The city will install 21 granular activated carbon filters and upgrade 26
The Ann Arbor, Mich., City Council approved a $750,000 increase to a previous $161,727 contract with Calgon Carbon Corp., to upgrade the city’s water treatment plant to include granular activated carbon filtration (GAC) in order to target per- and polyfluorinated substances (PFAS)–commonly used in non-stick cookware, firefighting foam and water-repellents–which have been detected in the Huron River and at low levels in the city’s drinking water. While the city currently uses 26 GAC filters, the council approved upgrading the remaining 21 filters and repairing all filters, as reported by MLive.
“The city has GAC filters, and the existing filters remove some of the PFAS,” said Sarah Page, the city drinking water quality manager. “In addition, the city has been piloting a new type of carbon in its filters since Nov. 2017, and this new carbon has demonstrated enhanced removal of PFAS. Because of this success, city staff propose to transition all of its filters to this new type of carbon in FY19.”
Ann Arbor currently replaces 20% of filter media annually, but the new proposal aims to replace 50% per year, accelerating the filter replacement process. While the city’s 2017 test revealed maximum levels of PFOA and PFOS at 15 ppt in the drinking water, still below the U.S. EPA’s advisory level of 70 ppt, lower recommendations or 7 ppt for PFOS and 11 ppt for PFOA are being considered.
“In the future, we will continue to track what is happening related to regulations associated with these chemicals,” said Brian Steglitz, the city’s water treatment plant manager. “We have volunteered to participate in several research initiatives that are going on to further study PFOS and PFOA and the family of chemicals and how we can remove them from our drinking water, so we intend to continue to stay engaged in this topic moving forward.”
In addition to an activated carbon system, the city is considering adding a new ultraviolet disinfection system by 2020 to treat the Huron River water for cryptosporidium.