Continuous recovery and enhanced yields of volatile fatty acids from a continually-fed 100 L food waste bioreactor by filtration and electrodialysis

Abstract

A novel method to recover VFAs from a continually-fed 100 L food waste bioreactor was developed using industrially applicable methods. The in-situ recovery of VFAs increased production rates from 4 to 35 mg_vfa g_vs^-1 day^-1 by alleviating end-product inhibition and arresting methanogenesis, and electrodialysis was able to concentrate the recovered VFAs to 4000 mg L^-1. There remains considerable scope to increase the production rates and concentrations further, and the VFAs were recovered in a form that made them suitable for use as platform chemicals with minimal refining. This is the first time that continuous VFA recovery from real-world food waste has been reported at this scale with continual feeding, and represents a promising means through which to produce sustainable platform chemicals. Furthermore the production of VFAs arrests methane production in bioreactors, which is a low value product around which there is a growing concern about fugitive emissions contributing to climate change.

Keywords: Anaerobic digestion; Electrodialysis; Food waste; Resource recovery; Volatile fatty acids.