"Finding More Water," Feature Article, September 2006

finding more water

A desalination roadmap seeks technological solutions to make brackish water drinkable.

by Peter Easton, Copy Chief

A document that should result in more fresh water in parts of the world where it's needed is nearing completion.

Following one final meeting in San Antonio April 17, Sandia National Laboratories researchers Pat Brady and Tom Hinkebein are now ready to write a final Desalination and Water Purification Roadmap.

The roadmap is the result of three previous meetings—two in San Diego and one in Tampa—and the last held in Texas, where many government agency, national laboratory, university, and private partners gathered to discuss the future of desalination in the United States. The first roadmap, identifying overall goals and areas of desalination research, was submitted to Congress in 2003.

Brady expects the second roadmap to be completed this month, when the Joint Water Reuse and Desalination Task Force will submit it to Sen. Pete Domenici, R-N.M., chairman of the Senate Energy and Water Development Appropriations Subcommittee, and Congress and, eventually, the water user and research communities. The task force consists of the Bureau of Reclamation, the Water Reuse Foundation, the American Water Works Association Research Foundation, and Sandia.

The roadmap will recommend specific areas of potential water desalination research and development that may lead to technological solutions to water shortage problems.

"Population growth in the U.S. is expected to increase 13.6 percent per decade [over the next two decades]," said Hinkebein, head of Sandia's Advanced Concepts Desalination Group. "There will be 29 percent more of us in 20 years. Put that together with an unequal distribution of people—more moving to Texas, California, Arizona, and New Mexico, where fresh water is limited—and it's easy to see we are facing a challenging water future."

According to the 2003 Desalination and Water Purification Technology Roadmap, only 0.5 percent of the Earth's water is directly suitable for human consumption. The other 99.5 percent is saltwater or locked up in glaciers and icecaps. As the world's population grows, the increased water demand will have to be met from someplace. Brackish water—water with a salt content—seems to be a natural source, Hinkebein said.

The new roadmap, Roadmap 2, will be a coherent plan outlining the specific research needed in high-impact
areas to create more fresh water from currently undrinkable brackish water. It will help to ensure that different organizations are not duplicating research.

Water desalination is not a new concept. In the United States, the largest plants are in El Paso, Texas, and Tampa, Fla. It is also commonplace in other parts of the world. Except for the Middle East, most desalination is done through reverse osmosis.

Sandia researchers Michael Hibbs (right) and Chris Cornelius check out an electro-dialysis system that removes salts or ions from water with an electric field and special ion-exchange membranes. Cornelius has worked on membranes for fuel cells.

According to Brady, 43 research areas have been tentatively identified and some projects are already under way, jump-started with $2 million made available for the preliminary research through a matching grant from the California Department of Water Resources. California provided an additional $1 million and members of the Joint Water Reuse and Desalination Task Force each contributed $250,000.

Another $4 million in fiscal years 2004, 2005, and 2006 through federal Energy and Water Development Appropriations bills secured by Sen. Domenici has also funded desalination research at Sandia.

"The task force will be the entity deciding which of the 43 projects get to the top of the research pile," Brady said. "As more money is made available, universities, research groups, national labs, and private companies will bid on projects."

Among the 43 research areas included in Roadmap 2 will be:

• Membrane technologies (mainly reverse osmosis process) that desalinate and purify water by pushing it through a semipermeable membrane that removes contaminants.

• Alternative technologies that take advantage of nontraditional methods.

• Concentrate management technologies that consider the disposal, volumetric reduction, and beneficial use of the mineral byproducts of desalination.

• Reuse and recycling technologies that examine the ways membrane and alternative technologies must be designed to handle increased contaminant loads.

Much of the research is expected to be conducted at the soon-to-be-completed Tularosa Basin National Desalination Research Facility in Alamogordo, N.M.

Solving the tough issues of desalination may take solutions that don't exist—yet.

That's where researcher Tom Mayer comes in. He leads a long-range research and development effort that takes fledgling ideas and helps them grow into rigorous research projects. Some pan out, others don't. He calls it high-risk/high-reward research.

"We recognize some of the research may provide just the answers we are looking for," Mayer said. "But we may not see the results for five or ten years."

He has the job of identifying researchers with knowledge in different fields and matching them up with new types of research that may lead to better desalination methods. Most people doing research on projects in the long-range R&D program have never before worked in water treatment.

One example of bringing together people from different fields—which Mayer said was done before he took the job—was teaming Jeff Brinker, a chemist who works at the nanoscale, and Susan Rempe, who does computer modeling, to try to make a high-efficiency membrane for the reverse osmosis process that mimics the process in biological cells.

Rempe's job is to do modeling to understand the function of the biological system and identify necessary functions that a synthetic membrane would need. Brinker's task is to make a synthetic structure that performs those functions. If they succeed, Mayer said, they may have a membrane that works at least 10 times better than commercial membranes.

In another instance, Mayer tapped Chris Cornelius, who has been developing membranes for hydrogen fuel cells, to build a better electrodialysis membrane. (Electrodialysis removes salts or ions from water with an electric field and special ion-exchange membranes.)

"Chris's work is farther along than Susan and Jeff's," Mayer said. "Electrodialysis is well-known, but not popular in the U.S. But there are real possibilities for its use. If we develop a better membrane, it may make the technology more attractive."

Even though there is more water to be had in the form of brackish water throughout the world, it will come at a price because of cleanup costs, according to Richard Kottenstette, who heads the Jumpstart R&D portion of Sandia's Advanced Concepts Desalination program. His goal is to identify and pursue technologies that are nearly ready for commercialization and can tackle this problem.

The problem of cleanup—what to do with the concentrate resulting from reverse osmosis—is at the top of his list. Concentrate is the salty residual liquid byproduct of desalination.

On the coasts, the solution is simple—return the salt and minerals to the ocean. But inland, getting rid of the residual becomes problematic.

Kottenstette and his team are involved in projects that deal with this, as well as related issues. Some of them include:

• A reverse osmosis project with the University of South Carolina that is investigating better mineral recovery— recovering minerals and leaving less or no salty water behind. The minerals, which have monetary value, can be sold. This will be piloted next year at the Tularosa Basin National Desalination Research Facility.

• A method to reuse water that comes from sewage so it is potable. Sandia recently completed a pilot project at the Rio Rancho wastewater treatment plant. "If you use it twice, you double its value," Kottenstette said. Treated wastewater is typically used to water parks and golf courses, but there is a possibility it could be made as fresh as if it came out of an aquifer. The phosphorous from the waste could be turned into fertilizer.

• A method of taking mineral waste after reverse osmosis and putting it into evaporation ponds. From there, the waste could be put into a landfill, over a liner that could self-heal if it were breached. Sandia is currently working with a New Mexico State University graduate student on this project as well as with the Texas Bureau of Economic Geology.

The next step after developing a better desalination method is commercialization. That task falls to Sue Collins, who works with Sandia's licensing department.

"Our customers and advocates have said repeatedly that the success of commercialization efforts will be measured in gallons of new water produced," Collins said. "That means accelerating the lab-scale success to pilot-scale and then to the manufacturer and end user."

The advantage of having a desalination roadmap, she said, is that it gives her the opportunity to work closely with end users and meet their needs.

"End-user interest is growing steadily and that is important to our work with the manufacturing community," Collins said.