It seems to be an annual occurrence. As soon as the heat of late summer hits, surface water sources around the midwest become victims of algae blooms, causing treatment challenges for municipalities and water departments and giving citizens concern for their water quality. In Osceola’s West Lake, the algae blooms have been increasingly difficult in the past few years. That, along with ageing filtration system challenges, has the Osceola Water Works team working hard to keep treatments ahead of the issue. Finally, after some engineering research and guidance from the DNR, they believe the issue can be addressed with some plant restructuring and changes in how the source water is being treated.
In August and September of this year, Osceola Water Works needed to send out a notice to consumers for turbidity treatment violations. While Brandon Patterson, Osceola Water Works Superintendent, is confident in the safety of Osceola’s water, some consumers in outlying areas may notice discoloration or taste changes.
“This year we were forced to change the intake levels for the West Lake source water to try to get ahead of the algae blooms,” said Patterson. “We had to increase our filtration and treatment processes to offset the changes in water quality at those levels.”
When changing the intake levels in West Lake, increased filtration along with more chlorine and permanganate treatments became a necessity. Because of the lack of filtration time Osceola’s source water has traveling from West Lake to the plant, pretreatment and basic filtration is restricted. That’s where the filter system at the plant does the heavy lifting. Passing through eight combination carbon filters and a chemical treatment process, testing for contaminants after they’re treated with chlorine are peaking just out of compliance. When chlorine or other treatments are added after the filtration, it is causing the increases in turbidity.
“We’ve been trying to change the water quality coming into the plant and through the filters by raising or lowering the intake,” said Patterson. “But all that does is change the input quality, not the output quality. And that just creates more issues.”
After having strategic discussions with the IDNR and Osceola Water Works chemical consultant, Patterson and the team landed on a tentative plan to address the compliance issues. By integrating a new pre-treatment strategy and trying to increase the carbon quality within the filters at the plant and at the lake, the source water will have a better chance for reduced contaminants. This will lower the turbidity levels before treatment and testing. They’re also looking at re-engineering the post-filtration procedure, before chemicals are added, to allow the filtered water more time to settle from the filtration as well as to be properly tested where it’s supposed to be – post filtration. With these changes and once a final treatment of chlorine is added, the…