Officials and workers from the Municipality of Bantayan did a water tasting test in a recently completed seawater desalination plant in this photo taken on March 8, 2022. | Photo courtesy of Municipality of Bantayan, Cebu
MANDAUE CITY, Cebu – Desalination is the process of removing salt and other minerals from seawater to produce freshwater that is suitable for human consumption and other use.
But is desalinated water safe for drinking?
It is, according to an article published by the World Health Organization (WHO) on March 1, 2011.
WHO said that the “advances in membrane technology have made desalination of seawater and brackish waters an increasingly viable alternative to produce safe drinking-water.”
The agency said that “desalination has been gaining foothold in the water-scarce WHO Region of the Eastern Mediterranean, along coastal areas of Australia, on the West Coast of the USA and in many Small Island States including Singapore and Maldives.”
What is the desalination process?
Traditional desalination is done by distillation or the boiling and re-condensation of seawater to leave salt and other impurities behind.
With the current technological advancements, it is now done either by multi-stage flash distillation or membrane-based process like reverse osmosis. The process filters salt and other impurities from seawater using semi-permeable membranes, transforming this into water that is suitable for drinking.
Lawyer Jess Garcia said, vice president for Vivant Water, said they apply a small amount of chlorine, between .4 to 4 parts per million, on the water that they desalinate at their plant in Cordova town to disinfect and eliminate the pathogens found in saltwater, something that is being done in all water treatment facilities.
However, he said that chlorine application remained within the acceptable standard that “you won’t really notice it.”
Garcia said that their plant in Cordova town was in the testing and commission stage and would start to supply water to the Metro Cebu Water District (MCWD) before the year ends.
As soon their desalinated water is sent to MCWD, it will now be up to the water district, based on the outcome of their own water testing and monitoring, to determine if there was a need to add more chlorine into the water, he said.
Cebu’s water shortage
Garcia said that desalination would be the way to go also because of Cebu’s shortage in surface and ground water supplies.
“For surface water, you need a river that has enough volume to supply what is needed, which we don’t really have in Cebu. The only way we can probably impound water is to build a dam but even that has its limitations in the size, cost and basically the infrastructure that’s needed to build one.”
The other option, he said, is groundwater which is “not also sustainable because we know about the saltwater intrusion that is happening, the nitrate contamination because of the septic tanks and all of that.”
“That’s also not necessarily an exhaustible solution,” he said.
“Desalination is one of the solutions that can address the supply gap, water security solution because your source is the sea which is practically exhaustible,” Garcia added.
Environmental benefits
Aside from providing additional water to the Cebuanos, desalination will help address environmental concerns that may result from the continued extraction of groundwater.
“Because a lot of people are doing it already, saltwater is coming in. It’s taking its toll on our environment,” said Arlo Sarmiento, Vivant Corporation Chief Executive Officer.
Sarmiento said that the environmental impact of water shortage also affects tourism and when paired with its economic impact, the outcome “is massive.”