**3. Conventional process of converting lignocellulose to bioethanol**

For a general chemical expression of converting natural glucose-based carbohydrates to bioethanol, it can be expressed as the following:

(C6 H10 O5)n + n H2O → n C6 H12 O6 → 2n C2 H5OH + 2n CO2

The input materials can be fruit juices, brewery residues, soya residue, peanut residue, rice, wheat, and especially lignocellulose types like straw, woods, grasses, etc. **Figure 3** presents a conventional flowchart of the process.

As mentioned above, pretreatment is a vital step followed by hydrolysis and fermentation of the pretreated lignocellulose. To hydrolyze lignocellulose, in principles, enzymes and chemicals can be employed. However, in this chapter, only enzymatic hydrolysis is the mean due to its feasibility, while the other leads to solutions with high concentration of chemicals (acid, alkaline, or salt), which is not friendly to the growth of fermentation microorganisms.

**Figure 3.** *Scheme of lignocellulosic ethanol production in general principle.*
