Fermentation of Microalgae Biomass through Mild Acid Pretreatment for Bioethanol Production

Abstract

Conversion of microalgae biomass to bioethanol is actively being researched to establish a cost effective and sustainable production technology. The main challenge is to break down the carbohydrates content in the biomass to obtain fermentable sugar for subsequent fermentation process. This study focuses on the effectiveness of the usage phosphoric acid pretreatment and capability of Saccharomyces diastaticus as the fermentation microbe to produce ethanol. Scenedesmus dimorphus microalgae biomass was used as the feedstock due to its high carbohydrate content. Mild acid hydrolysis at various conditions were carried out on biomass and the hydrolysates were subjected to fermentation. The optimum condition of acid pre-treatment using phosphoric acid was determined in this study. Based on the results, bioethanol yield of 94% was obtained at optimum condition of 2.5% v/v phosphoric acid at temperature of 120 °C for 30 min. This study proved that combination of phosphoric acid pre-treatment process with Saccharomyces diastaticus yeast provides a practicable method for the production of bioethanol from microalgae.