By Jay Landers

With much of California and other western U.S. states experiencing significant drought, the need to pursue further advancements in desalination has never been greater. This was a central theme of an Aug. 11 webinar, titled “Discussion on Desalination — Treatments, Research, and the Future,” conducted by the WateReuse Association.

Desalination and water resilience

Historically, desalination has been viewed as a separate component within the water sector, but that perception is changing, said Peter Fiske, Ph.D., the executive director for the National Alliance for Water Innovation and one of three presenters featured during the webinar. “Now we're learning that desalination is a critical element in a diversified water portfolio,” Fiske said.

Headquartered at the U.S. Department of Energy’s Lawrence Berkeley National Laboratory,  NAWI is a research consortium that also includes the Oak Ridge National Laboratory, the National Renewable Energy Laboratory, the National Energy Technology Laboratory, 19 academic institutions, and 10 industry partners. The organization examines how to improve the performance, lower the cost, and reduce the energy requirements of desalination.

For its part, the state of California has embraced desalination as one means of ensuring reliable water supplies into the future, said Wendy Ridderbusch, another of the webinar presenters and the executive director of CalDesal, a nonprofit organization that advocates greater use of desalination in the state.

California’s water policy entails an “all of the above” approach, rather than simply focusing on one or two main water sources, Ridderbusch said. “It’s not just groundwater or conveyance or recycling,” she noted. “It’s everything together.”

Last year, three California state agencies released the Water Resilience Portfolio, a document outlining measures to be taken to protect against future water disruptions. Ridderbusch noted that desalination was one of several technologies identified in the portfolio as requiring further development. Along with desalination, the portfolio called for greater use of stormwater recycling, direct potable reuse, and water recycling. “We’re really pushing the envelope in terms of water development and supply in this state,” Ridderbusch said.

As an example of desalination improving an area’s resiliency, Fiske pointed to the 50 mgd Claude “Bud” Lewis Carlsbad Desalination Plant in Carlsbad, California, noting that it provides 7% of the water supply for San Diego County (see “Tapping into the Pacific,” Civil Engineering, January 2017, pages 56-61, 79). “What’s great about this facility is it’s completely resilient to climate change,” Fiske said. “No matter what happens with a drought in California, this one piece of San Diego’s water supply is immune.”

Ongoing innovations

With multiple desalination facilities in operation within its borders, California is the site of ongoing technological innovations regarding desalination, said Mark Donovan, P.E., the other webinar presenter and the North American water treatment and desalination lead for the architectural, engineering, and construction firm GHD. “We’re a bit on the forefront here,” Donovan said. “We’re seeing some really good advancements across the field, both in seawater and brackish water (desalination).”

As an example, Donovan pointed to “more and more use of artificial intelligence and machine learning.” Such approaches enable engineers and others to create digital twins of desalination facilities to “optimize the operations or design” of the plants either before or after construction, he said.

In other cases, water agencies have improved system performance through the use of “real-time online water quality monitoring,” Donovan noted. Whereas the results of a traditional sampling process might not be known for as much as a week after the sampling occurred, the real-time monitoring “allows systems to optimize their operations and not be looking in the rearview mirror,” he said.

At the same time, advances in membrane materials have enabled desalination facilities to operate at lower pressures, reducing operating costs, Donovan noted. Similarly, improvements in energy-recovery devices have led to greater use of the cost-saving technology. “We’re now seeing smaller systems able to incorporate energy-recovery devices in their systems,” he said.

Improving reverse-osmosis membrane systems to boost rates of water recovery is another key advancement, Donovan said. “That’s another big field, especially if you’re in Southern California or the arid Southwest,” he noted. For example, desalination facilities that began operating a decade ago likely achieve on the order of a 75% recovery rate. “We’re now able to push the boundaries and maybe do a retrofit and put in an additional system to push that recovery rate up to 90% or 95%,” Donovan said. “It essentially makes a new water supply for a municipality or an agency.”

More improvements needed

If desalination is going to continue to improve in a timely manner, the industry must increase the pace of “technology diffusion,” Fiske said. He noted that decades often elapse between the introduction of a new water treatment technology and the point at which it is routinely specified by engineers.

“One of things we have to do as a community is compress this very attenuated time scale and make sure that we very rapidly identify innovations, get them fielded, (and) get the shakedown completed, so that … engineers can safely and confidently specify new technologies in the projects that come along,” Fiske said.

Improving the pace of technology development is one of NAWI’s key goals.

In particular, the program aims to spur advancements that will facilitate greater treatment and use of “nontraditional waters,” especially brackish groundwater and various wastewater sources that currently cannot be treated cost-effectively, Fiske said. “Our vision in the NAWI program is to develop new technologies to economically treat these nontraditional waters,” he said. “That way we can supply our industries and communities with a resilient, cost-effective water supply to augment our current centralized systems.”

In early 2020, NAWI began a “road-mapping” exercise to identify areas of interest within the desalination sector most in need of further research, Fiske said. In April 2021, NAWI indicated its intention to invest research funding in the following areas: autonomous operation, precision separations, resilient treatment and transport, intensified brine management, modular membrane systems, and electrified treatment processes.

Together, each of these areas is intended to promote the concept of a “circular water economy,” Fiske said. Ultimately, he explained, the goal is to answer the question, “How can we make sure that our water systems and the water we extract have multiple uses and can be reused over and over again?”

On Aug. 26, NAWI released its Master Technology Roadmap. The document summarizes the particular areas of interest for which the organization plans to provide research funding. “These are the areas that we believe are going to have the greatest potential impact for lowering the cost and increasing the reliability, safety, and affordability of desalination for our communities across the United States,” Fiske said.

All told, the DOE is expected to provide NAWI with $110 million over five years for its research efforts.

In July, the DOE and NAWI announced an award of $5 million in federal funding for six different projects pertaining to brine management research. Meanwhile, in May, NAWI issued a request for proposals for research projects related to the realms of automation and precision separations. In response, NAWI received 96 concept papers. Twenty-six of the submitters were asked to submit full proposals, and NAWI expects to announce the award winners in mid-October, Fiske told Civil Engineering.