Background/Objectives: In addition to routinely being found in food packaging, non-stick pots and pans, water and stain repellent clothing, and various other products that resist heat, oil and stains, per- and polyfluroroalkyl substances (PFAS) have been used in the manufacturing of firefighting foams. Due to their water solubility and persistent nature, PFAS end up in groundwater and require treatment. The historical use of firefighting foam at the Royal Australian Air Force (RAAF) Base Tindal has resulted in groundwater contamination, which has been identified off the base, impacting a bore used in the Katherine water utility supply.
Approach/Activities: The Australian Department of Defence (Defence) had contracted an ion exchange resin technology at two of its properties on the East Coast of Australia. Following the identification of the contamination in Katherine, Defence revised its treatment objectives for one of the contracted systems and requested that the provider accelerate fabrication to deploy the system to Katherine as a priority. A 12.5 L/sec turnkey, modular system was provided that could consistently produce treated water with PFAS concentrations below the limit of reporting (LOR). Defence accelerated the delivery schedule by air-freighting the system from Maine in the U.S. to Darwin, Australia in an Antonov An-225 transport plane.
The PFAS water treatment system, which supplements the existing potable water treatment plant, included pre-treatment filtration and ion exchange to remove solids and other fouling agents, and specialized ion exchange resins for PFAS removal. The system was installed in international shipping containers, which allowed for easier transportation and rapid, “plug and play” on-site readiness. By manufacturing the system in a central fabrication shop, design engineers worked directly with structural, mechanical, electrical and instrumentation trades to ensure quality, efficient construction. This also facilitated operational debugging prior to shipment and translated to faster on-site readiness. The field crew worked cooperatively with Defence and the Northern Territory Power and Water Corporation (water utility provider) to efficiently install and start up the PFAS-removal system following delivery.
Results/Lessons Learned: Despite the revised treatment objectives, the entire design, fabrication, shipping and installation process took less than four months. The system went online in late October 2017, with influent total PFAS concentrations averaging 310 ng/l. It has been meeting all project objectives, including consistently achieving less than LOR effluent concentrations for all 34 PFAS compounds being monitored. This includes ultra-trace monitoring, measuring PFAS levels as low as 0.1 ng/l (ppt).
No resin change-outs have been required, and no PFAS breakthrough has been detected from the treatment system. The primary lesson learned has been properly managing the potential precipitation of calcium carbonate and associated resin fouling, as the groundwater is pumped from a karst formation, containing elevated levels of calcium and bicarbonate alkalinity. This challenge has been successfully controlled through the addition of 1 to 2 ppm of sequestering agent at the head of the treatment system.
Andy Bishop, Co-Founder, Emerging Compounds Treatment Technologies
Andy Bishop is the co-founder of ECT (Emerging Compounds Treatment Technologies). ECT is an equipment company focused on developing and commercializing treatment technologies for emerging, difficult-to-treat compounds. Andy’s responsibilities include directing engineering and project management efforts for the company’s product line.
Andy has 19 years of experience in water and wastewater treatment. His focus is currently on delivering innovative technology and design-build solutions for the treatment of 1,4-dioxane, perfluorinated compounds, and other emerging compounds.