Assessing the Viability of Microalgae as a Bioremediation Method for Per- and Polyfluoroalkyl Substances (PFAS)

Abstract

Per- and Polyfluoroalkyl Substances (PFAS) are a class of emerging contaminants that accumulate in soils and groundwater, often finding their way into the bodies of humans and wildlife alike. Traditional treatment technologies for removing contaminants from water are either ineffective (chlorination, UV irradiation, advanced oxidization), or costly (granular activated carbon, ion exchange, reverse osmosis, nanofiltration). Thus, bioremediation has been looked into as a cheaper, more sustainable alternative for PFAS removal. This study seeks to evaluate the viability of biosorption via microalgae as a treatment method for PFAS-contaminated water supplies. C. sorokiniana was the algal species considered as it has exhibited the capability of removing toxic contaminants such as arsenic and uranium from groundwater. No significant growth inhibition was exhibited by the C. sorokiniana grown in 1 ppm PFOA and PFOS solutions. The linear growth rate of the control was 0.15 g/L/d while the linear growth rates for PFOA and PFOS were both 0.12 g/L/d. Over two weeks, C. sorokiniana exhibited 37% and 20% removal of PFOA in two sample flasks (PFOA 1 and PFOA 2 respectively) in addition to 9.2% and 20% removal of PFOS in two sample flasks (PFOS 1 and PFOS 2 respectively). Statistical significance was measured using a 2 – tailed Student’s t – test with a 5% significance level. The only statistically significant removal observed in these two weeks took place in the PFOA 1 flask. Using the Langmuir Adsorption Model, no adsorption of PFOA or PFOS to the algal cells was observed within the 24 hour experiment. These results imply that bioremediation via C. sorokiniana is feasible, but further work must be done to assess the efficacy and economic feasibility.