Surfactant-enhanced coagulation and flocculation improves the removal of perfluoroalkyl substances from surface water

Document Type

Article

Publication Date

8-13-2024

Abstract

Coagulation/flocculation is a widely used water and wastewater treatment process due to its low cost, simplicity, and effectiveness. However, the process is not effective in the treatment of per- and polyfluoroalkyl substances (PFAS), the presence and treatment of which is an ongoing challenge for water providers. Here, we explore cationic surfactant-enhanced coagulation as a process modification to target the removal of PFAS in existing coagulation/flocculation systems. Batch experiments, in jar testing apparatus, were performed to assess the removal of two short-chain and two long-chain PFAS at an initial concentration of 10 μg L−1 with the addition of cetyltrimethylammonium chloride (CTAC) as the coagulant-aid. Our findings suggest that elevated coagulant dose (60 mg L−1 of alum or 100 mg L−1 of FeCl3) coupled with the addition of a cationic surfactant (1 mg L−1 of CTAC) significantly enhanced the removal of both short-chain (perfluorobutane sulfonate: PFBS removal to >40%) and long-chain PFAS (perfluorooctanoic acid: PFOA and perfluorooctane sulfonate: PFOS removal to >80%), with FeCl3 showing better performance than alum. Sulfonates (PFBS, PFOS) were shown to be removed more efficiently compared to carboxylates (PFBA, PFOA), presumably due to their higher hydrophobicity leading to better interactions with the flocs. Furthermore, CTAC in combination with traditionally used additives such as powdered activated carbon (PAC), served as a better aid for PFAS treatment and improved the removal of PFBS, PFOA, and PFOS to >98%. This study highlights that introducing a cost-effective pre-treatment with a cationic surfactant to existing conventional treatment systems can improve the performance efficiency in treating PFAS-contaminated waters.

Identifier

85201774906 (Scopus)

Publication Title

Environmental Science: Advances

External Full Text Location

https://doi.org/10.1039/d4va00093e

e-ISSN

27547000

First Page

1714

Last Page

1721

Issue

12

Volume

3

Grant

ER22-3438

Fund Ref

National Science Foundation

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