00:00:00:00 - 00:00:39:02 Unknown By the same author. Thank you again, Christian, for giving the last but not the least presentation and the thought it would be a scalable active transport framework for peer peers. Thank you. Good. Okay, so I think we should start over here. All right. So, yes, this is about a scalable reactive transport framework for us. So this was a small project that we did for EM headquarters to look at reactive transport, a fast and at least an initial look here. 00:00:39:04 - 00:01:07:08 Unknown So let me come here. Mm hmm. So the objective of this is really to look at reactive transport and thinking about, you know, p fast pivots is really an interesting problem. And check them all still online. I worked with him. He did a great presentation at a Red Flex summit last fall. They did a workshop and presentation about bus issues with us. 00:01:07:10 - 00:01:40:08 Unknown And, you know, he's got a this discusses it in terms of like a bizarro world. Things are really different for POS versus some traditional contaminants, such as chlorinated solvents, TCE and things like that. But, you know, one thing I have looked at is that when we tackled chlorinated solvents back in the nineties, that was really an unknown and there was a lot of research that was done trying to figure out how do you remediate those, Can you remediate those? 00:01:40:10 - 00:02:02:02 Unknown I'd kind of expect PFAS to be the same. You know, there's a lot of work going on with that. And so with this, we're thinking we're going to need some tools to be able to look at in situ treatment of people. We're going to figure out how we can do that. And we need some tools that help us understand the flow and transport. 00:02:02:04 - 00:02:26:15 Unknown You know, what's the reactor transport look like if we put in a remedy? What does that remedy look like and how do we design that remedy? So that was the objective here, is to help us predict very fast movement and groundwater aid with a selection of fuel scale remedies and evidence basis for decision making about a remedy. Okay. 00:02:26:17 - 00:02:59:19 Unknown So as noted, I'm one of the authors on the RT3D reactor transport code. This is a sister code to empty 3-D mesh and uses the modular flow solution. Artemis 3-D is really good at doing reactive transport or a variety reaction. Kinetics Multispecies reaction Kinetics. And so with this, we wanted to do a literature survey to understand what's out in the literature. 00:02:59:21 - 00:03:45:01 Unknown And the objective was to come up with two reaction modules that could potentially be useful when looking at kinetic exhaustion. Desorption. And then when looking at biological or chemical transformation of previous compounds. So this was not intended to be the solution, but was intended as a starting point to show how now can you take information that people have garnered from their lab studies, you know, biological microcosms or looking at chemical treatment and lab studies and then translate that into something that you can use in a model to help design field scale solutions. 00:03:45:03 - 00:04:12:18 Unknown So possibly if a lot of folks are familiar with this, but this is just kind of a breakdown of some of the categories of P for us. There's lots of compounds, there's tens of thousands of different compounds. This is just a simplified categorization. So again, even if we came up with a, you know, spot on this, we know everything about this. 00:04:12:18 - 00:04:40:23 Unknown Here is a reaction module. It's not going to cover everything, right? Because there's a lot of different things going on. So right now, again, we did the literature survey and actually the carbon is really the only fully available in-situ treatment for PFAS for us. There's a bunch of different commercially available products and it's, you know, so all sorts of based right. 00:04:41:00 - 00:05:09:04 Unknown So this is still a lot of research going on in terms of this, in terms of what's the long-term performance of these this approach. And then there's some emerging medicines and people are looking at bioremediation and things like chemical oxidation or chemical reduction. Aerobic degradation of 8.2 and 6.2 FTCH was one that we found that was pretty well studied. 00:05:09:06 - 00:05:41:00 Unknown There's another article cited here on the PFAS. Most of the stuff is lab and a little bit at pilot scale and I'll distinguish here you know a lot of the research that's done is probably looking at more the exit you water treatment versus in-situ groundwater remediation. You know they're doing stuff in the laboratory. How do you actually implement it in situ is another question, or can you implement it in situ? 00:05:41:02 - 00:05:56:16 Unknown So again, we need some capabilities to model, feed and transport us in the environment to help us design and come up with strategies that will be effective for remediation. 00:05:56:18 - 00:06:34:00 Unknown So initial factors related to exhaustion, you know, the all the organic matter deal in content is going to be important because it competes with people's perception sites and it may promote people's desorption. What's the pH assumption? Coefficients will vary depending on the soil. Electric pore volume. That can be important, particularly for like the ionic or a longer chain PFAS compounds relative to the surface to capacity. 00:06:34:02 - 00:07:03:23 Unknown The chain length is going to be an important aspect. Longer chain compounds are going to work better than short chain ones and tied in with would be molecular weight rate relates to the length of the chain. And so these are all kind of important factors. Mm hmm. So, you know, we looked at what was available and elected to come to do this kinetically limited absorption. 00:07:04:00 - 00:07:33:06 Unknown So this would be where you're doing lab studies and you take into account all those different factors and come up with the kinetically limited adsorption constants that that are just for a field scale. And so these are these are equations here. It's a mass transfer based. So advanced mass transfer driven between an aqueous phase and a solid phase. 00:07:33:08 - 00:08:01:14 Unknown And we all account for the different units or the prosody and bulk density here. And right now, I mean, the initial approach was just a linear option, but you could plug in foreign langm linear absorption here for, for the relationships. So this is the describes the equations and then we did some, some example simulations just to show here. 00:08:01:16 - 00:08:27:14 Unknown In this particular case we put in a treatment zone that you might use for like a permeable reactive barrier. Right. So you inject carbon or some other media in the so and, and you can then say, well, here's what we know about the kinetic option and plug that into our model and be able to look at the change instruction or the effects of the absorption. 00:08:27:16 - 00:08:57:07 Unknown And this can help you design you know, how wide is this permeable reactive barrier need to be? Do you need two of these? What would be sort of the expected resonance time or longevity of the PRB? Right. So you can ask all these different questions and use your reactive transport model to assess that. So here's another picture of this again, with kinetically limited absorption. 00:08:57:09 - 00:09:31:10 Unknown This is the aqueous phase concentrations and I've just got time series here. You start with the source area that you cut off after a certain amount of time and so it moves down gradient. And so what's that look like over time? And then you can also looked at the sort of phase concentrations over time and how they increase here in the permeable reactive barrier and are maintained mostly maintained over time. 00:09:31:12 - 00:09:59:01 Unknown No, no, actually. So if when you have the video in here, so hopefully it comes through. So that was just a quick, quick video. Let me run that again here. This is the same information is in the previous plots. So you can put together videos like this and this this helps, again, understand what's happening and communicate about this with others as you make decisions about remedies. 00:09:59:03 - 00:10:33:01 Unknown So seems like the so the other module that we did was a biodegradation reaction network. And again, there quite a bit of information on the each reaction network. So probably the best described biotic pathways. So we use that as a model to build a reaction kinetics module. So this was this was the reaction network that we developed and we put in a lot of parameters in here so you can turn reaction pathways on and off. 00:10:33:03 - 00:11:02:07 Unknown So if you do some microcosms or studies at a particular site and it looks like, oh, you know, things, things go from 8.2 FDOH and they, they skip, let's say the seventh reuse acid step for some reason, right? You can turn that that step off. So you can customize this to whatever is appropriate for your site or if you started somewhere else in the pathway, you can customize this. 00:11:02:09 - 00:11:29:04 Unknown And this allows spatially variable reaction rates to reflect different zones of activity. So you might have different aerobic or nitrate reducing iron, reducing sulfate, reducing different conditions in the subsurface, and those can be reflected in the different spatial zones of activity. So again, I'm not going to there's a ton of equations to go with that because all the different species that are tracked. 00:11:29:06 - 00:12:00:10 Unknown But in general, this is the reaction network. We didn't sort of the standard approach of using a first order degradation rate. So you have if you have a parent, you know, there's a loss of the parent, a daughter gains parent and it's, you know, account for the stoichiometry between daughter and parent. And then we have, you know, that's and then you do so you lose the daughter and then you gain a parent from the parent. 00:12:00:12 - 00:12:30:16 Unknown So there's a whole set of these equations that are in the reaction model to describe the reaction kinetics. And then we did some we did some best reactions. And these are just two examples where we said they all start with this compound or that compound and was it looked like over time. And you'll see this is sort of a typical plots that you might see for like fluorinated solvents. 00:12:30:18 - 00:12:53:12 Unknown Again, it depends on what your site has for reaction rates for the different species transformations, what you start with for compounds and the bottom plot. We started with the three different compounds here and as they degrade over time, they produced shorter products. I think they turned off turned off some of the reaction pathways in some of these. 00:12:53:14 - 00:13:06:22 Unknown So it just really depends on what's at your site and what you information you have about those rates and transformation reactions. And you can you can model that. 00:13:06:24 - 00:13:43:08 Unknown So in summary here, this was really about trying to predict some people's feet and transporting groundwater to help with remediation strategies and designing field scale systems. You know, you have to have a defensible basis for making decisions about what are you going to implement for a remedy. And going could be, you know, I can talk about this can be founded upon what you know about the reaction network fracture pathways and what you know from laboratory work in terms of rates. 00:13:43:10 - 00:14:14:14 Unknown So we've got the source of an activated carbon. That's really a primary remedy. So there are multiple biological chemical remediation approaches on the horizons. We picked one that we looked at, but there's lots of work ongoing. And, you know, we see even with the one we selected, that reaction networks can be pretty complicated. So we had the to do reaction modules that we developed the kinetic adsorption and PFOH. 00:14:14:16 - 00:14:46:10 Unknown And this is really, like I said, intended to be a starting point for some reactive transport work as more and more information is learned. You know, this can be refined and changed. Change it up or add additional reaction networks. You could make it more complicated rather than just the first order. Maybe it be based on, you know, other indicator compounds or biomass levels. 00:14:46:12 - 00:15:14:10 Unknown So you could you could do things like that to track the reactions, progress and activity throughout the subsurface. And so these reaction models are available on RT3D web page. So if folks are interested in, you can download those and play with them in a vector transport model. And so there's the web page here. There's a report that goes with this, and the QR code will get you to the web page. 00:15:14:10 - 00:15:23:20 Unknown There. So if there's any questions, I'll take those. 00:15:23:22 - 00:15:53:20 Unknown Thank you Christian. Great presentation. Thank you. Now, we’re taking questions on this paper, and then later, try to open the floor for discussion as a whole with the speakers. Hopefully the speakers will be present to call a question on this paper. Jim Cummings. Very nice presentation, but I'd like to make a couple of major points. At the moment, one of the largest ENSCO vendors will not sell their products. 00:15:53:22 - 00:16:27:22 Unknown If you want to do in-situ chemical oxidation for PFAS, we got our products. Those, if you go back far enough, know about PCE and TCE degrading to vinyl chloride, which is even more carcinogenic. So at the moment, the conventional wisdom in almost all the literature suggests that there will be relatively limited, complete mineralization of the performance compounds with any of the major oxidants that are currently available commercially before will degrade a little bit, but it's not complete mineralization and the PFAS compounds don't degrade at all. 00:16:27:24 - 00:16:56:10 Unknown And similarly for the chlorinated solvents, and you've been around long enough, remember when there was a time when nobody thought that microorganisms could degrade chlorinated solvents? There's a lot of people out there that think, well, that was then and the same thing's going to happen again. What was the TV show Curb Your Enthusiasm? My point is, I don't think we're going to have the same breakthrough for treatment of PFAS with microorganisms that we had for chlorinated solvents. 00:16:56:12 - 00:17:20:16 Unknown There's actually a company called Ammonia whose objective is to save the world with bio. And much of their work that they're currently not going is trying to figure out how to get fungal mechanisms. This is the white rock fungus. Anybody go back to the dioxin era, the white rye fungus degrades lignin, which is what holds trees together. So it turned out that the white right fungus would in fact degrade the lignin. 00:17:20:18 - 00:17:46:09 Unknown But again, the chlorinated chlorine fluorine bonds are so much stronger than that. So the point is at the moment, in situ co in situ remedies, either biological or chemical for faster very speculative and I would agree. I'm I, I know you. I know you weren't, but I know you weren't promoting them because you were you were very, very cautious in your characterization. 00:17:46:09 - 00:18:12:02 Unknown But I, I wanted to put a point on your point. Yeah. No, I think that's well-taken. You know, if somebody comes up with something that's effective, it doesn't make a bigger mess with other products, things like that. Right. Than, you know, tools like this will be helpful in the design of those remedies. 00:18:12:04 - 00:18:45:16 Unknown Thank you. We have one online question. So the question is for bio for the bio degradation in case why was the first order reaction rate selected? And that's just a typical modeling approach that we've done and not knowing anything better. So I don't think we have information to say anything more detailed in terms of reaction models now that you could. 00:18:45:18 - 00:19:15:09 Unknown So if you did come up with more detailed mechanistic information, you could make it as complex as you want, right? So that we certainly we've done that with like fluorinated solvents, right? We re track biomass, we're tracking growth of biomass and activity and the implication on degradation of the chlorinated solvents. So that's certainly possible. 00:19:15:11 - 00:19:45:09 Unknown Okay. Thank you. One more question. So why the treatment zone in slide number seven and why was it kept so simple to attain the equilibrium conditions? Why was it kept so simple? Hmm. So it was it was just a an example to represent like a permeable or active barrier. So there's other things you can do with this. 00:19:45:09 - 00:20:21:18 Unknown We just put together an example here. But like I talked about, you could you could have different zones of activity. So if you wanted to represent a different, different distribution of sorbent in the subsurface, you could do that and be maybe a little bit more of a challenge to track like carbon in the subsurface, because our 3D is not a particular transport code, it's a groundwater transport code. 00:20:21:20 - 00:20:47:20 Unknown So it doesn't really have facilities for tracking particulate movement or kind of movement, things like that. But you can spatially represent changes over time as you inject different areas or things like that. Well, that hopefully that answers the question. Yeah, I think so. As you see, these were simplified for me as an example, if you mean and right. 00:20:47:20 - 00:21:38:15 Unknown Yeah, exactly. Yeah. That's all for online. Yeah, I had a question. Just. You mean we know that the phase two compounds, they are so many and they are different in their character or substance dissolved. The question is, and in many cases they are coexisting together. So in this case, when you think about those compounds and then thinking about using RT3D node to predict how can you differentiate between these different characteristics and can you just estimate what kind of compounds there and how can you identify those compounds in order to differentiate between the absorption destruction behavior. 00:21:38:17 - 00:22:03:13 Unknown So and see with RT3D again, as complex as you want, but at some point your simulation runs are going to take a really long time, right? It really, really complex and it's an awful lot of time to run those. So what I would probably suggest in that situation would be to have more categories or classes of compounds and you can define different equations. 00:22:03:13 - 00:22:46:21 Unknown So this is built for that, right? But you could take something like we've done and add additional categories and then track those categories of compounds separately to look at those different sorts and characteristics. One thing that we proposed to EM headquarters that's still pending, whether or not they want to go forward with that would be to do some additional reaction modules beyond these and look at exactly what you're talking about, some different categories of compounds, different mechanisms for absorption to provide a little broader suite that looks at the option. 00:22:46:23 - 00:23:10:14 Unknown So you can use if you are so we can identify those compounds and estimate the proportions and you take some kind of modeling or averaging so you can derive actually some kind of absorption resorption. So this is a possibility. That's what I was thinking about. So yeah, yeah, definitely. I mean, a lot of this is going to be based on what you see in the laboratory, right? 00:23:10:14 - 00:23:35:10 Unknown You take your studies in the laboratory using different analysis methods, looking at different media for resorption or whatever. And as you get that understanding about how different compounds or different classes of compounds work, you can build that into a reaction kinetics structure. Here to reflect that, right?