Cork boiling wastewaters were processed by nanofiltration (NF) in order to concentrate phenolic compounds, whose tanning power allows their application in the leather tanning process as a retanning agent, and to produce a permeate suitable for reuse in the cork boiling operation, according to the International Code of Cork Stopper Manufacturing Practice. Four commercial polymeric membranes were selected and tested at laboratory scale: NTR7450, Desal-DK, NF90 and NF270. The feed volume reduction factor (VRF) was defined to be equal to seven or higher, and the operation was carried out in a batch mode at 15 bar and 25 degrees C. The performance of the different membranes was evaluated determining membrane permeability and rejection coefficients for several pollutant indicators: total organic carbon (TOC), colour, absorbance at 254 nm and salt content. Two membranes were selected to perform pilot-scale studies, NF270 and NF90, based on their performance in this process. The results obtained in the laboratory and pilot-scale studies permitted the development of a mass balance model, which was calibrated with experimental data. Additionally, a technical and economical evaluation study was performed, which showed that the process proposed in this work is viable for industrial application. (C) 2008 Elsevier B.V. All rights reserved.