A slurry electrode integrated with membrane electrolysis for high-performance acetate production in microbial electrosynthesis

Microbial electrosynthesis (MES) technology employs electrotrophic microbes as biocatalysts to produce chemicals from CO2. The application of a slurry electrode can enlarge the surface area to volume ratio, and membrane electrolysis (ME) for online extraction can solve the problem of product inhibition. This study constructed a novel dual-chamber ME-MES integrated system equipped with a slurry electrode, and the effect of concentration of powder-activated carbon (AC) in the catholyte on chemical production was also evaluated. The integrated system amended with 5 g L-1 AC produced up to 13.4 g L-1 acetate, showing a 179% increase compared with the control group without AC (4.8 g L-1). However, further increasing the AC concentration to 10 and 20 g L-1 resulted in decreased acetate production. A high concentration of AC showed higher antimicrobial activity to methanogens, as compared to acetogens. Amending AC exacerbated the process of electroosmosis. Also, amending AC with 0 to 10 g L-1 decreased the electrochemical losses via both the membrane and electrolyte. The chemical production using H-2 or the electrode as electron donors showed a similar trend when amending AC. The present study provided important information for guiding future research to construct an efficient configuration of an MES bioreactor. (c) 2020 Elsevier B.V. All rights reserved.