Dyes present in industrial effluents can either be treated and destroyed by physicochemical or biological processes, or recovered and recycled to the initial process. The recovery of the dye is economically attractive if (a) is an expensive product and (b) is present in significant amounts and/or concentrations. Moreover, recovery of the dye is more difficult in the wastewaters that in the intermediate stages of the process. Membrane technology offers one alternative for the recovering of dyes. The performance of the nanofiltration membrane NF90SR for the recovery of the Acid Yellow 23 dye, which is widely used in the coloration of textiles or in food manufacturing, was studied. Colour removal above 97% was observed. Also, a permanent diafiltration process, achieving up to 90% elimination of the salt present in the solution, was implemented in order to enhance the economic value of the residue.