The importance of membrane processes in wastewater treatment is continuously growing. Membranes can be used for the separation of liquids, dissolved or suspended solids or solutes in the colloid form. The main features of membrane processes application for the treatment of spent solutions are possibilities of removal or recovery of valuable or harmful components as well as the possibility of closing water systems what reduce fresh water consumption. Very often the use of membrane processes allow to purify wastewater to a degree difficult to achieve by conventional techniques. The possibility of an application of pressure driven techniques such as ultrafiltration (UF), nanofiltration (NF) and reverse osmosis (RO) for oily wastewater treatment, has been presented. The studies on the two-stage treatment of bilge water combining UF and RO or NF have demonstrated a high effectiveness of purification. NF could also be applied to recover glycols from spent coolant liquids. The utilization of membrane distillation for saline wastewater concentration or for the treatment of spent metal pickling solutions was demonstrated.The potential application of a hybrid process combining photocatalytic degradation of organic matter with membrane separation for the treatment of wastewaters from textile industry has been shown.