During anaerobic digestion of organic waste, such as in the producing biogas, which one of the following is left undergraded ?

Options

A. Hemi-cellulose
B. Cellulose
C. Lipids
D. Lignin

Explanation

To solve the question regarding which substance is left undergraded during anaerobic digestion of organic waste (such as in biogas production), we can follow these steps:

### Step 1: Understand Anaerobic Digestion
Anaerobic digestion is a biological process that breaks down organic matter in the absence of oxygen. It is commonly used to convert organic waste into biogas, which can be used as a renewable energy source.

### Step 2: Analyze the Options
The question provides four options:
1. Hemicellulose
2. Cellulose
3. Lipids
4. Lignan

We need to evaluate each option to determine which one is left undergraded during the anaerobic digestion process.

### Step 3: Evaluate Each Option
- **Hemicellulose**: This is a polysaccharide found in plant cell walls that can be broken down by some microorganisms during anaerobic digestion.

- **Cellulose**: This is a complex carbohydrate that is also a major component of plant cell walls. While some microorganisms can degrade cellulose, it is more resistant to breakdown compared to hemicellulose.

- **Lipids**: These are fats and oils that can be broken down by anaerobic bacteria, although they may take longer to degrade compared to carbohydrates.

- **Lignan**: This is a complex organic polymer that provides structural support in plants. Lignans are particularly resistant to degradation due to their rigid structure.

### Step 4: Identify the Undergraded Substance
Among the options, lignan is known for its rigidity and resistance to degradation. During anaerobic digestion, it does not break down easily and is left undergraded.

### Conclusion
Thus, the substance that is left undergraded during anaerobic digestion of organic waste, such as in the production of biogas, is **Lignan**.

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