UV disinfection eliminates groundwater-borne pathogens at Wisconsin water utility
Prairie du Sac, a village of 3,400 located in south central Wisconsin, began its journey to UV disinfection when it was selected as one of 14 communities in the state to participate in a $2.3-million, U.S. Environmental Protection Agency (EPA)-funded study focusing on the role of drinking water in childhood illnesses. The Marshfield Clinic Research Foundation in Marshfield, Wisc., conducted the Wisconsin Water and Health Trial for Enteric Risk.
“There has been growing evidence that our groundwater is fairly heavily contaminated with human pathogenic viruses,” said Mark Borchardt, Ph.D., a microbiologist and research scientist at the Marshfield Clinic Research Foundation, who led the study.
The study set out to prove just that and to test the effectiveness of UV disinfection to inactivate any viruses present in the groundwater.
Before participating in the study, the village “had nothing in regard to disinfection—we were not putting any chemicals in,” said Patrick Drone, Prairie du Sac director of public works and utilities. This was an excellent opportunity for the utility to get firsthand experience with the advanced technology of UV disinfection. The community’s water utility has 1,800 connections served by 75- and 550-ft-deep wells that both tested virus positive at the outset of the study.
The village was outfitted with two WEDECO UV reactors, one in each of its well houses.
“The deeper well, which draws 1,500 gpm during the day from 300 ft, is served with an efficient, high-performance WEDECO BX 1800—a system employing 18 low-pressure UV lamps,” said Drone. “The shallower, 500-gpm well is pumped once during the night and is served by a six-lamp WEDECO UV system.”
The water is pumped to a 400,000-gal water tower before distribution to the community.
The study concluded that UV disinfection clearly eliminated the viral pathogens at the Wisconsin wellheads before introduction into distribution lines.
“Our target UV dose of 50 mJ/sq cm was very effective in eliminating viruses in a real-world setting,” said Borchardt.
For the community, Drone said the implementation of UV is significant because, “Number one, we do not have to use chemicals. Number two, we are taking care of a lot of bacteria that will not go out to the people in Prairie du Sac.”
Both systems have operated so well at disinfecting the well water and maintaining a quality distribution that in February 2013, Prairie du Sac’s water was selected as the nation’s best-tasting rural water in the Great American Water Taste Test, sponsored by the National Rural Water Association.
The Village of Prairie du Sac was so impressed with the results and effectiveness of the WEDECO UV systems during the study that it negotiated to purchase the technology for continued use.
The study’s findings showed that with proper operation, the WEDECO UV system can reliably eliminate bacteria and most viruses without resorting to the chlorine disinfection commonly used across the nation.