Public Release: 

Getting the salt out

Pitt engineering researchers receive nearly $500,000 DOE grant to explore new cost-effective method to treat high-saline water

University of Pittsburgh

PITTSBURGH (November 10, 2014) ...Developing a method to utilize waste heat from thermoelectric plants to treat high-saline water from hydrofracturing and other processes is the focus of a U.S. Department of Energy (DOE) grant recently awarded to researchers at the University of Pittsburgh's Swanson School of Engineering. "Development of Membrane Distillation Technology Utilizing Waste Heat for Treatment of High Salinity Wastewaters" (DE-FE00224061) was funded with a $496,000 grant from the DOE National Energy Technology Laboratory (NETL), with an additional $157,000 in funding from Pitt.

Principal investigator is Radisav Vidic, PhD, P.E., professor and chair of the Swanson School's Department of Civil and Environmental Engineering. Co-PI is Vikas Khanna, PhD, assistant professor of civil and environmental engineering. The grant was funded through the DOE's Fossil Energy's Crosscutting Research Program. Dr. Vidic and his group will target two goals of the grant to solve a mutual problem - utilizing low-grade waste heat in existing large scale power generation and gas transport systems, and developing a low-cost treatment of waste water produced from fossil-based resources and carbon dioxide (CO2) storage.

"The typical coal- or natural gas-powered electric plant produces a tremendous amount of low-grade heat and energy as a by-product, but capturing and using it is not cost-effective. Similarly, hydrofracturing and carbon sequestration produces water with high salinity, which is too costly to recycle and is typically disposed as waste," Dr. Vidic explains. "What we intend to explore is whether a membrane distillation technology can be adapted to utilize this waste heat to treat these wastewaters in a cost-effective manner."

According to Dr. Vidic, membrane distillation technology doesn't require high temperatures to separate the brine from the water and can function between approximately 70-80 degrees Celsius (160-180 degrees Fahrenheit). The first phase of the research would include developing the technology in the lab utilizing two processes - direct contact membrane distillation, which is the simplest form, and vacuum membrane distillation - to recover clean water from the salty brine. Systems analyses will also be performed to determine the availability and quantity of useful thermal energy from coal and natural gas power plants in Pennsylvania, Ohio and West Virginia, as well as from natural gas and CO2 compression facilities. This will enable the researchers to determine the economic viability of the treatment process.

In theory, the residual salts and other materials could then be stored in a landfill or disposed by deep well injection, and the recovered clean water could for example be used in place of fresh water in hydrofracturing and other power-related systems or for irrigation.

"Fresh water is a finite resource and so we need to examine the water footprint of the energy industry as a whole, which is very water-intensive," Dr. Khanna says. "Although the technology may ultimately be cost-prohibitive for power utilities, it could be practical for private industry to develop and build near power plants, creating a win-win situation. Most importantly, we hope to create a more sustainable solution for two distinct yet related problems - waste heat and waste water."

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Paul A. Kovach
Director of Marketing and Communications
Swanson School of Engineering
University of Pittsburgh
3700 O'Hara St
Benedum Hall Suite 104E
Pittsburgh, PA 15261

Phone: 412-624-0265
Fax: 412-624-1010
Cell: 412-427-9422

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