In the dairy industry, whatever the cleaning-in-place CIP mode of operation, the cleaning solutions, which become polluted due to the removal of fouling compounds, are drained periodically. The objective of the work is to investigate how large variations of the composition of industrial CIP caustic solutions alter nanofiltration reported to be an efficient membrane,separation for the recovery of caustic solutions. The obtained nanofiltrate was a clear regenerated cleaning solution with low soluble chemical oxygen demand, COD (0.2-3.5 g L-1) and surface tension (56-30 mJ m(-2)) which could be successfully exploited owing to its cleaning potential.