Optimization of Multi-Stage Filtration Processes for Treating AFFF-Contaminated Water

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Driven by forthcoming regulations on perfluorooctane sulfonic acid (PFOS) and perfluorooctanoic acid (PFOA) and their related fluorinated surfactants, there is a great need to develop cost-effective and efficient treatment technologies for removing these persistent and toxic chemicals from impacted waters, especially the waters contaminated by aqueous film-forming foams (AFFF). Because these surfactants are highly stable and resistant to microbial or chemical attacks, conventional biological or chemical treatments are either not effective or are very cost prohibitive. A clear effective and economical alternative is to use appropriate sorbent materials to capture these contaminants. Supported by an Engage Grant, a new collaborative partnership was established between Sanexen and the applicant at McGill University to evaluate the company's trademark multi-step filtration process with respect to the efficacy and efficiency of the AFFF treatment. Total removal efficiencies of 90-99% have been achieved in lab-scale and field-scale treatment systems. The results obtained in the previous work warrant going forward to further optimizing the trademark process. Specifically, the project will examine the impact of hydraulic retention time, concentration of colloidal materials, and chemical compositions of AFFFs. The continuous collaboration will benefit the industrial partner in improving its trademark treatment process for AFFF removal and expanding its client base. The project will benefit Canada's economy and environment by reducing the cost of dealing with PFOS and PFOA and their related persistent organic contaminants in many federal contaminated sites.