Repeated-batch Ethanol Fermentation of Kitchen Refuse by Acid-tolerant Flocculating Yeast Under the Non-sterilized Condition

Abstract

The ethanol production performance of the flocculating yeast S. cerevisiae ATCC26602 from non-sterilized kitchen refuse medium in repeated-batch culturing was investigated. Although no pH modification or asepsis technology was applied, no contamination occurred. Twenty cycles of repeated-batch fermentation over a period of 11 days were successfully carried out without any loss of productivity by the self-flocculating strain ATCC26602. In addition, from the third batch, the flocculent strain achieved the reduction of the fermentation time to half, which resulted in an increasing of ethanol productivity to 3.7 g/L/h. These results of ethanol fermentation from kitchen refuse under the non-sterilized condition by this acid-tolerant and self-flocculation yeast may pave the way to low-cost ethanol production in pilot applications.