Seawater desalination

While water occupies over 70% of the Earth's surface area, liquid fresh water only represents 1%. Its scarcity, in particular in arid areas, and the demographic pressure on the resources available are an incentive to seawater desalination. This alternative solution is developing rapidly given that one quarter of the world's population live less than 25 km away from the coast, very often in areas with limited fresh water resources.

Desalination consists of producing fresh water (drinking water, irrigation water or industrial water) from seawater or brackish water. 

There are two possible systems:

• distillation (condensation of seawater steam brought to the boil)
• membrane processes such as reverse osmosis (filters capturing impurities and salts).

With the development of membranes and the cost of membrane desalination cut in half, drinking water production plants have multiplied in the past ten years. However, the quality of local water can sometimes be an obstacle in the operation of these processes. There are also technical challenges to be met in order to make seawater desalination less energy consuming and more economical.

Our research aims at developing the best design and operation strategies for our desalination plants. It focuses on:

• improving our understanding of clogging phenomena;
• optimizing reverse osmosis pre-treatment methods.

In 2007 our work related in particular to:

• characterizing seawater by developing analytical tools and a database;
• monitoring the performance of pre-treatment processes in pilot units and desalination plants;
• developing a tool for the energy and environmental assessment of production processes.

2007 highlights include:

• the definition of the best possible pre-treatment process for Mediterranean water;
• the signing of an agreement for the installation of a test platform in the Persian Gulf and the definition of pilot processes to be designed;
• the validation of new seawater characterization tools and the development of adapted analytical tools for the autopsy of reverse osmosis membranes.