Recovering used cleaning-in-place (CIP) solutions in the dairy industry aims to maintain constant cleaning efficiency, minimize pH variations and effluent volume and save water, chemicals and energy. Although industrial membrane processes have been commercially available for the regeneration of an alkaline solution, few works have investigated the way to select a membrane process [M.A. Henck, Ph D Thesis, University of Zurich, 1993 and M. Dresch, PhD Thesis, National High School of Agriculture of Rennes, 1998]. Nanofiltration was recently shown to be more performing than microfiltration, ultrafiltration, decantation and centrifugation for the regeneration of an industrial alkaline solution [M. Dresch, G. Daufin, B. Chaufer, Lait 79 (1999) 245-259]. The present work is intended to compare different designs of integration of an NF plant in CIP systems. Two integrated CIP process (discontinuous, continuous) were compared with a common industrial re-use CIP system (periodical withdrawal and renewal of cleaning solution) by taking into account the evolution of pollution (chemical oxygen demand, COD) in the running CIP system. The most appropriate mode of operation (batch, fed-batch, feed and bleed) was previously determined by the evolution of NF performance established for each mode. Numerical simulations were completed using calculation hypotheses from Dresch et al. [M. Dresch, G. Daufin, B. Chaufer, Lair 79 (1999) 245-259]. The NF plant operating in fed-batch mode is better suited than batch and feed-and-bleed modes. The NF operation can be integrated in the CIP system according to two ways: (i) Discontinuous process with a membrane unit working when the CIP system is idle, the permeate being collected in an extra tank. Then, equations relate: (1) maximum pollution concentration reached in the tank after n regenerations to pollution rate, volume of solution to be treated V-CIP, cleaning cycle duration, Deltat and average pollution reduction; (2) membrane area, A to V-CIP, permeation flux, J, NF duration and volume reduction ratio. (ii) Continuous process, the permeate being recycled directly to the CIP tank. The equation relates pollution concentration (regenerated cleaning solution) to pollution rate, J, membrane area, A, pollution reduction, volume of CIP solution tank, V-CIP and NF duration. Whatever the selected integrated process, COD in the CIP tank stabilizes at a level depending on the membrane area: the larger the area, the lower the level. The membrane area can thus be calculated from a COD level that should not be exceeded in the CIP tank, provided the characteristics of the CIP tank (volume, increasing rate of pollution) and the performances of the membrane unit (J, COD reduction) are known. With sufficient NF membrane area, the membrane regeneration integrated CIP process allows lower COD content to be maintained compared to the common industrial re-use CIP. The continuous process is easier to set-up and less expensive than the discontinuous process. The pay-back time is long (over 15 years).