Potential and characteristics of bio-H production from brewery wastewater by a maltose-preferring butyrate-type producer: Investigation in batch and semi-continuous cultures.

In the context of "Peak CO emissions & Carbon neutrality", H energy, as the green and clean energy, will make an important contribution to the carbon emission reduction and carbon neutralization. Bio-H production from organic wastewater achieved not only pollutants removal, but also the H energy recovery and carbon emission reduction. In this study, a maltose-preferring producer of Clostridium butyricum NH-02 was investigated for the potential and performance of bio-H production from brewery wastewater in batch and semi-continuous fermentation. Appropriate initial pH 7.0 and organic loading of 21,173 mg/L chemical oxygen demand (COD) (2670 mg/L reducing sugar (RS)) stimulated the batch H fermentation efficiency with a maximum H yield of 1.89 mol-H/mol-RS and cumulative H production of 479.3 mL/L. Comparing to the batch fermentation, semi-continuous fermentation showed significant improvement in H productivity and yield. The maximum cumulative H yield of 5.21 mol-H/mol-RS and production of 254.78 mL were obtained with the optimal hydraulic retention time (HRT) at 47 h after a 120 h fermentation. This study demonstrated the potential of H production from brewery wastewater with C. butyricum, and a great improvement in H production in semi-continuous fermentation.