Ethanol production with natural carbon sources in batch and continuous fermentation using free and immobilized Saccharomyces cerevisiae

This study presents ethanol production from molasses, dates and sugarcane syrup with sugar concentration of 35g/l in batch culture. Molasses (retention time, 24 h; initial sugar concentration, 100 g/l) gave highest yield of ethanol [conc., 45.5 g/l (theoretical yield 89%)] in a packed bed reactor loaded with immobilized Saccharomyces cerevisiae beads (mean diam, 3 mm). After 16 h of cultivation, free cells were harvested for immobilization. Entrapment method was used to encapsulate free cells using 2.5% sodium alginate solution, solidified in calcium chloride bath. Growth kinetic model for S. cerevisiae in batch culture and rate model for performance of immobilized cell reactor (ICR) were determined.