Repeated Batch Fermentation Recycling Waste Water Of Fermentation With Cell Separation For Lipid Production

Biodiesel is a good alternative for fossil fuels, and microbial oil is particularly the most potential raw material of biodiesel production. Large waste water disposal was the major problem in microbial lipid fermentation because of the intrinsic property of low and intracellular product (lipid) yield. In this study, the repeated batch fermentation with water recycling and cell separation was investigated for the reduction of the waste water generated in the lipid fermentation of an oleaginous yeast Trichosporon cutaneum CXl strain. In the repeated batch fermentation, the waste fermentation broth was recycled in the next batch operation after the cells were separated with the fermentation broth using two different methods, centrifugation and flocculation. Besides, chitosan showed great effectiveness as a natural flocculant for the flocculation of Trichosporon cutaneum CXl. And the result showed that flocculation can be a good replacement of centrifugation as a separation method. Furthermore, when flocculation method was applied, it is an easy way for saving energy and lowing the risk of contamination. The result also showed that at least70%of the waste water was reduced using the proposed operation in the substrate of glucose and inulin, while lipid production maintained satisfactory in the initial four circles. Furthermore, it is suggested that T. cutaneum CXl cells might produce certain naturally occurring inulin hydrolyzing enzyme(s) for obtaining fructose and glucose from inulin directly. The proposed fermentation method provided a practical option for reducing the waste water generation of microbial lipid fermentations.