Use of waste fermenting liquor to produce bioflocculants with isolated strains

Dark fermentation from biomass can produce bio-hydrogen, which is a clean energy source and feedstock used in numerous industries. However, the hydrogen fermentation process produces strong waste fermenting liquor that requires polishing before disposal. This work utilized the waste fermenting liquors to produce bioflocculant from the residual organic matters. Three bacterial strains were noted to have high potential to produce bioflocculants from waste fermenting liquor. In particular, the strain BF-6, identified as Bacillus subtilis by 16S rRNA sequencing, was noted to effectively produce bioflocculant from ethanol-rich mixtures. The BF-6 produced carbohydrate bioflocculants from waste fermenting liquors at a yield of 2.1 g l−1.