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Houston researchers harness dialysis for new wastewater treatment process

Rice University's Menachem Elimelech and Yuanmiaoliang “Selina” Chen published a study in Nature Water on mimicking dialysis from the medical field to treat wastewater. Photo by Gustavo Raskosky/Rice University

By employing medical field technology dialysis, researchers at Rice University and the Guangdong University of Technology in China uncovered a new way to treat high-salinity organic wastewater.

In the medical field, dialysis uses a machine called a dialyzer to filter waste and excess fluid from the blood. In a study published in Nature Water, Rice’s team found that mimicking dialysis can separate salts from organic substances with minimal dilution of the wastewater, addressing some of the limitations of previous methods.

The researchers say this has the potential to lower costs, recover valuable resources across a range of industrial sectors and reduce environmental impacts.

“Traditional methods often demand a lot of energy and require repeated dilutions,” Yuanmiaoliang “Selina” Chen, a co-first author and postdoctoral associate in Elimelech’s lab at Rice, said in a news release. “Dialysis eliminates many of these pain points, reducing water consumption and operational overheads.”

Various industries generate high-salinity organic wastewater, including petrochemical, pharmaceutical and textile manufacturing. The wastewater’s high salt and organic content can present challenges for existing treatment processes. Biological and advanced oxidation treatments become less effective with higher salinity levels. Thermal methods are considered “energy intensive” and susceptible to corrosion.

Ultimately, the researchers found that dialysis effectively removed salt from water without requiring large amounts of fresh water. This process allows salts to move into the dialysate stream while keeping most organic compounds in the original solution. Because dialysis relies on diffusion instead of pressure, salts and organics cross the membrane at different speeds, making the separation method more efficient.

“Dialysis was astonishingly effective in separating the salts from the organics in our trials,” Menachem Elimelech, a corresponding author on the study and professor of civil and environmental engineering and chemical and biomolecular engineering at Rice, said in a news release. “It’s an exciting discovery with the potential to redefine how we handle some of our most intractable wastewater challenges.”

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A View From HETI

A rendering of a Quaise Energy geothermal plant. Rendering via quaise.com

Houston-based Quaise Energy, a producer of utility-scale geothermal power, raised $134 million in a Series B round to advance its “superhot” geothermal power plant.

Climate-focused San Francisco-based investment firm Prelude Ventures led the round, with participation from JERA Co., Japan’s largest power generation company, and Idemitsu Kosan, one of Japan’s largest energy companies. Nearly all existing investors, including cleantech-focused investment firm Safar Partners, participated in the round.

“We have backed Quaise since the beginning because we believed accessing superhot rock would unlock geothermal energy at a scale the world has never seen,” Mark Cupta, managing director at Prelude Ventures, said in a press release.

The startup expects more equity and debt deals to close “imminently.” Quaise has raised $230 million since its founding in 2018.

Quaise says some of the fresh funding will go toward building the world’s first commercial-scale “superhot” geothermal power plant —Project Obsidian in central Oregon. In addition, Quaise is earmarking money for continued development and commercialization of its millimeter-wave drilling system toward depths exceeding 5 kilometers (about 16,400 feet).

Quaise uses a millimeter-wave drilling system developed at the Massachusetts Institute of Technology to remove rock at depths and temperatures that aren’t economically feasible with conventional drilling. With this technology, Quaise can reach rock at temperatures of around 570 degrees to 930 degrees in most places worldwide, enabling construction of geothermal systems that rival fossil fuels and nuclear energy in power density and that rival renewables in cost.

“Our ambition is to power civilization with Earth's most compelling energy source. This round takes us from field-proven technology to first commercial revenues,” Carlos Araque, co-founder, president and CEO of Quaise, added in the release.

Quaise has demonstrated the capability of its millimeter-wave drilling system at its Central Texas test site, drilling more than about 330 feet through granite in 2025—the first time the technology penetrated basement rock at full scale in the field. The company is approaching a depth of about 3,300 feet at the same site.

Construction of Project Obsidian is underway at Oregon’s Deschutes National Forest. The project, which has the potential to generate gigawatt-scale power, is slated to deliver electricity to the Pacific Northwest grid by 2030.

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