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

Abstract

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 on-line 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 H2 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.