PFAS remediation in water and wastewater treatment

Motivation

The bioaccumulation of poly- and perfluoroalkyl substances (PFASs) poses a potentially significant threat to the health of humans and ecosystems. In response to the National Environmental Management Plan’s (NEMP) stance on PFAS, Victorian Environmental Protection Agency (EPA) regulations regarding PFAS disposal are expected to tighten in the future. City West Water have therefore identified a need to prepare for technology upgrades in order to comply with the EPA’s pending changes to regulations.

Approach

Analysis of site data identified that the reverse osmosis (RO) brine would be a suitable stream to target. This study evaluated several potential solutions for PFAS remediation and ranked each technology according to its maturity, efficiency, capital cost, operating cost, energy requirements, waste disposal requirements, and appropriateness in the context of the City West Water treatment plant. The ability of a zinc oxide and cellulose nanofiber (ZnO/CNF) photocatalytic reactor prototype to degrade PFASs in wastewater was also evaluated.

Figure 1: A) Sun-flow photocatalytic reactor with circulation system, B) Small scale Sun-flow photocatalytic reactor with syringe pump system.

Outcomes

This project identified granular activated carbon (GAC) and ion exchange as suitable methods for treatment of the RO brine stream. Experiments on RO brine samples from the Altona Treatment Plant identified an 88% reduction in the total PFAS concentration after 6 hours of operation, reducing from 2497 ng/L to 300 ng/L. This indicates that the photocatalytic degradation method of PFAS removal from wastewater is a promising strategy.