Long-term evaluation of methane production in a bio-electrochemical anaerobic digestion reactor according to the organic loading rate

• Published in: Bioresource technology 2019-02, Vol.273, p.478-486
• Main Authors: Park, Jun-Gyu, Lee, Beom, Park, Hye-Rin, Jun, Hang-Bae
• Format: Article
• Language: English
• Subjects: Anaerobiosis; Bio-electrochemical anaerobic digestion (BEAD); Bioreactors; Electrochemical Techniques; Fatty Acids, Volatile - metabolism; Long-term operation; Methane - biosynthesis; Methane production; Microbial community; Organic Chemistry Phenomena; Organic loading rate; Time Factors
• ISSN: 0960-8524; 1873-2976
• DOI: 10.1016/j.biortech.2018.11.021

•The maximum OLR for stable methane production in an AD reactor was 4.0 kg/m3·d.•Methane production was stable at an OLR as high as 10 kg/m3·d in the BEAD reactor.•Organic acid accumulation and pH decrease were overcome in the BEAD reactor.•BEAD increased communities of exoelectrogenic bacteria and H2-dependent methanogens. In this study, the effects of differing organic loading rates (OLRs) on methane production were evaluated via long-term operation of a bio-electrochemical anaerobic digestion (BEAD) reactor and an anaerobic digestion (AD) reactor. In the AD reactor, the maximum OLR was 4 kg/m3·d whereas the electro-active microbial community in bulk and on the biofilm of the BEAD reactor produced methane even at 10 kg/m3·d. The BEAD reactor rapidly removed volatile fatty acids (VFAs) and reduced H+ to H2 at high OLRs, thereby preventing VFA accumulation and pH decrease. After the steady state was achieved, both the AD and BEAD reactors exhibited similar organic matter removal and methane production at a low OLR. Thus, a BEAD reactor can stably produce methane under conditions of high OLR and severe OLR fluctuation and can even shorten the stabilization period over the long term.