Q&A: Sorbent Treatment for PFAS in Water

March 9, 2020

This article originally appeared in the July 2019 issue of Water Quality Products as "Sorbent Solution"

About the author:

Reyes Sierra is professor of chemical and environmental engineering at the University of Arizona. Sierra can be reached at [email protected] or 520.626.2896.


In 2018, the levels of chemical contamination in the water supplies of Tucson, Ariz., were dangerously high due to per- and polyfluoroalkyl substance (PFAS) contamination. These manmade chemicals commonly are found in a range of consumer products and household cleaning supplies because of their water and oil repelling capabilities. Engineers at the University of Arizona received a $1.2 million grant to make drinking water safe again in Tucson. WQP Associate Editor Frankie Corrado asked Reyes Sierra, the leader of a team developing a new method for removing PFAS contaminants, more about PFAS and the university’s research.

Frankie Corrado: What are some of the negative health effects associated with PFAS?

Reyes Sierra: Exposure to very low levels of PFAS chemicals has been linked to increasing incidence of a range of illnesses, including cancer, liver disease, decreased fertility, developmental delays, weakened immune system, among others. However, the potential impact of PFAS on public health is not fully understood; many questions remain that still need to be answered.

Corrado: Where has PFAS contamination been found in Tucson’s water supply and what is being done to manage it? 

Sierra: PFAS compounds have been shown to contaminate groundwater at two different locations in Tucson: the town of Marana (northwest of Tucson) and in southern Tucson. Groundwater is known to be contaminated with trichloroethene and dioxane, which is currently treated by Tucson Water at a site known as [the] Tucson Airport Remediation Project.

Corrado: Who funded the research? 

Sierra: Our project is supported by the Department of Defense’s Strategic Environmental Research and Development Program (SERDP). SERDP is currently supporting numerous projects that focus on the treatment of PFAS.

Corrado: How is your team working to create a new class of sorbents?

Sierra: We are developing sorbents that combine two different binding modes which we anticipate will make the sorbents more effective.

Corrado: Where will the sorbents be a viable treatment option?

Sierra: We anticipate that the sorbents we are developing could be applied to treat contaminated water. In the case of groundwater, the water would be pumped and treated in an adsorbent column containing the polymeric sorbent. It may also be feasible to inject the sorbent in the soil subsurface to prevent the spread of the contamination.

Corrado: When is granular activated carbon effective for PFAS removal?

Sierra: Granular activated carbon (GAC) can effectively remove [perfluorooctane sulfonate] (PFOS) and [perfluorooctanoic acid] (PFOA), but the process is very costly. GAC is much less efficient at removing shorter chain PFAS. That may be an issue due to the fact that [the U.S.] EPA also is looking at whether to regulate other chemicals, besides PFOS and PFOA, in the PFAS family. Some states are also considering regulating or establishing health advisory levels [for] other chemicals in the PFAS family.

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