Addressing Forever Chemicals PFAS and 1,4 Dioxane
Case Study: PFAS Water Treatment
PFAS & Water Treatment
Chances are you’ve heard of Per- and Polyfluoroalkyl substances (PFAS), an emerging contaminant group that’s garnered national attention. PFAS are a group of compounds that are man-made and have been manufactured globally over the last 70 years. They have been used in many consumer products and industrial applications due to their oil- and water-resistant properties, as well as their stability. There are over 4,700 compounds in this group, and they’re found in food packaging, stain-resistant rugs and upholstery, nonstick cookware, firefighting foams, and other industrial applications. Their widespread use, mobility, and persistence have made them problematic to the environment. Even though the use of some of these chemicals has decreased in the last 10 years, PFAS are still present in the environment and can be detected in public water systems, drinking water wells, surface water, soils, and sediments. PFAS can be absorbed and bioaccumulate in the human body. Exposure to PFAS even at very low concentration is believed to be linked to numerous health risks, including a higher risk of autoimmune diseases and cancer.
The same properties that make PFAS useful for consumer products and firefighting foam make them challenging to remove from soil and water, including drinking water supplies. If a community discovers high levels of PFAS in their drinking water, it could be the evidence that their current treatment system is not sufficient to remove these compounds to meet the regulatory limits. LaBella can help the community in engineering and implementing treatment solutions. LaBella would be interested to participate and work with academic entities to help them further the research in testing and evaluating different treatment technologies.
1,4-Dioxane1,4-Dioxane, another emerging contaminant, has graced the headlines of national newspapers, been the subject of high-profile lawsuits, and seen new state regulations across the United States. It’s no surprise that man-made and natural chemicals can threaten our health or the environment. Some we have been aware of for years, and have amassed information, technology, and experience to help deal with them. Others, like 1,4-dioxane, have only recently been recognized as a threat, so our understanding of them is limited.
What Is It Used For?
In the 1970s -1990s, 1,4-dioxane was used primarily as a stabilizer for chlorinated solvents, especially methyl chloroform. Methyl chloroform is associated with chlorinated solvent releases from industrial facilities, dry cleaners, landfills, and other sources. Until recently, the chemical often went undetected because it was not a required analyte at these kinds of facilities, and so it was often not considered when assessing release incidents.
The use of 1,4-dioxane as a solvent stabilizer has decreased since methyl chloroform was phased out by the Montreal Protocol in 1996, which aimed to reduce the production of CFCs that depleted the ozone layer.
We also see 1,4-dioxane in many manufacturing applications, from paints and varnishes to pharmaceuticals. It is also a byproduct of the manufacturing process in the plastic used in most drinking water bottles. While 1,4-dioxane is not intentionally added into consumer products in the U.S., it has been found as a byproduct or contaminant in many everyday household products, including cosmetics, deodorants, detergents, shampoos, and other cleaning products (ATSDR, 2012). It has even been found in some food products from packaging residues or from pesticides used in food production.
1,4-Dioxane in Groundwater
The most common source of 1,4-dioxane in groundwater has been from spills or leaks of chlorinated solvents, either from industrial activities, manufacturing processes, or dry cleaning facilities. Unlined solid waste landfills have also been found to be sources of 1,4-dioxane in groundwater. 1,4-Dioxane has been identified in at least 34 of the 1,689 USEPA National Priorities List (NPL) hazardous waste sites (USEPA 2016b); however, the number of those sites that remain unevaluated for 1,4-dioxane is not known.
According to the California State Water Resources Control Board (SWRCB, May 2019), 194 active and standby public water wells out of 1,539 sampled had at least one detection of 1,4-dioxane well above the EPA advisory number. Results of a 2006 U.S. Geological Survey study of 1,208 domestic wells detected the presence of potential 1,4-dioxane co-contaminants in as many as 102 wells (Zogorski et al., 2006).
1,4-Dioxane is considered a persistent and recalcitrant compound; it completely dissolves in water, it does not easily sorb onto soil or other particulates, and it does not readily biodegrade in the environment. As a result, it is very mobile in groundwater and can travel great distances with little change in its concentration. Most chlorinated solvents, like 1,4-dioxane, readily degrade under anaerobic conditions, so natural attenuation will often reduce the size and concentrations in a chlorinated solvent plume over time. However, since 1,4-dioxane does not degrade, not only can the 1,4-dioxane plume extend much farther than the solvent plume, but it is often left behind, even decades after a release.
Due to its physical and chemical properties, 1,4-dioxane is very hard to treat in groundwater. Although 1,4-dioxane is classified as a volatile organic compound (VOC), most of the conventional methods for treating other VOCs, do not work well on 1,4-dioxane. (Myers et al., 2018 and Chiang, 2016)
Groundwater Cleanup Challenges
In general, the most effective treatments require the impacted groundwater to be removed from the subsurface, treated above ground, and then discharged. However, there are some potentially effective technologies that do not require the removal of groundwater from the subsurface. The challenge with most of these effective or potentially effective technologies is that they are costly. Most plumes associated with unlined landfills have low-level concentrations of contaminants that are not large. Implementing these expensive technologies is cost-prohibitive for these types of plumes. They are more feasible to apply to a large superfund site.
An even bigger challenge is treating residential supply wells that are found to be impacted by 1,4-dioxane. Most commercial home water filters do not remove 1,4-dioxane effectively. The most practical solution may be to install a two-stage GAC (Granular Activated Carbon) filter system on the home, sample it frequently (at least quarterly) and then replace the first filter as soon as there is break-through. Breakthrough will happen much more quickly for 1,4-dioxane than for most other VOCs, so the filters will need to be changed often. Eventually, it may be necessary to replace the well with a new one farther from the 1,4-dioxane source; however, that is not always possible, especially given how far 1,4-dioxane can travel.
What Is Needed Now?
Researchers are continuing to study the human toxicology of 1,4-dioxane to give the EPA the data they need to establish consistent standards and policies. Federal, state, and local regulatory agencies are requiring more testing of groundwater, surface, water, and drinking water supplies for 1,4-dioxane at many facilities and release sites. In addition, many industries and manufacturers are removing 1,4-dioxane from their processes and products, as well as developing better management practices to prevent its release to the environment. Moreover, new treatment technologies and approaches are being developed and tested to help clean up 1,4-dioxane contamination sites.
In August 2020, New York adopted first-in-nation drinking water standards for 1,4-dioxane and approved a treatment standard. Scroll down for more.
Learn about NY’s maximum contaminant levels for 1,4-dioxane and PFOA/PFOS.
New York State has adopted the most protective method detection limit for 1,4-dioxane, setting the maximum contaminant level to be 1 part per billion (ppb). The new regulation requires public water systems in the state to regularly test and monitor for PFOA, PFOS, and 1,4-dioxane, regardless of the municipality’s size. The new regulation follows other actions taken by New York State in limiting the public’s exposure to PFOA and PFOS, such as investing millions to the State Superfund Program to install granular activated carbon filtration systems to successfully remove the chemicals from impacted water supplies in several communities. This has resulted in water treatment projects totaling $150 million to plan, construct, and run the advanced treatment systems, and a plan to spend $700 million more in the next six years.
Register to view our webinar by filling out the form at right.