Bioethanol is a renewable energy source as an alternative to fossil fuels. Bioethanol is produced from starchy biomass in the U.S. such as corn. However, a cheaper non-food value source is needed. In this context, wastes of industrial potato processing plant were utilized as carbon source for ethanol production. On the other hand, to reduce the cost of ethanol and improve the effectiveness of the process, cell immobilization was employed. Plastic composite supports (PCS) are solid supports that were used to stimulate biofilm formation in bioreactor (a.k.a. biofilm reactor) during microbial production of value-added products. Therefore, in this study, PCS were employed to promote the cell population and biofilm formation in the reactor. Response surface methodology was used to evaluate the various growth conditions, pH, temperature, and agitation, for enhanced ethanol production in biofilm reactors. The optimum conditions were found to be 4.2 pH, 34 °C, and 100 rpm agitation. An optimum ethanol concentration of 37.05 g/L ethanol yield, giving a 92.08% theoretical yield was achieved. The results indicated that biofilm reactors can enhance the ethanol fermentation from industrial potato wastes.