The periodic disappearance of fish from the marshes of Regliala (Algiers) caused by industrial waste alarmed responsible personnel at the Department of the Environment to pollution that threatens one of the most significant wet sites of Algeria. An anti-pollution plan was developed and put in action. This plan aims to provide an overall basis for evaluating the pollution generated by the various units in the industrial park of Rouiba-Reghaia, in order to reduce or to stop pollution affecting the marshes of Reghaia. Our work presents a complementary study on the effluent of a leather processing unit at Rouiba [1-4]. Our study was based on the effluent of liming baths which contain a great quantity of sulfides. To reduce the pollution generated by sulfides in the effluent, we were interested in the use of nanofiltration in order to refine post-processing such as precipitation.