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Using green nanotechnologies to improve water quality
Using green nanotechnologies to improve water quality

When the microscopic parasite Cryptosporidium was detected in multiple test samples from reservoirs in the Bull Run watershed (Portland’s primary source of water) earlier this year, it marked the end of an agreement between the city and the Environmental Protection Agency (EPA). The arrangement allowed the Portland Water Bureau to provide costumers water not treated for the microorganism. As a result of the potentially harmful parasite turning up in the city’s water supply, the Portland City Council recently voted to move forward with building a water treatment plant that could cost the city as much as $500 million.

For the price tag, you might expect the city’s future treatment facility to provide pristine water to its nearly one million customers. But that would depend on how you define “pristine.” The fact is, the Portland Water Bureau and thousands of other agencies like it around the nation are only required to meet standards set by the EPA and state agencies where they apply, and those rules do not regulate all of the contaminants found in water supplies.

According to the Environmental Working Group’s Tap Water Database, data from nearly 50,000 public water utilities across the nation shows that while the water we consume is considered safe by federal and state regulatory agencies, test samples taken from taps often contained as many as 250 contaminants at levels “authoritative scientific studies have found pose health risks.”

At Portland State University, Simon Fowler, who recently received a Ph.D. in physics from PSU, has developed a water purification technology that eliminates carbon-based compounds including pesticides, herbicides, pharmaceuticals, hormones, and bacteria, many of which are unregulated and often introduced into the water supply through human activity.

The invention works by using a process called photocatalysis in which interactions between light, water, and a titanium dioxide catalyst cause oxidation reactions that break the chemical bonds which hold carbon-based contaminants together. While oxidation reactions are common in water purification practices, they typically require the addition of other chemical agents that can be expensive and come with a substantial carbon footprint. Fowler’s innovative solution eliminates the need for such chemicals. Water merely passes through a continuous-flow reactor where it comes in contact with a specially designed reactor core coated with an ultra-thin layer of titanium dioxide and photons emitted from a light source. The water leaves the reactor free of carbon-based contaminants, and the only byproduct of the process is carbon dioxide, which can be captured and used for other purposes.

“The technology works a little like a solar cell,” Fowler said. “But, rather than converting the energy of photons into electricity, the photocatalytic reactor uses that energy for oxidation reactions that destroy carbon-based compounds in the water.”

Dr. Simon Fowler develops water purification technologies at Portland State UniversityFowler’s dissertation research, conducted under the direction of Physics and Mechanical and Materials Engineering professor, Dr. Jun Jiao, focused on designing the reactor and its components and evaluating and characterizing performance aspects of various iterations of the technology.
 

Since completing his dissertation, Fowler has shifted his attention to demonstrating the commercial viability of the reactor. He has engaged with PSU’s Office of Innovation and Intellectual Property (IPP), which has filed to patent the invention and is working to identify potential partners who can assist with commercialization. Those partners include Oregon BEST (Built Environment and Sustainable Technologies), a state-sponsored, non-profit, economic development organization that funds and assists innovative cleantech projects across the state. BEST recently awarded Fowler and Jiao a grant, funding from which will support the development and performance analysis of a scaled-up reactor capable of performing under conditions similar to those in commercial applications including pre- and post-consumer municipal water treatment facilities.

“What I find rewarding about working on projects like this is being able to apply my love for physics to addressing complex social and environmental issues such as improving water quality,” Fowler said. “There are issues we need to address as a society, and I think there’s real value to being able to contribute to finding solutions.”

Clean water is a critical resource for society and the environment. Water purification technologies like those developed by Fowler could soon contribute to a healthier population and cleaner waterways by working in concert with water treatment facilities such as the one which the City of Portland will soon begin building. As a final step in the purification process, this technology could remove many of the unregulated and potentially harmful contaminants that enter into our water supply primarily because of human activities. Likewise, if used in post-consumer treatment facilities, it could prevent carbon-based compounds like pesticides, herbicides, pharmaceuticals, and hormones from entering rivers, streams, lakes and oceans.

By Shaun McGillis - Research & Strategic Partnershihps