 Good morning and good afternoon dear friends and colleagues. I am Long Wang from the WhatTheChannel. I would like to send a very warm welcome to all of you to the IHE Delft Alumni Partner online seminar, a collaboration between IHE Delft and the WhatTheChannel. This seminar series consists of a collection of presentations by our speakers. It is geared towards a broad audience in different domains of expertise. It is my great pleasure and honor to introduce today's presentation and our speaker, Professor Marcos von Spelling. He is a full professor at the Department of Sanitary and Environmental Engineering Federal University of Minas Garais, Brazil. He is an IHE Delft alumnus and Professor von Spelling maintains very close contact with IHE since many years. He is the co-author of a respected collection of publication, including research papers, books, and many of which were translated into Portuguese and Spanish. I'm sure they are all very much appreciated by practitioners and also academies. He has been nominated an IWA fellow and an international honorary member of the American Academy of Environmental Engineers and Scientists. And very recently, Professor von Spelling was awarded the prestigious IWA Global Award, Global Water Award in 2021. And with that, our sincere congratulations to this great achievement, dear Marcos. In today's talk, Professor von Spelling will feature simple sewage treatment processes in low and middle income countries. In the course of the webinar, we look forward to hear about different low cost solutions that are out there, what make them suitable for low cost and make them suitable for low and middle income countries. And we are also looking forward to see what the big challenges are in terms of sewage treatment needs. Before we begin with the presentation, I would like to take a brief moment to mention some logistics and housekeeping matters. Please, could you all mute your mic throughout the presentations? And we also welcome you to have interactions with our speaker by posting questions in the chat box. We will collect all these and address them in the Q&A session that will follow. All information and recording of our webinars are available at the WorldChannel website, as well as the IHE dedicated website. My colleague Abraham Abishek will share the link in the chat box. And lastly, we would like to thank Ms. Maria Laura Sorrentino, who is also with us today for mobilizing IHE's faculty, students and its very active alumni network in organizing this webinar series. And without any further due, I would like to invite Professor von Spelling for his presentation. Please, over to you, Professor von Spelling. Thank you very much. Good morning, good afternoon, good evening to so many of you. I'm very happy to be here. I see the large list of participants here. It's fantastic. It gives me a lot of enthusiasm to share a discussion with you. And thanks a lot for the invitation for IHE. Maria Laura, you have been superb in the connection and keeping everyone always in the same pace and joining all the large program you have with alumnus. And also to the many friends, I have it at IHE, Professor Damir, who coordinated a fantastic project or sanitation for the urban poor. And Professor Carlos Vasquez, who I also saw his name here. I keep contact with him because I'm a guest lecturer in a course coordinated by Carlos Vasquez and many other friends I have at IHE or the professors and the students. And at Walter Channel has been a pleasure long and Abraham for coordinating this. And all to all participants again. So I think it gives a lot of responsibility for this talk. I will start sharing my presentation now. My presentation, I will cover simple sewage treatment processes in low and middle income countries. So we can see we'll talk about simple solutions. We will cover low and middle income countries and also shortly I will make an association with climatic conditions. So this gives more or less the framework of what we will cover here. So as it has been told I'm a professor at the Federal University of Minas Gerais Brazil. I am based in the city of Belo Horizonte, which is in Southeast Brazil. Okay, so what are the challenges we have to face in low and middle income countries when we're thinking about sewage treatment. Well, many, many challenges. I've just listed a few of them here. In most of the cases, we have a low coverage in terms of sewage collection and treatment. And even when we have coverage, even when we have treatment processes, we notice that we have an unsatisfactory performance at many treatment plants, regardless of process of activated sludge, stabilization funds and so on. In many cases we have an unsatisfactory performance. We also, we are faced with a challenge, which pollutants to remove. In most of the cases, we aim at removing organic matter and suspended solids. These are the major macro pollutants we aim to remove at most of our treatment plants. But we are pressured on many sides, especially from the more developed countries in which they are on almost on a routine basis now removing, or for many years, removing nutrients, nitrogen and phosphorus, thinking in terms of electrification control and other aspects related to nitrogen and phosphorus. We also have the challenge of removing pathogens. In many cases, they are very important, especially in our condition of less developed countries or middle income countries. And micro pollutants, we observed, we read the literature and I was focusing on removing micro pollutants that developed countries are talking about micro pollutants. How can we organize such a huge agenda and put this into perspective and select what shall I do next? Okay, and also we see that in many cases the regulations are based on high income countries. So many countries of middle and low income countries, they simply copied legislations from high income countries, which, as you can see, makes things very difficult. If we have to remove all of this. Okay, and again, we could be talking about technology and management. I will talk mostly about technology now, but I should take the risk of saying that most of our problems are related to management, because technology, as we will discuss, we have a large array of possibilities that we can use so choices are not our problem. Okay, so management problems are in most of the cases what we have to face. The presentation outline I will have so I will shortly show an open access literature. And long has already mentioned about some publications, some books I have been involved with. I will share with you the links for this open access literature. We will cover it as I told simple methods for a suits treatment and low and middle income countries. Of course, we will not have the time to describe the treatment process. So, most of the time, it will be dedicated to discuss about their applicability, a comparison in terms of performance and capacity of removing pollutants, and the focus will be mainly on domestic wastewater sewage. So, we will not cover, for instance, industrial wastewater. And also, we will talk about more on communal solutions or municipal wastewater, urban wastewater. We will not be able to cover on site treatment just for one household. Okay, so it will always be for a group of households. So what are we could say open access literature on simple methods for wastewater treatment. In many books, IIT Delft, Damir Carlos Lopez, they have made fantastic books, some of them available as open access. I'm listing here a complimentary possibility published by IWA International Water Association publishing. So we started in 2005 with these books here, which are called biological wastewater treatment in warm climate regions. Volumes one and two, they are large books summing up, they have more or less 1500 pages. In 2013, we negotiated with IWA in terms of asking them to make them free available to everyone, everywhere in the world, so they are now, or for some years from now, they are open access. You can see the links, the link here. Some years after we launched the large books, the two volume books, IWA publishing decided to split into a collection which they called biological wastewater treatment series. We also download volumes one to six. So these are the treatment processes we covered in the series of books. And very interestingly, later on in 2017, a group of people from IWA, from the wetlands specialist group, published a task force, and they made volume seven for treatment wetlands, which was the latest addition in a very welcome. And we have for this treatment wetlands, a Spanish version and a Hindi version as well. Well, last year I published with other colleagues, one from the United States, another one from the same university, this book assessment of treatment plant performance and water quality data. So this is mainly for helping people to plan monitoring works, how to interpret monitoring data, how to use, how to connect statistical analysis with evaluation of a performance of a treatment plant, and also quality of rivers, water quality in rivers, lakes and so on. So this is also a somewhat large book, 600 pages, and many Excel spreadsheets freely available for downloading. Okay. So now we're coming to the processes I would like to cover. Only the main treatment processes. We have a very large list of possibilities. We will cover only the most used ones. And I come from a warm climate region. Many of you come from warm climate regions as well. So I will make an interaction between low and middle income countries and the climatic conditions. I come from Brazil. I will quote several experiences from Brazil, many those in which I have been involved with. Okay. So I think we think in terms of climatic conditions, one billion people in the world, more or less one billion people live in the tropical zone. You know, if we also include some subtropical zones, this adds up to 1.5 billion people. So of course, if we think in terms of biological wastewater treatment, this makes a difference. What are the possibilities we can use if we have very favorable climatic conditions, meaning high temperature, and in some cases also high sunlight penetration, and the need for simple solutions. So we are going to discuss about that. So these are the statistics from Brazil. We still have a lot to do in terms of wastewater treatment coverage. But this is just to highlight to you, this is one of the several slides I have about this. I will show this one, the number of wastewater treatment plants per grouping of treatment processes. So stabilization points are the most widely used treatment process in Brazil. We will discuss about them. In the sequence, up flow anaerobic sludge blanket reactors, UASB reactors, either alone or in most of the cases and preferably followed by a post treatment stage in order to improve the effluent quality. If we sum up these two, you will see that anaerobic treatment is widely employed in Brazil, thanks to our favorable climatic conditions. And then we have other treatment processes like activated sludge and so on. So let's start now with stabilization ponds. Okay, facultative ponds. They are the most widely used variant, not only in Brazil, but they are hugely used in many, many countries. I think in terms of the United States, we should think, well, they don't have good climatic conditions in the north of the United States. There is a fantastic map I won't show here because of time shown 8000 stabilization ponds spread all around the United States from east to west from south to north. So regardless of climatic conditions, they are there, they are being used. But, and also, for instance, in Australia, they are the dominant treatment process. In France, more than 3000 stabilization ponds. Okay, but of course they have their difficulty as we will discuss. They are a very simple treatment process. They are limited in their capacity of removing organic matter. So we don't find very large treatment efficiencies, but they are able to remove many pathogenic organisms, though very important in terms of this. The major problem is the large land requirements, as we will discuss. So facultative ponds very important in many countries, which are represented here by all the participants who are joining this presentation. Because facultative ponds alone, we could call them primary facultative ponds, they take up a large area, one possibility to decrease the total length requirements would be to start the treatment using anaerobic ponds. So anaerobic ponds could be a possibility. And then you could remove 15 60% sometimes even more of the organic matter in the first stage of anaerobic anaerobic ponds and then decreasing the length requirements for the facultative ponds. So that's good. Some people say that, okay, that's the best arrangement. We should not use primary facultative ponds alone. We should always integrate them with anaerobic ponds. But now we have anaerobic reactors, which are open reactors, and we are concerned about problems with bad smell. So you can see here that ideally these treatment processes should not be surrounded by population because there could be complaints related to mild orders. Okay, now we improve our capacity. If we aim to remove pathogenic organisms, we can include the stage of maturation ponds. This is the largest system we have here in Brazil. It occupies 70 hectares, 70 hectares. There are much larger ponds in Argentina. They have 300 hectares in Australia, 300, 400 hectares. But in our case, that's the largest system. Notice that if we are aiming to remove only organic matter, just the anaerobic ponds and the facultative ponds could be sufficient. If we want to add an additional objective, which is removing pathogenic organisms, and then namely removing all categories of pathogenic organisms. Pathogenic bacteria, viruses, protozoan cysts, and helmet eggs, maturation ponds will do a superb job. Ideally, they should be arranged in series, and as you can see, it takes area. They are extensive treatment process, natural treatment processes. In Brazil, since I told you that we are applying upflow anaerobic sludge-blanket reactors, UASB reactors, one possibility could be to have the first stage. Instead of having anaerobic ponds, we could have a closed reactor, controlled reactor with higher removal efficiencies compared with anaerobic ponds. And then we could have the post-treatment, either to improve in terms of organic matter removal and, most importantly, also incorporating removal of pathogenic organisms. Okay, so this is a summary of important elements in the decision process, which process should I use. So these are typical removal efficiencies of the main arrangements I showed to you in terms of BOD, COD, in terms of coliforms. So you can see, well, removal efficiencies are not spectacular. They are in the range of 75% to 85% for BOD, slightly less for COD. We are not able to remove well suspended solids and also nutrients in these typical arrangements, but we are able to remove very well coliforms, especially if we incorporate maturation ponds. And requirements in warm climate countries are between 2 to 4 square meters per inhabitant, if you apply only a facultative bond, and more if you incorporate maturation ponds. Constructed wetlands, a treatment process that is increasing the number, we have thousands of tens of thousands of units, such as that in operating in Europe, in North America, and in other continents as well. A widely adopted treatment process are the horizontal subsurface flow wetlands. They need to come after a pre-treatment stage, in most of the cases, after septic tanks. But they are also applied after anaerobic baffled reactors, and in Brazil, we are starting to apply them after UASB reactor as an additional possibility. They are a natural treatment process. They will use a lot of area as well. Here I'm showing one in our experimental site. This one is for treating 50 inhabitants, 50 population equivalents. That's the real wetland, because it has plants. That's just a controlled unit for research purpose. It's an unplanted unit. It is a filter. And then the liquid falls this way, a subsurface flow. So this means that you don't have wastewater flowing on the surface. That's a positive thing we can discuss about clogging later on. That's a system I like very much. I think it has superb possibilities for application and our climatic conditions. The vertical wetlands, but the French system of vertical wetlands. So that's how they are called in the international literature. It's the French system of vertical wetlands. So the wastewater is discharged on top of the surface. We have a first stage here, a second stage here for improving the effluent quality. You can see that in the first stage we have three units in parallel and they work on an alternated basis. This filter is working and the two others are resting. And then we start operating after some days. We start operating this one and this starts to rest and so on. And then the filter in operation is fed on an intermittent basis on a batch mode. This brings important characteristics we can discuss later on, but in this type of system. Also, we can remove well organic matter, but we can also nitrify, remove ammonia and nitrogen, which is an important thing. This is from our research center as well, an example. We adopted only the first stage. Here's for 100 population equivalents. You can see a top view of the three units comprising the French system of vertical wetlands. And we and also the French in their former colonies in their current territories, they're doing research on do we really need the second stage. We think no, if we have good climatic conditions. And now the further question is, do we need three units in parallel? We just use two units because of the favorable climatic conditions. Usually this takes up one square meter per inhabitant, just the first stage. But if we adopt only two filters, you come down to 0.7 square meters per inhabitant. So again, this is a summary. We won't have much time to discuss tables. You can see that the removal efficiencies in terms of organic matter. So the wetlands stage is very good. I forgot to emphasize when I talked about the French vertical flow wetlands is that they treat raw wastewater. You don't need anything before, you don't need septic tank, the ASB reactors baffled an aerobic reactor. They just receive raw sewage. And this is very, very important because it simplifies the flow scheme very much. And they are natural treatment process, they take up a lot of area. In this case here, for instance, three to six square meters per inhabitant. And the French system is more compact, but still takes up a lot of area. Okay, you ASB reactors and post treatment. You ASB reactors, as we covered, they are widely applied in Brazil in some other countries. They have some units in Colombia, Mexico also explore this India. They implemented many and all these countries that has always been a controversy. Are they good? Are they performing well? We can discuss this later on. But here in Brazil, they are used for small populations. This again is in our research center. This is for 250 population equivalents, up to, that's the, as far as we know, the largest treatment plant using USB reactors in the world for one million inhabitants. It's in my city here, Belo Horizonte. Okay, the removal efficiencies of just the USB reactors, they are not very high. That's a characteristic. This is not a disadvantage. This is a characteristic of the USB reactor. You can see here that they remove between 65 to 70% of the beauty, for instance. And now we have to think, okay, but they help a lot. Now I have to think in terms of a post treatment stage. They are very compact. You can see here we started with extensive systems, natural treatment systems. Now we are coming to a compact treatment system. The land requirements are very, very small. Here in my city, Belo Horizonte, as I told you, we have this large, this number of USB reactors comprising one million inhabitants. And the post treatment is by trickling filters. Trickling filters is being widely adopted here in Brazil, in my state as well. This should say that it's the dominant treatment process. If you don't have a large area available, if you need a more compact system, there are USB reactors followed by trickling filters. In some cases, USB reactors followed by activated sludge. So this is a nearby city, very close to my city here. It's a large treatment plant performing very well. A summary again, if you use activated sludge, different alternatives, but we always have to remember about energy consumption, okay? The removal efficiencies are high, but we have energy consumption. But anyway, the arrangement of USB reactor followed by activated sludge among the possible arrangements involving activated sludge is the one which uses less energy and the one which produces less sludge to be treated and disposed of. Of course, we will not discuss about these tables here. This is just to show you that in that open access literature I mentioned to you, we have these summary tables for you to compare many characteristics of many, many combinations of treatment processes, expected average quality ranges of values in terms of concentrations, in terms of removal efficiencies, land requirements, power requirements for aeration, sludge production and so on. So I think these are good summary tables if we need to make a very short comparison, a very quick comparison. Okay, now quickly I will move and discuss with you about the capacity that these treatment processes have for achieving high removal efficiencies. So if we need to remove the major pollutants with a high efficiency. Okay, let's start with organic matter, expressed here for instance in terms of BOD. So we start with low removal efficiencies, moving up to 70%, 80%, 90% and coming up to 98% or even more. We have many possibilities. Some of them we have discussed here, so USB reactor stays in this range here, septic tank followed by anaerobic filter in between. I have not discussed with you in terms of overland flow, it's another possibility, an extensive treatment process. Ponds are not especially efficient in terms of organic matter. We have wetlands, more efficient, and then the compact systems, USB followed by compact systems for post-treatment, trickling filters, activated sludge and of course more advanced treatment processes like moving bed bioreactors, those involving membrane bioreactors, we will not discuss about them. Then you can reach high removal efficiencies. So if we need to remove ammonia nitrogen, the range of possibilities decreases. Okay, activated sludge, but it's not a simple treatment process, but you can achieve full notification. You can apply filters as well. Trickling filters, which we have been advocating, they are very important. If you apply stones, crushed stones or gravel as support medium, you will not achieve high nitrification efficiency. But if you use plastic media, and also even better than plastic media, some sponge-based media, you can have higher nitrification, higher removal efficiencies. Simple treatment processes like vertical flow wetlands or even maturation ponds, they are able to remove ammonia nitrogen. If we need to remove not only ammonia nitrogen, but total nitrogen, so all forms of nitrogen, the range of possibilities decreases sharply. We could apply activated sludge with biological nutrient removal, complex system, but also maturation ponds, they have been shown that they are good not only for removing pathogenic organisms, but they also remove nitrogen in the form of ammonia and nitrogen, total nitrogen. If we need to remove phosphorus, okay, activated sludge incorporated biological nutrient removal, but fortunately we have a chemical possibility. If you add a chemical salt that precipitates the dissolved phosphorus, okay, we can solve the problem related to, for instance, eutrophication. If we needed to remove phosphorus, and if phosphorus was the major constituent causing algal blooms. Okay, and then finally, in terms of disinfection removal of pathogenic organisms, I emphasize again that maturation ponds are able to remove the four categories of pathogenic organisms, pathogenic bacteria plus viruses via inactivation, so on cysts and helmet eggs, it's a physical removal by sedimentation. But of course you can apply disinfection, a compact disinfection for instance, UV radiation, and membranes are fantastic because they are a physical barrier. I have to think, if we want to apply this in a low income region, do we have good conditions for this? So that's a question I'm putting to you. And then coming towards the end of my presentation, the less grouping of slides, it's a personal interpretation of the expected removal efficiencies from the major wastewater treatment process used in warm climate regions and low and middle income countries, okay. We will use this color scheme here. Yellow, if we have only UASB reactor. Blue, if we are applying a natural or extensive treatment system. Blue, if it is a compact, intensive system, as we described. And this other color, this pinkish color here, is if you add an additional step, like a chemical addition for phosphorus or radiation, if you add chlorine for disinfection, okay. And I will show you in terms of low, intermediate, and high removal efficiencies. Thinking in terms of what is a high removal efficiency, I'm thinking about the reality of low and middle income countries. So it's a series of slides like that covering the major pollutants. See removal, starting with the typical removal efficiency. I will not discuss now, because I need to go fast now, about each individual possibility here. I would like to discuss about the grouping of alternatives. Yellow, UASB reactor, in green, the natural treatment systems, and here the compact systems. It's a personal interpretation. I classified as high removal efficiency, UD removal efficiency, which is higher than 85%. Okay. For a high income countries, you could think, no, this is too little for me. I would like to have 90, 95% UD removal efficiency. But I think 85% removal efficiency for the reality of the countries I'm covering here is okay. Intermediate removal efficiency between 70 and 85. And less than 70%, we could say low removal efficiency. Okay, UASB reactor is in the boundary here. So UASB reactor alone cannot do a good job. And here you can see that natural treatment systems are able to provide removal efficiencies, which are in some cases comparable to the compact systems. Okay, so that's an important characteristics. Ammonia removal. Now, ammonia removal is more difficult than organic matter removal. So I classified here, high removal efficiencies, those which are larger than 70%, in between 35 and 70, intermediate and lower than 35% low removal efficiencies. As you can see here, that's okay. Now we have things scattered. Many treatment process are only able to achieve low ammonia removal efficiencies, regardless whether they are compact systems or natural treatment systems. Others achieve intermediate removal efficiencies and only a few of the treatment process are able to achieve high removal efficiencies. We have natural systems and we have compact systems. Total nitrogen removal, total nitrogen removal is even more difficult. And most of the treatment process are able to achieve only low removal efficiency, unless you implement something like biological nutrient removal. Okay, and then even intermediate removal efficiencies only say ponds followed by maturation ponds. So that's a problem. We have to think about this when we establish discharge standards in our country. That was the discussion is somewhat similar. Biological means very few treatment processes give us high removal efficiencies. Most of them will give low removal efficiencies, but fortunately, we're able to get to use processes that give us removal efficiencies if we add chemical precipitation, followed by precipitation and so on, and biological nutrient removal. Okay, pathogenic organisms, I will not cover all pathogenic organisms, just the main indicator organisms. Escherichia coli representing pathogenic bacteria. In most of the compact treatment process, they do not have important mechanisms for pathogenic bacteria removal or for virus removal. The natural treatment processes are more efficient because they have longer retention times and more mechanisms. And of course, as I told you, if we incorporate maturation ponds, we are able to achieve high removal efficiencies. And of course, if you include in any of these treatment process, one stage for disinfection or a barrier like membrane. Okay, you can do a good job. So my concluding remarks would be what is the best treatment process. Because after presenting so many possibilities, it's natural that we think what's the best. There is no best treatment process. Each is site specific, and each is very important. So we need to do very good studies, conceptual studies to select in each case what is the best treatment process. We have to be open to different alternatives. I cannot say, well, I will use only this treatment process because I like it. So under other circumstances, you will need to apply a different alternative. It is very good that we have many, many choices. If you remember that large table I showed you, they showed more than 20 combinations of possibilities that can be applied under our circumstances, either simple treatment process or more complex treatment process. But we do have the choices. Okay, so many challenges. We started discussing about challenges. How can we solve this? There is no other way, instead of moving on a stepwise manner. We have to go little by little, but we have to improve each time. Okay, incorporate organic matter removal, increase our coverage, increase the status of the operation of our treatment process, and then incorporate other pollutants if necessary, and so on, and so on. We cannot tackle all the huge problems we are facing now at Southern. So when we are formulating regulations, legislations for our country, we need to think about this. Okay, now I'm coming to the end of my presentation. Thank you very much for your attention, and I'm looking forward to the questions and to our debate. Thank you.