Background Protection of water resources is a cornerstone of environmental protection in Europe. Clean water demands careful management to protect ecosystems, society and industry. However, water scarcity affects at least 11% of Europe’s population and 17% of EU territory. Poor or unsuitable water quality reduces its availability by restricting its possible uses and increasing supply costs. The industrial sector is the second largest consumer of water after agriculture, with the petrochemical industry being a major water user (cooling and processing); it generates 1 750 MT of wastewater per year in Europe. Efficient techniques for recycling and reclaiming this water are necessary. The Water Framework Directive identifies water re-use, recycling and the promotion of water-efficient technologies as an important measure for EU action in the field of water policy. The European Innovation Partnership on Water also identifies water recycling as its top-listed priority. Furthermore, the EU’s Blueprint to Safeguard Europe’s Water Resources includes the maximisation of water re-use and recycling as one of its core actions. Objectives The main objective of LIFE REWATCH is to decrease the environmental impact of the petrochemical industry by demonstrating an innovative water recycling system based on a combination of existing biological and separation processes. To achieve this aim, the project will analyse and characterise the wastewaters produced by different European petrochemical plants. It will then design and build a prototype plant in the facilities of a petrochemical complex in Tarragona (Spain). A key innovation of the new process will be its high versatility, making it capable of treating wastewater of different qualities to the standards required for various re-use applications. The project will evaluate the environmental benefits and the economic feasibility of the technology, based on its operation in the pilot plant, using life cycle analysis (LCA) and life cycle cost (LCC) procedures, and water footprint calculations. Finally, the project will develop a decision-support tool to boost the transferability of the technology, which will enable other petrochemical industries to design water treatment procedures based on their own wastewater compositions and the water quality needed for local re-use. This demonstration will be an important step towards sustainability in the European petrochemical industry. Expected results: A versatile water recycling scheme for the treatment of petrochemical wastewater streams (min. 65% water recovery); Treatment of at least 20 000 m3 of wastewater, providing 12 600 m3 of reclaimed water; Effluents obtained that could be re-used in different points of the petrochemical industry; A decision-support tool to predict the performance of the new process and to encourage other petrochemical industries to implement the new water recycling scheme; Decreased environmental impact related to water management in petrochemical plants. The project expects that a full-scale implementation will be able to decrease the water footprint by 15%, decrease energy consumption by 15% and decrease CO2 emissions by 10%, relating to water management in petrochemical plants; and Decreased economic impact related to water management in petrochemical plants by at least 10%.