Effectively converting carbon dioxide into succinic acid under mild pressure with Actinobacillus succinogenes by an...

The aim of the present study is to develop an effective bioprocess for converting CO₂ into succinic acid (SA) with Actinobacillus succinogenes by an integrated fermentation and membrane separation process. CO₂ could be effectively converted into SA using NaOH as the neutralizer under the completely closed exhaust pipe case with self-circulation of CO₂ in the bioreactor. Meanwhile, the optimal CO₂ partial pressure was 0.4 bar. In addition, a 300 kDa ultrafiltration (UF) membrane was preferred for constructing the membrane bioreactor. Moreover, a high conductivity was toxic to the cells during SA biosynthesis. After removing the high concentration salts by in-situ membrane filtration, the SA productivity and CO₂ fixation rate increased by 39.2% compared with the batch culture, reaching 1.39 g·L^-1·h^-1 and 0.52 g·L^-1·h^-1 respectively. Furthermore, nanofiltration (NF) was suitable for purifying the SA and recovering the residual substrates in the UF permeate for the next fermentation.