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Oklahoma researchers studying new ways to clean water

Thursday, October 26, 2023

Hands holding a drinking glass under a water faucet.


Oklahoma State University researchers are studying the potential process of cleaning wastewater for commercial and residential use.


Most water that people use in their daily living comes from rivers, groundwater or lakes, said Kiranmayi Mangalgiri, assistant professor in the OSU Department of Biosystems and Agricultural Engineering. It is sent to a drinking water treatment plant and then used in residential homes and industrial facilities. Afterward, it goes to a wastewater treatment plant, which cleans the water and returns it to a a river, ocean or other outlet.


“It is a very linear way of using water,” Mangalgiri said. “Water is scarcer nowadays, and our population is growing, so we need to find ways to supplement existing water supplies. One way we can do that is by cleaning up the wastewater we are using to the extent that it makes a better water source for drinking.”


Mangalgiri is teaming up with Tim Hubin, professor of chemistry and physics at Southwestern Oklahoma State University, who developed tetra azamacrocyclic catalysts for cleaning out contaminants in water.


A ligand is an organic molecule that binds a metal ion to form a metal-ligand complex. Hubin’s catalysts are iron and manganese complexes with ligands that have certain properties that allow its metal ion to perform a specific task, such as the modification of organic molecules. These ligands provide stability, allowing the catalysts to not decompose in water, a condition that typically causes similar iron and manganese complexes to fall apart. These metal catalysts activate oxygen or hydrogen peroxide to modify organic molecules.


“We would like to ultimately see an inexpensive solid-state catalyst material that could be packed into a cartridge that would become part of a water purification process,” Hubin said. “The catalyst would be able to remove contaminants to a greater extent than current technologies provide.”


Most treatments for removing contaminants from water – i.e., microfiltration, reverse osmosis, advanced oxidation – use a lot of energy.


“One of our research questions is, ‘Are there energy-efficient processes that can be used?’ That’s where the catalysts come in,” Mangalgiri said. “When we add the catalysts to the water, they degrade contaminants in water, and they regenerate to start the cycle again.”


In a preliminary study during the summer of 2023, Mangalgiri and Hubin’s team tested four catalysts against four types of antibiotic contaminants in three types of water.


They discovered that some catalysts were more effective than others, with one catalyst outperforming the others.


The next steps are to:

  • Understand what is happening to the catalysts and why some operate better than others.
  • Test the catalysts with other types of contaminants.
  • Further investigate how much chlorine helps with the process.

“We are trying to discover which catalyst will be most reliable in a real system while also being cost-effective. We want to know what aspect of wastewater most affects its treatability,” Mangalgiri said. “For example, if the alkalinity of the water is what affects these systems the most, that can help us decide what level of alkalinity is appropriate for this type of treatment system.”


She said the process could eventually be applied to water for agricultural use. Mangalgiri’s team hopes to eventually partner with city water and wastewater utility departments in Oklahoma for the next phase of the project.


“Our goal is to set up a pilot scale system with a 50-liter or larger water system. That will help us take this to full scale,” she said. “But before we get there, we need to understand how these systems work in real conditions.”

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