Primary Investigator:  Alptekin Aksan
Co-Investigators: Larry Wackett, Tony Dodge (Postdoctoral Scholar), Kelly Aukema (Postdoctoral Scholar), Joey Benson (Graduate Scholar)
Industry Partners: Minnepura Technologies SBC, King Technology Inc., DowDuPont, Sani Marc Group Pool & Spa
Award Type: Demonstration Grant

ProblemResidential pools use trichloroisocyanuric acid (Trichlor) as a disinfecting agent to protect against pathogens like Giardia. As Trichlor breaks down, the byproduct, cyanuric acid (CYA), reduces the chlorine disinfection activity. The only way to offset CYA is by draining and refilling the pool, which wastes water, energy, and chemicals.

SolutionA new patented technology removes CYA from water without requiring pool drainage. Bacteria that produce CYA-degrading enzymes treat water as it flows through a bioreactor. The bacteria are coated in a bacterial exoskeleton technology developed in Dr. Aksan’s lab to stabilize and protect the bacteria from chlorine. Researchers will now scale up the technology to demonstrate its effectiveness and economic feasibility in pools in Minnesota and Canada.

Impact: Draining just half the pools in the United States once a year to remove CYA requires three months’ worth of the water that flows through the Colorado River. On this scale, the wasted water, heat, and chemicals required to refill pools affects everyone. Developing a treatment for CYA that does not require pool drainage will benefit the environment while continuing to protect Minnesotans from waterborne pathogens.

Solution Demonstrated and Implemented: The PI and c-PIs worked with the industrial partners to demonstrate a solution to the problem that would save water, energy chemicals, and be cost-effective enough that a commercial product was feasible. The demonstration was successful. It has been implemented and a product is currently being marketed by the industrial partners. New patents that protect the technology are held jointly by the Danisco group of DuPont and the University of Minnesota.

The key conceptual leap was the realization that cyanuric acid (CYA) biodegradation could not be realized on the scale of large pools in the presence of chlorine. In light of that, an approach was developed to dechlorinate, treat the pool water, and rechlorinate. The successful method is described in detail in the paper and the patents included below. The method has further demonstrated at swimming pool scale at Danisco-DuPont, Sani Marc and King Technology.

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