**Author details**

**Sample**

NaOH or KOH.

Cerevisiae TISTR 5339.

**4. Conclusion**

**Ethanol concentration (g/l)**

Nondelignification\* 16.25 65.0 KOH delignification 16.42 65.7 NaOH delignification 16.35 65.4

176 Sustainable Degradation of Lignocellulosic Biomass - Techniques, Applications and Commercialization

**Table 9.** Comparison of resulting ethanol concentration (g/l) and yield (%) after 36 h fermentation

\*glucose obtained from steam exploded pulp that directly employed for ethanol production without delignification with

Comparison of resulting ethanol after 36 h fermentation of NaOH and KOH delignified pulp was shown. The obtained ethanol concentration and yield from non delignified pulp was 16.25 g/l and 65%, respectively. The fermentation of KOH delignified gave ethanol concentration and yield at 16.42 g/l and 65.7% whereas those obtained from NaOH delignified pulp were 16.35 g/l and 65.4%, respectively. Alkaline delignification process showed no significant influence on the fermentation process. When the ethanol yield obtained from pure glucose and hydrolyzed solution (Table 8 and Table 9) were compared, it showed that the three hydrolyzed solutions gave lower ethanol yield due to the three hydrolyzed solution contained toxic substances such as furfural, 5-hydroxy methyl furfural, phenolic compound and acetic acid derived from steam explosion process. All substances can inhibit the fermentation of S.

From this study on optimization of alkaline delignification and enzyme hydrolysis on steam exploded oil palm trunk followed by yeast fermentation to produce ethanol, an encouraging results were obtained. We concluded that delignification of steam explode pulp with NaOH was more influenced than delignification with KOH on term of less alkaline concentration consuming and lower reaction temperature. The comparison enzyme hydrolysis condition for both delignified pulp showed that NaOH delignified pulp gave higher the percentage of glucose yield than KOH delignified pulp. After optimizing the both delignification (NaOH and KOH) and both enzyme hydrolysis parameter by RSM, the highest ethanol yield of 65%

The empirical quadratic models successfully predicted the percentage of glucose in pulp after delignification and the percentage of glucose in hydrolyzed solution after enzyme hydrolysis and they used in the development of better estimation tools. In addition, response surface plot in three-dimension obtained from the empirical quadratic models can show the interaction effect of two variables on the studied response and the optimum values of the selected variables

were obtained from both fermentations with 50 g/l of glucose raw material.

are obtained from response surface plot, too.

**Ethanol yield (%)**

Vittaya Punsuvon1,2\*

Address all correspondence to: fscivit@ku.ac.th

1 Department of Chemistry, Faculty of Science, Kasetsart University, Bangkok, Thailand

2 Center of Excellence-Oil Palm, Kasetsart University, Bangkok, Thailand
