Following operating experience from a 500 m3/day pilot plant in El Gouna in Egypt, a low temperature distillation process has been launched which claims to produce water using less than 1.0 kilowatt hour per cubic meter (kWh/m3).
Called the Watersolutions low temperature distillation (LTD) system, the process is based on the principle of low temperature distillation and claims an operating cost of between one third and half of existing processes, according to the company.
LTD 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.
Significant amounts of low grade waste heat (6 - 30 MW) are required that can be derived from any source including thermal power plants, district cooling systems, general industry, mining and waste incineration.
Watersolutions said the LTD system with one cascade can produce pure water at less than 1.0 kilowatt hour per cubic meter (kWh/m3) in contrast to SWRO which typically uses 3.5 – 4.5 kWh/m3 of water production.
The company said that 1.5 m3 of seawater is needed to produce 1.0 m3 of clean water (< 10 ppm of dissolved solids).
Units are available in two sizes – a large module that produces 1000-2000 m3/d (pending the amount of waste heat available and number of cascades) and a medium module with capacity of 500-1000 m3/d.
According to the firm, LTD works efficiently over a broad range of salinity. “Because the process is very tolerant to the salinity of the feedwater, it can even handle brine concentrate from RO. As a result, retrofitting an existing RO plant with an LTD system would be an efficient way to increase the plant’s capacity,” said Watersolutions.