Enhancement of acidogenic fermentation for volatile fatty acid production from food waste: Effect of redox potential and inoculum

The aim of this study was to explore the effects of redox potential (ORP) and inoculum on volatile fatty acids (VFAs) production from food waste by acidogenic fermentation. Four experimental conditions with two ORP levels were tested: limited aeration conditions with ORP level of -100 to -200 mV inoculating anaerobic sludge (LA + AnS) or aerobic sludge (LA + AeS), and anaerobic conditions with ORP level of -200 to -300 mV inoculating anaerobic sludge with 2-bromoethanosulfophate (AN + BES) and without BES (AN). The maximal VFA yield (0.79 g COD/g VS) was attained in LA + AnS reactor due to enhanced hydrolysis of substrates, especially proteins (degradation efficiency 78.3%). A higher frequency of phylum Firmicutes under limited aeration conditions (42.2-48.2%) was observed than that under anaerobic conditions (21.1%). The microbial community was more diverse in LA + AnS reactors than LA + AeS. We conclude that appropriate ORP level (from -100 to -200 mV) and inoculum play essential roles in VFA production. (C) 2016 Elsevier Ltd. All rights reserved.