AbstractWine alcohol distilleries produce eight volumes of high‐strength waste from every volume of ethanol. This waste has an acidic character, an average COD of 21 g dm−‐3 and an average BOD of 13 g dm−‐3.This paper examines aerobic treatment as an alternative to anaerobic digestion for the reduction of waste strength. The process from the start‐up of the digestors until attainment of steady‐state conditions, and the optimization of the process to achieve an adequate purifying performance were studied.Once optimum operation conditions had been attained (at 8 days retention time), COD and BOD removals of 78% and 88%, respectively, were achieved.A Substrate Utilization Model predicted accurately the performance of the purifying process, except at retention times of less than 3 days, where the system works in unsteady conditions.