Conceptual design of an industrial - scale plant for ethanol production from by - products of sweet potato processing

Inclusion of bioethanol in the transportation fuel by displacing part of the petroleum-derived energy has become an emerging trend due to limited availability of fossil fuel and its potential association with global warming. With a suitable strain of microorganism, sugar from the agricultural waste could be fermented to produce bioethanol, which is a highly effi cient energy source generating minimal environmental impact. In this study, a conceptual design of ethanol production by Saccharomyces cerevisiae converting the byproducts from sweet potato processing was proposed based on experimental data and previous publications. An industrialscale plant was designed to produce 5 million liters ethanol annually, accounting for approximately 5% of the total sweet potatoderived ethanol production in Taiwan. The fermentation section of the plant consists of two feed tanks, in which sweet potato peel is pre-treated, diluted and standardized, one batch (aerobic) reactor for microbial culture enrichment, and two parallel systems each consisting of two continuous (an aerobic and an anaerobic respectively) reactors for further culture enrichment and ethanol production.