In this study, investigations were made to close water cycle in dye-houses. At the first stage, optimum operation conditions of a membrane nanofiltration were determined. Experiments were carried out for DL membranes (Osmonics, USA). The effect of temperature, pressure and pH was investigated. Investigations were performed for different types of real wastewater produced in a laboratory-scale Pyrotec S dyeing apparatus (Roaches) for various types of reactive dyes. An over 90% dye hold-up was obtained for all dye baths. At the final stage of the experiments, dyeing processes were carried out with the use of a filtrate from nanofiltration as water applied for dyeing, rinsing and washing after dyeing. In cooperation with the Technical University of Lodz. we have managed to apply biological degradation of the concentrate, carried out in two different reactor systems. (C) 2009 Elsevier B.V. All rights reserved.