An acid recovery system used in a hydrolysis operation includes a chromatographic unit to provide initial separation of sugar and acid. The sugar product provided by the chromatographic unit is processed to produce higher value products, such as ethanol. The remaining acid is contaminated by sugar. A nanofiltration unit containing a nanofilter membrane processes the sugar contaminated acid. The acid is allowed to permeate across the nanofilter membrane while sugar is rejected. The permeate is provided to a conventional acid recovery system and recycled for use in the hydrolysis process.