Background Surface water and groundwater are subject to pollution by waste water and various natural and synthetic chemicals, which are proven to be present in most water bodies in Europe. These include synthetic organic chemicals, pesticides, drugs and endocrine disruptors. Maintaining and improving the aquatic environment is one of the main objectives of European water policy. According to the European Water Framework Directive (2000/60/EG) “the ultimate aim …. is to achieve the elimination of priority hazardous substances and contribute to achieving concentrations in the marine environment near background values for naturally occurring substances”. One of the main challenges to achieving this is removing substances derived from the large quantities of pharmaceutical and personal care products (PPCPs) that enter water systems. Removal of PPCPs requires advanced ‘tertiary’ treatment to remove stubborn contaminants. However, existing tertiary treatment techniques – including advanced oxidation, nano-filtration and reverse osmosis - offer relatively low retention yields and are very costly, in terms of the initial investment, energy consumption and maintenance. Such treatments are, therefore, still not widely used in wastewater treatment plants (WWTPs). Objectives The main goal of the WATOP project is to develop a semi-industrial pilot plant to demonstrate a new purification system for remove PPCPs from wastewater. The project aims to show that a membrane filled with innovative nano-resins of cross-linked cadmium (CD) and sodium polyacrylate (PAA) will remove PPCPs and other pollutants from water in a highly effective and efficient way. The project has set a target of 82-94% removal of PPCPs from wastewater in the pilot treatment process. It also hopes to develop the regeneration capability of the membrane - by means of mild thermal treatment (lower than 120ºC) and by washing with a solution of methanol – and to reduce or even eliminate clogging problems on the membrane. By demonstrating the technological viability and environmental and economic benefits of the new tertiary treatment process, the project ultimately hopes to improve both water quality and the management of water resources. Expected results: The expected results of the pilot tertiary wastewater treatment process include: Demonstration of an active filter device capable of processing 3 000m3/day of wastewater with an energy consumption of 0.9-1.20kWh/m3 of permeated water; Retention of 82-94% of target compounds; High performance in different conditions: ptimal operating pH levels between 3 and 10 and temperature between 1 and 25ºC; Extended useful life of the purification unit, providing an efficient and long-term device; Reduction of operating pressure to below 15 bars, with an associated reduction in energy consumption per m3; Reduction of economic costs of the tertiary treatment to 0.20-0.12€/m3.