WEBVTT

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I now have the pleasure of introducing today's trainers. They have all volunteered time over the years for many ITRC products, including developing and delivering this training.

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I'm now going to turn this over to Levi with the US EPA to get us started.

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Hi, Taylor, thanks for that introduction, and thanks, everyone, for attending today's training.

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I'd like to… to get us started, I'd like to imagine a scenario to help set the stage, so to speak. Let's imagine that maybe you're a groundwater remediation specialist, or perhaps a drinking water utility with a.

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Body of contaminated, PFAS contaminated water that you need cleaned up or treated, continuous treatment for.

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And let's also imagine that a consultant has already told you that maybe a fixed bed adsorber system with granular activated carbon or ion exchange resin or possibly a foam fractionation system.

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might be a solution, a potential solution to your PFAS problem.

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However, maybe you're not sure what to do next or where to find information or how to choose between these major technologies. Well, the ITRC has collected a body of technical and regulatory guidance.

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Addressing PFAS problems, and specifically the newly released Section 18 covers this exact problem. And in today's training, which is going to be an overview and introduction and companion resource.

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Uh, to Section 18 in the Technical Regulatory Guidance document.

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Um, we're going to cover all the major sections of subsections of Section 18, which are listed here.

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And so, to more carefully refine what's the central challenge that this document is trying to help us answer is, so even once you've acquired some.

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Basic information from PFAS one, there's still a challenge of… there's not just one kind of activated carbon. There's not just one kind of anion exchange resin, and there are a lot of ways to configure foam fractionation systems.

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So with all of these options to pick from, even among sorption-based technologies.

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How do you pick the best one for your PFAS problem? And that's going to be the core challenge that we address in the training today.

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The application we're going to be focusing on is ex situ treatment, which is like pump and treat applications for drinking water, wastewater, and groundwater, and others.

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Over the course of this training, we're looking to accomplish the following learning objectives.

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First, we're going to discuss… The operating principles of the sorption-based technologies, which is how they work, and um… What they can be used for.

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Then we're going to turn our attention to treatment objectives and how site-specific conditions might influence which technologies you would want to test or consider for selection.

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Then we're going to discuss the testing methods that can be used to.

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To compare different technology options, optimize performance, and verify that the chosen treatment is effective.

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We're gonna discuss what characteristics of water to be treated might adversely affect the different sorption-based technologies and what countermeasures there are available to mitigate those challenges.

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And then lastly, we're going to discuss how. Testing data results can be combined with other considerations, like cost and sustainability, to ultimately select the best.

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I'd like to turn it over to Rich Evans to get us started with…

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Thank you, Levi. Good, we got control. Thanks, everybody. I'm just gonna leave my camera on for a few minutes so you can see that I'm not an AI bot, perhaps, or that's maybe what an AI bot would say. But we'll get you off on the first section here.

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So Levi introduced us. So we've determined that PFAS treatment is needed.

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So what's next? So a couple of things highlighted here, you know. First, we want to determine our treatment objectives, which is the a part of what I'll be talking about. We want to characterize.

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That liquid, whether it's a drinking water, groundwater, wastewater, stormwater leachate, lots of options there. With that information, we'll review the pre-treatment options that are available to us.

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And these will be based upon what we're thinking about for our primary PFAS treatment method, which will be one of the sorption options we're talking about today. And then there are a variety of other site-specific factors. I'll be able to get into some of those today, but there is more in the guidance document. The little puzzle I put on here, maybe some of you had this like I did when you were a kid, a little puzzle with.

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Plastic or metal balls, you had to move it around, get them all in the middle, and we got them all in the middle, then you won. Well, PFAS treatment objectives are a lot like that. You got to take all these, you know, these four little bullets we got here and some others.

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move it around a whole lot, and get them all in the middle. And that's how you win the PFAS treatment game. So, but before I move on beyond that, I do want to acknowledge that the PFAS one document, there is some good information in section 12.1 related to what we're talking about today on PFAS characteristics, properties, co-occurring constituents or co-contaminants, you might call them.

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Uh, and some of the media that's specific in addition to what we're talking about in Section 18.

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So 1st thing, what what are your reasons or objectives for treating PFAS? So the first thing we want to encourage you to consider is, can you reduce or eliminate the source?

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Because if you can reduce or eliminate the source, that's often going to be your most cost-effective method over treatment.

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So, for example, a publicly operated treatment works might require treatment for PFAS by the industrial users that discharge to them. That's one way that they could reduce or possibly eliminate PFAS into their system. If you're an industrial user.

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Maybe you could reduce some of the PFAS containing products within your process. Maybe you could recycle some waters that contain PFAS within the facility.

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And but even after doing those things, and you still need treatment, taking these steps to reduce or eliminate at least some of the sources of PFAS, that can help reduce your scope of treatment and extend the life cycle of whatever treatment, um.

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method that you ultimately choose. In our guidance document. We talk about there are the objectives of sorption based treatment are are tooth options. You're trying to treat the water liquid so that you can either use it for consumption or a consumptive use, as it's called in the guidance document.

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or some kind of discharge.

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So as we were putting this presentation together, we came up with 8 guiding questions we use throughout. And so I have these here. You'll see these little puzzle pieces. I'll use those throughout my section, so you'll see where they tie in. And these are great questions that whether you're a practitioner, a regulator.

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a responsible party, another stakeholder. If you ask these questions early in your decision-making process, they should be helpful to achieve a better outcome. So the first one is, you know, why are you treating it? You know, what are your drivers? Are there regulatory standards? Is there a directive? Are you part of a PFAS reduction program?

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Yeah, treatment objectives, right? Are they… is it consumption? Is it discharge? Those are the two primary options we consider.

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Now, are you treating carboxylic acid, sulfonic acids, long chain, short chain? Is it some other specific PFAS that you need to treat?

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And then there's, you know, what else is coming along with that PFAS that you need to treat. It could also be unregulated PFAS. It could be PFAS precursors that maybe wouldn't be on a permit, or it could be volatile organic compounds, dissolved metals, or any number of other things that might be in your your liquid stream.

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Are there things that might interfere with your selected treatment method? So some of these co-occurring constituents can adversely affect, you know, not only your treatment equipment, but also that discharge or use that you want for the water that you're treating.

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You need pre-treatment, you know, big question. And so those are… those are water quality chemistries, co-occurring constituent questions that will give some guidance on today and in the guidance document.

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You know, where are you treating? And what this means is, is it a centralized treatment location? So maybe a wastewater plant, a groundwater treatment system, a drinking water plant, or is it what we call distributed treatment? So think of that as a drinking water supply where maybe they get their water from a number of supply wells.

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And then maybe they also get some water from surface water. So that's a distributed example, or maybe you're treating at all of those locations versus at the treatment plant itself. And then how much.

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How much space do you have? So the treat methods we'll talk about today and the pre-treatment methods all have different footprints.

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We'll let Taylor get our polling going. But we'll do a series of knowledge check questions in here just to keep you guys engaged. Make sure you're in tune with us. But our 1st question is a true or false question is that source reduction or elimination are often more cost effective than treatment.

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So true or false? We'll give you guys.

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30 or 45 seconds here to answer. We appreciate you taking the time to engage with us, and… Grab ahold of your mouse and click on something for us.

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So, most of you answered, you know, correctly, and it may not always be an option for you, maybe that's why some of you thought that was false, but it's always something to consider whether you can reduce the sources of PFAS or even eliminate them. Obviously, we talk a lot about treatment today, so if you can do that, you don't need our guidance document, but.

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Um, in many cases, you may still need some treatment on there, and we are here for you on that.

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All right. So moving on here, we have our consumptive uses or consumption.

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drinking water is going to be your primary consumptive use that's in the guidance document. There were a few others that you might run into, like irrigation or non-contact cooling water, but most of the information is really around drinking water as the… by above and beyond the most common one.

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So the treatment objectives for drinking water, you know, they're related to public health and limiting the risk of potential health effects of PFAS and drinking water.

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whatever the source of water is in those cases.

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your target concentration basis you might be considering. So it might be primary standards or interim values, advisory levels, you know, whatever your regulatory agency has available or in place that you have to take a look at. It could be your treatment technique. There are limitations.

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Um, in that. to consider, or you… the stakeholder may just desire to go beyond the minimum. You know, maybe you have a numeric Pfoa standard.

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whatever that happens to be, let's say it's 13 parts per trillion, but maybe the stakeholder or the responsible party wants to go to non-detect, right? So that's another target concentration base that you might have. One thing I want to add on here is something to consider is how your analytical data.

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is used. And so, if you have a situation with PFAS, which is not uncommon, where you're getting estimated concentrations, maybe they're between the method detection limit and a practical quantification limit, or the laboratory limit of quantification, or maybe even a matrix interference.

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That could affect your data and also your ability to determine if you are meeting those numeric concentrations basis that you set forth. And this applies to also discharge scenarios, which segues me to the next slide.

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So these discharges, usually some sort of wastewater that's being discharged. So you know a sewage plant, industrial process, wastewater, landfill leachate, contaminated groundwater, storm water. These are all examples of wastewater where sorption based treatment.

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might be used to meet your treatment objectives. I want to also point out that you might also need to consider multiple discharge options as part of your analysis. So maybe that POTW sanitary discharge, as well as the surface water discharge to figure out what's going to work best as you look at.

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How are you going to reduce your concentration? Are there mass loading requirements? And then for a lot of surface water permits, you may find a standard terminology along the lines of restore and maintain the integrity of receiving waters, which, in simple terms, means not to add PFAS to those.

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those waterways in many cases. Like the drinking water side, there are some, you know, target concentration bases. You know, it might be, you know, they might include a specific use for that groundwater for protection of human health or ecological receptors, rather.

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Um, going back to those POTWs, they have discharge criteria that they need to meet, and they may apply those standards to the people that discharge to their system so that they're not getting PFAS into their system that they can't treat or can't treat sufficiently, because that could affect, you know, their treatment processes.

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or even their ability to take care of the residuals or land apply biosolids if they're impacted with PFAS. For the surface water discharges, or in the Us. The National Pollution Discharge Elimination permits or NPDs or NPDES, as you might like to call them.

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I want to point out there's some draft guidance from the US EPA on ambient water quality standards for PFOA, PFOS, PFBS, and then there are some recommended aquatic life criteria for some select PFAS.

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Those can also be factors in your treatment objectives. And I want to point to one document. I'll give you the long name of it, but it's the December 5th, 2022 EPA memorandum, and it's called Addressing PFAS Discharges in NPTES Permits and through the Pretreatment program and monitoring programs.

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I know it's a mouthful, you can play the recording back, but that document has a lot of valuable insight for considering your surface water discharges. You might also have something on the highest attainable conditions under standard variances or pollutant minimization program goals. So there's a very specific.

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to some regulatory agencies, and those are typically cases where your concentration reductions can occur over time, and you have some interim criteria while you work towards meeting those goals.

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Then you may also have some programs where there's no regulations that apply, but the responsible party wants to reduce PFAS. So they set their own treatment objectives based upon that goal.

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So here's a diagram that's only in today's presentation. So I'll start out here on the left. But what we're talking about is, where do you need to meet your treatment objective? You know, maybe where are you analyzing? Where are you assessing that treatment location at? So if I start on the left at the industrial facility.

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you know, maybe they got a pre-treatment plan. Maybe you need to sample the influence of that, the mid-fluent, the effluent, depending on what your technology is. Those might be your locations where you need to meet your treatment objectives. It could be your discharge to surface water from that system, or it could be your discharge to the local POTW from that system. Those could also be locations where you need to meet those treatment objectives.

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Um, you could have some other ones that could come up, like an indoor air concern based upon your technology, or maybe atmospheric emissions. But if we move over to the right a little bit.

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We have a wastewater plant, you know, they have their own discharge, so that might be where you're meeting the criteria. If we move just up a little bit, there's a monitoring wall network that could be associated with the industrial facility or our drinking water plant over to the right there. And so the industrial facility.

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Maybe their treatment objectives have to be met at some downgradient monitoring wells in a groundwater plume, or maybe for the drinking water authority, those are sentinel wells that protect their supply wells. It's also possible that the supply wells are the point where the treatment objectives need to be met. It could be from the surface water that's being intaked to the, um.

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to the drinking water treatment, or it could be their finished water that they're supplying to their customers. And we also wanted to show a residential option. You know, maybe there's some other treatment objectives that are associated with a groundwater plume, and that could include, you know, concentrations at a point of entry treatment or poet system.

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could be influent, mid-fluent, effluent, as with the a treatment system over at the plant. It could be ambient air, could be indoor air. So a variety of different places where you may have to meet your treatment objectives, and that's something you want to know as you're determining not only what technology you're going to use, but where you're going to put it.

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And there's more right? So the frequency of compliance. Now, that's just not how frequency frequently you sample, you know, daily, weekly, monthly, whatever that happens to be. But how you use the data.

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So are you averaging the data? Do you use the monthly maximum? Is there some other basis? Those can also be factors.

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for how you're meeting those criteria. Others include empty bed contact time and hydraulic residence time. Andy and Jason will get into those in more detail. But if you're not familiar, empty bed contact time that refers to the amount of time that the liquid being treated is in contact with the carbon or resin.

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and hydraulic residence time. That's the amount of time that the liquid being treated is in the foam fractionation unit. So those are those are some options.

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And there can be, you know, options where the treatment objectives are met based on minimum operation conditions. So you might have might be 20 minutes of empty bed contact time, or 6 min of hydraulic residence time. Those could be standards. There are also some regulatory agencies.

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That set the basis on how frequently you're going to replace or regenerate the treatment media, or if you're going to switch lead lag operation of, say, carbon vessels. And so Wisconsin DNR, Michigan Eagle are example of agencies that have that.

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Um, you know, there's redundancy. You know, maybe one vessel is enough, or one, you know, unit, if it's foam fractionation, um, or one set of units, but maybe you want to put a second one in to make sure you have ample treatment, or maybe the first one didn't meet your empty bed contact time requirements, so you put the second one in.

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And the last thing I'll mention here is your future regulatory changes. So those can continue to change, which might change our concentrations that we have to treat towards, or our mass loading, and then we also have advances in treatment technologies that are ongoing, and they can affect your ability to meet those criteria.

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hopefully improving your ability to meet the treatment criteria.

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So our next 2 slides, we're going to look at these 3 questions. So interference with your method. Do you need to pre-treat? And what else are you treating?

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So this is a summary version of the table that's in section 18.1 of the updated guidance document. So to evaluate these pretreatment needs, we have to understand that complete chemistry of the liquid. So whether it's a water or leachate, that's a really critical element is making sure you understand that geochemistry, because with PFAS.

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That chemistry has a significant impact on your treatment technology selection, as well as whether you need free treatment, how much space you're going to need for all this equipment. So that's something critical to look at. Always look at that water chemistry.

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But for your groundwater drinking water, where your PFAS influence levels are in the low parts per trillion range, which is… which is typical in many cases, sort of media are often going to be your most cost-effective treatment option. You know, you're going to get a long lifetime. The media's been studied, so that's generally a good option.

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But where you have a highly complex background chemistry, like a landfill leachate, that's typically going to have a rapid breakthrough of PFAS in your absorptive media. You know, so if you have a situation where maybe you've got high total dissolved solids, those in many cases, can adversely affect GAC or resin.

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But for foam fractionation, that can actually be beneficial to that process.

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Here's another summary of a table from the guidance document. This is table 18.2. In this table presents the most commonly used pre-treatment methods for PFAS impacted liquids so far to date, and it includes suspended solids removal, settling clarification, chemical addition.

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ion exchange. But the version of this table in the document, it actually matches these up, so it'll give you, you know, your carbon, your resin, your foam fractionation. It'll match up with these pre-treatment methods about which ones might be used for those. So, that's a good reference to take a look at.

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And your pre-treatment method does also affect your treatment method selection, but we're going to get into a few other factors after we do another quick knowledge check.

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I'll let Taylor get that launched.

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So true or false, regulated values are the only concentrations considered when determining your treatment effect.

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That's your state agency, your your federal agency, your national agency.

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But they're only concerned about their regulated values.

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So as you guys answer it again, thank you for both joining and participating in our quick questions here. They'll continue throughout this.

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keep you guys from sitting too far back in your chairs and get on the edge, and uh… visit your seat and answer. Here we go. Most people answer true, which is correct. I mean, there could be interim values, advisory values. There's a number of other values that might impact things, because in many, many places we don't have a lot of.

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regulated values in place that we can use. So we're often using these other guidance values in our decision-making process.

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So on the next couple of slides, 3 slides of the exam, we're going to take a look at. Do I need pre-treatment? And how much space do I have?

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Before I get into some examples for system sizing, you know your flow rate and variability. They're important. So do you have a high flow rate like? Is it fast? Is it slow? Is it a low flow rate? So you're kind of the turtle or the or the rabbit scenario here.

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Um, do you have flow variations that could occur? Maybe they're daily, it could be weekly, it could be monthly, it could be seasonally throughout the year. Um, you might be able to address some of these things through your design. So, for example, maybe a large equalization tank on the front of your system is a great way to balance out flow variability.

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Maybe you can do it through your pre-treatment system if you need one with the sizing and design of that system.

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And in some cases where you have multiple sources of water, where you might have a varying quantity and quality. Think back to that drinking water utility where maybe you've got 3 supply wells that operate at different flow rates and have different PFAS, and even, you know, chemistry concentrations with them. So.

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If you're doing centralized treatment in a scenario like that, you want to make sure you've characterized in that example, all three of those supply wells, and probably want to use the worst case scenario to make sure that your design is going to capture all those, and that can also include seasonal variation with your flow.

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You know, one of the great benefits with sorption technologies are expandable. So do you need 2 units? You need 4? You need 6. And I know these look like carbon or ion exchange vessels, but the same principle applies to foam fractionation. You can keep building on as long as you have space or can make space for them.

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And another consideration to make sure you think about is future needs. So if you think about, say, a wastewater treatment plant or a drinking water plant. Is the community planning on growing?

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So is there going to be a need to treat greater amounts of water of either wastewater or drinking water to provide? So, you may need to factor in additional 10 or 20%, or whatever the number is into your design to make sure you can accommodate that future change that you know about.

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or at least is reasonably predictable. So a couple of examples on putting in treatment systems into existing facilities. That is demonstrated to be a continuing need where you have an existing system of some type where now you need to treat for PFAS. So this is a hypothetical wastewater treatment system.

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showing some typical equipment in here. But what's important is this treatment equipment that's shown here.

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can't treat PFAS, or it can treat it to only minimal levels, not that it's sufficient to meet your discharge criteria. So now you need to start thinking about other things for your treatment system, because you need to add something for PFAS. Do I have space? Can I access it for maintenance or media rebetting?

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You know, where do I put it within the sequence of the system, or in the footprint of my plant? You know, do I have system hydraulics to consider? And then things like building code, and how do you comply with all those? So we have a hypothetical example in the guidance document. So I'm going to give you the details from that.

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But we assume this this treatment plant was built in a cinder block building. You've got 300 square feet of space available to add your PFAS treatment. It processes a million gallons a day, 24 hours a day. One option you're considering is is GAC. So the Gak vessels under consideration.

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They have a 20-minute empty bed contact time, and you're gonna need 3 sets in parallel. So… that looks like this.

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As you can see, I don't have enough space in this plant for the carbon vessels. And some other considerations that don't show on this layout is the carbon vessels in this case, they're 12 feet high. Is that an issue for your roof height? Can you get them in the building? How are you going to install them? Do they come in an overhead door that you have to take off part of the roof to get them in place?

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Um, and same thing for rebetting. If you put in carbon vessels, how are you going to re-bed them? Do you need a new overhead door? Do you need a hatch in the roof? You know, how can that happen? But since they don't fit.

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We'll go to our next slide, and we'll consider an ion exchange option.

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Um, and I want to make clear, iron exchange is not the right solution for all of these, but we're using the example here. Sometimes carbon or foam fractionation is the right thing, but if we look at ion exchange, um.

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the design in this case, you only need empty bed contact time of 4 minutes.

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and… but it requires 12 vessels, but they only take up 100 square feet of 108 square feet of space. So in this case, you have enough space, and the vessels are a little shorter, they're only 10 feet high. Maybe that helps you install them easier, or re-bed them more easily. But I'll reiterate, I'm not intending to show here that.

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Resin is the answer for everything. It's an example we show of considerations, and you always have to pick the best treatment technology for your scenario.

00:26:37.000 --> 00:26:54.000
We have a lot of great information in the guidance document. I unfortunately don't have time to get to all of it with you today. Some other great sections I'll point you to is the separated PFAS destruction disposal section and more information on sample collection and analytical support. So a lot of great information in the guidance document to take a look at.

00:26:54.000 --> 00:27:09.000
So, you know, here we're back to the 8 puzzle pieces we started with, and I'll leave you here with come back on screen, and I hope that my section has helped bring some of this together here for you into one puzzle, and I'm going to turn it over to Andy, who's going to talk about carbon and ion exchange.

00:27:09.000 --> 00:27:13.000
Thank you for joining today.

00:27:13.000 --> 00:27:25.000
All right. Thank you, Rich. I just want to welcome everybody and thank you again for your time and your interest in our topic today.

00:27:25.000 --> 00:27:31.000
I'm going to be talking… if I can advance the slide, yeah, about fixed bed adsorbers.

00:27:31.000 --> 00:27:43.000
And really, the two most common sorbents that are used for PFAS treatment today, and those being granular activated carbon and ion exchange resin.

00:27:43.000 --> 00:27:48.000
So…

00:27:48.000 --> 00:27:57.000
We have, as you can see here, the the fixed bed sorption of the topic is divided into these 3 sections.

00:27:57.000 --> 00:28:04.000
Uh, we have a brief technical overview, and we'll just cover some fixed bed concepts.

00:28:04.000 --> 00:28:20.000
And provide some information about GAC and ion exchange resin. Then we'll move on to performance evaluation, where we'll talk about how these media are tested and evaluated.

00:28:20.000 --> 00:28:31.000
Uh, and then we're going to wrap it up with a discussion as to how the spent media is handled.

00:28:31.000 --> 00:28:40.000
So starting with the the technical overview, and we'll just begin with just an introduction of some basic fixed bed concepts here.

00:28:40.000 --> 00:28:45.000
Uh, so first of all, what do we mean by a fixed bed?

00:28:45.000 --> 00:28:57.000
So when we say fixed. We're referring to a fixed volume of sorption media that's contained in a vessel, and the vessel could be a, you know, an enclosed pressure vessel.

00:28:57.000 --> 00:29:03.000
Um, or it could be a vessel open to the atmosphere, like a gravity filter basin.

00:29:03.000 --> 00:29:10.000
But the sorption media remains stationary in a packed bed, and the water flows through it.

00:29:10.000 --> 00:29:17.000
So in our simple diagram shown here, the water flows most commonly downward.

00:29:17.000 --> 00:29:29.000
Uh, through the fixed, uh, beta media. And the PFAS molecules diffuse from the bulk water phase into the sorbent particles.

00:29:29.000 --> 00:29:37.000
Um, so what happens when you operate a fixed bed with sorbent media for a period of time? You get a band of.

00:29:37.000 --> 00:29:41.000
saturated media developing at the top of the bed.

00:29:41.000 --> 00:29:57.000
And then further down the media is quote unquote clean because it still has some remaining adsorption capacity. So in between the saturated media and the clean media. There's this.

00:29:57.000 --> 00:30:03.000
transition zone that we call the mass transfer zone.

00:30:03.000 --> 00:30:21.000
So, as the bed continues to sorb PFAS. This mass transfer zone moves down through the bed until it starts to exit the vessel. And of course at that point we see breakthrough occur.

00:30:21.000 --> 00:30:28.000
So if you were to chart the effluent PFAS concentration over time.

00:30:28.000 --> 00:30:38.000
or over a total volume of water treated. you generate what we call a breakthrough curve, like the one we're showing here on the bottom of this slide.

00:30:38.000 --> 00:30:46.000
Um, something to keep in mind is that each organic compound moving through the sorption media will have its own.

00:30:46.000 --> 00:30:52.000
mass transfer zone, and thus its own breakthrough curve.

00:30:52.000 --> 00:31:03.000
So obviously, you know, the most significant operational task with a fixed bed is determining when to replace the media, right?

00:31:03.000 --> 00:31:11.000
You know, are we gonna be real conservative and do it at time step three? You know, before initial breakthrough happens?

00:31:11.000 --> 00:31:25.000
Or could we wait until time step 4, or even later as shown kind of at the top of this figure and possibly get more use out of our media?

00:31:25.000 --> 00:31:42.000
It really depends on how we configure our fixed beds, okay? Which we'll cover shortly. But before we do that, I just wanted to cover a couple of basic design parameters for fixed beds.

00:31:42.000 --> 00:31:47.000
So the parameters are the empty bed contact time.

00:31:47.000 --> 00:31:53.000
EBCT, as it's abbreviated, and the hydraulic loading rate, or HLR.

00:31:53.000 --> 00:31:59.000
Uh, so the empty bed contact time is the time usually measured in minutes.

00:31:59.000 --> 00:32:12.000
Uh, that the flow rate would take to… They'll fill up the volume of the media, as if the media weren't present. So it's a media contact time, so to speak.

00:32:12.000 --> 00:32:19.000
And it's a very important parameter, because. We need enough contact time to contain.

00:32:19.000 --> 00:32:27.000
The mass transfer zone. and to provide a good bed life.

00:32:27.000 --> 00:32:41.000
And then we have the hydraulic loading rate. Um, which is simply the flow rate divided by the cross-sectional area of the bed. And you can think of that like a theoretical velocity going through the absorption media.

00:32:41.000 --> 00:32:50.000
So we use the HLR, or hydraulic loading rate guidelines to put bounds on the on the lower and the upper flow rates.

00:32:50.000 --> 00:32:59.000
We know that if the hydraulic loading rate is too low, we could have what we call channeling, which can lead to premature breakthrough.

00:32:59.000 --> 00:33:07.000
But on the other hand, we don't want the hydraulic loading rate to be so high that we cause excessive pressure drop and high pumping energy.

00:33:07.000 --> 00:33:21.000
So maintaining a relatively constant flow within these bounds is really the ideal way to operate a fixed bed.

00:33:21.000 --> 00:33:32.000
Okay, so what are the typical ranges in these 2 parameters? So the typical empty bed contact time for Gac ranges from.

00:33:32.000 --> 00:33:44.000
10 to 20 minutes. Uh, per vessel, whereas for ion exchange resin, uh, it's significantly less at about 1.5 to 3 minutes per vessel.

00:33:44.000 --> 00:33:53.000
The shorter contact time for resin is due to its faster adsorption kinetics.

00:33:53.000 --> 00:34:04.000
There's a bit of an overlap between the two with the hydraulic loading rate, where we have 2 to 10 gallons a minute.

00:34:04.000 --> 00:34:12.000
per square foot, typically, for GAC. and 6 to 18 gallons a minute for ion exchange resin.

00:34:12.000 --> 00:34:17.000
And, uh, please keep in mind, these are typical ranges.

00:34:17.000 --> 00:34:30.000
But you will see deviations here and there. You know, based on site-specific or application-specific considerations.

00:34:30.000 --> 00:34:36.000
Okay, so let's talk a little bit about the different ways sorption vessels can be configured.

00:34:36.000 --> 00:34:45.000
The simplest configuration would just be a single tank or a vessel or column like you see here.

00:34:45.000 --> 00:34:57.000
The drawback with this, however, is that. Even if you timed the change out of the media perfectly, uh, just before initial breakthrough happens.

00:34:57.000 --> 00:35:08.000
You can see that you still have some unused capacity within that mass transfer zone.

00:35:08.000 --> 00:35:17.000
Now, if we broke that single column into two or more columns and put them in series.

00:35:17.000 --> 00:35:23.000
Uh, and we call the first column the lead bed, and subsequent columns, the lag beds.

00:35:23.000 --> 00:35:29.000
Now we can let the LeadBed break through to a greater extent.

00:35:29.000 --> 00:35:36.000
before changing the media out, and therefore we get more, um, overall efficient usage of the media for our system.

00:35:36.000 --> 00:35:45.000
So the lead lag configuration, as this is often called, provides a margin of safety.

00:35:45.000 --> 00:35:54.000
Uh, because we always have a relatively fresh lag bed of media online.

00:35:54.000 --> 00:36:03.000
And as we need to ramp the flow capacity up, we can simply arrange the fixed beds into parallel trains.

00:36:03.000 --> 00:36:13.000
Um, so each parallel train could consist of. Multiple vessels in series, kind of like we're showing here on the on the left-hand side.

00:36:13.000 --> 00:36:19.000
or if you have some flexibility in how you start your system up.

00:36:19.000 --> 00:36:25.000
You could have a parallel train of single vessels, as we're showing on the right-hand side of the slide here.

00:36:25.000 --> 00:36:37.000
where the media change-outs would be staggered to improve the media usage efficiency.

00:36:37.000 --> 00:36:46.000
Um, so our technical overview of fixed bed sorption probably wouldn't be complete without mentioning water quality impacts.

00:36:46.000 --> 00:36:54.000
Uh, because the background water quality can just have a very significant impact on performance.

00:36:54.000 --> 00:36:59.000
So we're showing here some of the more common parameters.

00:36:59.000 --> 00:37:08.000
Uh, that most fixed bed systems have to deal with. Those would be suspended solid total suspended solids, TSS.

00:37:08.000 --> 00:37:13.000
Uh, and iron and manganese, you know, these are things that can physically follow the media.

00:37:13.000 --> 00:37:19.000
And then you have oxidants that, um, that can cause some damage.

00:37:19.000 --> 00:37:29.000
Uh, to some type of sorbents. And then, of course, the background organics, which compete for sorption space or volume.

00:37:29.000 --> 00:37:33.000
Um, so that being, you know, total… total organic carbon.

00:37:33.000 --> 00:37:39.000
There is a great resource in the online technical guidance document.

00:37:39.000 --> 00:37:45.000
Um, Rich alluded to, but it provides a pretty extensive list of.

00:37:45.000 --> 00:38:06.000
Potential water quality impacts. Uh, along with recommended pre-treatment options. And so this information can be found in tables 18-1 and 18-2 of the document.

00:38:06.000 --> 00:38:18.000
Okay, so I want to transition now and talk about some of the characteristics of GAC and ion exchange resin, but first we'd like to poll the audience on something.

00:38:18.000 --> 00:38:33.000
So here's our first question of this section. And the question is, which types, which type of GAC generally has a higher absorption capacity for PFAS? Is it a bituminous or coal-based?

00:38:33.000 --> 00:38:40.000
B, coconut or C, it doesn't matter. All carbons are about the same.

00:38:40.000 --> 00:38:56.000
We'll give you all a few moments here to let us know what you think.

00:38:56.000 --> 00:39:03.000
Okay, so we have, yeah, about 60% of you said bituminous.

00:39:03.000 --> 00:39:15.000
Uh, with some coconut, some saying it doesn't matter. So the answer is actually a bituminous.

00:39:15.000 --> 00:39:26.000
There are many types of activated carbon that are made from different materials and using different manufacturing methods.

00:39:26.000 --> 00:39:33.000
For example, there are many bituminous coal-based products that are available in the marketplace.

00:39:33.000 --> 00:39:38.000
They're not, um, you know, they're not all going to perform the same.

00:39:38.000 --> 00:39:45.000
Another thing always to keep in mind, too, is cost, right? A media with the highest absorption capacity.

00:39:45.000 --> 00:39:51.000
may not always be the most cost-effective.

00:39:51.000 --> 00:40:02.000
Alright, so a bit of information now about the two sorbents that we're talking about today. And I'm going to start with granular activated carbon, GAC.

00:40:02.000 --> 00:40:09.000
The most common commercially available. Products are derived from coal.

00:40:09.000 --> 00:40:17.000
Uh, coconut shells and wood. In coal, we can subclassify it further into bituminous.

00:40:17.000 --> 00:40:25.000
Subbituminous and lignite. And it's the bituminous-based, or more specifically.

00:40:25.000 --> 00:40:39.000
Uh, the re-agglomerated by tuminous-based GIC products. that tend to outperform the other types based on… the absorption capacity for PFAS.

00:40:39.000 --> 00:40:48.000
Uh, average particle size for GAC, um, used in PFAS applications is around a millimeter.

00:40:48.000 --> 00:40:55.000
Core sizes range from two nanometers to about 50 nanometers.

00:40:55.000 --> 00:41:06.000
And the affinity of PFAS for GAC. is stronger as the carbon chain length in a given subgroup of PFAS increases.

00:41:06.000 --> 00:41:15.000
An example of that, within the subgroup of perfluoroalkyl carboxylic acids, the PFCAs.

00:41:15.000 --> 00:41:21.000
PFOA, uh, with 8 carbons is going to have a stronger affinity.

00:41:21.000 --> 00:41:37.000
Then, uh, PFBA with only 4 carbons. And then between the two common perfluoroalkyl acids, the sulfonates sorb more strongly than the carboxylates.

00:41:37.000 --> 00:41:43.000
And for ion exchange resin in general, there are many different types as well.

00:41:43.000 --> 00:41:52.000
There are antionic and cationic-specific resins. Uh, which can be categorized as either weak or strong.

00:41:52.000 --> 00:41:59.000
We can break resins down even further into either the gel or the macroporous type.

00:41:59.000 --> 00:42:10.000
And there's a lot more information available on resins that can be found in Section 18.3 of the online documents.

00:42:10.000 --> 00:42:20.000
But for PFAS applications. It's mostly the strong-based anionic resins that are used.

00:42:20.000 --> 00:42:26.000
Because many of the PFAS of regulatory interest exist as anions.

00:42:26.000 --> 00:42:33.000
Uh, in the environment. And these resins are typically provided in the chloride form.

00:42:33.000 --> 00:42:41.000
Which means that they exchange chloride ions for the PFAS anions.

00:42:41.000 --> 00:42:47.000
Pore sizes and particle sizes are not all that different from GAC.

00:42:47.000 --> 00:42:52.000
And then in terms of the relative affinity of resin for PFAS.

00:42:52.000 --> 00:42:56.000
Uh, we have the same general trends as GAC.

00:42:56.000 --> 00:43:03.000
But for resin, the perfluoroalkane sulfonic acids, the PFSAs.

00:43:03.000 --> 00:43:09.000
Those would be, you know, like PFOS, PFHXS, PFBS, etc.

00:43:09.000 --> 00:43:20.000
Um, these tend to sort much more strongly than the perfluoroalkyl carboxylic acids.

00:43:20.000 --> 00:43:27.000
Okay, so we have here a nice little summary table that's comparing the 2 sorbents.

00:43:27.000 --> 00:43:35.000
that we've been discussing. I'm not really going to read this or spend much time on it because we've essentially covered most of it.

00:43:35.000 --> 00:43:40.000
Um, it'll just be a nice little summary for those of you who may want to refer to it later.

00:43:40.000 --> 00:43:48.000
So now that we have a little bit of background on fixed bed sorption, you may be wondering.

00:43:48.000 --> 00:43:53.000
You know, what do we do with the media once breakthrough occurs?

00:43:53.000 --> 00:44:02.000
you know, do we have to dispose of it, or can we somehow restore its capacity? And the answer is, we can.

00:44:02.000 --> 00:44:12.000
restore the capacity in certain applications, and we'll start with how we do that for GAC.

00:44:12.000 --> 00:44:20.000
So restoring the capacity of spent GAC is primarily done by a process called reactivation.

00:44:20.000 --> 00:44:27.000
Which is essentially returning the GAC to a near-virgin state.

00:44:27.000 --> 00:44:34.000
Using a thermal process that destroys the organics sorbed to the carbon.

00:44:34.000 --> 00:44:39.000
There's a nice environmental benefit to using reactivated carbon.

00:44:39.000 --> 00:44:47.000
Um, due to its lower… the lower CO2 emissions compared to using virgin carbon.

00:44:47.000 --> 00:44:53.000
There are some losses of activated carbon through the reactivation process.

00:44:53.000 --> 00:45:00.000
These occur due to mechanical attrition and oxidative losses in the furnace.

00:45:00.000 --> 00:45:13.000
So it's pretty common practice to. To augment reactivated carbon with between 15 to 30% virgin carbon to make up for those losses.

00:45:13.000 --> 00:45:25.000
Reactivation's been commercially available now for many years. There are about… there are about 17 reactivation facilities in the Us.

00:45:25.000 --> 00:45:30.000
And reactivated carbon can be provided, uh, in two different ways.

00:45:30.000 --> 00:45:38.000
We call these dedicated reactivation or pool reactivation. Um, with dedicated, uh.

00:45:38.000 --> 00:45:44.000
Uh, with a dedicated method, basically the reactivated product goes right back to the original user.

00:45:44.000 --> 00:45:50.000
Which is, um, fairly common in the drinking water industry.

00:45:50.000 --> 00:46:00.000
With pool reactivation. However, spent carbons. Um, are pooled together from many different users.

00:46:00.000 --> 00:46:07.000
reactivated and then sold as a product, a reactivated carbon product in the marketplace.

00:46:07.000 --> 00:46:18.000
Important to point out that they're reactivated. Uh, carbon pool reactivated carbons are not used for potable use.

00:46:18.000 --> 00:46:30.000
So that's GAC reactivation in a nutshell. I'll also add that there are developing methods for regenerating GAC using.

00:46:30.000 --> 00:46:44.000
Chemical means instead of thermal. But these services are not yet widely available on a commercial scale.

00:46:44.000 --> 00:46:49.000
Okay, so now we're going to get into the regeneration of ion exchange resin. But before we do that.

00:46:49.000 --> 00:47:03.000
Let's check in with you all on another poll question first. And this is a true false question. The question is exhausted PFAS selective anion exchange resin.

00:47:03.000 --> 00:47:12.000
can be regenerated with brine. Just like with nitrate treatment. Is that true or false?

00:47:12.000 --> 00:47:32.000
So you should see your… selection box on your screens will give you a few moments here to let us know what you think on this one.

00:47:32.000 --> 00:47:37.000
We'll see the results here. Oh, interesting. So we had.

00:47:37.000 --> 00:47:56.000
Okay, about 40% said true, 60% said false. The answer is actually false. Brine alone. Maybe the question wasn't worded all that clearly. But but brine alone is not effective.

00:47:56.000 --> 00:48:03.000
for regenerating PFAS selective resins. Let's get into that a little bit.

00:48:03.000 --> 00:48:11.000
If you look at the schematic, kind of the blown-up view schematic, uh, lower left-hand side here of the slide.

00:48:11.000 --> 00:48:22.000
What we're showing is a typical PFAS molecule with an ionic head and a non-ionic tail.

00:48:22.000 --> 00:48:38.000
So, using salt alone to regenerate the resin would be, you know, it would effectively sever the ionic attachment, which would be… Uh, between the red and the green circles on that schematic there.

00:48:38.000 --> 00:48:44.000
But it would not be effective in severing the hydrophobic attachment.

00:48:44.000 --> 00:48:51.000
that exists between the non-ionic tail, which is sort of the small blue circles, and the polymer backbone.

00:48:51.000 --> 00:48:54.000
Um, turns out for that, you need a solvent.

00:48:54.000 --> 00:49:01.000
Uh, so to regenerate the resin, uh, effectively, a solvent, which is typically an alcohol.

00:49:01.000 --> 00:49:06.000
In addition to the brine or the salt is needed.

00:49:06.000 --> 00:49:15.000
Regenerable ion exchange systems using these methods have been commercially implemented since 2018.

00:49:15.000 --> 00:49:25.000
And I should point out for non-potable applications. The solvent-regenerated resin systems have not yet been approved for drinking water applications.

00:49:25.000 --> 00:49:39.000
And, uh, we got a picture here on the right-hand side shows an example of a ion exchange regeneration system.

00:49:39.000 --> 00:49:49.000
So after the regenerate sequence for resin is completed, as you might imagine, the resin is rinsed.

00:49:49.000 --> 00:50:03.000
And the spent regenerate solution can be collected and distilled to actually recover and reuse the alcohol for subsequent regenerations.

00:50:03.000 --> 00:50:11.000
So the PFAS in this way ends up being concentrated many, many times over into.

00:50:11.000 --> 00:50:21.000
Um, what are called the still bottoms. And the photo on the right-hand side shows samples taken from a resin vessel.

00:50:21.000 --> 00:50:28.000
Uh, in chronological order, uh, going from left to right, and then top to bottom.

00:50:28.000 --> 00:50:34.000
kind of showing samples from an entire regeneration sequence.

00:50:34.000 --> 00:50:42.000
So the color changes can be used by an operator as sort of a visual indication that everything.

00:50:42.000 --> 00:50:49.000
It's happening as it should throughout that regeneration sequence.

00:50:49.000 --> 00:51:08.000
Okay, so we're done with the the brief technical overview. Now it's time to talk about how we evaluate the performance of the sorbents. You know, this is a really important topic because oftentimes it's it's hard to know which sorbent to use.

00:51:08.000 --> 00:51:13.000
And importantly, then, how often it'll have to be exchanged for a given application.

00:51:13.000 --> 00:51:22.000
So, um, you know, here's where the testing comes in to help answer those questions.

00:51:22.000 --> 00:51:34.000
Now, before jumping right into, you know, testing on the bench or the pilot scale, uh, you know, it's always nice to use a model, if one is available.

00:51:34.000 --> 00:51:37.000
Uh, to get a rough look at things first.

00:51:37.000 --> 00:51:49.000
Um, and there are some models out there. Although not many at this point that are publicly available and open source.

00:51:49.000 --> 00:52:07.000
Um, the EPA does have a couple free and open source models for GAC and one for resin as well. And you can access those through the links on the bottom right-hand side of the slide. There are links to access those models.

00:52:07.000 --> 00:52:17.000
And there's an example output curve for background ions from the EPA resin model that's shown on the slide here.

00:52:17.000 --> 00:52:23.000
So there are models like these, and they're based on adsorption theory.

00:52:23.000 --> 00:52:29.000
But the challenge is that they require input parameters that could be difficult to determine.

00:52:29.000 --> 00:52:33.000
you know, for every specific water and sorbit combination.

00:52:33.000 --> 00:52:44.000
Um, so, uh, you know, modeling, unfortunately, is not at a point where, um, you know, it's going to be a reliable, accurate predictor of performance.

00:52:44.000 --> 00:52:55.000
But it's definitely not without any value. You know, modeling can help us with high-level conceptual design and budgeting for some applications.

00:52:55.000 --> 00:53:09.000
It can even help us to, you know, design more effective pilot studies. And another way, modeling can provide value is by sort of fitting or calibrating a model to actual pilot results.

00:53:09.000 --> 00:53:20.000
And then, using that model to answer, you know, what-if questions, like, what if my flow rate increases, or what if I extend.

00:53:20.000 --> 00:53:28.000
The empty bed contact time of my media. So it's helpful in those cases.

00:53:28.000 --> 00:53:43.000
Okay, so we sort of get into the meat now of performance testing, and we have at our disposal three performance testing methods that are commonly used to evaluate sorption media.

00:53:43.000 --> 00:53:49.000
And they're listed there in the first column. So we have the isotherm.

00:53:49.000 --> 00:53:55.000
The rapid small-scale column attest, and then the pilot test.

00:53:55.000 --> 00:54:01.000
And the last one listed there in the first column is called Full Scale Demonstration.

00:54:01.000 --> 00:54:09.000
I'm not really gonna spend much time on that. It can be an option for some, but oftentimes it's not.

00:54:09.000 --> 00:54:24.000
So, so this table is comparing the various attributes of these test methods. Okay? And those attributes are listed across the top row there, and we have we have time, cost, ability to compare multiple sorbents.

00:54:24.000 --> 00:54:32.000
And then, of course, accuracy in predicting predicting full-scale performance.

00:54:32.000 --> 00:54:42.000
Um, the test methods or the types are listed in the typical order in which they would be conducted on a project.

00:54:42.000 --> 00:54:47.000
So, they're listed sort of an increasing order of.

00:54:47.000 --> 00:54:51.000
Um, you know, time or time commitment, and cost.

00:54:51.000 --> 00:54:58.000
And as you might imagine. As you move down that list, the accuracy improves as you move down.

00:54:58.000 --> 00:55:06.000
So we're going to cover a little bit about each of these common test methods.

00:55:06.000 --> 00:55:19.000
And, um… So our first, you know, test method is the isotherm. In a nutshell. What we're doing is we're adding sorbents.

00:55:19.000 --> 00:55:25.000
in a very controlled way. to a series of contaminated water samples.

00:55:25.000 --> 00:55:33.000
And what we're doing is we're measuring the amount of contaminant the sorbent can hold at an equilibrium condition.

00:55:33.000 --> 00:55:42.000
Okay, and we call this test an isotherm. Because all the samples are tested at the same temperature.

00:55:42.000 --> 00:55:56.000
Um, sorbent particle size is important because the smaller the particle size, the faster the sorption kinetics are, and the quicker you drive the system to equilibrium.

00:55:56.000 --> 00:56:03.000
So SORP, you'll find in these tests, sorbents are often pulverized into a powder form.

00:56:03.000 --> 00:56:12.000
Okay, so why do we use this method? Well, first it can be kind of a kind of a go-no-go test.

00:56:12.000 --> 00:56:24.000
to evaluate the technical feasibility of a sorbent. Uh, because it tells us if the contaminant is strongly or weakly sorbed.

00:56:24.000 --> 00:56:30.000
And it's a convenient way to compare multiple sorbents against each other.

00:56:30.000 --> 00:56:43.000
Um, so then you can pick the best performing sorbent, for example, for future modeling or piloting efforts.

00:56:43.000 --> 00:56:59.000
Okay, so isotherm testing is great. It can provide some basic information, but it doesn't really tell us with accuracy when to expect, sorry, breakthrough.

00:56:59.000 --> 00:57:14.000
Okay, through a column of media. So, you know, to get at to get at that, we move up to the, uh, to an accelerated column testing method, or the rapid small-scale column test, or RSSCT.

00:57:14.000 --> 00:57:23.000
And basically, with this test, um, what we're doing is we're shrinking a full-scale adsorber down to a very small bench-scale column.

00:57:23.000 --> 00:57:29.000
and we're pumping a sample of water through it. And what we get out of the test.

00:57:29.000 --> 00:57:35.000
is a breakthrough curve, just like we would with a pilot or a full-scale column.

00:57:35.000 --> 00:57:47.000
And the theory behind the method is that sorption kinetics depend very strongly on the sorbent particle size. So by grinding the sorbent into very, very small particles.

00:57:47.000 --> 00:58:00.000
we accelerate the rate of that sorption. Now, there are different assumptions that you can make for the scaling parameters of this test.

00:58:00.000 --> 00:58:06.000
which result in differing scale factors, but just as an example.

00:58:06.000 --> 00:58:22.000
The RSSCT can compress. a one-year full-scale operating period, down to just a couple weeks in the lab. So that's the convenience. The convenience is that acceleration in the time.

00:58:22.000 --> 00:58:41.000
The theory behind the test was developed based on GAC sorption. So you tend to see these tests most commonly done on GAC. However, there are practitioners that are using the method on some other assortments like resin.

00:58:41.000 --> 00:58:54.000
But it appears… We're not at a point where we have a consensus yet on the accuracy, and, um, you know, how to appropriately interpret results for resin.

00:58:54.000 --> 00:59:03.000
And even for GIC, you know, the method isn't perfect. It definitely offers more useful information than an ISOtherm alone.

00:59:03.000 --> 00:59:09.000
But the accuracy does remain a topic of ongoing research.

00:59:09.000 --> 00:59:28.000
Nonetheless, you know, the method is a useful tool. We get the same information as the isotherm, but in addition, we get that breakthrough curve, and from that we can get a rough estimate of the sorbent usage rate.

00:59:28.000 --> 00:59:35.000
Okay, so the most accurate method for evaluating performance is the pilot test.

00:59:35.000 --> 00:59:46.000
or the pilot test column. These tests commonly use multiple columns mounted on a skid, such as the one you see here on the picture.

00:59:46.000 --> 00:59:56.000
and they're conducted on site instead of a lab where a small slipstream of flow is pumped through the columns.

00:59:56.000 --> 01:00:11.000
The multiple columns come in handy for evaluating multiple sorbents against each other, or possibly even evaluating a combination of sorbents, like GAC followed by ion exchange resin.

01:00:11.000 --> 01:00:38.000
So, unlike the RSSCT. The pilot column exactly matches the parameters of the full-scale bed. Um, so… you know, while there's no acceleration in the test results, the benefit is that there really are minimal errors associated with scaling up.

01:00:38.000 --> 01:00:54.000
Okay, so we're kind of done now with our brief technical overview and the performance evaluation methods. So we'll get into the third and the final topic, which is what do we do with the media once it is?

01:00:54.000 --> 01:01:06.000
bent. And before I get into the options for handling the spent media, I just wanted to first define what I mean by spent media.

01:01:06.000 --> 01:01:20.000
Um, so spent media here is media that is at the end of its useful life. Okay, so if it's a single-use media, we're saying its capacity is spent, and it needs to be disposed.

01:01:20.000 --> 01:01:34.000
Likewise, if we have a regenerable media, like the regenerable ion exchange resin, we're saying it's gone through enough regeneration cycles that its capacity is spent.

01:01:34.000 --> 01:01:44.000
So, when we're at that point, there are currently 2 commercially available options for disposing of spent resin and GAC.

01:01:44.000 --> 01:01:49.000
And these would be landfilling and high temperature incineration.

01:01:49.000 --> 01:02:10.000
Landfilling, of course, it's not a destructive option. So, you know, if the gas and leachate emissions from a landfill aren't effectively controlled, you know, we run the risk of the PFAS getting back into the environment. So some jurisdictions will limit what types of landfills.

01:02:10.000 --> 01:02:17.000
will accept PFAS waste. And then we have high temperature incineration.

01:02:17.000 --> 01:02:31.000
Which, of course, is a destructive process. Um, and similar to landfilling, some jurisdictions will limit incineration to only certain types of facilities, such as permitted hazardous waste.

01:02:31.000 --> 01:02:41.000
incinerators. And as we discussed earlier, GAC has this additional option of recycling the spent media.

01:02:41.000 --> 01:02:53.000
Through the process we call reactivation. And depending on how far away the source of the spent GAC is from the nearest reactivation facility.

01:02:53.000 --> 01:02:59.000
This method could be the least expensive handling method of the three shown here.

01:02:59.000 --> 01:03:05.000
Now, there are other waste disposal options that are currently being developed.

01:03:05.000 --> 01:03:18.000
Um, but they're not yet widely commercially available. These would include the PFAS destruction technologies. Examples of those would be SQO, supercritical water oxidation.

01:03:18.000 --> 01:03:24.000
in a piezoelectric ball milling.

01:03:24.000 --> 01:03:38.000
For regenerable ion exchange resin systems, we have the still bottoms that I mentioned before, and these contain the highly concentrated PFAS.

01:03:38.000 --> 01:03:50.000
And, um, one way to handle this is the still bottoms are pumped through a sorted media in a process that's called super loading.

01:03:50.000 --> 01:03:58.000
Um, which, you know, basically vastly reduces the overall volume of PFAS waste.

01:03:58.000 --> 01:04:12.000
So, the super-loading media, um, would then be, uh, you know, once it's spent, would be disposed of in the same way as GAC or ion exchange resins. So you have those landfilling and incineration.

01:04:12.000 --> 01:04:26.000
methods available. Uh, but there's another way to handle the still bottoms, and that's by using a destruction, a PFAS destruction method. So the HALT process, which stands for hydrothermal, alkaline water treatment.

01:04:26.000 --> 01:04:37.000
And, uh, plasma and electrochemical oxidation are some examples of some of the destructive processes that have been demonstrated on still bottoms treatment.

01:04:37.000 --> 01:04:49.000
And, uh, there's some ongoing halt and SQO demonstrations, uh, that, um, are happening through the Defense Innovation Unit funded projects.

01:04:49.000 --> 01:05:03.000
And that's it for my time. That's it for fixed bed technologies. And I think before we turn it over to Jason, who will be our next speaker, he'll be talking about a different kind of sorption.

01:05:03.000 --> 01:05:15.000
Um, technology for removal of PFAS. I think we're gonna pause here for a bit and open up with a brief question and answer session.

01:05:15.000 --> 01:05:22.000
All right. Yes, thank you, Andy. As Andy mentioned, we will be taking a quick break to do some Q&A.

01:05:22.000 --> 01:05:29.000
And I do have a couple of questions for each of our trainers from the first half of our training today.

01:05:29.000 --> 01:05:34.000
And I will start with a question for Levi, who did the introduction to our training.

01:05:34.000 --> 01:05:47.000
In the published section 18 of ITRC PFAS 1 Guidance, our application of sorbent in situ for groundwater plume control discussed.

01:05:47.000 --> 01:05:54.000
Hello, thanks for the question. So no, in section 18, we do not discuss in situ methods.

01:05:54.000 --> 01:06:04.000
Um, because in situ methods, for instance, injecting colloidal activated carbon down into a well or an aquifer to catch a contaminant plume.

01:06:04.000 --> 01:06:11.000
That operates by a very different set of principles and has a different site considerations than.

01:06:11.000 --> 01:06:24.000
Um, the pump and treat… applications that we're talking about, and it would be a much longer document and training. If you're interested in learning more about some in-situ methods, especially colloidal activated carbon.

01:06:24.000 --> 01:06:36.000
ITRC's PFAS 1 Section 12 does have does discuss this technology and there's also a case study in PFAS one section 15.

01:06:36.000 --> 01:06:47.000
All right. Thank you, Levi. I'll now be asking a question to Rich, who did our treatment objectives and site specific consideration section of the training.

01:06:47.000 --> 01:07:00.000
You mentioned the importance of pre-treatment of the water before the absorption-based treatment method. Can you briefly explain why high total dissolved solids are bad for GAC and ion exchange?

01:07:00.000 --> 01:07:10.000
And how does high total dissolved solids help with foam fractionation?

01:07:10.000 --> 01:07:31.000
Sorry, excuse me. So the Tds, it's associated with fouling typically with the carbon vessels and iron exchange. It's there are some processes where it's not necessarily a problem like we're using brine solutions with GAC to remove organics, but there are, you know, times where Tds is can, you know, causes scaling in in the GAC. It's…

01:07:31.000 --> 01:07:48.000
Probably more… it's more prevalent in ion exchange, so that's where it can be a problem. With the ton of solids and foam fractionation. I know we got Jason coming up next, but, um, with the way that process works, those can be beneficial, and I think it's better to let Jason.

01:07:48.000 --> 01:07:55.000
And that this conversation, and to go in now, since we haven't had that content yet.

01:07:55.000 --> 01:08:04.000
All right. Thank you, Rich. Yeah, we'll hear more from Jason in just a little bit. But I do have a question or 2 for Andy before we move on to the next section.

01:08:04.000 --> 01:08:15.000
What ion exchange resins are used for PFAS? Which PFAS groups are more strongly absorbed to the resin?

01:08:15.000 --> 01:08:35.000
Okay, yeah, thank you for that question. I think we did, um… We did touch on that a little bit in the presentation, and I'll just reiterate. So mostly you find strong base anionic exchange resins.

01:08:35.000 --> 01:08:40.000
used for PFAS treatment. They're anionic.

01:08:40.000 --> 01:08:52.000
Again, because most of the PFAS of concern. That we're dealing with, uh, exist as anions in the aquatic environment.

01:08:52.000 --> 01:09:01.000
And I would say most anion exchange resins will work to some extent on removing PFAS.

01:09:01.000 --> 01:09:18.000
But it's really the quote-unquote PFAS selective. Um, resins that are available in the marketplace, and those are the ones with polystyrene backbones, and they have specialized functional groups.

01:09:18.000 --> 01:09:25.000
Um, those… those products tend to have much higher, you know, relative affinity for PFAS.

01:09:25.000 --> 01:09:33.000
Um… See, I think there's the second part of that was… and we…

01:09:33.000 --> 01:09:39.000
The second part of the question was which PFAS groups are more strongly absorbed to the resin?

01:09:39.000 --> 01:09:50.000
Right, right. Um… So, for these resins, the sulfonic acid PFAS, like, such as PFOS.

01:09:50.000 --> 01:10:01.000
tend to soar more strongly than the carboxylic acid PFAS, like PFOA. Quite a bit more strongly actually.

01:10:01.000 --> 01:10:12.000
The same general trend holds for, um, you know, most other sorvants, but for resins, it's particularly.

01:10:12.000 --> 01:10:25.000
the sulfonated PFAS just absorb much, much more strongly. And I believe there are there's a reference to a few published studies actually in the online guidance document.

01:10:25.000 --> 01:10:33.000
Um, that, um, that cover that particular topic.

01:10:33.000 --> 01:10:50.000
All right. Thank you, Andy. and in the interest of time, I think we will go ahead and move on to the next section. But thank you, everyone, for continuing to interact with that Q&A pod. We do have subject matter experts in the background who are monitoring it throughout the training, and we will try to get to as many questions.

01:10:50.000 --> 01:11:00.000
As we can, but I'll now pass this off to Jason from Alonia to talk about foam fractionation.

01:11:00.000 --> 01:11:14.000
All right. Thank you, everyone, for attending. As we said, just before the break, this is going to be a little bit of a shifting gears, because we're not going to talk about a physical sort of media, but a process called foam fractionation.

01:11:14.000 --> 01:11:27.000
So, just like with the other topics we covered today, we're talking about some of the general terminology and the options that are available for foam fractionation, what kind of tests are available to evaluate performance.

01:11:27.000 --> 01:11:37.000
So that when it comes time to choosing this technology, you can talk to vendors, understand the technology, and ask the right questions to figure out if it's a good option for your site.

01:11:37.000 --> 01:11:55.000
To get started, we have a couple helpful definitions here. The first thing I want to cover is foam fractionation itself. In the course of this guidance document and in the course of this training, foam fractionation refers to any adsorptive bubble separation technique.

01:11:55.000 --> 01:12:11.000
Where you get a amphiphilic substance, in this case PFAS, that absorbs itself onto a gas-water interface. So that's why this is an absorptive removal technology. Your absorptive media here is a gas, and.

01:12:11.000 --> 01:12:27.000
We're calling all of those techniques foam fractionation, whether or not you actually have a foam being formed, which is kind of the overarching term that we use. Within that foam fractionation category, you could have something like bubble fractionation, where you're not actually getting a stable foam.

01:12:27.000 --> 01:12:45.000
But you do have bubbles that are fractionating PFAS out of water. And then at the bottom here, we have aerosol fractionation, where the PFAS are actually removed by bubbles that burst, so you don't have a foam, but you have bubbles that burst, and those little aerosol droplets have PFAS in them that can be harvested and collected.

01:12:45.000 --> 01:13:07.000
So I've already used the word foam several times. What do we mean when we talk about a foam for foam fractionation? A foam is a stable mixture of gas and liquid, right? We all have seen foam, but to really think about what that means, it's that stable mixture. And like I said, you don't need a stable foam. You don't need that stable mixture to remove PFAS through what we're calling foam fractionation.

01:13:07.000 --> 01:13:22.000
But it does help. And then when we start talking about foams, you can have wet foams or dry foams. That kind of has to do with how much water is in the foam, so a wetter foam would have more water and less gas, and a dry foam would have a lower proportion of water and more gas.

01:13:22.000 --> 01:13:38.000
And then the stability of the foam basically is how quickly it collapses into a liquid versus how long it retains that gas phase inside and stays cooling.

01:13:38.000 --> 01:13:48.000
Alright, so how does phone fractionation actually work? So, like we said in the previous slide, this is a sortive technique where the PFAS are adsorbed onto a gas bubble.

01:13:48.000 --> 01:13:57.000
So, when you create a bubble, you have a lot of surface area, and PFAS really like to accumulate at those gas-water interfaces or surface areas.

01:13:57.000 --> 01:14:10.000
So they have that hydrophilic head that likes to be in the water phase or an aqueous phase, and then a hydrophobic tail that wants to get away from the water phase, so it will preferentially partition into a gas phase.

01:14:10.000 --> 01:14:27.000
So you have a lot of surface area for those PFAS to accumulate, and so if you have a water column, the gas bubbles typically rise up through the water column, they're lighter than the water. As they rise through that water column, they grab onto those PFAS molecules, and at the top of the water column, you have an enriched.

01:14:27.000 --> 01:14:35.000
Area with more PFAS, and then the water down at the bottom of the column should have the PFAS removed from it.

01:14:35.000 --> 01:14:39.000
So, somehow you have to harvest those PFAS out of that top layer.

01:14:39.000 --> 01:14:52.000
You could do that with a phone, which is that stable mixture that we can harvest off the top. You can have aerosols, so when those bubbles reach the top and burst, you could start harvesting all those little aerosol droplets that have PFAS in them.

01:14:52.000 --> 01:15:01.000
Or you can just take that whole aqueous layer off the top of the column where all the PFAS are enriched, and you can just kind of scoop up all that water to remove the PFAS from the rest of the.

01:15:01.000 --> 01:15:18.000
water below it. So this technique has been used for a really long time in aquarium businesses and other industries. It's only in the last 5 to 10 years that it's been applied to PFAS water treatment.

01:15:18.000 --> 01:15:27.000
So how does a foam fractionation vessel work? What are the different sources or things coming in, and what do we need to consider in a foam fractionation vessel?

01:15:27.000 --> 01:15:40.000
So the first thing to consider is how are we collecting those PFAS out of our aqueous stream? So, some of the ways you can do that is a spillover weir. So that's kind of what's shown in the cartoon on the right.

01:15:40.000 --> 01:15:45.000
As the liquid is pushed up to the top of the vessel by the gas bubbles.

01:15:45.000 --> 01:16:02.000
They spill over that weir and you collect what spills over the top. So that would be a spillover weir collection method. You can also have a vacuum that kind of sucks that foam or sucks that top layer off like you would in a multiphase extraction well. So you're sucking that foam off the top.

01:16:02.000 --> 01:16:21.000
Or you can have some kind of clean water displacement, where at the end of the treatment, you push clean water in from the bottom and push out the PFAS-containing waste from the top. So you may have some combination of those. You can have a spillover weir with a vacuum and some clean water displacement, so they're not mutually exclusive.

01:16:21.000 --> 01:16:28.000
When it comes to flows of different products, you have impacted water coming in, that's your PFAS-containing water.

01:16:28.000 --> 01:16:32.000
After your process, you have that treated water that comes out.

01:16:32.000 --> 01:16:49.000
Your only other addition is usually air or some other gas that you're adding to your treatment vessel. And then from that air that you're adding, you have a gas stream that comes out, so wherever that gas that you added has to come out somewhere. So you have a gas stream coming out, and then you have what we call a fomate.

01:16:49.000 --> 01:17:00.000
So that's your foam that you collected from the top of the water, and it usually collapses into a liquid, so you end up with a liquid waste that we call fomate.

01:17:00.000 --> 01:17:08.000
Also, an important thing to know about foam fractionation in general, just like with the granular activated carbon or the ion exchange resin.

01:17:08.000 --> 01:17:17.000
The effectiveness for removal depends on the affinity of those PFAS for those air-water interfaces, or their adsorption coefficients.

01:17:17.000 --> 01:17:32.000
So our long chain PFAS are more easy to remove than short chain PFAS. And then when you have PFAS of the same carbon chain length, the sulfonic acids are easier to remove than the corresponding carboxylic acids, typically.

01:17:32.000 --> 01:17:43.000
When it comes to arranging, uh, designing foam fractionation vessels, there's really two different ways you can do it. You can do a batch process or a continuous process.

01:17:43.000 --> 01:17:54.000
So on the left-hand side, we have a batch process, just like you would expect, you fill the vessel up, you run your Fractionation cycle, and then at the end of that batch, you would discharge a treated water.

01:17:54.000 --> 01:18:02.000
The benefit of that is you have a lot of control over your operating parameters, you can adjust aeration and chemical dosing throughout each batch.

01:18:02.000 --> 01:18:16.000
But you do have a lower or a more irregular throughput, because you have a period where you take on water, and then when no water is being added or discharged, and at the end of the batch, you're discharging water very quickly.

01:18:16.000 --> 01:18:29.000
On the right-hand side, we have continuous processes, so those have the benefit of a continuous influence and effluent stream. And then you can configure those where you either have a counter current process or a co-current process.

01:18:29.000 --> 01:18:34.000
So in the countercurrent process, you have the air and the water moving in opposite directions.

01:18:34.000 --> 01:18:57.000
So you can see in this graphic, the water is moving downward, and the air bubbles are moving upward, so they run in opposite direction. And then in the co-current, they run in the same direction. So you have the… air and water both moving up in that process. The benefit of the continuous process is the continuous nature of it, so you have a constant influence of effluent.

01:18:57.000 --> 01:19:08.000
The downside would be you don't have as much fine-tuning of controls, so your aeration rate is kind of fixed, because you always have new influence coming in, you can't adjust that over the course of a batch.

01:19:08.000 --> 01:19:20.000
When it comes to preparing the systems, they could be skid mounted, pre-assembled in a container, or constructed on site, all those different configurations are available.

01:19:20.000 --> 01:19:26.000
Another thing with operating mode is how you configure multiple vessels.

01:19:26.000 --> 01:19:37.000
So this is also similar to what you could do with a granular activated carbon or ion exchange vessel. You can arrange multiple vessels in different ways to get different… to accomplish different things.

01:19:37.000 --> 01:19:50.000
So, for each of these graphics, we have the orange lines are influent, the blue lines are effluent, and those green lines are fomate as it's moving through to the vessels and then being collected.

01:19:50.000 --> 01:19:53.000
So on the left, we have multiple vessels in series.

01:19:53.000 --> 01:20:09.000
So the benefit here would be to increase your PFAS removal rate. So in your first fractionator, you remove PFAS and you have an effluent, and you collect the foam, and then that effluent goes through a second fractionation process for removing even more PFAS.

01:20:09.000 --> 01:20:20.000
At the cost of producing more phones. You're gonna have more waste volume in this multiple vessels in series, but you could increase your PFAS removal by configuring them that way.

01:20:20.000 --> 01:20:38.000
In the middle of the slide, we have multiple vessels in series, but here we're actually trying to reduce our waste volume and not improve our PFAS removal. So after our first vessel, you can see the influent comes in, and the effluent goes out, and that's our only place where we remove PFAS.

01:20:38.000 --> 01:20:54.000
Uh, from our treated water. Those subsequent stages, it's actually the fomate that is going through a subsequent fractionation, and that's to reduce the volume of foam that we produce. So by the time you get to the bottom, that waste product is a small volume of very concentrated foam.

01:20:54.000 --> 01:21:00.000
And all that water that you treated would get recycled back in to have the PFAS removed for discharge.

01:21:00.000 --> 01:21:07.000
So that would be to reduce your waste volume, but it's not going to improve your PFAS removal, because it's only one vessel of removal.

01:21:07.000 --> 01:21:20.000
And then on the right-hand side, we have multiple vessels in parallel. That would be to increase throughput. So you have multiple vessels that are running in parallel to get, you know, if each one is 100 gallons per minute, and I have 300 gallons per minute by having 3 in series.

01:21:20.000 --> 01:21:23.000
So that's a way you can improve your throughput.

01:21:23.000 --> 01:21:31.000
Now, it's important to note that these are not mutually exclusive, so you could have a configuration of vessels where you're doing.

01:21:31.000 --> 01:21:44.000
Multiple stages of treatment, and then that foam is also going through subsequent treatment, and you're running multiple things in parallel. So they can all be combined together to reach your performance objectives.

01:21:44.000 --> 01:21:55.000
So here, we're going to do a preview question. We didn't get into this answer yet, but which of the gases below have you heard about using most often for foam fractionation?

01:21:55.000 --> 01:22:16.000
So I know I haven't said the answer yet, so don't think you're not paying attention.

01:22:16.000 --> 01:22:33.000
All right, so air got 44% of the vote. That is the most commonly used. Ozone we'll talk about on the next page. That's also a gas that's been used. Nitrogen has been proposed to be used. I don't know how often it has actually been used, and I don't know that there's any other gases, but I.

01:22:33.000 --> 01:22:38.000
Sure, you could use some other gas that would absorb PFAS.

01:22:38.000 --> 01:22:49.000
So if we go to our next slide here, we can see what gas types are available that we showed on the previous poll. So air is the most commonly used. It's the lowest cost. It's all around us.

01:22:49.000 --> 01:22:59.000
It does have oxygen in it, so that oxygen will oxidize some precursors or co-contaminants that are in the water, but it's a very easy gas to use because it's all around us.

01:22:59.000 --> 01:23:09.000
Ozone is the other gas that's commonly been used for foam fractionation. It will oxidize precursors, and it can oxidize co-contaminants as well, so that can be a benefit.

01:23:09.000 --> 01:23:23.000
Um, it does add cost and complexity, because even though it's created from air, it's not present in the air all around us. It also has the risk of producing some potential byproducts, because it is so oxidative, you can produce bromate or other things in your water.

01:23:23.000 --> 01:23:34.000
Some studies have shown lower total PFAS removal using ozone, but also lower waste volumes. So, some pros and cons there for using ozone.

01:23:34.000 --> 01:23:41.000
nitrogen was pretty popular in that poll. I actually haven't seen it used. It does have limited field applications.

01:23:41.000 --> 01:23:57.000
The benefit there to using nitrogen would be to prevent oxidation. So if you had a lot of metals and you didn't want to add any oxygen that would oxidize and precipitate metals, or transform PFAS precursors, maybe nitrogen could be a candidate gas.

01:23:57.000 --> 01:24:03.000
Another thing to consider with phone fractionation beyond which gas you're going to use.

01:24:03.000 --> 01:24:10.000
are foaming additives. Are you going to use something in your water to enhance the foaming or enhance the PFAS removal?

01:24:10.000 --> 01:24:17.000
So we said up front, you can do a bubble fractionation where you don't get a stable foam, and you can still remove PFAS.

01:24:17.000 --> 01:24:27.000
But adding a foaming additive could enhance that removal or reduce your waste volumes by giving you a more stable foam and a smaller volume, and more options for harvesting those PFAS.

01:24:27.000 --> 01:24:32.000
So, some of the best enhancements for foaming are cationic surfactants.

01:24:32.000 --> 01:24:48.000
Because PFAS are mostly anionic, at least the regulated ones that we care about, a cationic surfactant can bind to that anionic PFAS molecule and create a complex that's easier to remove and produces a very stable foam that can be harvested.

01:24:48.000 --> 01:24:57.000
It helps a lot with the shorter chain PFAS that do not have an affinity to the air-water interface on their own. Something like PFBS or PFBA.

01:24:57.000 --> 01:25:02.000
Uh, you can get enhanced removal by using a cationic surfactant.

01:25:02.000 --> 01:25:09.000
The downside of using a cationic surfactant, they tend to be toxic, either to humans or to the environment.

01:25:09.000 --> 01:25:26.000
Um, so even though that surfactant that you add should end up in the foam, in the foamate, there's always the risk that some of it will not be completely removed, so you may want to look at a non-ionic or biologically derived surfactant. If your downstream use of that water, um, cannot have a cation in it.

01:25:26.000 --> 01:25:31.000
Whether it's direct discharge to the environment or drinking water, there may be concerns with using that.

01:25:31.000 --> 01:25:36.000
Um, salt is something that has been shown to improve fractionation.

01:25:36.000 --> 01:25:42.000
So this was a question that came up about the TDS that maybe will enhance foam fractionation.

01:25:42.000 --> 01:25:58.000
So salts will actually stabilize foams, they help things accumulate at air-water interfaces. So TDS or naturally occurring salts can improve fractionation, and you can add salts to improve fractionation. The improvement may be minimal.

01:25:58.000 --> 01:26:14.000
And it could increase your maintenance, because you do have a lot of salts, and if you have salting out or buildup of salts in your system, it could… Could be a negative, but there's a it can be used as a foaming additive to enhance or stabilize foams.

01:26:14.000 --> 01:26:30.000
When it comes to what sorts of source water are applicable to foam fractionation, we have a list here. On the left are things that are applicable. On the right are some things where, you know, maybe foam fractionation is not going to work so well. If you have a lot of really high PFAS concentrations.

01:26:30.000 --> 01:26:52.000
So something like an AFFF. Uh, you're gonna produce so much foam that you're not going to get a meaningful volume reduction if you try doing foam fractionation on that super foamy liquid, so… You're gonna keep aerating it, and you're gonna keep recovering foam, and at the end of the day, you're gonna have more foam than you started with liquid, or an equal amount of liquid that you started with, so you're not going to get much removal with those really foamy waters.

01:26:52.000 --> 01:27:00.000
Also, really dense liquids. It's going to be hard to push air bubbles through those and get that same removal if you have very dense liquids, like sludge.

01:27:00.000 --> 01:27:23.000
or things with a density greater than 1.15. And then on our next slide, we're going to talk a little bit about pre-treatment considerations, but oily waters are something that will impact removal by foam fractionation. So oil will coat an air bubble and prevent PFAS from sticking to it, so you're not going to get meaningful PFAS removal with very oily waters.

01:27:23.000 --> 01:27:27.000
So all these other waters, though, foam fractionation can work great.

01:27:27.000 --> 01:27:36.000
Uh, the thing you're gonna run into with foam fractionation is cost versus benefit. So, the cost of foam fractionation tends to be in the capital up front.

01:27:36.000 --> 01:27:53.000
And it has low operating costs, but when you have pretty clean waters, you know, with not a lot of PFAS in them, that upfront investment in foam fractionation may not be worth it. So, really, you're looking at more contaminated waters, so PFAS greater than about 100 nanograms per liter or more.

01:27:53.000 --> 01:28:23.000
And then for flow rates, commercially available systems tend to be pretty small, so the currently designed systems are small, so you're probably looking at, you know, less than about 0.2 MGD systems for foam fractionation. Another place to consider foam fractionation is if you have a lot of co-contaminants, so… We talked about the pre-treatment needs for GAC and ion exchange resin. If you have a lot of those co-contaminants, those other sorptive media may not work as well, so foam fractionation can be a great option.

01:28:23.000 --> 01:28:37.000
Um, for high co-contaminants. One of the big benefits of foam fractionation is that it requires little to no pre-treatment for most waste streams. This gives you a lot of flexibility in where you put it in a treatment train.

01:28:37.000 --> 01:28:48.000
And a lot of the co-contaminants, even the ones listed here, don't really affect PFAS removal. So even though they're listed here as something you want to consider pre-treatment for.

01:28:48.000 --> 01:29:03.000
They're not going to affect your PFAS removal. They're really just going to affect your maintenance or other design parameters in your design. So total suspended solids, that's something that you could have PFAS that stick to the solid, so they don't get removed from.

01:29:03.000 --> 01:29:16.000
Uh, during foam fractionation, so you could consider pre-filtration, higher air injection rates to try to get all those solids to the top, or some kind of chemical to break up those solids and allow them to be separated.

01:29:16.000 --> 01:29:24.000
Oil and grease I already talked about a little bit. You don't want to have your air bubbles coated with oil, because then they're not going to fractionate and gather up PFAS.

01:29:24.000 --> 01:29:32.000
If you do a volatile co-contaminants, those aren't going to affect your PFAS removal, but they could partition into that gas.

01:29:32.000 --> 01:29:42.000
and be admitted through the exhaust. So we'll talk a little bit later about gas exhaust treatment, but if you did have a lot of VOCs, you would want to treat that exhaust.

01:29:42.000 --> 01:29:55.000
Metals, because we're oxygenating the water by adding air or ozone or… maybe not with nitrogen. You could have oxidation of metals, which tends to cause them to precipitate, especially iron and manganese.

01:29:55.000 --> 01:30:13.000
Those precipitated metals will build up on pumps and tanks and valves and vessels and increase your maintenance, because you'll have to keep descaling and cleaning those out. So you could consider pre-treatment or chemical addition for metals. And the same thing with a hard water carbonates. You'll get scaling and increased maintenance if you have very hard water.

01:30:13.000 --> 01:30:18.000
So you could consider some kind of pH control to reduce that maintenance.

01:30:18.000 --> 01:30:26.000
Admissions are definitely something to consider. It's something we get asked asked about a lot.

01:30:26.000 --> 01:30:44.000
When you do foam fractionation, you're generating a gas, that's the air or other gas that you added, and in that air, you could have mists or aerosols, or other things. So usually with PFAS, we're not thinking about volatile PFAS, at least the ones we typically measure in water have pretty low volatility.

01:30:44.000 --> 01:30:55.000
But they are going to be present in those water droplets, whether they're aerosols or mists, because those are a lot of air-water interfaces, and we already established that PFAS love to stick to those air-water interfaces.

01:30:55.000 --> 01:31:01.000
You also have volatile components in water that could volatilize, so VOCs or BTECs or things like that.

01:31:01.000 --> 01:31:07.000
Um, so you do want to have some kind of off-gas treatment for groundwater remediation if you have VOCs present.

01:31:07.000 --> 01:31:12.000
But our off-gas treatment, typically a vapor phase granular activated carbon.

01:31:12.000 --> 01:31:26.000
Works best for dry air. So we want to dry out that air through some kind of mistreatment or recirculation to get those mists and aerosols out of the vapor stream before we do any kind of treatment.

01:31:26.000 --> 01:31:40.000
When it comes to PFAS emissions limits, there's usually not well-established standards. Different states may have different requirements for permitting or what's de minimis. And some states do have some guidance for some PFAS.

01:31:40.000 --> 01:31:48.000
So an example here would be Michigan standards for ambient air. So they are something to keep in mind when it comes to.

01:31:48.000 --> 01:31:54.000
designing a foam fractionation system, if you have air emissions concerns.

01:31:54.000 --> 01:31:59.000
If you do have air emissions concerns, people are worried about it. There is a standard.

01:31:59.000 --> 01:32:14.000
OTM 45 is the standard method for testing PFAS in air. This is a very difficult and expensive sampling train to set up. It's an isokinetic method where the velocity.

01:32:14.000 --> 01:32:21.000
at the sample nozzle has to match the gas stream, which requires very specific temperature and pressure controls.

01:32:21.000 --> 01:32:36.000
This can be very cost prohibitive, and for a small system, like most foam fractionation systems, we're talking about less than .2 MGD, it's going to be very hard to design an OTM45 sampling train that works for that system.

01:32:36.000 --> 01:32:55.000
So there is a way to use a non-Isokinetic method, which is basically collecting a sample with EPA method 2013, and then doing an OTM45 analysis on that collected sample. So there are ways to get good PFAS data from foam fractionation systems.

01:32:55.000 --> 01:33:20.000
They're also OTM 50 and 55. Otm 50 is a Summa canister method, so it's really easy to collect, but… It has a different analyte list than your aqueous analysis. So it may not be very effective to collect that sample, because you'll measure PFAS that you can't detect in your water, and won't have any idea where they came from. It's more applicable to destruction technologies.

01:33:20.000 --> 01:33:30.000
So we already talked about some of these, but this is just for your reference at the end. If you need to go back to these slides, some of the advantages and disadvantages of foam fractionation.

01:33:30.000 --> 01:33:36.000
So, a big advantage is that you get a liquid waste, you don't have a solid media waste.

01:33:36.000 --> 01:33:52.000
We'll talk about this at the very end, but these liquid wastes are very easy to destroy some of our emerging destruction technologies. Your costs don't depend on your PFAS concentration, which can lead to some lower O&M costs for very high PFAS-containing liquids.

01:33:52.000 --> 01:34:15.000
little pre-treatment and a smaller footprint. On the disadvantaged side, the current commercial offerings have limited capacity, although companies are working on larger fractionation vessels. It's more difficult to scale up a vessel to a larger size, and then we do have lower short-chain removal if you're not using some kind of foaming additive.

01:34:15.000 --> 01:34:30.000
When it comes to site-specific considerations, you want to consider where you're going to put the system. It needs to be very level, because those bubbles need to move vertically. You want to have secondary containment, because we are going to be producing a high PFAS liquid waste.

01:34:30.000 --> 01:34:38.000
Um, typically power is one of your biggest input. What type of power is available? Is there enough amperage for that?

01:34:38.000 --> 01:34:47.000
equipment. Where's your water gonna be? Do you need to have brake tanks if your flows are intermittent and your process is continuous?

01:34:47.000 --> 01:34:57.000
Where are you discharging, and where are you going to store and dispose of this concentrated PFAS waste that you generate?

01:34:57.000 --> 01:35:05.000
Now that we talked about what foam fractionation is, how it's configured, we want to talk about some of the tools to evaluate foam fractionation for your site and your water.

01:35:05.000 --> 01:35:11.000
The first one, just like with granular activated carbon, is some kind of performance modeling.

01:35:11.000 --> 01:35:23.000
Unfortunately, this is a very turbulent multi-phase system, so we don't really have a numerical model that will predict PFAS removal for any given water based on some kind of mathematical principles.

01:35:23.000 --> 01:35:38.000
There are empirical models that companies have developed, but they're probably, and they're going to be owned by a company. They're going to be specific to one technology, and they may not be representative across different waters or different scales.

01:35:38.000 --> 01:35:53.000
So because of that, physical testing is really the gold standard for determining if foam fractionation is going to work, and that it could be benchtop, field pilot testing, or full-scale testing.

01:35:53.000 --> 01:36:07.000
When it comes to designing a foam fractionation test, you want to consider if foam fractionation can meet your objectives, how much waste are you going to generate? How are you going to configure your system, and what are those total costs?

01:36:07.000 --> 01:36:23.000
Uh, some things you want to consider, what gases are you going to test? Are there different sizes of bubbles that will make a difference? What are my aeration rates? How… Do I change my aeration pattern over the course of treatment? How high do I fill a vessel?

01:36:23.000 --> 01:36:27.000
Am I going to produce too much foam if I fill the vessel too high?

01:36:27.000 --> 01:36:39.000
Uh, for batch treatment, it's how long is your batch treatment time for a continuous flow, what's your hydraulic resonance time? And then, are you going to use any foaming additives, and what is the dose?

01:36:39.000 --> 01:36:50.000
And then when it comes to that fomite itself, you want to think about how are we going to collect that foam? Are we getting a foam? Are we getting just bubbles or aerosols? How much foam are we going to get?

01:36:50.000 --> 01:37:07.000
How stable is that foam? Can I collapse it down into a liquid, or is it always going to be a very voluminous foam? How much am I reducing my waste volume? And then, are there any anti-foaming agents that can help or hurt the foaming process?

01:37:07.000 --> 01:37:16.000
So, my last knowledge check for you is that you do a shake test. So you shake up some water and you don't see any foam.

01:37:16.000 --> 01:37:23.000
That means that foam fractionation will not work. True or false?

01:37:23.000 --> 01:37:28.000
So I didn't talk about what a shake test is yet, but I did cover the answer to this.

01:37:28.000 --> 01:37:33.000
So we'll talk about shake tests and different bench scale tests next.

01:37:33.000 --> 01:37:47.000
Let's see what our answers are.

01:37:47.000 --> 01:38:03.000
Alright, so it looks like the audience got this wrong. The answer. Oh wait, no, the audience got it right. Yeah, the answer is false. So some people said true, but the answer is false. Just because you don't see foam, you can still remove PFAS through the aerosols or the bubble fractionation or some other process.

01:38:03.000 --> 01:38:14.000
So, good job, audience. Thank you. Just like we had for the JCN ion exchange resin, here's a table showing some of the different tests that are available.

01:38:14.000 --> 01:38:23.000
How quick you can do them, how much they cost, their ability to assess PFAS removal, and then how well they translate to full-scale performance.

01:38:23.000 --> 01:38:39.000
So at the beginning, we have those kind of shake tests. We're just seeing if you get a foam. That doesn't really tell you if you remove PFAS, but it tells you if you have any kind of foam. It's very quick. Modeling, like we said, is probably not very predictive, but if you could do it, it's pretty cheap, pretty fast.

01:38:39.000 --> 01:38:54.000
Bench scale testing, then now you're starting to get into something that's going to… I actually have some substantial costs, but it will tell you how well foam fractionation rose PFAS, and does a pretty good job of predicting full-scale performance.

01:38:54.000 --> 01:38:59.000
And obviously, pilots and full-scale demonstrations are going to give you the best.

01:38:59.000 --> 01:39:07.000
answer as to how well the system will perform at the having taken a longer time and having a higher cost.

01:39:07.000 --> 01:39:17.000
So the shake tests, like I said, you can just put some liquid into a vial and shake it and see how much foam is produced. You can see a picture here on the right.

01:39:17.000 --> 01:39:23.000
Um, you could also do this in a column, where you're aerating a fixed volume to see how much foam is produced.

01:39:23.000 --> 01:39:35.000
That will give you a sense of how much foam are you getting, is the foam stable? Does it collapse quickly? But really, there's no way to measure the PFAS removal in this configuration.

01:39:35.000 --> 01:39:49.000
To measure PFAS removal, you need some kind of benchtop apparatus where you can collect a sample of the treated water, and then collect a sample of the foam so that you can see how much PFAS has concentrated into the foam.

01:39:49.000 --> 01:39:59.000
The difficulty when it comes to bench testing can be the limited volumes that are available. So you may be doing this on a smaller system that doesn't translate directly to your real world application.

01:39:59.000 --> 01:40:07.000
Um, and because you have to bring the water into a lab to do testing, you may be limited as to how many different tests you can perform.

01:40:07.000 --> 01:40:15.000
So that would bring us to pilot testing, which is a preferred method to evaluate foam fractionation performance.

01:40:15.000 --> 01:40:35.000
When designing a pilot test, you want to consider your cost and your data quality, so a longer test where you do more different conditions could give you better data, but it's going to cost more. Pilot tests can also require some infrastructure upgrades, because you are bringing in a lot of equipment, so you could need power, plumbing, or some kind of hardscape to put your equipment on.

01:40:35.000 --> 01:40:54.000
Um, and then this can be done either with a full-scale unit, like the actual final sized design unit, or sometimes you can use a smaller unit that may or may not be representative of the full-scale system.

01:40:54.000 --> 01:41:05.000
Alright, so when you're collecting data during your performance evaluation, the key things to look at typically are the first two. So, how much of each PFAS are we removing?

01:41:05.000 --> 01:41:20.000
Um, and what conditions improve or negative or lower removal rates? And then what are my post-treatment PFAS considerations? Have I reached my performance objective, or do I need some kind of additional treatment or polish needed?

01:41:20.000 --> 01:41:38.000
To, uh, to meet my objectives. The other things on here to consider really come down to cost. So, how much foamate am I producing? How much is it going to cost to dispose of that? What operating parameters give me the best bang for my buck when it comes to removing PFAS versus producing waste?

01:41:38.000 --> 01:41:45.000
How much maintenance is there? How much downtime can I expect? Is this equipment easy to operate or complicated?

01:41:45.000 --> 01:41:52.000
And then how much electricity is being used during the process?

01:41:52.000 --> 01:42:03.000
Our last topic here is fomate management. So we've collected that foam, we've collapsed it down into a liquid. Now we have to do something with that. So right now, there's a few commercially available options.

01:42:03.000 --> 01:42:17.000
So you can solidify that waste and put it into a landfill like you could for that spent still bottoms for IX resin. You can incinerate the waste in a high temperature incinerator, like a hazardous waste incinerator.

01:42:17.000 --> 01:42:22.000
Um, deep well injection is an option for disposing of liquid waste containing PFAS.

01:42:22.000 --> 01:42:34.000
And supercritical water oxidation, or SQO, is a commercially available technology at a few locations that can dispose of or destroy liquid waste containing PFAS.

01:42:34.000 --> 01:42:48.000
There are also a lot of emerging technologies that are suitable for destroying a liquid waste. So halt electrochemical oxidation, plasma, and photochemical oxidative techniques are all available and are in different stages of commercialization.

01:42:48.000 --> 01:42:54.000
But when it comes to considering it, you want to look at where you're located, are there anything nearby?

01:42:54.000 --> 01:43:00.000
Do I need to do something on site to have kind of a closed loop where no PFAS molecule ever leaves my site?

01:43:00.000 --> 01:43:08.000
And then is there equipment that's commercially available that fits your needs? And what things can be permitted and accepted?

01:43:08.000 --> 01:43:26.000
So again, in summary here, this is for your reference in the future, but this foam fractionation can be cost-effective and a sustainable tool to remove PFAS, because you don't use any solid media, you get a liquid waste that can be disposed of or destroyed using multiple technologies.

01:43:26.000 --> 01:43:38.000
Now, with that, I'm going to pass it over to Masa to talk about some of our decision tools.

01:43:38.000 --> 01:43:58.000
Awesome. Thanks, Jason, and hi, everyone. Thanks for being here. So, now that we've covered various sorption technologies and discussed how site-specific factors can influence performance of these technologies and reviewed pilot testing.

01:43:58.000 --> 01:44:11.000
approaches for foam fractionation, GAC, and ion exchange. The question becomes, how do we actually choose the most appropriate PFAS treatment technology for our site?

01:44:11.000 --> 01:44:22.000
In this section of the training, I'm going to talk about this and introduce some resources for such decision making.

01:44:22.000 --> 01:44:43.000
Okay, it's easy to assume that the best performance technology in a pilot test is the obvious choice. But in practice the decision is more complex. Performance is just one piece of the puzzle and cost effectiveness relative to treatment goal is equally important.

01:44:43.000 --> 01:45:00.000
Post capital costs and long-term operation and maintenance costs can be informed by pilot data, but they also depend on site location, actual full size, full scale system size and design configuration.

01:45:00.000 --> 01:45:20.000
Changes in material costs and availability, including desorptive media itself, policy changes that can affect not only the treatment target, but also waste stream handling and disposal requirements, and many other site-specific factor that were already discussed in the duration of this training.

01:45:20.000 --> 01:45:32.000
Including and not limited to variability of influent PFAS concentration, changes in general geochemistry and co-contaminants that can control pre- and post-treatment requirements.

01:45:32.000 --> 01:45:43.000
Uh, beyond performance and cost, there are also several additional considerations that include scalability of the treatment methods.

01:45:43.000 --> 01:45:59.000
and associated costs with that implementation, logistic, and community level factors, such as stakeholder preferences, local permitting requirements, and local familiarity with a specific technologies.

01:45:59.000 --> 01:46:21.000
Affordability and sustainability factors also play a major role and can vary from site to site. And in this section I'll walk you through how all these factors can come together and introduce some tools that can help support a more structured, holistic decision-making process. And this is based on section 18-5.

01:46:21.000 --> 01:46:38.000
of the guidance documents. Before we go further, let's do a quick knowledge check. Imagine that in a pilot study, iron exchange resident treats significantly more bed volume before breakthrough than GAC.

01:46:38.000 --> 01:46:42.000
Does that automatically mean iron exchange is the better choice?

01:46:42.000 --> 01:46:51.000
So the answer is the choices are definitely maybe or no way. Let's see.

01:46:51.000 --> 01:47:03.000
What'd we get?

01:47:03.000 --> 01:47:20.000
Okay, perfect. Uh, the correct answer is maybe most of you got it right. As I just mentioned, while performance is important. It has to be weighed alongside other factors like like cost benefit analysis, waste generation.

01:47:20.000 --> 01:47:35.000
operational complexity and site constraints. And my goal is to introduce some tools that can help us evaluate these trade-offs side by side, so decisions are based on a more complete picture.

01:47:35.000 --> 01:48:00.000
For example, some of you might be already wondering, how do we even evaluate affordability of the potential or the potential economical impacts of PFAS water treatment on a community? One useful resource is the US EPA's Clean Water Act Financial Capability Assessment Guidance. This framework helps utilities and project teams assess the financial.

01:48:00.000 --> 01:48:18.000
better than that new treatment system or upgrading the existing one may place on a community. It considers factors like median household income, existing debt obligation, and projected impacts on user rates over time.

01:48:18.000 --> 01:48:39.000
This is especially important for technologies with high O&M requirement while securing funding for initial capital cost is often achievable. Long-term sustainability depends on communities ability to support continued operation, things like media replacement costs, energy use.

01:48:39.000 --> 01:48:58.000
And even availability of trained local labor to complete routine maintenance and change outs. So affordability isn't just about upfront costs, it's also about whether the system can be sustained over its full life cycle.

01:48:58.000 --> 01:49:10.000
For estimating cost, the EPA has developed a spreadsheet-based cost models for technologies like iron exchange and GAC.

01:49:10.000 --> 01:49:28.000
These models use a work breakdown structure or WBS, where users input system design and water quality parameters to estimate capital costs, O&M cost, and total annualized cost per volume of water treated.

01:49:28.000 --> 01:49:44.000
These models are most appropriate for technology screening and alternative analysis, order of magnitude, cost comparison, supporting feasibility studies and decision documents, and translating pilot scale performance data.

01:49:44.000 --> 01:49:59.000
into lifecycle cost. Key inputs of the model include factors such as flow rate, influent water quality, media lifespan, and bed configuration. There are also optional input parameters such as land costs.

01:49:59.000 --> 01:50:04.000
System automation and building requirements that can be added.

01:50:04.000 --> 01:50:28.000
Although these models are originally developed for drinking water treatment application, which often involve treatment of groundwater, the tool can be adapted and applied at a screening level to groundwater remediation systems, too, that involves extraction and above ground treatment. Of course, with appropriate engineering judgment and provided that assumptions are clearly stated.

01:50:28.000 --> 01:50:53.000
And cytospecific factors are addressed outside the model. Also, the default embedded unit cost in the model need to be updated for different applications and different media, for sure. The output of the model are most defensible when the remediation systems have a reasonably defined flow rates and influence water quality which can be a challenge and a limiting factor.

01:50:53.000 --> 01:50:59.000
in groundwater treatment application due to the natural variations.

01:50:59.000 --> 01:51:22.000
Uh, the cost model can also be adopted and used for technologies like reverse osmosis and point-of-use point of entry systems. However, there's, as Jason mentioned, limited data available to reliably model foam fractionation in this framework.

01:51:22.000 --> 01:51:38.000
And beyond cost and affordability, it's also important to consider sustainability and broader environmental, social, and climate impacts of PFAS water treatment system. Epa provides several tools that support.

01:51:38.000 --> 01:51:55.000
Lifecycle-based evaluation of treatment technologies. These tools allow for side-by-side comparison across key sustainability metrics. That includes factors like greenhouse gas emissions during technology implementation.

01:51:55.000 --> 01:52:01.000
Energy demand, water use, and potential human health, ecological, and climate impacts.

01:52:01.000 --> 01:52:14.000
This consideration can be especially important in regions with limited accessibility and limited water or energy resources where operational demands may significantly influence feasibility.

01:52:14.000 --> 01:52:27.000
In addition to the tools shown here on this slide, there are additional lifecycle assessment tools and software packages that are referenced in the guidance document if a more detailed analysis is needed.

01:52:27.000 --> 01:52:39.000
To summarize, selecting a PFAS treatment technology, especially specifically sorption-based systems required balancing multiple factors.

01:52:39.000 --> 01:52:46.000
These include performance, cost, affordability, sustainability, site constraints, and risk.

01:52:46.000 --> 01:53:07.000
Site location plays a central role in all of this. It affects not only regulatory and permitting requirement, but also construction and labor costs, material availability, transportation, logistic, and disposal options, all of which influence cost and overall project sustainability.

01:53:07.000 --> 01:53:28.000
Uh, so as already discussed, these factors need to be considered together, and their relative importance will vary depending on site specific and client priorities. There's no one size fits all solution, and a stakeholder and regulators engagement is critical throughout the technology selection process.

01:53:28.000 --> 01:53:44.000
For practitioners, and it's called the key takeaways is to align technology selection with site condition, conductoral feasibility studies and incorporate sustainability and lifecycle cost analysis early on.

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Using the tools introduced in this section for policymakers on the call, there is an opportunity to provide clear and more consistent guidance around PFAS treatment selection, piloting, and permitting.

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Some progress has been made. For example, Arizona DEQ has developed a decision tree to support technology selection. The Department of Defense or war has also funded research on life cycle comparison of PFAS treatment technologies.

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However, there's still a need for broader consensus and uniform approaches across our industry.

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With that… with that, I'll hand it back to Levi to cover some additional challenges and what we can expect moving forward in this evolving world of PFAS water treatment. Thank you.

01:54:40.000 --> 01:54:54.000
Hi, thanks, Masa. So… I'd like to close out today. As we close out today's training, I'd like to discuss some of the key barriers and challenges that still remain for selection and deployment of sorption-based technologies for PFAS treatment.

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The most general one is that the technological landscape is evolving and new treatment technologies are coming on the market. And accordingly, the regulatory frameworks such as permitting requirements are changing right alongside, and it can be a challenge to keep up.

01:55:11.000 --> 01:55:22.000
There are also some practical. Um, challenges with availability of operators and infrastructure for more to support more complex treatment strategies.

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Um, and there are other challenges in… that we've touched on in residuals management, handling of short chain PFAS. The lack of available.

01:55:32.000 --> 01:55:45.000
Strongly predictive modeling. and also limits of analytical techniques can make testing test results difficult to interpret, and for many applications there is a lack of.

01:55:45.000 --> 01:55:59.000
consensus and standards and institutional knowledge for designing systems. Next slide, please.

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So as we look, as I mentioned before, the landscape of treatment and testing is evolving, and several upcoming developments are going to influence.

01:56:11.000 --> 01:56:22.000
absorption-based technology selection in the future. One of these is the emergence of novel or alternative sorbents, such as cyclodextrins and surface-modified clays, which may be more effective than.

01:56:22.000 --> 01:56:33.000
Uh, GC or ion exchange per cost in certain situations. There are also advances in residuals management and updated.

01:56:33.000 --> 01:56:45.000
Test methods such as… Consensus on rapid small-scale column tests, and the ITRC PFAS Treatment Technologies team is.

01:56:45.000 --> 01:56:52.000
collecting and collating information relating to these. Next slide, please.

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So I hope you've learned a lot from today's training, and if you have more PFAS questions, ITRC does have several other PFAS.

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resources, including the full guidance document, complete with fact sheets, data tables, and figures. Next slide, please.

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And again, if you found this training useful, there are several other ITRC trainings for helping you address your PFAS problem, which are all freely available.

01:57:22.000 --> 01:57:30.000
And next slide. And yes, with that, I'm going to return it to the moderator to close out.

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All right. Thank you, Levi, and given we are 1 min from 3 o'clock. I will go ahead and wrap up the training today. Thank you all for being here and for using the Q&A pod to interact with our trainers and subject matter experts.

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behind the scenes, and once again, I thank all of the trainers and subject matter experts for getting us through the training today.

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We would like to hear back from you, so please be sure to fill out the online feedback form that's linked on this last slide. I also dropped it in the chat a little while ago. I'm filling out the feedback form and certifying that you participated will allow you to receive a certificate of completion by email.

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If you need further clarification on the answers, or would like to ask more questions, feel free to email us at itrc@itrcweb.org, and we will follow up with our trainers to get your questions answered. And I also dropped our email in the chat as well. Thanks again, everyone, for being here, and we hope to see you at future ITRC trainings.