By Francis Boodoo, Ted Begg, Theresa Funk, Toby Kessler, Emily Shaw, and Michael Pickel
In mid-2016, shortly after the U.S. Environmental Protection Agency (EPA) revised the health guidelines for perfluorooctanoate (PFOA) and perfluorooctanesulfonate (PFOS) to 70 ng/L (or ppt), the township of Horsham, Pennsylvania, together with Horsham Water and Sewer Authority (Authority), the Township’s public water supplier, set a goal of reducing these two contaminants to non-detect (ND) level in all drinking water supplied. To achieve this aggressive goal, the Authority installed granular activated carbon (GAC) filters on selected wells. A newly developed PFAS-selective ion exchange resin was installed downstream of the GAC filters on one well to evaluate the effectiveness of the resin in further polishing the water to the ND goal. After several months of operation, the GAC filters were bypassed and the resin continued to operate until the concentration of PFAS rose above the detection level. This case study provides details on the performance and consistency of both the GAC and the PFAS-selective resin in meeting the ND goal. A comparison is made of operating costs for both treatment options.