Production of Bioflocculant Using the Effluent from a Hydrogen-Producing Bioreactor and its Capacity of Wastewater Treatment

In this study, compound bioflocculant-producing bacteria, named F
₂
-F
₆
, were adopted as bioflocculant (BF) producer. In order to domesticate the strains of F
₂
-F
₆
to utilize the effluent from a hydrogen-producing bioreactor as the only carbon resource, a method of poor-rich alternative nutrition was developed. After acclimation, the optimum fermentation conditions were investigated using only the effluent as culture substrate. The optimum fermentation conditions were to be initial pH of 7.0, fermentation time of 21 h, rotation speed of 140 rpm, temperature of 30degC and no sterilization of the culture. Under these conditions, the maximum flocculation rate of the BF produced was over 93.0%. The weight-average molecular weight of BF was more than 106 Da according to the result of molecular exclusion chromatography. It was also found that the bioflocculant has high capacity of turbidity-removal, color- removal and organic-removal up to 98.7%, 90.3% and 62.6% respectively when it was used to treat domestic wastewater, black ink wastewater and Chinese medicine wastewater.