Solution – ENVMAT

Eliminating PFAS from Used GAC Water Filters

Tom Huang — Tue, 30 Aug 2022 02:22:48 +0000

As part of a greater government push for scientific funding of PFAS research, many projects have captured my interest. I’m here to share one of them with you today. Recently, the National Science Foundation (NSF) has awarded $250K to Dr. Onur Apul, assistant professor of environmental engineering from the University of Maine, to study how to remove PFAS from used GAC filters.

Granular activated carbon (GAC) water filters are one of the most reliable ways to remove PFAS from drinking water sources. I’ve covered this topic in previous blog posts (here’s a recent example). Once GAC filters are spent, they are usually discarded or incinerated. Both disposal options for GAC are detrimental, because they cause environmental pollution. In previous blog posts, we have discussed how PFAS tend to be extremely resistant to breaking down in the environment. Once in a landfill, PFAS will eventually find their way into the environment, contributing to human exposure. Incinerating PFAS will cause it to leak into the air.

Dr. Apul and his team hope to identify factors that lead to PFAS breakdown, which will be useful in mitigating environmental PFAS release from used filters. Additionally, if successful, Dr. Apul’s research on PFAS breakdown could be expanded to other PFAS-laden objects that are commonly discarded in landfills or incinerated, such as food packaging and other consumer waste.

GAC filters are used in water treatment plants and household plumbing to reduce, if not completely mitigate, PFAS concentrations in water at the point of entry (source)

Mitigating the release of environmental PFAS is a crucial step that can immediately lessen the effect of PFAS exposure on human populations. Although research into PFAS may be time-consuming and not conclusive, actions taken to reduce environmental PFAS concentrations is a step in the right direction.

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Household PFAS Treatment

Tom Huang — Mon, 08 Aug 2022 18:41:54 +0000

As the PFAS issue becomes more prevalent in national news, an increasing amounts of homeowners want to mitigate the threat of PFAS in their water supply. Even though fluorocarbons have many different forms, there are general PFAS solutions for drinking water that exist for the average homeowner. I’ll go over which viable solutions exist, and then I’ll write about my thoughts.

State governments commonly recommend two kinds of water treatment systems: granular activated carbon (GAC) filters and reverse osmosis (RO). According to the New Hampshire Department of Environmental Sciences (NHDES), GAC is better suited for treating water at the point of entry (POE), which is the point where the water main connects to the house. The NHDES recommends this specific placement of GAC because, while the filter system can remove a significant amount of PFAS, it cannot filter out other contaminants. Therefore, RO is better applied at the point of use (POU), which is the point where water is accessed by humans for use.

Water filter system containing a GAC filter (source)

Reverse Osmosis Tank (source)

Even though GAC filters may seem inferior, a recent study (published in 2020) by Duke University found that cheap GAC dual-stage POU filters may be more effective at removing PFAS from residential water. Dual-stage filters and RO were able to remove, on average, more than 90% of PFAS from POU, while other GAC filters were less effective and had varied results.

The previously mentioned systems may not always remove all PFAS from water. In order to eliminate PFAS from a household’s water supply, a custom, comprehensive system of filters is required. The NHDES says that a water system containing the following has “proven to be effective at removing PFAS to non-detectable levels in New Hampshire and other New England states.”:

Five-micron particulate filter for pre-filtering;
Two GAC treatment vessels (two cubic feet each) in series with a test port installed after the lead treatment unit (the exact size and number of carbon vessels required depends on flow rate and flow volume associated with the home);
Five-micron particulate filter for post-filtering;
Totalizer meter;
Ultra-violet treatment system and associated controllers if untreated water from the well exhibits bacteria contamination;

Such a system would look like this! (source)

In my opinion, whether it is feasible to implement household PFAS mitigation systems all depends on cost. On Amazon, an RO POU system costs around $200, and various small household GAC systems cost $100 or more. The comprehensive filter system I mentioned earlier is difficult to price, but taking into account how household GAC filters can exceed $1000, the total price would be no lower than $2000. In addition to these PFAS treatment systems, there are water testing costs. Each lab test for a single water source will cost around $250. At the bare minimum, $500 dollars will be spent on testing, because a homeowner would need to know two things: whether their water contains detectable amounts of PFAS and whether the installed PFAS mitigation system was effective.

Sources:
NHDES website
Duke University PFAS study

EPA National Testing Strategy

Tom Huang — Wed, 03 Aug 2022 00:46:34 +0000

In October 2021, the EPA developed a new national testing strategy for PFAS that attempts to bypass some difficulties in screening for the thousands of PFAS in the environment. The EPA is now adopting a strategy of categorizing PFAS according to chemical structure and toxicity. In categorizing PFAS, EPA hopes to select a few specific PFAS that are representative of all PFAS, which allows sample testing to provide more substantive information. In this post, I’ll unpack how EPA proposes doing so.

Flowchart of EPA initial selection process for PFAS (source)

The EPA has a large database of chemicals called DSSTox, which provides extensive chemical-related data on over 800,000 compounds. From DSSTox, EPA has applied structural filters to weed out all chemicals that generally cannot be classified as PFAS. From there, EPA applies “primary structural categories,” which divide the selected PFAS into specific categories depending on chemical structure. After that, each primary category is divided into secondary categories that classify PFAS based on length. In literature, the length of PFAS have shown to affect how long they spend in the human body, in addition to adverse health effects.

Flowchart of EPA final selection process for PFAS (source)

When the PFAS has been categorized by structure, the EPA then applies filters based on whether a specific chemical has toxicity data and is industrially prevalent. On its initial selection run, the EPA selected 24 PFAS candidates that were representative of the numerous PFAS categories.

I believe that the categorization of PFAS based on structure and toxicity is a step in the right direction. Currently, official EPA drinking water testing methods analyze for ~30 PFAS, which were picked based on their industrial prevalence. In selecting specific PFAS candidates, EPA testing methods can be improved to provide more information about all PFAS in a sample, not just a select few.

Furthermore, I think that systematically categorizing PFAS by a central authority has implications beyond sample testing. If this standard of PFAS grouping is established in academia, the health effects of PFAS can be more extensively studied. In addition, adopting standards by which PFAS can be categorized will prevent chemical companies from avoiding regulations by inventing new PFAS.

For more information, check out this link.

PFAS Problem in Small Towns: A Case Study

Tom Huang — Wed, 29 Dec 2021 00:39:45 +0000

Wellesley, Massachusetts is a small suburb located approximately 12 miles away from Boston that I live in. Currently, Wellesley is facing a PFAS crisis that threatens its water supply and is likely to raise taxes for its residents.

On Thursday, December 16, 2021, the Wellesley Department of Public Works (DPW) held a public forum presenting the current threat posed by PFAS pollution to town water utilities. The Morses Pond Water Treatment Plant (Morses Pond WTP), which according to information presented at the meeting provides 30-40% of Wellesley’s water, has been shut down since May because of severe PFAS contamination. The source of this contamination is at present unknown, with PFAS coming from seemingly everywhere.

This poses many problems, as increased strain on Wellesley’s system would increase reliance on the MWRA (Massachusetts Water Resources Authority), which provides water to many towns from the Wachusett and Quabbin Reservoirs in Western Massachusetts. Using the MWRA’s water to replenish the void left by the Morses Pond WTP is projected to cost upwards of $1M annually for Wellesley residents, which will inevitably increase tax rates.

Presentation slide from Wellesley DPW Public Forum, Dec 16

To combat this, Wellesley has approved a $1.5M budget for the implementation of an interim treatment plant at Morses Pond. This system features granular activated carbon (GAC) filters and ion exchange (IX), which have been both shown to remove PFAS, and has the objective of lowering PFAS concentrations to undetectable levels (non-detect). It should be noted that so far, no screening method has been considered by Wellesley. The lifespan of this solution, while effective, is projected to last for only 16 months. Thus, long-term solutions are actively being sought out.

Flow Diagram of Proposed Morses WTP Changes

Wellesley’s choice follows the footsteps of many other towns, including Sharon, MA, which found out about PFAS pollution in one of its wells in April and implemented interim treatment. This month (December), they accomplished non-detect. Hopefully, Wellesley will achieve non-detect in Morses Pond as well and eventually, working with other towns, find a long-term solution to the PFAS problem.

Existing PFAS solutions

Tom Huang — Sat, 24 Jul 2021 18:02:01 +0000

PFAS have not been extensively studied, but they have been a concern for decades. In fact, two of the most well-known PFAS – PFOS and PFOA were phased out by 3M, a large manufacturer of PFAS, in the early 2000s. However, 3M, as well as other companies locally and internationally, still manufacture PFAS for use in their products. This has caused continued contamination of PFAS into water sources, where it continues to find its way into humans and the animals that we eat.

The production of PFAS does not seem like it will come to a stop anytime soon, so what can be done about it to prevent risk to public safety?

In my state of Massachusetts, every town is required to monitor its water sources for PFAS levels, which is done by sending a water sample to a lab for analysis. If the PFAS level is higher than the limit set by Massachusetts law (see previous blog post), then the wells are either shut down or diluted with water from other wells to lower their concentration. Additionally, homeowners can install a specialized PFAS filter in their household if the PFAS level in their water exceeds the EPA’s limit.

Recently, the House of Representatives passed the PFAS Action Act of 2021, instructing the EPA to pay more attention to regulating PFAS in drinking water and doing more to spread awareness. This includes setting a national limit for the level of allowed PFAS in drinking water and indicating whether PFAS is present on the packaging of consumer products. This places looking for a better solution for testing, removing, and managing perfluoroalkyl substances at the forefront of protecting the environment from pollutants. With this political momentum, I hope to see more solutions being developed.

Sources

3m.com

bostonglobe.com

congress.gov