Microbial community dynamics and volatile fatty acid production during anaerobic digestion of microaerated food waste under different organic loadings

Abstract

This study examined the effects of microaeration pretreatment and varying organic loading rates (OLRs) on volatile fatty acids (VFAs) production from food waste (FW) via anaerobic digestion process. FW was pretreated with 6 mL O₂/g VS and digested at OLRs ranging from 10 to 25 g/L VS. Microaeration pretreatment increased the VFA yield to 7.4 g/L, whereas without pretreatment, it was 5.19 g/L, with butyrate as the dominant VFA (92 % at 25 g/L OLR) due to Firmicutes enrichment. A relatively high OLR initially increased VFA production but later favored propionate without pretreatment. Microbial analysis revealed that aerobic conditions promoted lactic acid bacteria such as Lactobacillus, increasing lactic acid production, whereas anaerobic conditions promoted Prevotella and butyrate producers such as Clostridium, which specialize in acetate and butyrate production. This study highlights that microaeration and an optimal OLR can increase and stabilize VFA yields, modulating the microbial community for tailored VFA profiles that are useful in biofuel and biochemical applications.