Abstract

A bioflocculant seen as an environmentally friendly flocculant with potential for development, with the capacity to improve its activity and yield has become a hot topic of research among scholars in various countries. This study found that a bioflocculant produced by Bacillus subtilis is able to treat leather wastewater, but the flocculation activity of the bioflocculant needs to be improved. In this paper, the culture conditions of Bacillus subtilis were optimised by single-factor and orthogonal tests. The results showed that the bioflocculant produced by Bacillus subtilis through optimising the culture conditions had good flocculation efficiency. The optimal culture temperature after optimisation was 36°C, the inoculum dose was 5% (v/v), at pH7.5, the culture time was 48 hours, the flocculation efficiency increased from 46.12% to 73.71%, an increase of 59.82%, and the production of flocculant increased from 0.45g/L to 0.61g/L, an increase of 35.56%. Through optimising the culture conditions of Bacillus subtilis the flocculation efficiency of the bioflocculant, was improved and both the cost of flocculation and secondary pollution were reduced.