- Has the discussion with MPART about treatment and testing of PFAS chemicals discussed financial considerations since neither WRRFs nor landfills are generators? Is there thought about alternative funding for treatment or linking sources or generators to treatment costs?
Answer: This is an excellent question. The short answer is no. So far, our discussions with MPART/EGLE have focused on source reduction. Treatment funding sources is a planned discussion topic for future meetings.
- Any efforts underway to better understand air emissions in landfill gas, potential gas to energy plant emissions and leachate evaporators?
Answer: As of now, based on my knowledge of recent developments, the impact of PFAS emissions from LFG WTE and evaporators is at the beginning stages. I am not directly involved with these discussions, which are likely to expand with MPART/EGLE/MWRA soon.
- You stated that the Rule 57 numbers are drinking water standards, but they are not.
Answer: Correct. Rule 57 PFAS HMCV are applicable to surface waters used as a source of drinking water or not.
- Do we know how much PFAS is in the WRRF residuals?
Answer: Biosolids PFAS concentrations vary at individual WRRFs statewide, ranging from ppt to ppb values, depending if influent is "industrially-impacted". MPART, working with AECOM, published a summary biosolids report a few weeks ago. Here is the link: https://www.michigan.gov/documents/egle/wrd-pfas-initiatives_691391_7.pdf.
- Much of Michigan is rural and the homes use septic systems. Have you heard if EGLE is considering investigating private septic fields?
Answer: To my knowledge, MPART has not yet initiated a study regarding PFAS septic field discharge, which is needed to fully understand the overall mass balance and fate-and-transport of these compounds in the environment. The results of such an investigation would be both interesting and useful.
- You said that WRRFs do not create PFAS, they only receive them, but earlier you said that more go out than come in, due to conversions occurring in the treatment process. Is there an understanding of how those conversions occur and how to potentially prevent them?
Answer: As discussed, the total WRRF PFAS mass balance is under-studied and not fully-understood. In cases where effluent PFAS concentrations exceed influent concentrations, current evidence suggest transformation of PFAS cogeners and precursor compounds to PFOA and PFOS, both "terminal" products, within the WRRF system. Another explanation is residual PFAS concentrations with the WRRF piping/equipment that is released randomly or a result of changes in the treatment system that allows desoption of PFAS from these infrastructure components and/or biosolds.
- What are landfills doing to look at their upgradient sources?
Answer: If you are referring to refuse accepted for disposal, each landfill is implementing source reduction procedures that include PFAS waste isolation, load rejection, including biosolids and plating sludge wastes that have elevated PFAS concentrations.
- Seems to me reduction of PFOS and PFOA at the source would be money better spent.
Answer: I agree with you; however, except for industries that use PFAS in manufacturing processes (e.g., platers and AFFF producers) who are able to replace our substitute componds, it is very difficult to remove all impacted materials from the waste stream (landfills and WRRFs). Also, PFAS removal systems create concentrated residues, exacerbating the problem. PFOA and PFOS are two of nearly 5,000 PFAS compounds with a plethora of other emerging contaminants on the regulatory horizon that may be best managed economically using existing, centralized treatment systems as opposed to individual systems that will require upgrades to handle future demands.