Cellulosic ethanol production from highland bamboo (Yushania alpina) grown in Ethiopia

Abstract

This study describes the production of lignocellulosic bioethanol from highland bamboo (Yushania alpina) via pressurized hot water pretreatment, dilute acid hydrolysis and fermentation using Saccharomyces cerevisiae yeast. The highland bamboo was collected from Enjibara (Ethiopia), dried in air and further dried in an oven at 50 °C. The dried sample was milled to 1 mm mesh size for chemical composition characterization and 2 mm mesh size for cellulosic ethanol production. The powdered bamboo sample was subjected to acid hydrolysis under optimum pretreatment conditions (128 °C and 10 min) to yield the highest content of cellulose. The pretreated solid samples were hydrolyzed using 2.5, 5.5 and 7.5% sulfuric acid, at 121, 128 and 135 °C for 20, 40 and 60 min. The maximum reducing sugar (12.14%) was obtained by hydrolyzing at 121 °C for 60 min with 2.5% sulfuric acid. The fermentation of hydrolysates with instant yeast at 27 °C for 72 h yielded 23.81% ethanol. This study shows that Ethiopian bamboos can be used for the production of bioethanol with good yield by dilute sulfuric acid hydrolysis and fermentation with yeast at low temperature. The experimental conditions also suggest that the bioethanol production cost will be cheap and reasonable.

Keywords:

• Highland bamboo
• reducing sugar
• hot water pretreatment
• acid hydrolysis
• cellulosic ethanol

Acknowledgements

The authors acknowledge the support from the Chemistry Department, College of Natural and Computational Sciences, Addis Ababa University, and from Wood Technology Research Center staff and Bioenergy and Biochemical Research Division team members, especially Mr. Amsalu Tolesa, Mr. Tegenu Tantu and Mr. Teshale Gebera. The authors are also thankful to the Ethiopian Environment and Forest Research Institute (EFFRI) for providing financial support and technical assistance for the completion of this work.

Disclosure statement

No potential conflict of interest was reported by the authors.