REMOVAL OF PFAS CONTAMINATION IN WATER SUPPLY | Santa Clarita, CA
Santa Clarita Valley Water Agency (SCV Water) is the first water agency in California to use Purofine® PFA694EBF PFAS selective ion exchange resin from Purolite for PFAS treatment. This buffered resin allowed SCV Water to meet their strict chloride discharge limit as well as treat and remove PFAS to non-detect levels.
Addressing PFAS was SCV Water’s top priority after detecting PFAS in local wells. SCV Water operates a service area of approximately 195 square miles serving over 273,000 people in northern Los Angeles County. When the State Water Resources Control Board – Division of Drinking Water (DDW) decided to lower its response level guidelines to 10 parts per trillion (ppt) for perfluorooctanoic acid (PFOA) and 40 parts per trillion (ppt) for perfluorooctanesulfonic acid (PFOS), two chemicals in a family of per- and polyfluoroalkyl substances (PFAS), SCV Water moved quickly. First, they voluntarily shut down nearly half their wells, and second, they expedited design and construction of a PFAS treatment facility.
SCV Water hired the consulting firm, Kennedy Jenks, to design a treatment plant. They evaluated various options and proposed the most cost-effective and efficient process to reduce PFOS and PFOA to non-detect levels – PFAS-selective ion exchange resin.
Resin was chosen over granular activated carbon (GAC) for many reasons:
- Using GAC would have required three times the number of vessels compared to ion exchange. GAC would require twenty-four 12' diameter vessels for proper treatment design. PFAS-selective ion exchange resin has much faster kinetics, so only six 12' diameter vessel are needed to provide effective PFAS removal. Beyond the savings in equipment, the process took dramatically less real estate to accomplish the same goal. Additionally, having one third the number of vessels saves money on the amount of analytical testing that needs to occur both at startup and for regular compliance testing.
- Ion exchange is much more selective for PFAS than GAC. While this is important for PFOA and PFOS, the selectivity is especially apparent with some of the short-chain PFAS like perfluoroalkylbutanesulfonic acid (PFBS.) GAC has a very short bed life for PFBS breakthrough, while ion exchange resin will last a long time while also treating PFOA and PFOS. This means ion exchange provides treatment for the PFAS chemicals under the most scrutiny today, and also the ones scientists are considering for treatment goals in the near future due to the potential health effects.
- Ion exchange would take five times fewer changeouts than GAC over the same time period of treatment time. Eighty percent fewer changeouts translates to savings on labor costs and reduces the impact on both the process and the community by reducing the number of disruptions experienced during a changeout. The system is also less vulnerable to bacteriological contamination the less it’s disturbed.
- SCV Water’s previous experience with ion exchange resin provided them with the confidence that this PFAS site would be relatively easy to operate.
By the summer of 2020, SCV Water installed the first treatment system on three of its wells which included using Purolite’s PFAS-selective ion exchange resin PFA694E.
With the new system running, SCV Water is returning 6000 gallons per minute to service, the amount used by about 5,000 families in a year. The system is an investment in the Agency’s long-term water supply, providing safe, high quality water to its customers.