Effects of a novel auxiliary bio-electrochemical reactor on methane production from highly concentrated food waste in an anaerobic digestion reactor

• Published in: Chemosphere (Oxford) 2019-04, Vol.220, p.403-411
• Main Authors: Park, Jun-Gyu, Lee, Beom, Kwon, Hye-Jeong, Park, Hye-Rin, Jun, Hang-Bae
• Format: Article
• Language: English
• Subjects: Anaerobic digestion; Auxiliary bio-electrochemical reactor (ABER); Food waste; Methane production; Microbial community; Organic loading rate (OLR)
• ISSN: 0045-6535; 1879-1298
• DOI: 10.1016/j.chemosphere.2018.12.169

In this study, the effects of indirect voltage supply to an anaerobic digestion (AD) reactor on methane production and the removal of chemical oxygen demand (COD) were studied at different organic loading rates (OLRs) of food waste by the circulation from an auxiliary bio-electrochemical reactor (ABER) with stainless steel (STS304) electrodes. The effects of the indirect voltage on microbial communities in the AD reactor were also investigated. In a bio-electrochemical anaerobic digestion (BEAD) reactor with direct voltage, it was possible to achieve stable COD removal and methane production even at a higher OLR of 10.0 kg/(m3·d). However, in the AD reactor, the COD removal efficiency and methane production decreased sharply at an OLR of 6.0 kg/(m3·d) due to the accumulation of volatile fatty acids (VFAs) and decreases in the pH and alkalinity. The supply of indirect voltage through the ABER increased the community of exoelectrogenic bacteria and hydrogenotrophic methanogens in the AD + ABER bulk solution. As a result, rapid oxidation of the accumulated VFAs occurred, and methane production increased in the new AD + ABER system. The results confirm that an indirect voltage supply to the new AD + ABER system can have effects similar to those of a direct voltage supply to the BEAD reactor, and the findings are expected to provide useful information for the development and application of BEAD technology for commercialization. [Display omitted] •An auxiliary bio-electrochemical reactor was studied for treating food waste.•With the auxiliary reactor, anaerobic digestion reactor performance improved.•An increase in electro-active microbial communities was seen.•Methane production and organic removal rates were stable at high organic loads.•Implications for commercialization of bio-electrochemical anaerobic digestion.