LIFE REWATCH: a demonstration project for water reuse in the petrochemical industry
The petrochemical industry is, in many countries, the major consumer of water resources and a significant hazardous waste producer, and is therefore subject to increasingly stringent environmental standards. The DOW North petrochemical complex in Tarragona, Spain has an annual water demand of 5.3 hm3/year and generates an annual wastewater of 1.9 hm3/year. Currently, the sources of feed water are the Ebro River (75%) and reclaimed water from the Water Reuse Project Camp Tarragona (25%). This water is primarily used for cooling water make-up (92%) and boiler feed (8%).
The challenge of the LIFE European funded REWATCH project is to improve the environmental footprint and sustainability of the petrochemical industry. The aim of the project is to demonstrate and disseminate the technical feasibility of an innovative water recycling scheme as well as its economic and environmental benefits.
The REWATCH demonstration plant is located in the ethylene cracking facility of the DOW North petrochemical complex in La Pobla de Mafumet, Tarragona. Three different industrial wastewater streams (process water, intermediate water and oily water, that account respectively for 11, 71 and 18% of the total wastewater flow) can feed the plant at different points in the process, either mixed together, or individually. Due to the complexity of wastewater characteristics, a robust treatment scheme has been proposed based on complementary technologies. The presence of oil, possible toxic compounds for biological COD removal and nitrification process, high concentrations of recalcitrant COD, and membrane fouling are the technological challenges to be addressed. The implemented Veolia technologies, provide an effective barrier against wastewater variability. Following these physico-chemical and biological treatment steps, ultrafiltration, reverse osmosis and ion exchange resins process steps are provided by DOW Water & Process Solutions to generate different water qualities suitable for various uses onsite. The process treatment train is shown in the figure below.
The technological solution has been designed to be fully flexible so that each unit can be operated separately. It allows changes in configurations and conditions. The design also allows plant operators to generate several qualities of reclaimed water in order to satisfy the demand for different water uses. For instance, water obtained after ion exchange resins can be used as boiler feed water because of its high quality and water produced by reverse osmosis can be used for cooling water make-up. Other generic usages like landscape irrigation, firefighting, and equipment cleaning could be conducted with water from the ultrafiltration step.
The demonstration plant is planned to be operational in a year’s time. With all results and data compiled, a decision support tool will be developed in order to predict the environmental and economic benefits of the technology so as to be able to design the most adequate wastewater treatment in other petrochemical complexes.
Fundació CTM Centre Tecnològic de Manresa (CTM), DOW Chemical Ibérica (DCI), Veolia Water Technologies (VWT), KWR Water, European Water Supply and Sanitation Technology Platform (WssTP)
This project has been funded with support from the European Commission. This publication [communication] reflects the views of only the author, and the European Commission cannot ne held responsible for any use which may be made of the information contained therein
Elisenda Taberna - Process, Innovation & Methods Engineer, Veolia Water Technologies