 Hello everyone, welcome to join us on the IWA webinar of New Insights and Innovations for Advanced Water Treatment. I am Yu-Meng Zhao from Harbin Institute of Technology in China, and I will be moderating today's webinar. So before the start of the webinar, there are a few notes that I would like to remind you. This webinar will be recorded and made available on demand on the IWA website with presentation slides and other information. And the speakers are responsible for securing copyright permissions for any work that they will present, of which they are not the legal copyright holder. The opinions, hypotheses, conclusions, or recommendations containing the presentations and other materials are the sole responsibility of the speakers and do not necessarily reflect IWA opinion. And also during the presentation, if you have questions for our panelists, please use the Q&A box at the bottom right hand side of the Zoom meeting to send questions to the panelists. So make these questions and answer them during the Q&A session. And then I will briefly introduce the IWA specialist group, design operation and maintenance of drinking water treatment plants. This specialist group aims to enhance networking and exchange of practices and experience on operational issues for those involved in the design and operation of drinking water treatment plants and contribute to better understand the operational needs and help solving operational problems. This specialist group aims to promote the discussion and communication of the core issues related to the drinking water treatment plants, including health risk related to emerging parameters, NON removal, advanced treatment processes for new microfluidants removal, application and case studies solving operational issues, and smart tools for analyzing plant data. The specialist group is organized by Professor Jun Ma from Harbin Institute of Technology and Dr. Yiqiao Hou from University Technology Patronus in Malaysia. The committee members include Professor Qian Hongshu from Nanyang Technological University in Singapore, Dr. Ines Breda from Silhorko Eurowater in Denmark, Dr. Stravka Dokwon from Swiss Environment in France, Mr. Qian Kampemangor from Ghana Water Company in Ghana and Mr. Rio Central from Water Safety Plan in Portugal. And back to today's webinar, we are very honored to invite three well-known scholars to talk about new insights and innovations for advanced water treatment. They are Professor Erzman Gwentun from IWAC or EPFL in Switzerland, Professor Simsia from Georgia Institute of Technology in the US and Dr. Ria Berbecki from Keiluva in Belgium. The talk by each speaker should be controlled in 20 minutes and afterwards we will have another 20 minutes for the Q&A session. So without further ado, let's welcome our first speaker, Professor Erzman Gwentun. He will be talking about the application of chemical oxidants for enhanced water treatment. So welcome Professor Gwentun, the floor is all yours now. Thank you. Yeah, thank you very much for the invitation to give a talk here. It's a pleasure and also for the kind introduction. And as mentioned, I will talk about chemical oxidation processes for enhanced water treatment. So if you look at the application of chemical oxidants for micro pollutant abatement, and this is now the main topic, this was initially really a success story and it was mainly applied for drinking water, originally for removal of inorganic compounds such as sulfite, nitrite, iron and manganese and also tasting other compounds and color. And then gradually the field moved into organic contaminants and there was the focus on biologically active compounds. They are abated, they can be abated, but the question is what happens to them? They're typically not mineralized, so we have to know something about these transformation products. And then also currently more and more applications are done in wastewater for enhanced wastewater treatment and water reuse. And there, of course, the matrix becomes a much more important factor as well. So if you look for a perfect oxidant, this surge has been going on for quite a long time. We basically have to look at the feasibility. So this is the availability of oxidants. So for example, chlorine is quite readily available. So it's quite a feasible oxidant, but then we also have to look at the side effects. So for example, this infection byproduct formation and then the broad applicability to micro pollutant oxidation. So we should have an oxidant that is maybe not so selective. So for example, chlorine is very feasible. So this should be much higher this bar here, but then we form a lot of these infection byproducts and it's also not broadly applicable for micro pollutant oxidation. So this means chlorine is probably not a very good choice. Pyrmanganate, for example, would be very feasible. Also little disinfection byproduct formation, but not such a broad applicability for micro pollutant oxidation. So basically we have to move back in this figure to this corner here and there we see that we have mostly UV and ozone-based processes that have this potential for a broad applicability for micro pollutant oxidation. Limited disinfection byproduct formation and they're also quite feasible. So I will mostly concentrate on these kinds of oxidants. Including ozone, but also hydroxyl radical oxidation. So now if you look at an oxidation, an oxidant, and the primary goal is to disinfect the water. So we would target microorganisms, but also micro pollutants. And this is now the focus of this talk. And then we transform these micro pollutants into transformation products. But at the same time, these oxidants also react with the matrix. So with bromide and iodide, but also phenolic substances in the dissolved organic matter. And this leads to the undesired side effects, these infection byproducts. We have the formation of halorganic compounds, so such as fluorinated and brominated compounds. But we also form oxygen-rich compounds such as aldenites and ketones. And then we can also form halogenates, such as, for example, the bromide. So this is basically the scheme that we have to consider if we apply advanced oxidation processes to water treatment. So now I would like to zoom in to the micro pollutants and the efficiency of micro pollutant debatement is given by the kinetics. And these are typically determined by laboratory experiments. And but also nowadays, we can use quantum chemical calculations. And then these micro pollutants are transformed into transformation products. So we need to know something about mechanisms. And there we also have to use advanced analytical tools, mostly some separation techniques coupled with MS. We can also use prediction tools. I will show you that in a minute. And then we also have to assess the toxicity of these transformation products relative to the target compounds. So here this is mostly done by biosays. But also there are some in silico toxicity evaluations that are available. And then also another factor is the biodegradability of these transformation products. So we can do this with culture experiments but also biofiltration experiments in pilot or full-scale or then used by degradability models. So now I will focus on some of these aspects in my presentation. So here I have an example of this platform that we developed. This is to predict the kinetics and transformation products for during ozonation. Here I show you the example of carbamazepine. And we have an in silico tool. So this is a computer-based tool that we have developed. And we can determine the reactivity. So we can determine second order rate constants. Basically look at these molecules in terms of the reactive sites. And then we can use quantum chemical calculations and also quantitative structure activity relationships to determine the second order rate constants for reactions with ozon. On this side we basically look at the transformation products that can be formed. So there is also a predictor for this. And this includes about 100 reaction rules that are applied to certain functional groups. And then we can predict what kind of compounds are formed. And the blue ones here they are compounds that can actually be found during ozonation process. So this can help us for a targeted analysis of such compounds. We can determine what kind of masses these compounds are. And then we can also find them in these on the realistic conditions. The other thing that I mentioned is the kinetics. So this here is an experimental approach to measure kinetics. And here we looked at the oxidation of sulfur methoxazole by ozone and OH radicals. Here you see the second order rate constant as a function of the pH for this molecule. This molecule has two pKa values. One is for this aniline group that's the lower one and the higher one is for this nitrogen here. And we see that there is a pH dependence but in the pH range that is relevant for water treatment we have more or less a stable second order rate constant almost 10 to the 6 per molar per second. And if you calculate the half lifetime of this compound for a concentration of ozone of one milligram per liter we have less than 0.1 seconds. So this compound is very quickly oxidized and we wanted to know what happens with its antimicrobial activity because sulfur methoxazole is an antibiotic and therefore we plotted the residual potency. So this is the antimicrobial activity as a function of the relative residual concentration. So if this compound is by the first attack loses its biological activity we should follow this one to one line here. And we did this for ozone. So you see here this is really nicely on this one to one line. So this means the degradation or the disappearance of this compound is directly connected to the loss of its antimicrobial activity. And we also did this for OH radicals and this also lies on this line. So this means that basically the attack of the or the slide transformation of this molecule leads to a complete loss of its antimicrobial activity. And we have done this for other types of compounds for pesticides but also for estrogenic compounds etc. and we have found quite the similar behavior. So this is actually good news. We don't have to decorate these compounds completely but we can already find the degradation of their biological activity by the great partial degradation of these molecules. So this is kind of the normal case. There are also cases where this doesn't happen and I just want to show you a very nice and classical example. This is a fungicide that was applied a lot in the European Union. And this fungicide toluene fluoronide is transformed biologically in the soil. About 20% of this is transformed to this DMS. So this is dimethylsulfamide. And what happens with this dimethylsulfamide is that when it's ozonated, it's transformed with very high yield of 50% to nitrosodimethyramine NDMA which is a mutagenic and carcinogenic compound. This was discovered by some researchers at the TZW in Karlsruhe and basically they found it during ozonation of drinking water. The DMS levels, so the levels of this compound, they were in the low microgram per liter range and this led to several hundred nanograms per liter of NDMA in the drinking water. So this is above what is recommended by the World Health Organization. They had to shut down the ozonation and this led to a very fast ban of toluene fluoronide in most European countries. So we were approached by these two researchers to find out what's actually going on and we were quite naive. We just added some ozon to a solution that contains this DMS but we didn't find any NDMA. So there must be something in the matrix. So this was done in ultra purified water. There must be something in the matrix that leads to the formation of NDMA and we found that actually bromide catalyzes this reaction. So if you look at the NDMA formation for low concentrations, there's almost none but then if you increase the bromide concentration just a little bit, it shoots up. If bromide would be involved in a one-to-one reaction here then we should be on this line. So there is a dramatic enhancement of NDMA formation in presence of bromide and this points towards bromide catalysis and we also have a very high yield of larger than 50%. So this is an enormous yield for a precursor for NDMA formation. So finally we figured out what the mechanism of this reaction is. So if you have bromide in the water this can be oxidized by ozone to hyperbromosacid and then the hyperbromosacid can react with this DMS. So this hyperbromosacid reacts much more quickly with DMS than ozone. We formed a brominated DMS and then this brominated DMS can react with ozone to form more than 50% NDMA and the rest is nitrate. So this was quite an interesting discovery and it's actually an unpredictable cocktail. We have a fungicide that is applied. We have some bacteria that transform it. Then we have bromide and we add ozone for water treatment. We mix this and we form a toxic compound. So there are not so many examples like that but I think we always have to be careful that the unintended reactions can occur. So now I would like to go to the next topic. This is the biodegradability of transformation products and we did a study in a pilot plant that consisted of an oceanation and the sand filtration of lake water. We spiked 51 compounds. We found 187 transformation products and we looked at the structures that can be abated. They contain mostly oxygen such as aldehydes, carbonate compounds, carboxylic compounds, alcohols and amides. And they're mostly formed from aromatic and olefinic compounds. But what we saw is that only 24 of these 187 so this is 13% of the transformation products were better biodegradable than the parent compounds. So this is shown here. So here we see basically in blue compounds that are similarly abated as the target compound then in orange verse and better. And we see mainly that for aromatic and olefinic target compounds we have a better biodegradability and these are also the compounds that lead mostly to aldehydes and carbonate compounds that can be degraded. So what we can learn from this is that basically the assumption that we only have to partially oxidize a micro pollutant and then we can easily degrade it biologically is not always true. And I think there's certainly more research needed to further investigate this correlation between target compound structure and the abatement of the transformation products. So now to end this talk, I would like to go into the reactions with the dissolved organic matter and dissolved organic matter as I showed before is the main consumer of oxidants and this leads to the well-known disinfection byproducts and the most reactive sites are phenolic moieties. We have about one to two millimoles of phenol per gram of DOC so if you have five milligrams per liter of DOC this means there's about 10 micromolar of phenols. If you look at the sum of micro pollutant concentrations in a wastewater effluent in a study in Switzerland we found that the concentration of micro pollutants is about 0.2 micromolar. So this is significantly a factor of 50 lower than the concentration of the phenolic moieties. So this means that the ozone will only be available 2% to react with micro pollutants and of the OH radicals we have even a smaller percentage. So we have to look at these products from the reaction of DOM with ozone and OH radicals and the phenolic moieties are of course also important precursors for disinfection byproducts. So we did a study in a full-scale ozonation of wastewater effluent. We derivatized the samples with TSH and this is specific for carbon compounds. We found 46 carbonyl formulas and we looked at the formation of these carbonyl formulas as a function of the ozone dose. We applied 0.25, 0.5 and 1 milligram of ozone per milligram of carbon. We saw that this is correlated to a measuring parameter the electron donating capacity that is a parameter that is a summary for aromatic compounds and we also found that there is a bi-degradation during sand filtration. So here you see the increase of the relative areas of these compounds as a function of the ozone dose and then we see that there is a significant decrease of these areas again in the sand filtration. So this means that these products that are formed from the matrix they are quite easily biodegradable in the biological sand filtration after ozonation. So that's why it's also very important to have a biotreatment after ozonation. So with that I would like to come to the outlook and I think we have to develop more predictive reaction tools for kinetics and product formation that too many compounds that we can measure one after the other. Then we should combine experimental studies with quantum chemical computations. This has shown we have shown that this is quite fruitful to investigate mechanisms. Also the prediction tools they can be coupled within silico toxicity evaluation and bi-degradation tools. So we don't have to do all the measurements. Then we also need to have a better understanding of DOM and we have started to work on tailored chemical approaches. So we do selective titrations, derogatizations and tagging. And then we also need improved tools for the interpretation of non-target MS data because these workflows are not efficient enough and very time consuming if one wants to look at transformation products. Finally, in recent studies and also in our laboratory we have started to use stable isotopes to elucidate reaction mechanisms and I think this is also a very nice new tool that can be applied. So with that, I'm at the end of my talk. I would like to acknowledge quite a lot of people who were involved in the studies that I've shown. Then also some funding from various funding. I think there might be some connection problem from Professor Van Quinten. So moving on to our next speaker is Professor Sincja from Georgia Institute of Technology in U.S. He will be talking about the locally-enhanced electric field treatment or LEAPT for drinking water disinfection. So Professor Sincja, the floor is all yours now. Thank you. Okay. Sincja, you moved on to a nice introduction and also Sincja Ida Berry for the invitation. So it's really my great pleasure to be here and sharing a new technology we've been working on in the past few years and then technology is locally-enhanced electric field treatment. We are currently mainly used for drinking water treatment, drinking water disinfection. So I think most of the audience here are familiar with water disinfection. So let me just directly explain what is the electric field treatment. Okay. So yeah, so here is a schematic showing what is the electric field treatment. So basically we have two electrodes here. So one is positive and one is negative, right? So I know there will be a... If it's a parallel electric field, there will be a uniform electric field distributed in between. And then if we have microorganisms indicated by these shapes and then basically there will be a strong electric field, basically they'll be exposed to this electric field. So what happens in this condition is that there will be charged ions in the solution and then the positive ions will move towards the negative electric field and then the negative charged ions will move towards the positive electric field. And then so the movement of these ions will basically generate what we saw is called transmembrane potential across the membrane. So and at least transmembrane potential will increase along ways the external electric field. So if the electric field strength, external electric field strength is high enough, basically we'll be able to generate pores in the cell membrane. So this is different to an electrical chemical reaction which will trigger electrical chemical oxidation or reduction. In this case, it's pretty much... We can see there is a physical process, you can see there is an ionic sensor which really cut the membrane open and generate the pores. So in this case, it really depends on the strength of the external electric field. In some cases, these pores can be recovered. We call it reversible electric polarization. And then if the electric field strength is high enough or last for a long enough time, and this electro-porated pores can be permanent. In this case, these microorganisms can be inactivated. So in the biomedical field, people have tried to use this process to do drug delivery, gene delivery. In most cases, they still want to keep the microorganism alive after these processes. In some special cases, they also want to inactivate some cells. But basically, we have been thinking about whether we can use this for large-scale water disinfection, water treatment. The challenge is really that to generate a very... Electric field is strong enough to inactivate most microorganisms. The electric field strength needs to be very high. So with a certain distance, the electric field strength is determined by the applied voltage divided by the distance of the two electrodes. So in this case, usually we cannot have the distance between the electrodes to be very, very narrow. So in most cases, we have to apply several kilovolts of the voltage to realize a strong energy field that's good enough to kill microorganisms. So this is fine for very small-scale applications, but it's definitely not applicable for large-scale water treatment or water disinfection. So basically, this is the idea we come up with. We want to use that to do water disinfection, but there's also an obvious challenge there. So in the past few years, we have tried to work on two directions, trying to basically minimize or reduce the voltage that we need to apply. And then in that case, we can apply this technology for at least a larger-scale water disinfection. So basically, we call this technology locally-enhanced electric field treatment. The general concept is that rather than generating the uniform electric field strength between two parallel electrodes, we want to enhance the electric field at a local position or a location in the reactor. And then the next step is basically trying to use the mixing or other mechanisms and then push the microorganisms to these regions so they can be exposed to the strong electric field and then be activated. So to realize this locally-enhanced electric field, we have tried two strategies, which one is in the macro-scale and the other is in the micro-scale. And in the macro-scale, basically we design different configurations of the chambers or the reactors. One example is that we can have this coaxial design of the system. For example, we have a positive electric center and then we have a negative electric outer ring. So in this case, actually we will be able to generate a much stronger electric field near the center electric. It really depends on the ratio and the size of these coaxial electrodes. This can be at least 20, 30 times enhanced based off the background electric field stress. Another scale is a micro-scale. Basically what we are doing is that we modify the electric surface with these kind of tip structures. And then it really depends, again, the aspect ratio of these tip structures. It can be nanowales, microwales. But basically if this is a sharp tip, what we can do is that we can significantly enhance the electric field stress near the tip of these structures. It's also called a lightening effect. Basically you will have a highly concentrated charge density at the tip and then around this area, the electric field stress will be much higher. This enhancement can be easily increased to several orders of magnitude, two to three orders of magnitude, really depends on the design and the size. By doing that, what we really want to achieve is that with a much smaller voltage, a few volts, or at least less than 100 volts, we will be able to realize strong electric field that's high enough to kill microorganisms. To demonstrate this idea, we have developed this co-excel electric lift device which combines this micro-scale and micro-scale enhancement effect. So this is schematic. Basically we have a center electric show, we have outer electric show, and then for the center electric show, we modify the surface with these nanowire structures. We usually will set the center electric show as a positive electric show because most of the microorganisms, they have negative surface charge. So by doing that, basically we will be able to drive the microorganisms towards the center part which will have the enhanced electric field treatment. So here is the simulation indicating that how these electric field strengths can be really enhanced by several orders of magnitude when it's close to the center, actually especially close to the tips of these nanowires. And then just show you a kind of a first prototype developed in our lab a couple of years ago and then showing a very small scale applications to at least point. And then we test this system with different voltage, different flow rate, basic ideas that we have successfully demonstrated with a very small voltage, just one more or two volts. And then we can with a reasonable flow rate, we can already achieve more than six log removal of a model bacteria E. coli. We also test the system with different strains of bacteria where positive, where negative. We also dose the river water, natural water system with model bacteria also achieved similar results. We also have tried to scale up this process a little bit. This is the kind of second generation of the prototype in our lab. We basically increase the length from about just 10, 12 centimeter to close to two meter. And then basically we can successfully increase the flow rate. Basically, we try to maintain the retention time and then increase the flow rate using this larger device. We basically, we have been thinking about the real application of this kind of system, specifically for this coaxial electrical design. Still far away from the credit applications in very early stage for bench scale demonstration, but we believe maybe this technology can be used in the pipeline systems for water disinfection, for a secondary water disinfection distribution systems. We also demonstrate that also do some theoretical calculation that the energy required for these devices is actually very, very low and potentially this can be directly recovered from the flowing water. We can just incorporate a very straightforward water turbine generator there to recover a little bit of energy from the flowing water. That's already good enough to power the lift device. So basically in the past couple of years, we have been working on this technology on different aspects of this technology. For example, we have been developing electros. As you can see, the electros is really the kind of a core component of the lift device. So at the beginning, it only lasts for about 10 minutes, 20 minutes after a couple of years of development currently. The state of our electros can last for at least a couple of days. And then by still testing the pretty much controlled lab environment, still not ready for real practical water application. We also try to develop different power sources as you can see before, which is using the flowing water. We also try to use a hand pump, hand powered pump to power the system. The system because the voltage is very low can be also easily powered by our cell phone. We have demonstrated the lift device itself can achieve pretty high microbial energy region efficiency by still in kind of with a pretty low throughput, pretty low flow rate. So we have also developed a lift technology combined with conventional disinfection disinfectants. For example, we have combined lift with copper. We also combined lift with ozone. Basically, the idea is that we can use much lower concentration, either copper or ozone combined with the lift to realize a very high performance in terms of microbial activation. So this is a really kind of very brief introduction of this technology we probably lived. One basically the second thing, the later part of today's presentation, I really want to highlight one kind of a sound of our recent progress in terms of trying to figure out what's the really mechanism of this process. So basically, as I mentioned, we have demonstrated this lift device can achieve very high performance. But and we also know that the micro scale enhancement in this instance, the basic of this nanowires play a very important role to further enhance the electrical strength. But overall, this is just a device looks like, really looks like a black box. We're still not quite sure what is exactly happening when water is being traded by this device. We believe there's electric operation, just as I mentioned at the beginning, but we are not sure whether there are some other mechanisms which also play a very important role in this process. So basically, this is like a black box for us. We know water goes in and goes out, microorganisms being activated with very high efficiency. But the key point for our current recent research is that we want to open this black box. We want to really study. And then we want to look at this process in situ with this so-called lab ownership devices to really study what's really going on during this lift process. So a little bit detail about the methods. So basically, we developed this kind of lab ownership devices on the piece of glass slide. So this is a piece of glass slide with gold coating on the surface. So this gold-ish color is the pattern with gold coating. And then between these very narrow gap between these two pads, we have patterned this kind of micro-scale nano needles or nano wedges, which we're trying to use that to demonstrate the locally-enhanced treatment. So basically, the next step, once we have this step on the chip device, we basically use some staining message. And then we also basically immobilize the model of bacteria that are caught on the surface. And then you will look like this after this loading of the microorganisms. And then we just put it under the microscope and then we apply the electric field treatment. And then we do this institute characterization during this process. So, and this is the image before the lift treatment. We just want to use a simulation to make sure this is basically like electric field strength can be much stronger and then reach the threshold of the strength that can cause my coping activation. And then this is the image showing that after this loading of the microorganisms. And I'll show you a very short video and showing basically how this process happening. Basically the red dots here indicates the microorganisms has been activated. So they are death cells. So basically at the beginning, there are already some death cells, right? So it's basically some, but most of the majority of the cells are still alive. And then you can pay attention to these basically the near the, these lines indicating where the tip structures are. So please pay attention to these, the tips of these nano structures. And then you will see when the time starts from zero, these places will get light up, right? And also only this process get light up. Basically these areas are the locations we have the strong electric field and other places actually the cells were still maintained alive. So this is the results after a little bit of the processing of the image. So basically we are indicating the locations where the lift process really happening. So we notice that this is really a very fast process in the previous video. And then there's a couple of seconds really limited by the time, the speed, we can use a camera to capture the image. But we try to, we notice that it's a very fast process, but we want to figure out how fast this process can be. So we keep pushing the electric field passes. Basically there's a duration of the electric field down to a very, very short period to see what's the limit there. Eventually we figure out that even with a single pass of 20 nanoseconds, okay, with a certain electric field strength, the 20 nanoseconds is already really, really fast, right? So one nanosecond is 10 to the minus 9th of a second. So you create, and then this 20 nanoseconds is really limited by the instrument we have. Basically you apply the pass, it takes some time for the voltage to increase and then it takes also some time for the voltage to decline. So really 20 nanoseconds is pretty much the shortest electric process we can apply using the equipment. And then we notice that even this one single pass treatment and then the line here indicates the for instance intensity, basically indicating how much this kind of dye has been diffused into the cell, indicating the cell membrane damage. So as you can see here, there will be some variations of different cells. Each individual line indicates in one single cell that we monitor the individual cells. But basically the idea is that for one typical sample, so basically at the beginning there's no any diffusion of the dye into the cells, but as the time goes on and then eventually the cell will be completely, pretty much right. And keep in mind that this diffusion actually, the time here is actually limited by the diffusion rate of the dye rather than the treatment speed. So the treatment really happens at the very early beginning, just 20 nanoseconds. Okay, so if I take some time and then for the dye it's to diffuse into the cell. And then the sum of the damage should probably be more severe and then it takes much shorter time for the dye to diffuse. Basically the general idea is that the treatment can be extremely fast because this as I mentioned is the physical process relies on the movement of the ions rather than the chemical reactions so usually which will take some time for the chemical oscillation or reduction to happen. So just a comparison with this kind of conventional electric field treatment without the nanostructures and then also the other is a lift with the nano enhancement. You can see that for the conventional electric field treatment we there's no any further enhancement just a flat light show without the nanowire structures. And then even though we keep the pulse waste of the 20 nanoseconds but basically this total in fact effective treatment timing so you have applied multiple of these pauses right. So even for one over one million or 10 million of these nanosecond pauses to the total treatment time of 20 milliseconds which is still pretty fast compared to other process but still you don't see a very significant enhancement enhanced in activation. But for the lift process you can see if you compare the 20 nano 200 microsecond treatment basically we can achieve the voltage being reduced the electric field strength can be reduced by eight times and also if you compare the single pulse treatment like 20 nanosecond with the 200 millisecond treatment with the with the similar voltage similar electric field strength 55 kilovol per centimeter you can see basically a time scale has been reduced by 10 to the six times. So basically that means that we can either reduce the voltage significantly by eight times which is actually already a significant reduced or we can significantly enhance you know increase the treatment speed all the way from 200 milliseconds to only just 20 nanoseconds one pulse that's good enough to kill the microorganisms in most cases. So based on this platform we also we also have done some basic mechanism study we're trying to make sure we want to demonstrate that this this fast ultra-fastest microbial activation is really due to the electroploration other than other mechanisms. So I'll just show you some experiments quickly to demonstrate that. So first one is that one of the unique property of the electroploration process is that before a very strong irreversible electroploration there'll be a reversible one basically with the pulse we'll be able to to seal or recover after this treatment. So we demonstrate that by by by doing you know the the lift process with a much lower voltage should have much lower electrofuel strength. So in this case it's still 20 nanosecond pulses but the electrofuel strength is 12 kW per centimeter. As you can see here basically we this is a tie and then we also monitor the fluorescence intensity. As you can see basically the pink area we turn on the electrofuel pulses and then you can see the fluorescence increase but once we turn off the electrofuel treatment the basically the increase of the fluorescence intensity will immediately stop and then which really indicates the recovery of these pores. It's also happening in a very very fast time in a time phase. So basically after that you become flat and then once you turn it on you will increase and then you become flat again when it's turning off. So it takes really a couple times on the off and then to accumulate enough in the electrofuel treatment to eventually fully get inactivated then you will see a significant increase after that. We can see this phenomenon on different cells or positive electro, negative electro. Really that indicates that the actual proliferation is the main mechanism induced the microbial inactivation. Especially in this case we have the similar phenomenon for both positive and also negative electro which is usually not the case for the electrochemical reactions. We also rule out the possibility of our S-generation in this system. So basically I will just quickly show you where I have demonstrated that we have we have applied a dye to indicate oxidative stress. So basically under the conditions we already achieved using the 20 nanosecond pauses we already achieved more than 90% microbial inactivation but we don't see any oxidative stress built up in the system which is a control sample is that if you use a two microsecond pauses it will be very obvious oxidative stress. Last basic experiments we done is that we try to use these floating nano structures or nano wedges. We also demonstrate that even these nano wedging materials they are not directly connecting to the bulk electro on the two sides. They also achieve pretty high performance in terms of microbial activation. This is also not possible for electrochemical reactions which will really you the electrodes have to connect it to the to the bulk electrodes to the connect it to the circuit. So this is also indication of this is the electrofield treatment rather than the electrochemical reactions or others. Okay so to summarize today's presentation I just want to show you the slides which shows the basically either the demonstrated or potential advantages of the lift technology. So we really believe this can be a transformative technology for the water disinfection sector. And then especially this technology is very high efficiency you had demonstrated. It theoretically has a very broad spectrum and very effective to all pathogens. And then we also demonstrate it's a very very fast process. So one of the intrinsic advantage of this technology compared to other existing you know some especially the chemical based technology that theoretically this is the electrical physical process. Theoretically this process should not generate any disinfection byproducts. Even though in some cases it will probably still some current consumption still some disinfection byproduct generator. But theoretically it can be really this more a very very very pretty much negligible. Some of the other technology were still on the way trying to push push forward. But theoretically or potentially these are the really advantages we can have for the in the future. With that I would like to thank all my students especially my current post-doc in one and then a PhD student Joe graduated years ago who really contribute most of the work I presented today. And I also want to thank all my funding agencies for this one. Thank you very much. I hope to answer any questions you may have later. Thank you Professor Sia for the wonderful talk of lead technology for water disinfection. And now let's welcome the third speaker Dr. Ria Verbecki. She will be talking about the open membrane database and open access user-sourced library of water purification and desalination membranes. Ria you can start now. Thank you. Okay thank you Euman. Thank you very much for the warm welcome. Hello everyone. It's a real pleasure for me to be here to showcase the OMD OMD to you. So what is the OMD? It's actually an archive of membrane performance data. So what do we do? We input data from peer reviewed articles, commercial data sheets and patents. And then the output of the database is selectivity permeability plots and also some other information on how the membranes were made. And right now we have over 1000 reverse osmosis data points. We launched it in August 2021. And if you want you can have a look online. This is the URL of the database but I would really much appreciate if you could first follow my talk and then afterwards go and look at it. But apparently we have quite some visitors. I looked it up just recently and we have about 500 unique visitors per month. So it's quite well visited. And we also wrote an article about it in the Journal of Membrane Science of which you can find the details here. The topics of my talk today are the following. So first I want to start on a high level. So the water crisis we are in right now and how membrane desalination can help to tackle this crisis. Then I want to ask a question like why would a database actually be useful? Would it be useful? And I hope I can convince you after my talk today that it could be useful. And then I want to dive in a bit deeper into the founding principles of the OMD and then how we collected the data with the constraints on the data are. And then I would also like to share with you the online tools that we installed on the website. So these are the membrane submission forms and also the calculators and then lastly I would like to conclude with where we are right now and where we would like to go. So first of all the global water crisis just on a very general level it occurs when the demand exceeds the availability of water. So what are the factors that are increasing the demand? This is the growing world population, the increasing living standard and also the change in consumption patterns for example towards more meat which is a very water intensive product. Then on the other hand the availability also goes down because of climate change because of the changes in our hydrological cycle and also the quality of the water goes down because of increased pollution. So what can we do to fight a water scarcity? Well I think we need combined solutions so we can change our own human behavior, what we do, what we buy, what we eat. We can also enforce policies to take place so for example restore and protect our water reservoirs and then thirdly there is also technology which can play a role and while I will focus on technology through the OMD I think it's important that we don't forget the global picture. So with respect to technology I want to focus on desalination on desalination membranes and how they can help tackle the global water crisis. So how could these desalination membranes do that? Well actually the overall picture is very easy so I'm showing you a membrane here we foresee water over it we pressurize it the salt the green balls here are being rejected the water passes through the membrane and so at the end we have two output streams a highly concentrated salt solution and a fresh water solution which can then be used for human consumption or for other applications. When we look at membrane research on specifically on desalination so on reverse osmosis membranes then we actually see that these membranes didn't improve that much over the last 30 years. So I'm showing this in a plot so on the y-axis we have water salt selectivity and on the x-axis we have water permeability and so actually the best membrane ever would be the one in the upper right corner right at the top there and so all these data points were gathered from the OMD and you can see two curves which we call upper bound curves and the more up the curve goes to the right top corner the better the membrane is and you actually see that between 1990 and 2021 when we launched a database very little improvement was made which to me is really striking because so many researchers are working on this a lot of research resources are going in it a lot of time but apparently it doesn't seem to work that well to increase to drastically increase the membrane performance. Why is that? Well I think again here we have a black box topic it's because we don't really understand which factors are governing a membrane transport and how we can maximize them so in our field we call these the synthesis structure performance relationships and these are all intertwined so how the synthesis parameters of a membrane influence the structure of the membrane and then how this structure is influencing the performance and right now we don't know so what do we do? We just have a trial and error approach we try stuff in the lab we try to do it as best as we can but apparently it's not working so well so my argument is how can we solve this? Well we need data we need a database so this is one argument of why I taught in 2020 why we needed a database but there's actually also a second one and that is to increase resource and time efficiency and so I'm showing you a picture here you can imagine this was me during my PhD I developed a new type of membrane and I wanted to benchmark it with the state of the art and then I was so frustrating because the data of the membranes are scattered in different journals it's just all over the place then you don't really know if you can use it you don't really know how they were collected etc so it's just very time consuming to find the data that you want to compare your membranes with and then secondly very often the data is not readable so you're looking at your screen you're zooming in the resolution is not that good but the raw data is never shared so what is that actually the real data point that you need? very often it was not readable and then thirdly the data is not standardized so very often the data that other researchers publish the other researchers publish is not collected in the same way as I did it and we know that operational conditions play a very big role in how the membrane performs and so it's actually not completely correct to compare these data points and then I was thinking if I'm having all these frustrations probably many other PhD students and other researchers also have these frustrations so why they're not trying to come up with another idea to make our field more resource and time efficient and again with and in mind to help tackle the global water crisis by optimizing membrane performance so then why would the database improve the field? Well first of all to better understand as I made the point earlier to better understand the synthesis structure performance relationship secondly to standardized membrane data so that we're actually able to compare them in a correct scientific way and thirdly to share the knowledge that we have and to share our data and then we started looking into databases that were already in place and that could serve as inspiration and then we found these too so the Cambridge structural database which is in the field of metal organic frameworks and the protein data bank and it's when you look at when they were founded 1960s 1970s I thought we're really far behind we really need to step up our game and because the database wasn't there we thought okay let's create one and then this is how the OMD came into play I co-founded the OMD with in total 12 people from four different universities and these the foundational principles of the OMD I will show you here so first of all it was really important that it's completely free and open access and the strong advocate for open science and open data so this was really like crucial for us that it would be completely free and that you don't need to register at all so you can just go to the URL and all the data will be there secondly we wanted it to be crowd sourced so that it would be a community effort to get all the data in there and that it would be sustained over time by the whole community then thirdly to have a high quality of data we decided to only incorporate peer reviewed data from peer reviewed journals from commercial data sheets and from patents and then fourthly we wanted to unify the membrane reporting to really show how all the data were collected and under which conditions and then fourthly I think it's really important that we look at the problems we're having on a global scale and so I wanted this to be an international collaboration which in the end worked out quite well because we had a Yale university on the team KU Leuven my home university in Belgium the University of Technion in Israel and then also Hong Kong University so what are then the advantages of the OMD over the status quo I will share with you a table here so what do I mean with the status quo it's quite simple I just mean review articles which let's say are published every one to two years so then all the data is present in the review articles but you only have it every two years when someone decides to write it right well for the OMD the data would be updated in real time every time an article would be published it would directly be imported into the OMD then regarding the sources of the data often reviews are written with a specific scope in mind so you will only find the data that is related to that specific scope well for the OMD we want to cover the whole field of membrane desalination totally the processing of the data as I mentioned before in articles it's quite variable it really depends on the research groups and just the history of that research group how they did it over time well for the OMD it's very uniform and transparent you can have a look at the OMD how we did it also in the article it's really well written data exploration well in the status quo in review articles it's just not possible you just have a 2D graph you cannot do anything with it well for the OMD it's super interactive I will show this to you a bit later you can hover over the points you can select different points but I will come back to this later so it's really super interactive with a very nice user interface and then a very important other point is accessibility so when you want to compare your own research with research for example in review articles and you want the data points you need to contact the authors themselves and very often this is with low success rates just because the data has not yet been shared well for the OMD you have just complete open access to all the raw data points so how can then the OMD help advance membrane technology so first of all it would help us to benchmark novel reverse osmosis membranes so for example those made with different chemistries or which were modified with respect to the state of the art and then very important it would allow us to conduct meta analysis to amongst others better understand these membrane synthesis structure performance relationships which I think are really primordial for optimizing in a significant way desalination membranes and M4D also wanted it to be a tool that the field could use so we incorporated membrane calculators or calculators just for membrane performance concentration polarization and osmotic pressure because we found out that actually these let's say routine calculations are not so easy for people who are not so familiar with the field and actually this is let's say relatively often because membrane technology is really at the I would say at the crossroads of many different disciplines many fields of science and so we thought it would be nice if we could really make this a high interdisciplinary research field with information available to everyone so then I would like to dive a bit deeper into the data itself so the origins and the constraints now we had to put on the data yeah just as what we decided to do to the data so you're all aware of this as I mentioned before this is coming from peer reviewed literature commercial data sheets and patents and as of now I just did the calculations last week with all the data that is out there 77 percent is coming from peer reviewed scientific reports 4 percent from commercial data sheets and then 90 percent from patents but this will of course vary over time depending on what the inputs fields are and then we decided to define a reverse osmosis membrane as a membrane which has an intrinsic rejection for sodium chloride of 80 percent so this is the limit that we put just the constraint that we had to put in order to select which articles we would be we would upload to the OMD but this is I want to stress this is not a general definition or anything this is just what we decided to do however what is really important is that we are not interested in only the best performing membrane we want to understand the general principles that are governing or that maximize membrane performance so if you for example have membranes that range from 60 percent to all the way up to 99 percent sodium chloride rejection then it's really important to upload all the different data points because it's actually in the series that there is a lot of information present on what is really crucial to obtain a good membrane the input collected by the OMD so first of all we want to know which type of membrane it is so asymmetric TFC TFN in organic this is just very general but then we also need some more detailed information on how the membranes were tested so the solution chemistry the concentration polarization modulus and then also we want to know some physical characteristics whether they were post treated which chemicals were used to make the membranes and whether they were modified or not and then thirdly of course very important the performance characteristics so it's important to know the A and B parameters of the membrane as well as observed rejection and real rejection the functionality of the OMD so this is what I stressed already in the table that I showed you before so when you go to the OMD website it would look a bit like this so you have many different filters that you can apply on the data the chart is super interactive so when you hover over the data points you will see data callouts popping up so you can see the actual data so the A and B parameters here for example then you can also select data points on the graph and then automatically a table will appear on the bottom which will have all the information in tabulated form on how the membrane was made the article of which it's coming from etc etc and then you can also export this table as a CSV file so you can just do whatever you want with it on your own computer and also the image so the graph itself can be exported as a PNG file then it's important to know that the submissions are open to everyone if these if they are excuse me this is submissions are open to everyone if they are eligible according to the criteria I showed you before so you need to enter the report data then you need to provide some contact information of yourself and then thirdly you need to of course submit the membrane data and when you have done that then the data will be reviewed by someone from the O&D team and if it is accepted then it will be directly uploaded online and then your data will be there essentially for the calculators are really important to help the users so we decided to incorporate four calculators so the membrane performance the concentration polarization and the osmotic pressure calculators and then also a common unit converter so to go from the US system to the metric system and this we did to just facilitate the determination of membrane performance and all the other parameters that I mentioned here to avoid errors because for some people the formulas that are being used are not so common and so we just wanted to facilitate the whole process and also here this is a step-by-step process so I'm showing you here a little picture of how it looks like so you just input the water flux you input the applied pressure and then the calculator will give you the output as the A parameter so where do we stand now and we actually received a lot of positive feedback many people are visiting the OMD also the paper is being highly cited so we're really happy with that however I want to stress that we have only one external submission since August 2021 which is kind of alarming also disappointing and shocking to be honest with you so the field is not really engaging it's not yet uploading their own data even though they are really using the database a lot so we really need to involve the field in this because data is only relevant if it's a lot of data otherwise the conclusions that you draw might not be correct so how can we do this to involve the field? Will all of you you and your colleagues please upload your data and talk about it I think it's really important that people are aware of the OMD also secondly we're talking with journals who would mandate the researchers to upload their data on an open repository and then the OMD can be populated directly from this open repository to increase the sustainability of the database but if you have any other ideas if you think of something then please let me know I would be very happy to get your feedback on this and then also a little outlook of the OMD for reverse osmosis so what do we want to do? We want to revisit some of the assumptions we made for concentration polarisation so that people yeah so that this is now we are assuming I don't want to go into too much detail on this but now we are assuming a thousand 100 LMH for the mass transfer coefficients and we want to yeah facilitate this assumption through opening the discussion with the field actually on this because this is really not uniform for dissemination membranes then we also want to highlight the membranes that were tested under standard conditions so that those would become a gold standard and this is then to ignite the field to really use the same condition so that it would facilitate comparison between different membranes we also want to incorporate trace organic contaminants so move away from sodium chloride and incorporate yeah let's say pesticides and pharmaceuticals etc to see if we could also establish these synthesis structure performance relationships for these contaminants specifically and we also would like to include a dynamic upper bound so depending on the filters that you apply that you can see the line changing and then lastly as I already mentioned I think it's really important to tie the journals to the O&D so that it would facilitate the automatic data transfer so that we can actually ensure the sustainability of the database and draw really strong conclusions of the data that are there however I also want to share with you my long-term vision for the O&D we actually would like to see it as a real database hub so not only for reverse osmosis membranes but also for all the other membrane technologies that are out there so nano filtration ion exchange membranes even for batteries and for gas separation for solvent separation etc so every field would have their own database and the hub would be the O&D as such so right now we are also working on the development of the solvent resistant nano filtration and organic solvent nano filtration database so yeah to summarize this is the idea is that to make the O&D a very collaborative project really advance our field so once again I would like to ask you to submit your membrane data talk about this with the people around you because really the more data we have the more knowledge we have and the higher chance that we have to reach a scientific breakthrough which is I think really worth it especially provided the very scary water crisis we are in right now so thank you all to all the involved parties you can see that many people were involved it's been really my pleasure to lead this project and I hope it will be sustained by all of you so please spread the word and get involved and thanks again to everyone who was already involved and thanks to all of you for listening thank you Riya for introducing us the very useful O&D database so everyone who's working on our own membrane you can share your data and upload your data on the O&D database so that is all for today's presentations and now let's and now let's move on to the Q&A session so we've collected some questions for from the Q&A box and the first question is for Professor Ersmann Gwinton so the question is since water can contain various microfluidins has there been development of any special index which considers those current microfluidin of concern in the drinking water and allows generation of pollution index for the water similarly is there any index for toxicity level thank you yeah so thank you very much for this question so the drinking water regulations are of course thing that are quite national or you know for countries like in the EU they have a common drinking water regulation and they're based on standards drinking water standards for individual compounds or for some parameters but toxicity parameters are not included yet in these in the drinking water regulations also typically you need to pre-concentrate the drinking water quite dramatically to find toxicity caused by micro pollutants so this is sometimes done to assess the toxicity for example by the mutagenicity by Ames test or the estrogenicity of the drinking water but then you need to pre-concentrate it very significantly and this is not something that this required by the regulations drinking water regulators thank you professor for the detailed answer and now we also have two questions for professor as yet so the first question is if I understand the leave technology cannot replace primary disinfectants such as chlorine UV and ozone it can also be used for stability in the distribution system you must I think the both questions are kind of similar I thought about the scale maybe you can also read out the second question so I can answer them together okay the second question is can electric field be also scaled up and utilized for disinfection of treated water from small municipal wastewater treatment plants such as decentralized unit with capacity below 50 cubic meters per day or about two cubic meters per hour yeah thank you very much for both questions I think both about the scaling up of the process so I think this this technology is really scaling a very very early stage we are kind of very very careful cautious in terms of you know claim that this technology can be used for how big the scale it is but theoretically or if you just look at a mechanism fundamental mechanism there's no any limit of this technology cannot be used for much larger scale even the primary treatment so we start with the very small scale demonstration like you know bench top devices and also the flow rate currently is pretty small like there's only a few milliliter per minute something like that I think one of the biggest challenge at this point is that the actual development especially when we want to combine the the macro scale and micro scale enhancement especially when we when we need to use nano-wile structures on the actual as I mentioned in my presentation even the best the actual materials we have with the nano-wiles you can only last for a couple hours with the you know synthetic model we prepare in a lab and then it is probably good for some point of use devices for our emergence emergency applications at this point so for these cases you probably just use one time or you know you only need to last for a few minutes on and off but at least for this kind of design for large scale applications that is definitely not ready yet even for pipeline applications but we only use the the macro scale enhancement without the nano-wiles just basically designing bulk electrodes or designing assistance by you know different configuration of the electrodes we will be able to already enhance the electrical stress at certain locations by at least 20-30 times so in this with that direction actually it's already getting much closer to skating up but to be honest in that case the electrical stress will not be pretty in most cases will still not be strong enough to kill microorganisms just by electrical treatment itself so in that case most of these still need to be combined with either also nation or copper or other disinfection process but that should be able to significantly reduce the doses of the conventional disinfectants so yeah so basically we're also considering all these where you know which you know whether the technology can be skating up or not or which part but definitely this is something we want to we want to you know push forward in the future thank you very much thank you Professor Xi and we also have a question from Urs Teria so how do you guarantee a long-term operation or organization of OMB is there some long-term funding for this? yeah that's a really good question that I often receive so yeah right now we don't have any long-term funding we're trying to get funding for it but it's not so easy because it falls into different categories and yeah there's not really a specific funding for this type of infrastructure yet in Europe at least in the U.S. they do have it but at Europe it's more difficult so right now I'm doing this as part of my postdoc and we are trying to yeah get it funded just from other project that we have funding from but the idea is to in the future through funding that hopefully we would get is to have one person dedicated to it half a day a week to revise the membrane data to upload it and to yeah to make it sustainable but in the end like the real vision the idealistic vision would be that it would sustain that it would be sustained by the community itself so not that the OMD team would be uploading the data so may I quickly react to this or you know we had we are kind of developing this platform for pathway prediction in oxidation processes and we actually had the problem of the long-term funding because it doesn't count as like research project so the National Science Foundation will not fund this and also the our institution does not fund it so it's very difficult to kind of have such databases in long-term there is a database from NIST in the US for oxidation kinetics and this was financed until maybe the 1990s and since then there's no new data in there and I mean it's still very useful but it's a pity then it was discontinued with the retirement of the people who were in charge of it so I think it's really important to think about the long-term funding of such a platform to guarantee that it will also be active in 10 years from now yes it's a very valid point yes however hopefully we would be able because now I'm negotiating with different journals to make it more automatic so that we are not depending on the individual researchers but this is just part of it of course the database should still be there also in 10 years so yeah thank you for the comment it's an important one okay so we have another question for Ria sometimes the journals are not interested on publishing regular performance papers for memories as there may not be an innovative component in the information presented how the OMD would tackle this situation also with the OMD cover ultra-filtration memories in the future yeah so we would like so let me first answer the second question so we would like to extend it to ultra-filtration memories so if you have interest in collaborating we're more than welcome to open the OMD to other universities and other researchers and regarding the first question so the idea is that journals would mandate researchers to upload their raw data into an open repository and that's via data screening tools the OMD would be automatically fed from this open repository so then the journal is actually kind of the intermediary between the researcher and the OMD and this would make it completely self-sustainable okay thank you Ria for the answer so I think it well it is a very meaningful thing to work on but it might be very difficult to keep working on it right so we also have a question for Professor Siam so what is the cost estimation of the for treatments? Yeah so that's also a very good question we always ask ourselves so but the answer so answer is that still too early to estimate the cost at this stage especially depends on the scale right and then like but I can tell you that the the main cost will really be the capital cost of the device right so rather complain to others in the chemical disinfectants you are consuming a lot of chemicals but in this case the energy consumption is really really low much lower than conventional electric fuel treatment which maybe at least two or three orders auto-magnetic lower but also even lower than UV or also nation at least one auto-magnetic lower because we only generate passes which are not supposed to be very small current so the energy consumption the electricity consumption directly converting to a cost is extremely low almost negligible but really the main cost is the is the capital cost of the system to generate the electric passes we need and also the stability of the actual if they can be really really stable lower cost can be much lower thank you Thank you Professor Sia and also we have another question for Professor Van Quinten wish to know professors observations on application of ferret for treatment of recalcitrant pollutants yeah thank you very much for this question I think that's very interesting question I mean there has been quite a lot of research on ferrite to oxidize micro pollutants and ferrite is quite a powerful oxidant but it's also quite selective so you don't have this broadband oxidation capacity as for example ozone where you have direct ozone reactions but also always radical reactions and then the other thing is that so far there's no commercial production of ferrite so it's still quite unclear whether ferrite could actually be applied in larger scale treatment so I think they're still missing and you know the ferrite the synthesis is not so easy and is relatively expensive so I think it's at the moment moment it's not competitive to other oxidative treatment thank you Urs and we also have two questions for you the first one is biodegradable organic matter how an after filtration system will it still be anti-microbial as per the graphs in normal cases I didn't understand the beginning of the question I can type the question in the chat box for you so the biodegradable organic matter typically the biodegradable organic matter doesn't have anti-microbial activity so typically this degradation of the biodegradable organic matter leads to a better stability of the water so then for the distribution system you don't need such high residual disinfectants and this leads to a much better quality so in many countries in Europe such as Switzerland, Germany the Netherlands, Austria there is only very little use of disinfectant residual in distribution systems because there is usually a bio-filtration to get rid of the biodegradable organic matter so the microbial regrowth in the distribution system can be limited and this is the main reason why we do a biological filtration to get rid of these compounds Hello, I think that we lost Professor Yuman so in terms of the questions we do have we have received some more but I think that considering of the time I would recommend that we follow up on the conclusion of this I would like to conclude this webinar on behalf of IWA and the SGS and before concluding I would like to invite all of you to attend our following webinar on sunny action understand urban sanitation regulation challenges is in partnership with WaterLynx and it's going to be next week on 8th of February and I also want to invite all of you to join our networks of water professional you can use this exclusive discount that we have for a 20% discount off for a new membership and on behalf of IWA and the SGA I would like to thank for all the speakers for attending today and also the participants for making all the questions and coming to our webinar thank you everyone