A novel and environment-friendly bioprocess of 1,3-propanediol fermentation integrated with aqueous two-phase extraction by ethanol/sodium carbonate system

• Developing an efficient integrated system of fermentation and separation by ATPS.
• The system can dramatically increase the fermentation and separation efficiency.
• The system could recover most of salt.
• The system could dramatically reduce the energy expenditure and CO2 emissions.

An integrated fermentation–separation process for the production of 1,3-propanediol (1,3-PD) was investigated. Aqueous two-phase system (ATPS) not only recovered 97.9% of 1,3-PD, but simultaneously also removed 99.1% cells, 81.9% proteins, 75.5% organic acids, and 78.7% water. Furthermore, after extraction the bottom phase of ATPS was used to adjust the pH of the culture during fermentation, leading to 16% and 126% increases in the concentrations of 1,3-PD and lactic acid, and dramatic decreases in the concentration of acetic acid and formic acid. The total mass conversion yield of three main products (1,3-PD, 2,3-butanediol, and lactic acid) from glycerol reached 81.6%. The salt-enriched phase could also be used to absorb carbon dioxide (CO2), resulting in 94% recovery for carbonate. Finally, process simulation using the program PRO/II showed the use of ATPS reduced 75.1% of the energy expenditure and 89.0% of CO2 emissions.