South African state-owned power utility, Eskom’s Research, Testing and Development (R,T&D) department in Rosherville, has developed a water research facility, which is undertaking several water treatment research projects to ensure that water conservation and efficiency is at the forefront of its strategy.

One project in particular aims to recover as much water as possible from the usual waste streams and recirculate it for re-use, the utility said in a company statement.

Adding that this will in turn reduce the amount of raw water intake at Eskom’s power stations – water is a key input in the power generation process used to drive steam generators, for system cooling and for general consumption, hygiene and cleaning.

New technology for water treatment

The innovative technology, eutectic freeze crystallisation, “is based on the principle that when water freezes or the temperature drops sufficiently, salts and impurities are excluded from the water matrix and solidify out”, the utility explained.

“It can be thought of as the opposite of distillation, which separates substances based on their boiling points. Various salts are removed at different points in the cycle and the temperature of the water is restored to ambient.

“This results in clean water and a dry salt cake which is much easier and cheaper to manage than traditional saline slurries.”

Launch of the pilot

[quote]Eskom highlighted that the pilot plant will be commissioned in April 2016 and once completed the research conclusions will be used to design a fully operational plant at some of the utility’s power stations.

As a result, this will decrease the amount of water deposited in ash dams and boost the reuse of water, which will in turn reduce the amount of raw water intake.

The pilot plant will be able to treat 40,000 litres of water every 20-day cycle, to a potable water standard.