Bioelectrochemical reduction of carbon dioxide (CO2) to multi-carbon organic compounds particularly acetate has been achieved in microbial electrosynthesis (MES) using the reducing equivalents produced at the electrically polarized cathode.
MES based on CO2 reduction produced 7–10 g L−1 acetate at the cathode while operating the CO2 fed reactor in batch mode using the homoacetogenic activity enriched mixed culture. An integration of acetate extraction from the catholyte is interesting, firstly to recover the product and secondly to reduce the probable product inhibition due to the accumulation of fatty acids.
We investigated acetate production from CO2 in MES in combination with a batch-wise removal of acetate from the broth using a commercially available anion-exchange resin (Amberlite™ FPA53). Acetate sorptions of 10–20 mg g−1 resin were observed from the catholyte broth. The production of acetate from CO2 continued at 0.5 g L−1 d−1 after the acetate removal by sorption.
Overall, an MES system for the production and separation of acetate from CO2 was technically feasible through the integration of MES with an anion exchange resin.