Photo by Dani Machlis/Ben-Gurion University of the Negev
Even as one of the world’s smallest countries, Israel is in its second decade of progress toward tackling one of the world’s largest problems: water scarcity.
One of Israel’s efforts toward making its water usage more efficient and environmentally sustainable came to fruition in 2005 with the construction of the Ashkelon Desalination Plant on the Mediterranean coast. Now, just over a decade later, four plants are operating, and a fifth is scheduled to open later this year at Ashdod.
The most recent one to open was at Sorek in 2013. The desalination company IDE technologies partnered with Mekorot, Israel’s national water company, to implement a much more advanced reverse osmosis process converting salty water from the Mediterranean Sea into potable water.
“Ten years before, the question was: Who can make desalination? Of course, in those days a lot of companies made desalination,” said Boris Liberman, chief technology officer and vice president of IDE.
Liberman explained that Israel does not have separate water systems for drinking water and irrigation, but Sorek treats water for both purposes.
“It’s one common system, but the standard of the water we are producing is the highest standard,” he said.
With the production capacity of 624,000 cubic meters of water per day (164.8 million gallons), Sorek is the largest seawater desalination plant in the world. Water first undergoes the pre-treatment stage, where all suspended solids are removed, and “we try also to remove a little bit of the dissolved organic material as much as we can,” Liberman added.
The water then passes through long, tube-like structures called membranes, where dissolved salts are removed from the water in two stages: first from the seawater and then from the brackish water (mixture of seawater and freshwater). Due to increased production, Sorek uses 16-inch membranes, which are twice the size of those in any other plant in Israel.
“The size of the membrane is related to the size of the desalination you’re doing,” Liberman said. But “when you actually start to design this plant, you understand that a huge membrane is not cost-effective.”
In the post-treatment stage, a bit of limestone is added to the water in the absence of fluoride, for drinking water.
“People need calcium for their bones, so somehow we have to add calcium,” he said. Limestone provides it.
Liberman said each pump can produce about 2,500 cubic meters of potable water, which, he said, is unique.
Despite the larger, more expensive membranes, Liberman said Sorek’s production cost is no different from that of Ashkelon’s or a plant in Hadera.
Drought Propelled Innovation
For many years, the Sea of Galilee was Israel’s major source of water. However, drought conditions in the 1990s caused lake levels to become low and led to contamination, said Ehud Zion Waldoks, a spokesman for Ben-Gurion University of the Negev. But the desalination plant project initially lacked public support. That caused delays and put Israel in “dire water straits,” even to the point of people not washing their cars.
“In 1999, it rained a lot, and people asked, ‘Why do I need an extremely expensive desalination plant?’” he said.
Israel now uses a combination of freshwater from the Kinneret and desalinated seawater from the Mediterranean as its potable water sources for both drinking and irrigation. More than 80 percent of Israel’s treated wastewater is recycled and is used for irrigation of crops, which is higher than anywhere else in the world. Spain, which is next, recycles 20 percent of its wastewater.
At the helm of much of Israel’s water innovation has been BGU’s Zuckerberg Institute for Water Research.
The university was established in 1969 by the government with the purpose of economically rejuvenating the Negev. It has produced a number of technological innovations, including the startup company ROTEC, which designs mineral scaling technology that prevents mineral salt deposits from collecting in membranes during the desalination process. The company also has brought its technology to Jordan, the United States and several countries in Europe.
Dr. Noam Perlmutter, one of ROTEC’s founders, explained that the desalination in Israel has ballooned to a roughly $30 billion to $50 billion a year industry for revenue.
“The unique thing about our technology is that you can incorporate it into a new system, or you can also incorporate it in an existing system.”
Desalinated water has become a hot commodity around the world, used by large corporations such as IBM and Coca-Cola. Perlmutter said ROTEC is in the initial stages of entering a contract with Coca-Cola; the details have yet to be worked out.
“In the United States, desalination is taking out water from the sea and [creating] potable water,” he said. “But desalination is much more than that. Today, you’re using desalination in every aspect of the industry.”
Wastewater Treatment
ROTEC’s latest pilot project is a flow reversal unit that is being tested at the Shafdan Wastewater Treatment Plant. The facility supplies water to the Dan region of Israel, which includes Tel Aviv. It is the largest wastewater treatment plant in the country. Treating wastewater requires less pressure than seawater, Perlmutter explained.
Shafdan can process 7.5 cubic meters of wastewater an hour (almost 2,000 gallons) and can recover up to 90 percent of the water by reversing the direction of the water’s flow and create a highly concentrated brine. The unit would be used only for nonpotable water purposes.
Perlmutter said that in Israel brine can be put back in the sea — there is no current use for it — but other countries, including the United States and Australia, forbid this practice.
“This is why in some cases the desalination of brackish water is not economically viable,” he said. “This is a big problem when you’re trying to get this much water [out of] the desalination process.”
But the presence of an advanced water infrastructure in Israel dates back further than 15 years.
The remains of the ancient Israelites’ irrigation system from the seventh century B.C.E. can be seen on the site of Tel Beersheva, just east of the modern-day city of Beersheva, and is open to the public.
BGU archeology professor Steve Rosen said the water system was set up to manage flash flooding at Wadi Beer Sheba. Rosen said all of the work in constructing the cistern would have been done with iron picks. He called its engineering “genius” for its time.
“They have no optical instruments. They have obviously no mechanical instruments. The whole thing is dug by hand with picks. The dirt is removed on the backs of donkeys and on the backs of people,” he said.
“You’d take three steady rods to line them up, and if they’re lined up in a straight line, you get plumb bobs to get a straight line going down. And you had to do all of that to make sure that they had a slope that would bring the water into the system.”
Rosen said most likely the majority of the work was done by slaves, due to the pyramid-like social structure of the ancient Israelite society.
“You would come out during the season and work on the king’s lands unless you were part of the aristocracy,” he said. “If you got to be in the upper class it was great, but how many people were in the upper class, 2 percent?”
Rosen, a member of the excavation team that uncovered the site in the 1970s, said that upon digging, researchers discovered that much of the rock that was used in the construction collapsed.
Rosen said the ancient civilizations typically did not drink the water due to the fact that it was full of waste but typically would elect to drink alcohol.
“We know from the Roman and Byzantine texts that you would not drink the water,” he said. “You would mix the water with wine, and they actually say it cleaned the water, which makes a little bit of sense because the wine had alcohol and the alcohol probably killed some of the bugs.”
Rosen added that some of Israel’s ancient cisterns still collect water, but it typically turns into green sludge that “you don’t want to put your toe in, let alone drink.”
