The historical use of fire-fighting foam containing various per- and polyfluroroalkyl substances, commonly known as PFAS, at The Army Aviation Centre Oakey (AACO) in Australia led to the contamination of groundwater at the base. These compounds are commonly found in fire retardants and several other products, including food packaging, non-stick pots and pans, water and stain repellent clothing, etc. Due to their water solubility and persistent nature, they can end up in groundwater and require treatment.
Australian Department of Defence (Defence) needed to identify a technology to address PFAS contamination. ECT2’s ion exchange resin technology was selected by Defence because it met the following criteria:
- Capable of treating a host of PFAS compounds to less than limit of reporting levels
- Amenable to modular, mobile, “plug and play” installation inside international shipping containers
- Sustainable, i.e., create minimal waste
For the project, ECT2 designed, fabricated, assisted with delivery and installation, and performed startup/commissioning and operation of a 50-gallon per minute (192 liters per minute) PFAS removal system. ECT2 designed the system to treat groundwater with influent PFAS concentrations in the range of 1 to 120 parts per billion. The system consists of pretreatment filtration to remove iron and solids, followed by PFAS removal using multiple vessels in series (lead/lag configuration) containing ion exchange resin. The mechanisms of PFAS removal included both ion exchange and adsorption. ECT2 used multiple ion exchange resins to provide superior PFAS removal, allowing Defence to consistently meet the project objective to remove all PFAS compounds in the influent groundwater.
Two vessels filled with ECT’s Sorbix A3F resin were initially specified to provide consistent compliance with the original target limits of 0.5 ug/l for PFOS + PFHxS, and 5 ug/l for PFOA. The Australian Commonwealth Department of Health subsequently lowered drinking water quality standards by roughly an order of magnitude to 0.07 ug/l and 0.56 ug/l, respectively, before the system was delivered to Oakey. After the treatment system was delivered, the treatment objective was lowered even further to less than the limit of reporting for all monitored PFAS. ECT2 adjusted to the changing treatment goals by adding two polish vessels at the tail end of the existing treatment train. Each of the polish vessels contains Sorbix LC1, a specialized resin that effectively removes an array of PFAS compounds, including the more difficult to remove short-chain compounds.
The system started operating in September 2017 and has met all treatment objectives since start up, including achieving less than limit of reporting for all monitored PFAS compounds.