An integrated biological hydrogen production process based on ethanol-type fermentation and bipolar membrane electrodialysis

• Bipolar membrane electrodialysis (BPEM) can separate acetate and recover glucose.
• BPEM operation can create a pleasant pH range for ethanol-type fermentation.
• Separation of acetate has a great role in promoting biohydrogen producing capacity.

An integrated bio-hydrogen production system involving fermentative hydrogen production and product separation is proposed. In this process, microorganisms conduct ethanol-type fermentation and generate H2 gas in anaerobic bioreactor, and acetate is removed from fermentation broth by using a two chamber bipolar membrane electrodialysis as separation unit. A comparative study of fermentative hydrogen production of Ethanoligenens harbinese B49 in the integrated system with traditional fermentation process was carried out. Compared to traditional process, accumulated H2 elevated 23%, glucose utilization ratio increased by 135% and cell growth increased by 27% in the integrated system. The specific hydrogen production rate reached 2.2 mol H2/mol glucose, indicating that separation of acetate from fermentation system has a great role in promoting hydrogen producing capacity. Bipolar membrane electrodialysis showed high acetate separation efficiency and low glucose loss rate. In the integrated system, pH could be used to direct electrodialysis operation, since it has an exponential correlation with acetate concentration in fermentation broth. These results provide a new method for achieving efficient and stable H2 production with simultaneous glucose recovery and acetate inhibition release.