Thirsty Work: The Hunt For Another Water Supply
FAYOUM, EGYPT—Two years ago, Ethiopia began to reroute the Blue Nile, the famed waterway that flows through Khartoum, Cairo and Alexandria.
The diversion allowed for construction to start on a controversial dam that the government in Addis Abba says will produce as much electricity as six nuclear power plants. But if the project is good news for Ethiopian energy, it could drain Sudanese and Egyptian water supplies.
Earlier this year, the Egyptian and Sudanese governments signaled acceptance of the project. But both countries know that in the long run they need to develop alternative water supplies.
Egypt has a tantalizing abundance of water on its coasts, but the water is filled with salt. Egyptian scientists are trying to advance desalination, which is currently a costly and inefficient way to get fresh water. While researchers hope their work will help Egypt to keep the taps flowing once the new dam is operational, it could also benefit many other Arab countries.
“Even though we have the Nile, we will face a supply issue with this new dam,” says Abeer Moneer, an associate professor at the National Institute of Oceanography and Fisheries. “It’s a large problem and we will face it in the next few years so we have to work hard to overcome it.”
From Morocco to the Arabian Gulf, water is usually scarce. Worldwide, the Organisation for Economic Cooperation and Development estimates the number of people living in areas affected by “severe water stress” will increase by another billion people to reach 3.9 billion by 2030. (See the related Al-Fanar Media article “One Solution for A Water-Stressed Future.”)
Desalination in the Arab world currently accounts for just 1.8 percent of the region’s total water supply—though the United Nations points out in a recent report that it still accounts for nearly all the supply of many Arab cities.
In a new paper published in the Water Science & Technology journal, Moneer and a team of fellow researchers in Alexandria say they have created a new membrane that can extract more fresh water from the sea and improve the energy efficiency of doing so.
The research was supported by the Science & Technology Development Fund of Egypt.
“The new membrane can desalinate seawater of exceptionally high concentration,” says Moneer. That’s crucial, she added, because the Red Sea on Egypt’s east coast is one of the saltiest bodies of water in the world.
The new technology could also be used to squeeze more fresh water out of the saline byproduct that remains at the end of traditional desalination.
“The membrane is also more efficient and can tolerate viruses and bacteria better than traditional membranes,” boasts Moneer, “It’s not expensive. It’s not a complicated piece of equipment.”
The new membrane consists of cellulose acetate powder, which is made in Egypt. This material, in concert with other components, traps the larger salt impurities as the water passes through. The liquid is then heated and the vapor is condensed, which gets rid of smaller particles. (Moneer cannot reveal some unique components of the membrane until a patent application is processed.)
Meanwhile, other researchers up the river at Fayoum are tackling the issue from a slightly different angle. They’re trying to make the membranes that are already used in desalination plants last longer. At the same time, they hope to increase the amount of fresh water the plants yield.
“The lifetime of traditional membranes is not long, sometimes as little as three months,” says Ahmed Khalil, a researcher at Fayoum University’s physics department.
His work is supported by the German Academic Exchange Service, or DAAD.
To extend membrane life, Khalil’s lab is running experiments to figure out the optimum “wet-ability” of a membrane. The wet-ability is a measurement of how hydrophobic or hydrophilic a membrane is—whether it attracts or repels water.
Paradoxically, it’s good for a desalination membrane to be hydrophobic because it stops the membrane from getting clogged with impurities, but it’s also bad because it means a lot of energy is required to force the water through.
On the other hand, hydrophilic membranes require less pressure and energy, but risk getting clogged.
It’s a classic trade-off.
“You have to make a compromise,” says Khalil, “but the question is where on the spectrum.”
His research seeks to answer this question by creating a membrane with a wet-ability that can be manipulated. “We’re trying to make a membrane that can switch between hydrophobic and hydrophilic,” he explains. “That how we can find the optimum conditions under which they operate.”
Both Khalil and Moneer aren’t sure when their research can be put to practical use by desalination plants.
But the clock is ticking for technologies like those being developed by Khalil and Moneer to get out of the lab and into industrial use. Ethiopia’s dam should be completed in just two years’ time, and the need to secure new water supplies couldn’t be clearer.