Waste organizations must monitor local and state wastewater activity and conduct sampling and analysis of waste streams for PFAS and co-contaminants. Segregating sources of PFAS before treatment and defining PFAS treatment objectives and potential future requirements will enable you to select the right technologies with a thorough understanding of their pros and cons.
By John Peichel
Per-and polyfluoroalkyl substances (PFAS) contamination in wastewater is a growing concern for the industry. As a result, the EPA issued interim guidance on PFAS disposal and destruction in 2020 and 2021. Earlier this year, Maine announced a ban on PFAS in landfill leachate following a ban on sending biosolids to incinerators and land applications.
Elsewhere, the Minnesota Pollution Control Agency (MPCA) announced it is expanding its Burnsville Sanitary Landfill disposal capacity as part of a larger effort to address PFAS, also creating a PCA process and specific requirements to sample and test for PFAS. This effort followed a report that found PFAS contamination in 97 percent of the state’s closed landfills.
Waste companies know that more regulatory changes are coming. While PFAS might be better known as a drinking water problem, wastewater is increasingly associated as the source of PFAS, and studies have identified more types/variations and greater prevalence of PFAS.
The waste industry has plenty of questions, and is starting from behind, as PFAS research and testing capabilities have historically lagged. One thing is clear: The waste industry urgently needs new and improved methods to manage PFAS in wastewater and landfills.
PFAS Removal Depends on How It Entered the Stream
PFAS chemicals are problematic because they are “forever chemicals” that do not break down or go away. What’s more, improved testing is uncovering more types of PFAS and PFAS precursors, with a long list of
contaminated sites, including drinking water, wastewater, and remediation.
There are many points at which PFAS enters the water, including wastewater treatment plants, industrial emissions from PFAS production sites, airports, and landfills. As a result, PFAS finds its way to wastewater treatment plants’ influent and effluent. The unique chemical structure of PFAS means conventional wastewater and sludge treatment processes cannot efficiently remove PFAS and PFAS precursors, so the release of treated effluent or the use of biosolids means that PFAS can be re-released downstream.
Another type of PFAS contamination occurs when leachate is produced from rainwater or other surface waters that filter down through a landfill and attach to dissolved materials from decomposing wastes. The resulting leachate can range from mostly benign to quite toxic. In a recent study of three wastewater treatment plants, PFAS was 67 percent more prevalent in landfill leachate than influent. If landfills do not have the proper liner, there is the risk of PFAS-contaminated leachate getting into the groundwater, and, in other cases, landfill leachate is bound for sewer infrastructure and wastewater treatment plants, threatening wastewater with further PFAS and organic compound contamination.
Range of Methods Now Available to Deal With Reject Streams
One solution does not fit all PFAS contamination, and waste companies and facilities must consider the impact of constituents to be treated, lifecycle costs, and whether a solution is reliable and flexible enough to scale. With the right technologies, waste companies can treat PFAS where its concentration is highest and the volume of water is lowest, so there is less material when the PFAS is removed. Fortunately, there are more options than ever to deal with PFAS remediation. Understanding the different types of treatment options will help identify the right technology for your site.
Clarifiers
Given the nature of extreme co-contaminants in wastewater and landfill leachate, pretreatment technologies such as clarifiers, dissolved air flotation, and hollow fiber membranes are often critical parts of wastewater treatment, as activated carbon media and reverse osmosis membranes used to remove PFAS are negatively impacted by suspended solids and dissolved organics. Landfill leachate is higher in total dissolved solids (TDS), dissolved organics, fats, oils, and greases. This means pretreatment prior to filtration, concentration, and adsorption are even more critical than treatment systems used in drinking water and soil remediation.
Separation
Separation treatment offers proven technologies increasingly used in PFAS remediation, especially high-pressure membrane technology like reverse osmosis (RO) and nanofiltration (NF) that can remove PFAS or sequester the compounds long-term. In fact, the number of membrane technologies in use is expected to triple by 2025.
Reverse Osmosis
RO offers the best PFAS removal efficiency, while NF removes some PFAS but not as well as RO for smaller concentrations. Low-pressure membranes like ultrafiltration (UF) work best for dissolved organics and can play an important role in NF/RO pretreatment for performance, water quality, and multi-barrier benefits.
Ultrafiltration Membrane Technology
UF membrane technology with proper chemical additions is ideally suited to treat wastewater for downstream concentration and capture of PFAS. RO membrane technology is ideally suited for concentrating the PFAS and reducing the overall flowrate of PFAS containing wastewater. Evaluating established and emerging membrane technologies is essential when selecting processes for use and future research.
Newer Solutions
Capture techniques that incorporate granular activated carbon (GAC), ion exchange (IX), or organoclays are not a good fit for wastewater containing PFAS. This stream contains high levels of TSS, TDS, TOC, organics, and other contaminants—all of which impact the effectiveness of capture media. However, RO-treated wastewater (concentrate) can then be fed to GAC, IX, or other PFAS capture media with higher empty bed contact time (EBCT) since flow volume is reduced by 2 to 4x, thus lowering the size necessary for PFAS capture.
As the cost of PFAS disposal/destruction rises, more waste companies and wastewater treatment facilities are exploring newer solutions like electrochemical oxidation, which offer a host of additional advantages like low energy costs, operation at ambient conditions, mobile capability, and no requirement for chemical oxidants as additives. New research may offer even more options: cold plasma technology is promising to destroy PFAS completely.
Increased Attention Now Will Pay Off Later
Waste organizations must monitor local and state wastewater activity and conduct sampling and analysis of waste streams for PFAS and co-contaminants. Segregating sources of PFAS before treatment and defining PFAS treatment objectives and potential future requirements will enable you to select the right technologies with a thorough understanding of their pros and cons.
Do not wait to start; it is wise to screen technologies in the lab and use pilot equipment. With more regulations on the way, a ready-made PFAS treatment plan will help future-proof your operations. | WA
John Peichel is a Global Market Developer for SUEZ – Water Technologies & Solutions. With more than 30 years of experience in industrial water treatment, specializing in RO/NF membranes and related technologies, John has experience in Applications, Engineering, Product Management and R&D. Recently, he has focused on the development of PFAS treatment solutions using both established and emerging technologies. He can be reached at [email protected].
References
www.epa.gov/newsreleases/epa-releases-interim-guidance-destroying-and-disposing-certain-pfas-and-pfas-containing
• www.epa.gov/newsreleases/epa-announces-plans-new-wastewater-regulations-including-first-limits-pfas-updated
• https://wasteadvantagemag.com/proposed-permit-for-burnsville-sanitary-landfill-expansion-is-designed-to-protect-groundwater-and-minnesota-river/
• www.swnewsmedia.com/savage_pacer/news/the-pfas-problem-state-looks-to-address-forever-chemicals-in-groundwater/article_bb0a2a34-0b23-5af2-b1c3-9835da95eb22.html
• https://pubs.rsc.org/en/content/articlelanding/2020/ew/d0ew00045k
• www.fox2detroit.com/news/msu-researchers-hope-new-technology-will-bring-total-destruction-to-pfas
• www.epa.gov/newsreleases/epa-releases-interim-guidance-destroying-and-disposing-certain-pfas-and-pfas-containing