Sandia LabNews

Desalination roadmap seeks technological solutions to make brackish water drinkable


After one last meeting in San Antonio April 17, Sandia researchers Pat Brady and Tom Hinkebein (6118) are now ready to write a final Desalination and Water Purification Roadmap that should result in more fresh water in parts of the world where potable water is scarce.

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

Pat expects the second roadmap to be completed this month when the Joint Water Reuse & 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 WaterReuse 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 US is expected to increase 13.6 percent per decade [over the next two decades],” says Tom, manager of Geochemistry Dept. 6118 and 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 is easy to see we are facing a challenging water future.”

According to the 2003 Desalination and Water Purification Technology Roadmap, only

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 come from someplace. Brackish water — water with a salt content — seems to be a natural source, Tom says.

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 ensure that different organizations are not duplicating research.

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

Pat says 43 research areas have been tentatively identified and some projects are already underway, jumpstarted with $2 million made available for the preliminary research through a matching grant from the California Department of Water Resources. California provided $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 45 projects get to the top of the research pile,” Pat says. “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/recycling technologies that look at 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.

Sandia’s long-range R&D seeks novel solutions

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

That’s where Tom Mayer (6118) comes in. He leads a long-range R&D effort that takes fledgling ideas and helps them grow into rigorous research projects. Some pan out, others don’t.

Tom calls it high-risk/high-reward research.

“We recognize some of the research may provide just the answers we are looking for,” Tom says. “But we may not see the results for five or ten years.”

Tom 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 never before worked in water treatment.

One example of bringing together people from different fields — which Tom says was done before he took the job — was teaming Jeff Brinker (1002), a chemist who works at the nanoscale, and Susan Rempe (8333), who does computer modeling, to try to make a high-efficiency membrane for the reverse osmosis process that mimics the process in biological cells.

Susan’s job is to do modeling to understand the function of the biological system and identify necessary functions that a synthetic membrane would need. Jeff’s job is to make a synthetic structure that does those functions.

If they succeed, Tom says, they may have a membrane that works at least 10 times better than commercial membranes.

In another instance, Tom 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.) Also working with Chris are Michael Hibbs and Cy Fujimoto (both 6245).

“Chris’ work is farther along that Susan and Jeff’s,” Tom says. “Electrodialysis is well-known but not popular in the US. But there are real possibilities for its use. If we develop a better membrane, it may make the technology more attractive.”

Labs water research looks at all aspects of multifaceted issue

Byproduct cleanup

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, says Richard Kottenstette (6118), who heads up the Jumpstart R&D portion of Sandia’s Advanced Concepts Desalination program. His goal is to identify and pursue technologies nearly ready for commercialization that 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.

Richard and his team are involved in projects that deal with this, as well as related issues. Some 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 in Alamogordo, N.M.
  • 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,” Richard says. 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, placed over a liner that could self-heal if it were breached. Sandia is working with a New Mexico State University graduate student on this project as well as with the Texas Bureau of Economic Geology.

Commercialization

The next step after developing a better desalination method is commercialization.

That responsibility falls to Sue Collins (6118), who works closely 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,” Sue says. “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 says, is that it gives her the opportunity to work closely with the end-user and meet their needs.

The successes of the previous year have attracted local advocates to the commercialization efforts. For example, the City of Alamogordo — with funding from the State of New Mexico — is doing complementary testing on a reverse osmosis project at the Tularosa Basin facility. The Alamogordo tests will confirm the economic potential of the mineral byproducts resulting from the Sandia tests on the system.

Also, the State of New Mexico is matching Sandia-funded work at New Mexico Tech. Last year, researchers from the university and Sandia identified enzyme treatments that remove slimy biological buildup from reverse osmosis membranes. These natural cleaners could replace the harsh acid and caustic cleaners used today.

This year Sandia will fund studies at Sandia and New Mexico Tech to determine what small-scale processes can cause the best enzyme treatments. The state will fund New Mexico Tech to perform large-scale tests of enzyme treatment using a typical reverse osmosis unit with produced water from the San Juan area.

“End-user interest is growing steadily and that is important to our work with the manufacturing community,” Sue says.