Lauren Nicole Core

Kevin Pataroque, a student working in the Elimelech Research Group at Yale University, passed the PhD Area Examination and officially became a PhD candidate. His PhD proposal is titled Performance of RO Membranes in Ultrahigh Pressure and Hypersaline Environments. The Elimelech Research Group focuses on problems involving physicochemical and biophysical processes in engineered and natural environmental systems.

This article highlights the work of NAWI Research Consortium researchers Kurban Sitterley, a water treatment expert at NREL, and Alexander Dudchenko, an associate staff scientist at the Stanford Linear Accelerator Center, who worked together to build a new ion exchange model that can be used to guide utilities in identifying the best ion exchange systems. Read the article.

Yian Chen, recent graduate of the University of California, Los Angeles and postdoctoralresearcher at the National Renewable Energy Laboratory, received the 2023 California-Nevada Section Award from the American Water Works Association (AWWA). She also received AWWA’s 2023 National Academic Achievement Award, which encourages academic excellence by recognizing contributions to the field of public water supply. Learn more by visiting this link.

Maria Soto, a graduate student at the University of California, Los Angeles, received the Great Minds in STEM Ray Mellado Memorial Scholarship. Her talent and dedication were further recognized when she secured first place in the poster competition at the annual Great Minds in STEM Conference. Her award-winning poster, titled “Technoeconomic Analysis of Distributed Water Systems,” exemplifies her exemplary work and contributions to the field.

This article is published by WateReuse Association in collaboration with National Alliance for Water Innovation (NAWI). Lauren Nicole Core is water specialist consultant with the World Bank Group and communications lead with Lawrence Berkeley National Laboratory, Berkeley, CA;  and .

Artificial Intelligence (AI) grabs headlines for its ability to mimic, in its own distinctive way, human expression, from writing to artwork. However, its most important applications venture beyond generative AI to address challenges that have confronted humankind since the dawn of civilization. Secure and sustainable access to freshwater, for instance. Our most important natural resource has never been more severely threatened, and the global need for new sources of usable freshwater has never been as great.

As such, nations, regions, and communities around the world are actively pursuing alternative water supplies such as brackish water or potable reuse of municipal reclaimed water. However, purifying these sources means increases in energy, chemical use, and the need for talented, highly trained advanced water treatment operators.

It is therefore important to find ways to drive down the costs of energy and chemicals associated with water treatment, and to support operators.

In an effort to address such challenges, research supported by the United States Department of Energy’s National Alliance for Water Innovation (NAWI) is using AI and machine learning (ML) to reduce energy and chemical use, improve operational support, increase treatment system uptime, and improve confidence in purified water quality. The research aims to lower the cost of Reverse Osmosis (RO)-based advanced treatment (RBAT) by developing new—and improving existing—technological solutions to make treatment of nontraditional waters competitive with conventional water sources for specific end-use applications.
“The researchers are part of the NAWI Alliance, which focuses on making desalination and water treatment technologies more efficient, effective, and reliable,” explains Peter Fiske, Executive Director of NAWI. “These technologies will enable 90% of our current non-traditional water sources to achieve pipe parity – when the levelized cost for treating and reusing nontraditional water sources are equal to the cost of today’s marginal water supplies.”

NAWI is the largest federal investment in water treatment, desalination, and water reuse since the 1960s. The innovative national research program and public-private partnership brings together industry, academic, national laboratory, and other stakeholders across the country to advance next-generation desalination and water recycling technologies.

Reverse Osmosis to Reverse Water Insecurity

RO is a long-proven water treatment process that lies at the heart of most potable reuse systems. RO-based facilities can render water from nontraditional sources safe for use in a wide range of applications, lessening our reliance on groundwater and other often overtaxed freshwater supplies.

But the effectiveness of RO comes at a cost. The RBAT approach consumes a great deal of energy. This limits its scalability, especially for less affluent communities, and leads to questions about more environmentally sustainable alternatives.

Nevertheless, “the adoption of water reuse is gaining momentum. Studies like this that help improve the energy efficiency of water reuse keep that momentum strong, improving the health and resilience of communities across the United States,” said WateReuse Association Executive Director Patricia Sinicropi.

Sampling Wastewater…Without Samples

Researchers use AI to deliver more efficient testing and assessment of wastewater and to eliminate contaminants more adaptively and cost-effectively than traditional control methods allow. Take N-nitrosodimethylamine (NDMA) for example. NDMA once played a key role in the production of rocket fuel, but these days is mainly present in water as a disinfection byproduct. It is considered extraordinarily carcinogenic based on a study linking it to liver tumors in mice.

Because it is a very small molecule, NDMA can partially pass through RO. So, RBAT uses ultraviolet (UV) radiation to destroy NDMA, among other water quality benefits. This method destroys certain chemicals found in water through photolysis, which uses intense UV light to shatter the chemical bonds characteristic of targeted contaminants. UV also inactivates many pathogens, and in combination with certain chemicals like hydrogen peroxide, can further break down unwanted contaminants. Like RO, this process consumes a great deal of energy.

Traditionally, water treatment engineers have sampled wastewater from the multiple treatment processes that make up an RBAT array and sent them to be tested for NDMA and other dangerous contaminants. This process can take up to one month. These samples contribute to a database reaching back months or years, and the updated series is analyzed to identify the highest concentration of NDMA across all samples.  Since NDMA is an important contaminant and measuring it at a lab is slow and expensive, engineers and operators assume the worst. The intensity of UV light is set based on the highest or near-highest NDMA levels ever measured, and not changed.

The research team proposes to address the energy inefficiency typical of traditional RBAT-based treatment solutions by using an AI- and ML-based approach. It goes beyond direct sampling in favor of analyzing enormous datasets to train “soft sensors.” Soft sensors are AI models that use faster, cheaper data sources to predict the concentrations of slower, more challenging contaminants like NDMA. The result is a real-time estimate of key contaminants in a water source, including its most elusive. Researchers have demonstrated that AI can predict NDMA concentrations within ±3 parts per trillion of their actual value. This analysis informs the treatment process, reducing unnecessary UV treatments by roughly 50% while still reducing NDMA levels far below regulatory limits. Further AI research in the same NAWI project is modeling microfiltration and RO with AI to detect faults or optimize energy and chemical use within those steps of RBAT systems.

“The development and implementation of advanced controls for optimization, such as ML and AI, is an area that is ripe for innovation,” said Andrew Salveson, Project Lead and Water Reuse Chief Technologist, Disinfection Chief Technologist, and Project Manager at Carollo Engineering. “In some cases, advanced controls are built into individual processes, but the controls are not integrated across the entire system and don’t account for impacts on upstream or downstream processes. To the best of our knowledge, no studies have applied ML or AI to the operation of integrated RBAT trains in potable water reuse.”

Advanced Fault Detection for Better Reliability

This research organizes AI to support RBAT systems under two umbrellas: process control and fault detection. A pilot scheduled for 2024 will test the team’s efforts to provide better fault detection through real-time AI analysis. Adaptive process control and intelligent monitoring of treated-water supplies will allow water-treatment facilities to address fluctuations in water quality before they threaten to impact the delivery of usable freshwater.

This approach will also save energy and lower costs to water consumers, and researchers have hope that it will increase public confidence in its water supply. Those pilots will be conducted at Las Virgenes Municipal Water District (LVMWD) in Calabasas, California – an early adopter and innovator of such technological interventions – and Orange County Water District (OCWD) in Fountain Valley, California.

In advance of the pilot, researchers are currently conducting a series of simulations against historical data collected from high-frequency online sensors used by water utilities partnering with the project. These simulations encompass five different fault-detection and process-control methods, the results of which will be assessed at the end of this phase of the project. Researchers expect that more than one method will achieve their target of 10% energy savings, 20% cost savings, or 50% improved reliability. The most promising set of controls will be tested more rigorously at two demonstration-scale RO-based water-reuse facilities designed to produce potable water.

These are still early days for AI in general, and especially for its use as a facilitator of water reuse and as treatment of nontraditional water sources. But this research has already demonstrated significant advantages in water-testing methods, and researchers expect similar results in their efforts to inform fault detection and process controls with AI. Full implementation of the research team’s findings for commercial and municipal purposes will only be possible after a thorough real-life trial mirroring large-scale water treatment and reuse. For now, AI holds immense promise for a new generation of more efficient, steadier water treatment facilities capable of safely delivering freshwater from a wider variety of nontraditional sources than current technology allows.

Author’s note: The views expressed in this column do not necessarily represent the views of the US Department of Energy or the US government.

NAWI is a public-private partnership that brings together a world-class team of industry and academic partners to examine the critical technical barriers and research needed to radically lower the cost and energy of desalination. NAWI is led by DOE’s Lawrence Berkeley National Laboratory in collaboration with National Energy Technology Laboratory, National Renewable Energy Laboratory, and Oak Ridge National Laboratory, and is funded by the Office of Energy Efficiency and Renewable Energy’s Industrial Efficiency and Decarbonization Office.

There are many more NAWI-supported research projects and innovators leading the charge for a circular economy through desalination and water supply research. NAWI provides several opportunities for participation, from applying for Alliance membership to volunteering to advise a project team as a Project Support Group member. Through relentless dedication to enhancing water accessibility, purity, and affordability, NAWI’s visionary research instills optimism for a future where access to clean water becomes a reality for all.

Research Partners: Baylor University: Amanda Hering; Carollo: Amos Branch, Andrew Salveson, Charlie He, Wen Zhao, Daniel Hutton, Kyle Thompson; Las Virgenes Municipal Water District: Burt Bril, Darrell Johnson, John Zhao, Steve Jackson; National Water Research Institute: Kevin Hardy; Orange County Water District: Han Gu, Jana Safarik, Megan Plumlee; United States Military Academy: Katheryn Newhart; West Basin Municipal Water District: Alejandra Cano-Alvarado, Margaret Moggia, Uzi Daniel, Veronica Govea; Yokogawa Corporation: Steve Hayden, Yasuhiro Matsui.

This article describes how a new NAWI-supported materials-screening platform is advancing breakthroughs in water treatment technologies. The full article was published in the September 2023 Journal AWWA. A free, flipbook version is available here.

If you drink tap water, you can probably thank Abhishek Roy.

A good amount of the world’s drinking water gets purified through something called a reverse osmosis membrane, which filters out salt and other contaminants. And if your water squeezes through this kind of filter, it is likely that Roy helped build it. But even if you cannot thank Roy for that particular membrane, there is a good chance you will benefit from at least one of his many others. He currently holds 75 patents worldwide.

“Membranes are an enabling technology,” said Roy, a senior staff scientist at the National Renewable Energy Laboratory (NREL). “Membranes play a very, I would say, behind the screens—or scenes—role to provide one of the most crucial parts of today’s life: clean water.” (“Screens” was not a slip of Roy’s tongue; it’s a membrane pun!)

As greenhouse gases like carbon dioxide trap heat in our atmosphere and a warming climate strains our water supplies, these little enablers are becoming even more valuable. Roy’s most prolific membrane not only improves water quality by 40%, but it also uses 30% less energy than its predecessors. Those energy cuts could help reduce global carbon emissions and slow climate change—and so could Roy’s hydrogen-powered fuel cells, which need membranes to generate clean energy for things like power plants, cars, or even laptops.

But Roy is not only preventing new emissions; his inventions could also help remove carbon that has already escaped into our atmosphere or our oceans.

“There is now a global need for decarbonization, right?” Roy said. “And we are trying to help in every possible way.”

In short, Roy is an enabler for the enablers.

Roy first encountered membranes during his doctoral studies at Virginia Tech. His background was in polymers—the molecular chains behind synthetic materials, like plastics, but also natural structures, like DNA. But his advisor, James McGrath, was “a very forward-looking person,” Roy said. And McGrath wanted to find a way for polymers to boost the green technology movement.

“I got my Ph.D.,” Roy said, “but also a doctorate in understanding membranes and how they can solve world problems.” (He got something else, too: a prestigious R. A. Glenn Award from the fuel division of the American Chemical Society for his doctoral thesis, which led to a breakthrough in fuel cell research).

Membranes require energy—sometimes a whole lot of energy—to push substances through their selective layers. So, if researchers could build more energy-efficient membranes, those energy savings could significantly reduce global carbon emissions (and costs), too.

Roy’s inventions do exactly that. His favorite invention, the water purification membrane that cut energy use by 30%, earned him the Gordon E. Moore Medal, one of the most highly esteemed awards available for members of the chemical industry. Now, he is working to realize yet another of McGrath’s antipollution plans.

“Thirty years back, fuel cells were a dream,” Roy said. “Now, they’re no longer a dream; they’re a reality.”

That reality runs on membranes. In fuel cells, membranes separate hydrogen to generate energy while emitting nothing but water. Roy also helped invent more energy-efficient membranes for petrochemical industries, which produce products like plastics, medical equipment, fertilizers, and even clothing. With Roy’s membranes, those industries could both reduce their overall energy consumption (and therefore their carbon emissions) and capture carbon, too.

Now, at NREL, Roy is working to make fuel cells, water-purification devices, and carbon-capture technologies more efficient and cost effective. “That’s my goal—to establish the lab as a national hub and help to address those challenges,” Roy said.

Before Roy joined NREL in 2021, he spent about 15 years at Dow Chemical. Throughout that time (and even in the two years since he joined the laboratory), Roy has earned many high-profile awards, especially for his water purification technologies. Most recently, he and Mou Paul, a materials scientist at NREL, won the 2023 Polymer Science and Engineering Cooperative Research Award for their work in global water sustainability. Roy also earned the 2014 Virginia Tech Outstanding Recent Alumni Award and Dow Chemical’s coveted Sustainability Innovator Award (as of 2014, Roy was one of just five recipients). And he was recently elected to the board of directors for the North American Membrane Society.

In May 2023, the membrane magician was awarded funding from the National Alliance for Water Innovation (NAWI), whose mission is to make water more affordable, energy efficient, and accessible. With his award, Roy, a member of the NAWI Alliance and research consortium, is crafting yet another multipurpose membrane.

“As you purify water, you leave behind salt. What happens to this salt? That’s a big question,” Roy said. “And salt water will also contain water, right? Every drop of water counts.”

Typically, that salty byproduct is tossed away or left to evaporate. But Roy’s latest membrane can extract those precious drops of pure water, as well as salts needed for chemical processes. This kind of purification often demands huge amounts of energy (the more stuff that is in the water, the harder it is to push it through a membrane). But Roy’s solution, which he is working on with collaborators at the University of Texas and Lawrence Berkeley National Laboratory, will reduce both energy use and costs.

“That’s the major goal—reducing the overall cost of water,” Roy said. (He is also adapting that membrane to remove carbon from seawater thanks to a grant from the Office of Naval Research). “But if you want to develop this decarbonization technology,” Roy continued, “it’s very important that you engage not only the top leaders but also people who are emerging.”

About five years ago, Roy was chosen to join the National Academies of Sciences, Engineering and Medicine’s New Voices project, which aims to expand diversity in the sciences and encourage early-career scientists to tackle national and global challenges. With the group, he helped author an opinion piece, published in Scientific American, that argued for increasing diversity across all scientific disciplines. When more women became cardiologists, the article argued, that led to better outcomes for women with heart disease.

“Of course, technology is the key, right?” Roy said. “But engaging the young scientific community into the whole process—that’s so critical.”

Now, Roy is not only an enabler for his mini membrane enablers but also for the next generation of scientists who will take up the fight against climate change, one polymer, fuel cell, water droplet, or carbon molecule at a time.

The National Alliance for Water Innovation is a public–private partnership that brings together a world-class team of industry and academic partners to examine the critical technical barriers and research needed to radically lower the cost and energy of desalination. The alliance is led by the U.S. Department of Energy’s Lawrence Berkeley National Laboratory in collaboration with DOE’s National Energy Technology Laboratory, National Renewable Energy Laboratory, and Oak Ridge National Laboratory and is funded by DOE’s Industrial Efficiency and Decarbonization Office.

Researchers at the Department of Energy’s Oak Ridge National Laboratory are developing advanced automation techniques for desalination and water treatment plants, enabling them to save energy while providing affordable drinking water to small, parched communities without high-quality water supplies.

Climate change and growing populations are straining the lakes, rivers and aquifers that traditionally provide clean water. Today, more towns need to be able to treat brackish, salty or biologically-polluted water to drinking water standards. But operating this more complex treatment often requires expensive technical expertise.

Through DOE’s National Alliance for Water Innovation research program, ORNL, universities and private companies are working together to develop and demonstrate fully-automated, multi-stage treatment systems that are effective at making nontraditional water sources clean and healthy for drinking or irrigation.

Co-founded by ORNL and the National Renewable Energy Laboratory, NAWI is a research initiative that also seeks to make this treatment affordable, decentralized and energy-efficient even for water sources that vary daily in content and quality.

“Fully treating and reusing water creates a circular water economy,” said ORNL lead researcher Kris Villez. “We want to make a nontraditional water source economically competitive against a traditional, mostly pure water source, something we call ‘pipe parity.’ These nontraditional sources vary a lot in quality and availability. This means that they can only achieve pipe parity through automated controls,” allowing cost-efficient water treatment even for historically underserved or rural communities without a large tax base.

A team led by Villez is developing software based on machine learning that can make decisions about the best actions to maintain a high quality of treatment in the most efficient way, saving energy, money and water. Choices can be influenced by daily weather, drought conditions, real-time energy and water prices, plant maintenance and changes in the composition of the untreated water.

Villez said this type of water treatment automation could eventually be vital not only for municipal water systems in thirsty areas like the Colorado River Basin but also in water-intensive industrial facilities, such as food and beverage processors or utilities with water-based cooling systems.

“The central concept of NAWI has always been to increase water availability,” said Yarom Polsky, a NAWI topic area lead for process innovation and intensification. “Advanced automation is a critical element.” It enables optimization of the performance of water treatment systems, with benefits such as cost reduction and efficient adaptation to changes in the composition of source water.

“Making advanced automation accessible to small water utilities and small stand-alone systems is essential for widespread adoption,” said Polsky, who is also director of ORNL’s Manufacturing Sciences Division. “Small and medium-size system providers typically have fewer resources for hiring technical experts to implement advanced controls.”

Villez’s team already demonstrated similar but smaller-scale automated controls on a single-unit treatment system established in Aurora, Colorado, by the Colorado School of Mines. The city of Aurora, Baylor University and several software vendors are also partners in the project, which uses reverse osmosis to remove salt from water.

Researchers are currently pursuing the next step, developing controls for plant-wide optimization. This will be tested for the first time on a treatment train of six units that can flexibly switch between various levels and types of water treatment. Doing so enables an automated choice between using all units to produce municipal drinking water or only using a few to supply irrigation, depending on markets, costs and other changing conditions.

“We want to deliberately introduce changes to see if our model is accurate, so we have the ability to respond to adversarial events, inadvertent errors or gradual changes in the bacterial treatment process that you might not notice if you don’t compare,” Villez said. “We’re balancing economic performance with resiliency.”

In a related NAWI project, ORNL researchers are also building a digital twin of a real-world desalination plant owned by Orange County, California. This digital twin is a dynamic model of the plant, which allows testing diverse designs and controls in a virtual laboratory without affecting customers. Ultimately, the digital twin will enable a real-time response to changes in electricity pricing, avoiding water production at times when energy is most expensive.

Polsky points out that water treatment is both an energy-intensive process and an energy necessity. Clean water heats and cools today’s power plants and industrial processes. “As we proceed through our energy transition, water treatment is also likely to be critical for energy applications of the future,” such as producing green hydrogen for industry, transportation or long-term energy storage, he said.

Other researchers who contributed to these water treatment automation projects include ORNL’s Alexander Melin and Sally Ghanem, along with former ORNL postdoctoral researcher Dhrubajit Chowdhury. Funding was provided by NAWI and the DOE’s Advanced Materials and Manufacturing Technologies Office.

UT-Battelle manages ORNL for the Department of Energy’s Office of Science, the single largest supporter of basic research in the physical sciences in the United States. The Office of Science is working to address some of the most pressing challenges of our time. For more information, please visit energy.gov/science.

Innovative water treatment and desalination technologies hold promise for building climate resilience, realizing a circular water economy, and bolstering water security. However, more research and development is critical not only to radically lower the cost and energy of such technologies, but to effectively treat unconventional water sources. Conventional water supplies, such as fresh water and groundwater, are typically used once and thrown away, rendering this valuable and finite resource inaccessible for further use. Since its launch in 2019, the National Alliance for Water Innovation (NAWI) has made strides in developing new technologies to economically treat, use, and recycle unconventional waters (such as brackish groundwater, municipal and industrial wastewater, and agricultural run-off), which could point to a future where water equity and security is accessible to all.

Led by Lawrence Berkeley National Laboratory  (Berkeley Lab) and supported by the United States Department of Energy, NAWI is a five-year, $110 million research program and public-private partnership. NAWI brings together over 1670 individual NAWI Alliance members, over 400 partnering organizations, and numerous water research facilities.

“NAWI is driving breakthrough research to reduce the price, energy costs, and greenhouse gas emissions of new water technologies,” said Peter Fiske, executive director of NAWI. “Our work also bridges cutting-edge research with real people and places, such as producing secure, reliable, and affordable water for communities that are most in need.”

NAWI’s robust research portfolio spans analysis for water-energy grid integration to development of algorithms, models, and adaptive process controls for resilient operations. Now in its third year of operation, NAWI is supporting pilot projects that will treat unconventional water sources to provide usable water in real-world environments. Many of the pilot projects partner directly with communities and groups that have historically been underserved by existing water supplies. Each project will also generate a range of data sets usable by other researchers seeking to advance the field of data analysis and automation, and fault detection in water treatment systems.

These 5 NAWI pilot projects are transforming water treatment and desalination technologies.

 

Removing Arsenic from California Well Water for Rural Communities

Arsenic, a naturally-occurring carcinogenic contaminant, is widely present in groundwater. In both California and around the world, many wells are contaminated with arsenic levels surpassing safety thresholds. This compels communities to either set up costly and intricate purification setups or cease using their local wells, resulting in the inconvenience of traveling long distances to procure water for domestic purposes. This initiative will demonstrate a new simple, dependable, and highly automated electrochemical arsenic-removal process employing iron and electrical currents. This method ensures the secure elimination of arsenic from well water while requiring minimal human intervention. Collaborating with the residents of Allensworth, California – a rural community whose residents travel significant distances to pay for retail water from a kiosk – is central to this project.

Turning Waste to a Valuable Resource for a Circular Economy

Desalination methods commonly recover a portion of pure water while generating a byproduct known as brine or concentrate, which contains high levels of salt and poses challenges for economical and environmentally friendly disposal, particularly at onshore desalination plants. This project centers on creating and implementing an innovative approach to intensify the concentration of brine through electrodialysis. This technique not only increases water yield but also converts the dissolved salts into valuable industrial chemicals. The initial testing of this system will take place at the Kay Bailey Hutcheson Desalination Plant situated in El Paso, Texas.

Enhancing Water Treatment Efficiency to Minimize Waste and Maximize Sustainability

The concept of desalination and repurposing of municipal, industrial, and agricultural wastewater presents an appealing strategy to enhance the dependability and resilience of water resources. However, the existence of dissolved minerals capable of obstructing reverse osmosis membranes and components, a phenomenon known as scaling, imposes constraints on the volume of water that membrane processes like reverse osmosis can restore. This project seeks to incorporate an innovative, exceptionally efficient technique for extracting scale-forming ions from concentrated brine solutions, thereby enabling significantly elevated water recovery rates and reducing waste brine volume. Through a mobile testbed, this advancement will help ensure high-recovery desalination across five locations in California.

Advancing Membrane Technology for Greater Resource Recovery

Electrodialysis Metathesis (EDM) is a desalination process that employs specialized membranes and chemical processes to generate fresh water. It also converts residual brine into two distinct streams: one rich in calcium and the other rich in sulfate. These streams hold the potential for further refinement into valuable industrial chemicals, thereby creating an additional revenue stream from the desalination process. This approach also aids in diminishing the volume of waste brine generated. Historically, EDM has necessitated the addition of sodium chloride (NaCl) to provide the essential ions for forming these distinct solutions. This NAWI-supported project implements a novel ion-selective membrane technology to eliminate the requirement for supplementary NaCl, potentially leading to a reduction of up to 50% in the energy demands of conventional EDM. The effectiveness of this system will undergo rigorous testing at the Brackish Groundwater National Desalination Research Facility, situated in Alamogordo, New Mexico, under the oversight of the U.S. Bureau of Reclamation.

Transforming Municipal Wastewater to Drinking Water to Improve Water Security

Municipal wastewater can be reprocessed into drinking quality water. Reverse osmosis has traditionally been a final treatment step that can provide the high purity required to satisfy drinking water quality regulations, but reverse osmosis generates a brine waste stream and drives up the cost and energy required for direct potable reuse. This project will perform a side-by-side demonstration at Silicon Valley Clean Water’s treatment plant in Redwood City, California, of both a reverse osmosis-based treatment train and a novel treatment train that achieves nearly the same purity without using reverse osmosis. The team will also investigate how different types of wastewater treatment technologies produce effluents that are either easier or harder to transform into drinking quality water.

NAWI is led by DOE’s Lawrence Berkeley National Laboratory in collaboration with National Energy Technology Laboratory, National Renewable Energy Laboratory, and Oak Ridge National Laboratory, and is funded by the Office of Energy Efficiency and Renewable Energy’s Industrial Efficiency and Decarbonization Office.

# # #

Founded in 1931 on the belief that the biggest scientific challenges are best addressed by teams, Lawrence Berkeley National Laboratory and its scientists have been recognized with 16 Nobel Prizes. Today, Berkeley Lab researchers develop sustainable energy and environmental solutions, create useful new materials, advance the frontiers of computing, and probe the mysteries of life, matter, and the universe. Scientists from around the world rely on the Lab’s facilities for their own discovery science. Berkeley Lab is a multiprogram national laboratory, managed by the University of California for the U.S. Department of Energy’s Office of Science.

DOE’s Office of Science is the single largest supporter of basic research in the physical sciences in the United States, and is working to address some of the most pressing challenges of our time. For more information, please visit energy.gov/science.

As climate change flames a megadrought in the U.S. Southwest, the country is hitting some worrisome records. The water level of Lake Mead, which provides water for millions of people, is hovering near its lowest ever. And in some places, the shrinking Colorado River, which irrigates about 5 million acres of farmland and quenches the thirst of over 40 million people, is just desert and dust.

Meanwhile, as of 2018, about 80% of the country’s wastewater—including water used in agriculture, power plants, and mines—gets dumped back into the world, untreated and unusable, a wasted opportunity. And although today’s go-to purification technologies, which use a process called reverse osmosis, are still the most cost-effective and energy-efficient way to treat seawater and briny groundwater, conventional reverse osmosis cannot handle super-salty waters—those containing double the salt content of the ocean. As U.S. water supplies shrink (and get saltier), the country can no longer afford to dump even the saltiest sources back into the world.

Now, in a new study published in Desalination, members of the National Alliance for Water Innovation (NAWI) research consortium analyzed an emerging form of reverse osmosis, called low-salt-rejection reverse osmosis. These novel systems could treat even highly salty water. But the design is so new it is still theoretical.

So, to learn how these technologies might compete with other water treatment options, the NAWI research team developed a mathematical model that could, with help from a supercomputer, quickly evaluate the cost, clean water output, and energy consumption of more than 130,000 potential system designs. Their results show that, in many cases, low-salt-rejection reverse osmosis could be the most cost-effective choice, potentially reducing the overall cost of producing clean water by up to 63%.

“The ultimate goal of this research is to conduct a thorough techno-economic evaluation of a new technology that hasn’t been tested in the real world yet but has the potential to enable high-water-recovery desalination,” said Adam Atia, a senior engineer at the National Energy Technology Laboratory and the paper’s lead author.

Although a few studies have evaluated the potential cost and efficiency of low-salt-rejection reverse osmosis systems, this study offers a more comprehensive analysis of their design, operation, and performance. To better understand the potential promise of these theoretical systems, the team used a supercomputer to hone in on the most optimal, cost-effective designs. They then explored how those designs might function in hundreds of thousands of scenarios (as opposed to just a handful).

Because low-salt-rejection reverse osmosis systems allow more salt to pass through each membrane, they require less force—and therefore less energy—to push the water through. But, if more salt can squeeze through, the resulting water is, not surprisingly, still too salty to drink. To produce potable water, this still-too-salty water gets recycled back into the previous membrane stages. Once the salt content is low enough, standard reverse osmosis can take care of the rest, generating high-quality drinking water.

All that recycling adds to the system’s complexity. So, the team needed to find out: How many membrane stages are optimal? How many recycling loops are needed? And how much cost and energy do those loops add? To answer these questions, researchers could calculate, individually, how much clean water each design could produce from waters with different concentrations of salt.

“That would potentially take a really, really, really long time for them to solve,” said Ethan Young, a researcher at the National Renewable Energy Laboratory (NREL) and an author on the study. “We were able to do it in a few minutes with high-performance computing.”

And, in those few minutes, they examined not one but hundreds of thousands of potential scenarios.

“The novelty of our study is the computational force power we brought to bear on this analysis,” added Bernard (Ben) Knueven, a fellow NREL researcher and author.

Without a supercomputer, all those calculations would take about 88 days instead of one hour or even a few minutes, Young said. Of course, the supercomputer also needed Knueven and Young’s mathematical magic to solve these complex design problems both quickly and accurately.

With all that speedy math, the team discovered that low-salt-rejection reverse osmosis could outperform its competitors in both cost and energy use—at least for water containing less than 125 grams of salt per liter. But the team’s model could also help other research teams identify, build, and test the most promising system designs.

“The hope is, by doing these computational analyses, we can give the experimentalists information to say, ‘Oh, here’s an interesting thing to study,’ or, ‘No, this is probably completely ruled out,’” Knueven said.

The model could be expanded, too, to help experimentalists hone in on the best designs for reverse osmosis systems, generally. Their study is the first to both use and add to NAWI’s Water treatment Technoeconomic Assessment Platform (WaterTAP). A publicly available software tool, WaterTAP gives users the power to model and simulate various water treatment technologies and evaluate their cost, energy, and environmental trade-offs.

“I think it’s so cool. We’re building a tool that can help us and other researchers assess the potential of new and exciting technologies,” Knueven said of WaterTAP, which was built through a collaboration between NREL, Lawrence Berkeley National Laboratory, the National Energy Technology Laboratory, Oak Ridge National Laboratory, and the Regents of the University of California.

Next, the researchers hope to partner with experimental teams to build and evaluate how low-salt-rejection reverse osmosis systems function in the real world. Mineral buildup, for example, could slow the system down and should be accounted for in future evaluations.

Even so, Atia said, this emerging form of reverse osmosis could be a valuable tool to maximize water recovery from high-salinity sources. “And our model can play a key role in supporting the technology’s deployment,” he said.

“To me,” Knueven said, “it’s a demonstration of what we can do with a little bit of computation and a little bit of optimization.”

Learn more about NAWI and its members’ efforts to secure an affordable, energy-efficient, and resilient water supply for the United States.

The National Alliance for Water Innovation is a public-private partnership that brings together a world-class team of industry and academic partners to examine the critical technical barriers and research needed to radically lower the cost and energy of desalination. The alliance is led by the U.S. Department of Energy’s Lawrence Berkeley National Laboratory in collaboration with the National Energy Technology Laboratory, the National Renewable Energy Laboratory, and Oak Ridge National Laboratory and is funded by the U.S. Department of Energy’s Industrial Efficiency and Decarbonization Office.