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Project Description

Project Description

The production capacity of desalinated water in Spain has significantly increased in the last years, as shown in the following table:

Based on the current forecasts, Spain will be the fourth country worldwide in production capacity of desalinated water.

The most recent plants in Spain use reverse osmosis (RO) technology to desalinate seawater, with conversion rates of about 40 - 50%. The plant generates a brine effluent waste product with approximately twice the salinity and with a higher density than that of seawater, behaving like a negatively buoyant effluent in the receiving seawater body. In the Mediterranean Sea, at depths in which brine is usually discharged, the average salinity is about 37.5psu (practical salinity units), the temperature in the water column oscillates between 15ºC and 27ºC and the density varies approximately between 1027.7kg/m³ and 1024.5kg/m³. Therefore, with typical conversion rates, the average salinity of brine effluent is about 68.2psu and the density varies between 1051kg/m³ and 1047.5kg/m³.

In the study of brine discharged into receiving waters, there are two regions with different behaviour of the effluent: the near and the far field region, where the brine discharge behaves very different.

The Mediterranean Sea displays endemic relevant marine ecosystems, such as the Posidonia oceanica and Cymodocea nodosa seagrasses, protected under European legislation as priority natural habitats. Both of them are stenohaline species, tolerating only slight variations in salt concentration.

The increase of desalinated water production in Spain, the negative impacts of brine on marine ecosystems, together with the recent environmental concerns regarding brine management and the lack of legislation, justifies the urgent need to develop a methodology in order to improve brine discharge system designs which guarantee the marine environmental protection. The R&D project “MEDVSA” is conceived with this main objective in mind, financed by the Spanish Ministry of the Environment and Rural and Marine Affairs. The project “MEDVSA: Development and implementation of a Methodology to reduce the brine discharge environmental impact” aims to make compatible the use of desalination as an important water resource in some Spanish coastal areas, with the environmental protection of the marine areas, while following Sustainable Development principles.

(1) Sánchez-Lizaso, J.L.; Romero, J.; Ruiz, J.; Gacia, E.; Buceta, J.L.; Invers, O.; Fernández Torquemada, Y.; Mas, J.; Ruiz-Mateo, A. & Manzanera, M. (2008). Salinity tolerance of the Mediterranean seagrass Posidonia oceanica: recommendations to minimize the impact of brine discharges from desalination plants. Desalination (ELSEVIER), vol 221, pp. 602-607.

(2) Palomar, P & Losada, I.J. (2009). Desalination in Spain: Recent developments and Recommendations. Desalination (ELSEVIER), vol 255, pp. 97-106.