Effect of hydrolysis time and acid concentration on bioethanol production of microalga Scenedesmus sp.

Scenedesmus sp. has tremendous potential to produce bioethanol due to its high content of carbohydrate, approximately 10-52%. This study aimed to investigate the effect of hydrolysis time and acid concentration on ethanol production fermented by Saccharomyces cerevisiae. The analysis included in this research were cell density calculation, pH level, carbohydrate content, reducing sugar content, and ethanol content tested by Gas Chromatography. Biomass of Scenedesmus sp. was hydrolyzed using 1%, 2%, and 3% sulfuric acid for 75 minutes and 105 minutes. The hydrolysate was adjusted its pH to 4-5 using NaOH 50% then it was added with nutrients. The fermentation process was carried out for 5 days and samples were collected every day. The results showed that the highest ethanol content was 1.1 % and achieved on the 1st day of fermentation with 75 minutes of hydrolysis process using 3% sulfuric acid. It was followed by a 105 minutes hydrolysis process using 3% sulfuric acid which yielded a value of 1.095% on the 2nd day of fermentation. Optimization of the hydrolysis and fermentation process are needed for a further study to obtain high ethanol content.