From Stanford University Engineering (US) : “New research looks to lower the high cost of desalination” 

From Stanford University Engineering (US)

September 17, 2021
Andrew Myers

A suite of analytical tools makes it easier for innovators to identify promising research directions in making saltwater potable.

New analytic methods that could help desalination engineers weigh the many factors that go into building a desalination plant. | Stocksy/Jesse Morrow.

Removing salt and other impurities from sea-, ground- and wastewater could solve the world’s looming freshwater crisis.

And yet, while industrial-scale seawater desalination plants do exist in coastal areas where the freshwater challenge is most acute, the process of making undrinkable water drinkable is largely out of reach for inland water sources due to the high cost of concentrate disposal.

“When we desalinate water, we are left with a pure water stream and a concentrated waste stream. Inland brackish water and wastewater desalination plants are costly to build and to operate because we don’t have easy disposal options for the concentrate stream,” said Meagan Mauter, associate professor of civil and environmental engineering at Stanford.

Compounding this problem is that some inland wastewaters from industrial sources can have up to 10 times higher concentration of dissolved solids than seawater. “Concentrating and disposing of concentrated brine could unlock vast new water resources, but it’s just too expensive at this time,” she said.

It is not for lack of trying, however, added Mauter, who in her newest paper in PNAS introduces a suite of new analytic methods that could help desalination engineers weigh the many technical and financial factors that go into building a desalination plant.

Still waters run deep

Mauter’s team applies this “innovation assessment model” to analyze membrane-based desalination in which impure water is separated from freshwater by a permeable material with pores just large enough for water molecules to flow through, but too small for salt and other solid impurities. Under osmotic or hydraulic pressure, the molecules of freshwater migrate through the membrane barrier and leave the impurities behind.

While it sounds easy, membrane separation is technically quite difficult. High-salinity membrane separation processes can involve hundreds of interdependent components or design variables – each with bearing on the ultimate efficiency and cost of the underlying process. Using Mauter’s approach, engineers aiming to lower the cost of desalination can now test their innovative ideas before they build their prototypes.

“Innovation is not always intuitive. Often, the cost increases of these new technologies negate any performance improvements,” Mauter says. “A better process or component is not much good if the end result is a further increase in overall separation costs.”

Her approach helps desalination designers look at all components in a process when trying to understand the relationship between cost and performance. Many times, she said, the best way to reduce the costs of a treatment technology is not to improve performance, but to reduce the manufacturing costs of a particular component.

“That is a very different set of scientific questions to consider,” Mauter added. “Our method helps prioritize the research and development pipeline and helps to earmark scarce research dollars for innovations with the greatest potential benefit.”

Innovation into action

The method is actually three distinct approaches. The first is a relatively simple cost-benefit analysis of materials and manufacturing methods that helps winnow a long list to a few contenders with the most promise. The second increases the rigor a bit, balancing performance gained with the cost to make a new component. The most advanced method in the suite is a simulation of expected impact of a component innovation on reducing costs that also accounts for the impact of improvements in other, coupled components.

Mauter and co-authors then used their newly developed approaches to suggest one potential innovation that has high probability of substantial reductions in the “levelized cost of water” – the industry standard criterion – for treating high-salinity brine.

High-pressure reverse osmosis processes, she says, could hit the sweet spot for cost-effective high-salinity water desalination. For these technologies to displace existing thermal processes, however, will require new high-pressure membranes able to withstand pressures of up to 4,000 pounds per square inch without compromising water permeability or salt rejection.

“Anyone in the desalination research and development spectrum – a researcher, an investor or a corporate executive – should be very interested in these techniques for bringing down the cost of desalination,” Mauter said.

See the full article here .


Please help promote STEM in your local schools.

Stem Education Coalition

Stanford Engineering (US) has been at the forefront of innovation for nearly a century, creating pivotal technologies that have transformed the worlds of information technology, communications, health care, energy, business and beyond.

The school’s faculty, students and alumni have established thousands of companies and laid the technological and business foundations for Silicon Valley. Today, the school educates leaders who will make an impact on global problems and seeks to define what the future of engineering will look like.

Our mission is to seek solutions to important global problems and educate leaders who will make the world a better place by using the power of engineering principles, techniques and systems. We believe it is essential to educate engineers who possess not only deep technical excellence, but the creativity, cultural awareness and entrepreneurial skills that come from exposure to the liberal arts, business, medicine and other disciplines that are an integral part of the Stanford experience.

Our key goals are to:

Conduct curiosity-driven and problem-driven research that generates new knowledge and produces discoveries that provide the foundations for future engineered systems
Deliver world-class, research-based education to students and broad-based training to leaders in academia, industry and society
Drive technology transfer to Silicon Valley and beyond with deeply and broadly educated people and transformative ideas that will improve our society and our world.

The Future of Engineering

The engineering school of the future will look very different from what it looks like today. So, in 2015, we brought together a wide range of stakeholders, including mid-career faculty, students and staff, to address two fundamental questions: In what areas can the School of Engineering make significant world‐changing impact, and how should the school be configured to address the major opportunities and challenges of the future?

One key output of the process is a set of 10 broad, aspirational questions on areas where the School of Engineering would like to have an impact in 20 years. The committee also returned with a series of recommendations that outlined actions across three key areas — research, education and culture — where the school can deploy resources and create the conditions for Stanford Engineering to have significant impact on those challenges.

Stanford University

Leland and Jane Stanford founded the University to “promote the public welfare by exercising an influence on behalf of humanity and civilization.” Stanford opened its doors in 1891, and more than a century later, it remains dedicated to finding solutions to the great challenges of the day and to preparing our students for leadership in today’s complex world. Stanford, is an American private research university located in Stanford, California on an 8,180-acre (3,310 ha) campus near Palo Alto. Since 1952, more than 54 Stanford faculty, staff, and alumni have won the Nobel Prize, including 19 current faculty members

Stanford University Seal