A patented low-temperature cost-effective distillation process for seawater desalination has been introduced by Swiss company Watersolutions AG.
A pilot plant in El Gouna, Egypt has proven the principle, with very pure water being produced reliably and efficiently.
The Watersolutions LTD system condenses water at low temperature and pressure, using waste heat (50‑110°C) from thermal processes including renewable energy sources such as solar energy or geothermal energy. The system requires significant amounts of low grade waste heat, which can be derived from any source including thermal power plants, district cooling systems, general industry, mining and waste incineration.
Operating costs, excluding depreciation, are projected at only a third to a half of existing processes. For example, the Watersolutions LTD system with one cascade can produce pure water at less than 1.0 kWh/m³. By contrast, seawater reverse osmosis typically uses 3.5‑4.5 kWh/m³ of water production.
Another benefit is the high conversion ratio, with only 1.5 m³ of seawater needed to produce 1.0 m³ of clean water (<10 ppm of dissolved solids). Maintenance requirements are very low.
The Watersolutions LTD system is modular, scalable and easy to install. The expected lifetime of an LTD plant is 25‑30 years, due to the simplicity of the design, the combination of high quality materials used, and its ability to function at relatively low pressure. Due to the robustness of an LTD plant and its high conversion ratio, the plant operates using a relatively small amount of chemicals for pretreatment etc.
Distilled water is used in innumerable ways in many industries, and being able to produce it in as efficient and environmentally-conscious a way as possible will bring even further benefits. The Distilled Water Company already provides excellent quality distilled water to our customers, and hopefully the technology into making distilled water will continue to develop.