Construction of a fuzzy control system for a bioreactor using biomass support particles

A fuzzy control system was applied to a bioreactor in which the flocculent yeast Saccharomyces diastaticus ATCC 60715 was immobilized by entrapment in a reticulated polyurethane foam cube (6 mm×6 mm×6 mm, biomass support particle (BSP)). The fuzzy inference algorithm was used to calculate the suitable level of glucose feed rate from the monitored data of the CO2 evolution rate (CER) and the integrated amount of CO2 evolution. One of the main concerns is the mass transfer of glucose in the BSP in which S. diastaticus was immobilized. With the BSPs, glucose diffusivity becomes lower and starvation of the cells can occur if the control system is not quick enough to respond to the starvation. The fuzzy control system was successful in controlling the glucose feed pump to maintain a suitable glucose concentration for the smooth continuation of ethanol production.