A nature-friendly, economic approach to desalination

MANILA, Philippines - With water fast becoming almost like liquid gold, especially in drought-prone regions like coastal areas with growing populations, an obvious solution is to take the salt out of seawater. After all, desalination technology has been around for thousands of years already. 

Tantalizing as desalinated water sounds, the energy costs in producing fresh drinking water out of seawater have made it rather unpalatable — until now.

“Until recently, seawater desalination was a very expensive water source solution,” said Jose Antonio Soler, president of Solerex Water Technologies Inc.

Drinking seawater straight is a bad idea. You may think you have expelled the salt by urinating but you are actually losing more water than salt. Seawater contains roughly 130 grams of salt per gallon. With desalination, this technology can reduce salt levels to below two grams per gallon, which is the limit for safe human consumption.

Currently, between 10 billion and 13 billion gallons of water are desalinated worldwide per day. That’s only about 0.2 percent of global water consumption, but the number is increasing.

Aristotle’s efforts

Though Greek philosopher Aristotle envisioned the idea of removing salt from seawater through the use of “filters” arranged consecutively, he was not the first one to do it. The first duly recorded desalination practice was done by collecting freshwater steam out of boiling seawater. Sailors back in around 200 A.D. practiced desalination through the use of simple boilers in their ships. It was that simple.

However, in today’s environment, desalination on a large scale has become unbelievably expensive because of energy requirements. This meant that only countries rich in oil but lack enough water supply are those that can afford “thermal desalination.”

But advancements in technology saw researchers working on filters to take out the salt from seawater, just like how Aristotle saw it. The technology, which employs the use of “membranes,” now called “reverse osmosis,” needs a smaller amount of energy and costs around half the price of current saltwater distillation techniques used today.

Energy is the key

But even with membranes, large amounts of energy are needed to generate the high pressure that forces the water through the filter. In the 80s and 90s, the technology required about 14 kilowatt-hours of energy to produce 1,000 liters per cubic meter of desalinated seawater.

However, strides in energy recovery have decreased the energy requirement from 4.8-5.5 kilowatt-hours to 2.5-2.75 kilowatt-hours to produce 1,000 liters of desalinated seawater.

An island resort development, Balesin in Quezon province, is currently enjoying the savings from installing the new-generation Solerex desalination units introduced by Solerex Water Technologies whose water brand, Crystal Clear, is the leader in the home and office water delivery market.  

“All our desalination units now are equipped with PX Pressure Exchanger, an energy recovery device that basically recycles pressurized water that does not pass through the RO filters back into the high pressure loops at a 98 percent efficiency, reducing the amount of energy required by 60 percent,” Soler said.

Hotels, resorts and communities that rely on producing their own water will benefit from the maximum savings and reliability as the energy recovery unit is built to last a lifetime — of no less than 25 years. 

“As a result the PX technology offers the best economic solution to all stakeholders,” Soler said.

(For more about Crystal Clear and Solerex Water Technologies Inc., visit www.crystalclear.com.ph or www.solerex.com.ph.)