Use of chitosan as an antifouling agent in a membrane bioreactor

While most studies regarding the biocatalytic chiral resolution of 1,2-epoxyoctane by Rhodosporidium toruloides have been done in batch processes, a dead-end bioreactor was used in this research. Due to the observed fouling of the membrane by the biocatalyst (yeast cells), the aim of this study was to investigate the suitability of chitosan as an antifouling agent. The process was optimised in terms of flow rate as a function of the pressure, as well as the amount of chitosan and biomass in the reactor. It was found that higher and stabilised flow rates for extended periods of time were obtained in the presence of chitosan. For 1 g chitosan the flow rate increase was 130% with a resistance reduction of 57%. Using a response surface statistical method the maximum flow rate (0.233 ml.min−1) was obtained at a pressure of 40-43 kPa, using the minimum amount of cells (0.4 g) and the maximum amount of chitosan (1.6 g). Finally it was shown that by increasing the flow rate a decrease in the percentage of enantiomeric excess of the substrate (eesubstrate) and an increase in the percentage of enantiomeric excess of the product (eeproduct) was obtained.