Director of Engineering Design
Ms. Sinnett is the Lead Mechanical Engineer for Emerging Compounds Treatment Technologies (ECT2), an equipment company focused on developing and commercializing treatment technologies for emerging, difficult-to-treat compounds. Ms. Sinnett’s technical focus is on the mechanical design of water treatment systems including synthetic media vessels, steam generation systems, cooling systems, and automated control. She has over ten years of experience in consulting and manufacturing environments, with expertise in industrial project management; environmental remediation and process design; permitting; air, soil and groundwater sampling; and engineering construction and fabrication experience from pilot testing through system commissioning, optimization and operation.
What is Really in Aqueous Film Forming Foam and Does it Matter?
INTRODUCTION: Per- and polyfluoro¬alkyl substances (PFAS) contamination as a result of historical uses of aqueous film forming foam (AFFF) is a significant concern for military, aviation, fire authorities, bulk fuel storage owners and other similar entities. The primary triggers to manage PFAS contamination in water are perfluorooctane sulfonate (PFOS), perfluorooctanoic acid (PFOA) and perfluorohexane sulfonic acid (PFHxS) as these are the PFAS compounds most commonly found in legacy AFFFs that were used prior to the change in training, storage and use practices in the early to mid-2000s. These historical PFAS compounds have been replaced with shorter or longer chain compounds, or with modified structures, including ether linkages. These new compounds may result in unanticipated PFAS contamination, especially given that their toxicological impacts are not yet well understood. This is a concern particularly when managing waste water from current fire training activities, hangar foam tests or unintended releases and other similar activities.
APPROACH: As a result of requests to manage waste water from activities using a variety of foam products, ECT2 has undertaken laboratory research into the makeup of these foams to determine the PFAS compounds that can be identified, and the precursors which may degrade into PFAS of concern. The foam products were procured from manufacturers and mixed in accordance with their instructions for use; generally, 1%, 3% or 6%. The mix was then analysed using LC-MS-MS, with further dilution occurring to enable accurate analysis where necessary. The foam/water mix was also trialed in column testing using multiple ion exchange (IX) resins and granular activated carbons (GAC) to examine the ability of these treatment media to remove PFAS, including the shorter chains and precursor compounds.
RESULTS AND DISCUSSION: Initial analysis of foam concentrates identified a range of precursors which degrade to PFAS compounds of primary concern, as well as a number of long and short chain compounds which were not able to be identified. The columns tests demonstrated that the IX resin and GAC systems required for management of waste water from fire training activities, hangar foam tests and the like require EBCTs far in excess of those needed to manage the relatively dilute concentrations normally found in surface and ground water. These extended EBCTs point to the need for high-capacity absorbent media to reduce the need for treatment plants requiring large footprints and the associated high capital and O&M costs.
CONCLUSIONS: Caution is required when making assumptions about the content of the “newer” foams currently in use. It is not always accurate to assume that these foams do not include PFOS, PFHxS and PFOA, as active ingredients include compounds which may degrade into these compounds if not managed appropriately. Sustainable onsite treatment processes are available, and if appropriate research is conducted, will manage waste water from foam training activities in a manner which is effective, efficient and economical.