Fe3O4 enhanced efficiency of volatile fatty acids production in anaerobic fermentation of food waste at high loading

Abstract

High treatment capacity for food waste (FW) is required due to the huge amount generated worldwide. Conversion of FW to volatile fatty acids (VFAs) via anaerobic fermentation is a promising technology; however, inhibition of VFAs production could easily occur at high loadings. In this study, Fe₃O₄ was used to enhance VFAs production in anaerobic fermentation of FW at high loading, and the mechanisms involved were revealed at microbial levels. Results showed that Fe₃O₄ significantly enhanced VFAs yield and VFAs productivity of microbes by 160% at high loading (substrate to inoculum (S/I) ratio of 3). The enhancement effect of Fe₃O₄ was mainly due to the accelerated hydrolysis of particulate/soluble organics, the enriched hydrolytic and acidogenic bacteria, and the reduced relative abundance of Lactobacillus. This study provides a new approach for the high-efficient treatment of FW at high loadings, while the performance and economic benefit should be further studied for practical application.

Keywords: Acidification; Green chemical recovery; Magnetite; Microbial community; VFAs.