The leather finishing process requires high water consumption that becomes considerably contaminated wastewater. The normal processes for treating this waste based on lime precipitation succeed in reducing tbe chemical oxygen demand , chromium, suspended solids and colour, but do not usually satisfy the regulation in force. Considering the inadequacy of the conventional processes to vironmental demands and aware of the growing scarceness of water, this has the prime objective of develop a waste treatment system that guarantees the environmental demands whilst saving water, by recycling it. The technolo that will be studied is the membrane processes (reverse osmosis and nanofiltration). By means of the membrane processes, all components present in the wastewater are retained, while high quality water pass through the membrane. In this way, two steams are obtained: a concentrate and high quality water, that is cycled back to the production process. So, the wastewater problem is solvedbut the concentrate must be treated or disposed off, because it is a toxic residue. Different alternatives like incineration, chemical oxidation and eleemical oxidation will be studied for the treatment of the concentrate. The oject consists of the following stages: basic studies, pilot and demonstration plant studies with synthetic and real wastewaters, and studies of the concentrate treatment .