane production from cattle dung is used as manure.

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