Enhanced immobilisation of per- and polyfluoroalkyl substances (PFAS) using a combination of sorbents and plants: A controlled rainfall simulation study.

Activated carbon (AC) has been widely used to remediate soil contamination caused by per- and polyfluoroalkyl substances (PFAS). Groundcover by vegetation has also shown potential in limiting off-site movement of PFAS from contaminated sites. However, the effectiveness of AC and groundcover in mitigating PFAS migration from soil has not been adequately studied. A rainfall simulation was conducted to investigate the migration of PFAS from PFAS-spiked soil via leaching, runoff and suspended materials during storm events. The efficiency of two AC sorbents (1 % w/w) and groundcover (perennial ryegrass) individually or together were evaluated as PFAS remediation techniques. On average, AC reduced perfluorooctanesulfonate (PFOS) concentrations by 91 % in leachates and 85 % in runoff. Groundcover reduced PFOS concentrations by 44 % in leachates and 43 % in runoff. The combined use of both AC and groundcover reduced PFAS concentration by 94 % in leachates and 86 % in runoff. Though its efficacy was lower than AC, groundcover was able to mitigate the movement of short-chain PFAS, e.g. perfluorobutanesulfonate. A significant proportion of PFAS migration was mitigated via plant uptake when plants are present, reducing the amount of PFAS in leachates and runoff. This study suggests that a combination of AC and groundcover could be a more effective method of reducing PFAS migration during storm events.