Session 7 – Per- and polyfluoroalkyl substances (PFAS) contamination in Maine and mitigation strategies: Where are we today and where do we need to be going?

COVID-19 Protocols – As the main conference organizer, the Mitchell Center is required to have conference attendees follow University of Maine System COVID-19 protocols. Please go to the COVID-19 page for more information.

This session have been approved for two (2) training contact hours (TCH) through the State of Maine Board of Licensure of Water System Operators.

This session have been approved for two (2) training contact hours (TCH) through Maine’s Wastewater
Operator Certification Program.

Afternoon Session: 1:30PM-4:00PM

Fort Western Room (First Floor, North Wing)

Session Chairs:
Onur Apul, Civil & Environmental Engineering, UMaine, Orono, ME
Louise Roy, Maine Dept. of Environmental Protection, Augusta, ME
Caroline Noblet, Economics, UMaine, Orono, ME

Per- and polyfluoroalkyl substances (PFAS) contamination was reported widely throughout Maine and the United States in the last several years. Mitigation strategies are urgently needed to address the technical and social aspects of this environmental catastrophe. Due to PFAS’ environmental mobility, difficulties in detection, biological and physicochemical recalcitrance, and limited social awareness, mitigation strategies require holistic and sustainable approaches at the intersection of technical, environmental, social and economic feasibility. This session aims to present results and perspectives about the current understanding of PFAS contamination and mitigation strategies with an extended focus on detection, fate, and transport, remediation, toxicity, and social awareness.

Presentations in this session are 20 minutes.

Presenters are indicated in bold font.

1:30PM-1:50PM
Five-years of studying PFAS contamination in agricultural settings: What we have learned from modeling, field studies, and the evolving scientific literature

Andrew E. Smith, Thomas Simones
Maine Center for Disease Control and Prevention, Augusta, ME

A PowerPoint slide presentation is available for this talk

In 2016, the discovery of elevated PFOS levels in water from a municipal monitoring well located in close proximity to a dairy farm well resulted in testing of milk at the farm. The measurement of elevated levels of PFOS in dairy milk that could not be explained by water levels led to the testing of soils and hay. The PFOS levels in hay could explain the observed milk levels, yet the soil PFOS levels were lower than existing health-based soil screening levels. Thus, began a multi-year effort to develop a model of the soil-to-fodder-to-cow-to-milk exposure pathway and to improve model inputs through field studies of hay and corn uptake of PFOS from soil. These models were pressed into service as two more dairy farms with elevated PFOS in milk were identified. During this time, modeling efforts, field studies, measurements of PFOS and other PFAS in dairy milk, beef, eggs and dear meat along with review of the evolving scientific literature has resulted in an improved understanding of the challenges and opportunities in responding to PFAS contaminated agricultural lands. This talk will review what we have learned over the past several years through the themes of variability in soil PFAS levels with and among fields land applied with contaminated biosolids, differential uptake and transport of PFAS in crops grown for animal fodder, growing recognition that the forever chemicals are not forever in certain agricultural commodities, and profound differences in the propensity of various PFAS to move between environmental media.

1:50PM-2:10PM
Maine DEP Collection of Agricultural Field Soil Samples and Residential Drinking Water at Residuals Application Sites

Chris Evans, Tracy Kelly
Maine Department of Environmental Protection, Augusta, ME

A PowerPoint slide presentation is available for this talk

Maine is in the initial stages of a statewide sampling program to assess soils and drinking water at sites where residuals application was licensed.  Department Rules also currently require all residuals to be tested prior to use. Field and laboratory methods and general sample design will be summarized along with some initial data, and implications for the future.

2:10PM-2:30PM
Water Treatment Technologies for PFAS: Current and Next Generations

Baxter Miatke, John Anderson, Corey Theriault
Arcadis, U.S., Inc., Portland, ME

A PowerPoint slide presentation is available for this talk

PFAS consist of a broad range of compounds whose characteristics can affect treatment technology effectiveness. Characteristics like whether a compound is a perfluorinated or polyfluorinated alkyl substance, fluorinated tail length (short-or-long), and head group can drastically affect which treatment technology will work best. While the USEPA Health Advisory Limit of 70 nanograms per liter is not yet a maximum contaminant level, to be protective of human health, PFAS impacts in both drinking and wastewater will require some form of management. In recent years, individual states have applied variable criteria on the ppt level for more than just PFOS and PFOA. This presentation identifies and evaluates available and emerging forms of water treatment technologies that can address both current and future regulated PFAS.

The use of conventional sorbents, such as granular activated carbon (GAC) and anion exchange (AIX) resins, to address PFAS in water have become a “de-facto” interim measure for PFAS removal. GAC and AIX have varying degrees of effectiveness on short chain PFAS and both GAC and AIX are relatively unproven against polyfluorinated compounds and may struggle to handle geochemical and/or co-contaminant competition, which may be addressed using other established technologies (e.g., membranes depending on water chemistry). Emerging solutions for water treatment, such as flocculation/electrocoagulation technologies, foam fractionation, novel AIX resins, new engineered sorptive media, electrochemical treatment, sonolysis, and advanced reductive processes can be integrated to affect better treatment. Best-match site treatment often requires a treatment train, combining conventional treatment technologies with more innovative and emerging solutions for PFAS.

2:30PM-3:00PM
Afternoon Break (Main Auditorium)

3:00PM-3:20PM
Understanding the competitive sorption between short-chain and long-chain poly- and perfluoroalkyl substances during granular activated carbon treatment

Yi Zhang1, Cheng-Shiuan Lee1, Onur Apul2, Arjun K. Venkatesan1

  1. New York State Center for Clean Water Technology, Stony Brook University, Stony Brook, NY
  2. Department of Civil and Environmental Engineering, University of Maine, Orono, ME

A PowerPoint slide presentation is available for this talk

While Granular activated carbon (GAC) is effective in the removal of long-chain poly- and perfluoroalkyl substances (PFASs), poor removal efficiency and early breakthroughs have been reported for hydrophilic short-chain PFASs. In this study, we conducted controlled batch adsorption experiments using Filtrasorb 400 GAC to understand the competitive sorption behavior and common cations impact on short-chain and long-chain PFASs. Additionally, we examined differences in sorption behavior between structural isomers of PFOS. Adsorption experiments were performed for three short-chain (PFBA, PFBS, 4:2 FTS) and three long-chain (PFOA, PFOS, 8:2 FTS) PFASs. The adsorption capacity of short chain PFASs was significantly reduced (by >50%) in the presence of long-chain PFASs. This reduced sorption was observed at early kinetics stage, indicating that the presence of long-chain PFAS can inhibit the short-chain PFAS sorption at early treatment stage. Introduction of long-chain PFASs to GAC that was pre-adsorbed with short-chain PFASs, replaced all the previously adsorbed short-chain PFASs irrespective of the molar ratio of their initial concentration. These results confirmed the higher affinity (hydrophobic interactions) of long-chain PFASs to GAC relative to short-chain PFASs leading to the early breakthrough of short-chain PFASs. The long-chain PFASs’ sorption on GAC, however, was not impacted by the presence of short-chain PFASs during both competitive and replacement tests. The branched-to-linear isomer ratio of PFOS increased from 0.4 to 0.6, indicating that linear PFOS isomer exhibited higher hydrophobicity and hence better sorption. Different performance was also observed over short-chain and long-chain PFASs in the presence of cations Na+ (0.1 M) and Ca2+ (0.05 M). Our results showed that while long-chain PFAS was unaffected in the presence of these cations, short-chain PFAS was greatly inhibited in the presence of cations. Overall understanding of the different performance of short-chain and long-chain PFASs is critical to design treatment systems targeting the removal of short-chain PFASs that are considered for regulations in the near future.

3:20PM-3:40PM
Integrated assessment of alternative management strategies for PFAS- contaminated wastewater residuals

Molly Shea (student), Charity Zimmerman (student), Caroline Noblet,
University of Maine, Orono, ME

A PowerPoint slide presentation is available for this talk

Per- and polyfluoroalkyl substances (PFAS) of the ground and surface water in Maine is a growing concern in the state and globally (Miller, 2021; DEP, 2020). Agricultural fields in Maine historically received, and were permitted to use, residual wastewater sludge as a fertilizer. However, scientific advances have shown that PFAS chemicals migrate from agriculturally applied sludge, via leaching into groundwater, surface water runoff, and plant uptake by agricultural crops (Beecher, 2020) endangering Maine citizens. Enhancing understanding of the factors that influence citizens’ knowledge of PFAS risks and their associated support for addressing this contaminant strengthens the ability of federal, state, and local decision-makers to make informed decisions about policies and projects for Maine’s environment and human health needs. This study collects baseline data on knowledge of PFAS risks, prioritization of management options (including preventative vs. mitigative) and tests the impacts of information messaging and trusted sources on Mainers support for addressing PFAS.

This paper presents the methodology and results of our empirical analysis of Maine citizen baseline knowledge and factors impacting risk assessment from PFAS. We designed and implemented a mixed mode survey to collect data from Maine residents (target n of 1000 in Winter 2022). Preliminary results suggest that citizens prioritize human health and safe drinking water when considering possible PFAS contamination. Furthermore, citizens exposed to messaging with consumer-centered responsibility have a higher WTP for PFAS mitigation strategies than those exposed to industrial-centered responsibility messages. Final results will offer additional insight into preferences for managing this group of chemicals.