Duo develop low energy desalting process

Dubai: Salt could power future desalination plants cheaply thanks to a new patent-pending technology devised by a team of Canadian engineers who have developed a seawater desalting process that reuses the rejected brine from traditional plants.

They claim the process requires 80 per cent less energy than a traditional recycling plant to treat an equivalent amount of water, and its creators believe this system could work alongside the numerous plants dotting the Arabian Gulf.

Speaking to Gulf News on the sidelines of the International Desalination Association's (IDA) World Summit on Monday, Ben Sparrow, chief executive officer and founder of Saltworks Technologies, said this technology is the first of its kind.

"We're going the other way. People are trying to decrease the salinity, but we increase it. We use the salt brine to fuel our plant," said Sparrow. A process called thermo-ionic desalination uses concentrated saline water for its energy source.

"Highly salty water is conductive so we are able to create a salt circuit, or a seawater battery, to process the water and draw out the salt," he said.

Ion transfer process

At a pilot plant in Vancouver, seawater is sprayed over a man-made pond to allow it to evaporate, increasing salinity. Low-pressure pumps pipe this concentrate, along with three other streams of untreated seawater, into the desalination unit.

By increasing salinity in seawater by up to 18 per cent from its natural 3.5 per cent, an ion transfer process, rather than electric current, removes salt from the water.

Salt naturally contains chloride and sodium ions which then flow in opposite directions around the circuit passing through the four streams that eventually generates purified water.

Multistage flash, or thermal desalination is the most widely used process in the Middle East, according to the IDA, and the plants using this have grown annually at 11 per cent. Thermal desalination distils seawater by heating it up and condensing the steam.

Reverse osmosis is the other widely used technology with plants using this having grown at 18 per cent annually.

The climate in the Middle East makes the evaporation process particularly well suited to the region, said Joshua Zoshi, co-founder of Saltworks Technologies.

The low pressure of the pumps means that plastic pipes are used instead of stainless steel. No chemicals have been used so far.

The plant in Vancouver will have a desalinating capacity of 1,000 litres to begin with and will be in continuous flow mode by the end of the year.