Performance of continuous fixed bed reactor with pumice stones as retarding medium to produce ethanol

Abstract

Fermented ethanol production is influenced by the type of raw material and sugar content. In the fermentation process, glucose will be converted to ethanol. The higher the glucose concentration, the higher the concentration of ethanol produced. The process limited by the problem of substrate inhibition and product inhibition. The general aim of this study was to determine the best conditions based on variations of glucose concentration (40, 100, 150, 200, and 250) g / L in terms of ethanol concentration, ethanol yield, and number of loose cells produced from ethanol fermentation process using continuous fixed bed reactor with a pumice stone as its retarding medium. The specific aim was to compare the best condition in the process of fermentation of immobilized cell and free cell with recycle in ethanol fermentation process which is done based on ethanol concentration value and ethanol yield percentage. Based on the result of study, the best condition was obtained in immobilized cell condition with a mesh size of 6/8 with 2 days residence time with ethanol concentration of 20.53% v/v, and ethanol yield value of 37.56% w/w at a glucose feed concentration of 150 g/L. Fermentation of ethanol with immobilized cells in fixed bed reactor with pumice stone had better performance compared with ethanol fermentation with free cell condition with recycle in terms of ethanol concentration in product and yield percentage.