 Good morning, everyone. I'm Ibrahim Abhishek from the Water Channel. Welcome to the webinar. We are lucky to have with us today Dr. Sergio Salinas, who will be discussing with us how to turn water into wine. Sorry, I meant to say how to turn sea water into fresh water or desalination. But if you think about desalination, it is a potentially miraculous process, at least to a layman. It appears like that to a layman like me. It seems that if we are able to perfect the process of desalination, at least theoretically it will solve all the water scarcity problem of the world. And it appears to the layman that if we can tap into, if we can do this, we can tap into the vast oceans to satisfy our freshwater needs. So the question that comes to mind is what keeps us from doing that? Is it the technology? Is it the cost? Or is it something else? These are some questions that I have personally and I'm sure a lot of us have. And we hope that some of these questions will be answered at this webinar today. And Sergio is the right person to be leading the discussion today because he's a widely recognized expert in this topic. He has a PhD in desalination and water treatment from Technical University Delft. And he has a master's in water supply engineering from UNESCO IHE. He has worked as an expert consultant and as a teacher or lecturer in desalination in several countries in Latin America, Europe and the MENA region. Before I hand over the proceedings to Sergio, I would just like to request you to please put your questions and comments into this tab box here, which you have already located. I see from the introductions that have been coming in and we will keep collecting them throughout the webinar and we will discuss each one during the Q&A session, which will be after the presentation. So please keep them coming, your questions and comments, and please keep this webinar interactive. With that, Sergio, I would like to hand over the stage to you. Please go ahead. Thank you very much, Abraham. Well, it is for me a pleasure and honor to be here in front of my computer and through the Internet being in front of your computers, wherever you are in the world. So this is an introduction to desalination and membrane technology. My name is Sergio Salinas. I work at IHE since 2011 in the field of desalination and membrane technology and I'm part of the group of water supply engineering. I hope that by the end of this webinar you will be interested in the field and perhaps we can get in contact to collaborate together. Let's start with a question if there is a need for desalination. As we know, or we may know, there is plenty of fresh water on the earth. However, for making use of this fresh water on the earth, there are some limitations, starting with the rainfall is not evenly divided. The top right figure, it's a world map in which we are observing the regions and when there is a lot of rainwater or not. Another limitation is that population is not evenly divided. We have areas that are densely populated in brown in the middle figure, or areas which are scarcely populated. More and more we are talking about mega cities as an urban problem. And another consideration is that the water use is not evenly divided. As we are observing in the figure on the bottom right, the use we have of water is very different from depending on the country we are from. Many countries we use water for agriculture, for industry, municipal use, etc. etc. I have to use the click, I forgot. So many countries are running out of water and many more will run out of water. Why is this happening? Because we are abstracting more than available renewable resources. And this has happened already for many years. In the future this is going to get worse because of population growth. Last year the World Population Prospects report estimated by 2050, the world population will increase to 9.7 billion. In addition, the economies are influencing the water use we have. The better we have our income, the more water use we may use of it. So as a result of this exaggerated attraction of renewable resources, we come across to what is the water stress all over the world. And we are looking at here, not from water stress, from the Water Resources Institute, highlighting the areas in the world where water stress is high in colors red or reddish. There are some areas already in the world in which there is arid plant or low water use. Those are the great areas. It is expected, well, yesterday I came across to a Twitter from the United Nations World Water Assessment Report, in which they mentioned that by 2050, 40% of the population is expected to live under severe water stress. Including almost the entire population of the Middle East and South Asia, plus significant parts of China and North Africa, which is a worry in fact. And this is going to happen because of population growth, urbanization, climate change. How can we solve these local water stresses? Well, we can start by saving water, by increasing the productivity in agriculture and industry, reducing leakages in public water supply, and by applying progressive tariffs in the distribution of water. We can also transport water, large distances, and I think there are many countries with examples of this, of several hundreds of kilometers of transport from one basin to a region where there is not so much water. Another alternative is storing, for instance, the overflow in rainy season in aquifers. So this is possible, but not everywhere. It's feasible. It depends very much on the geology and the soil aquifers. And then, of course, we have water reuse. And we should increase water reuse for industry or domestic waste water in agriculture, for instance. And finally, we have desalination as an alternative to alleviate these local water stresses. And desalination not only of seawater but also of brackish water, which is present in the groundwater, and also of wastewater. So to the question, can desalination alleviate water scarcity in developing countries, we believe that seawater is considered to be a drought-proof water source. As it does not depend on river flows, rainwater, rainfall, reservoir levels, or even climate change. So it's a kind of infinite resource. And we believe that desalination may be an option to alleviate scarcity, perhaps with priority in industry, and of course in coastal cities. Let's talk about now what are the desalination technologies or the main desalination technologies that are applied in the world. There are basically three main groups, starting with distillation processes, then we have membrane processes, and then ion exchange. In the case of desalination processes, we can have two types of thermal technologies, starting with multi-stage flash evaporation and multi-effect evaporation. These thermal processes require a form of energy in the form of a steam and also electrical energy. When we talk about membrane processes, we can differentiate reverse osmosis membranes, none of insulation membranes, electrolysis, or electrodeionization, which demand a form of energy in terms of electricity. And we have ion exchange, which is mainly used for polishing water, for instance, for municipal and industrial use. And we have resins that are in charge of cationic and anionic removal of ions. The form of energy in this case, we have chemicals for regeneration. What are the applications of these technologies? If we are thinking about sea water, we have basically two options, either distillation, a thermal process, or we have a membrane-based process, which is reverse osmosis. If we have brackish water or even fresh water, we can apply mainly reverse osmosis and electrolysis. If we are interested, for instance, in polishing, in further removal and further decreasing the concentration of ions in the water, we can use ion exchange. And if we have, for instance, surface water or groundwater, that this heart would have with a high concentration of carbonate, for instance, and with high concentration of organic matter, non-concentration could be perhaps the most appropriate solution. The normal operation range of these desalination technologies is observed in this figure. In the horizontal axis, we have the total dissolved solids from 100 mg per liter up to 100,000 mg per liter. And we can start here from the bottom right to the top, in which we see that distillation can be applied for waters starting from 25,000 mg per liter up to 100,000. Ion exchange, as we mentioned, can be used for polishing further removal of ions in the water, concentrations less than 500 mg per liter, electrolysis between 400 and 3,000 mg per liter, so fresh water and slightly brackish water. In the case of brackish water, we can use reverse osmosis membranes that are specific for sea water or specific for brackish water. The salinity of sea water is not constant all over the world. Actually, it has a wide range. The average salinity in the world is about 35,000 mg of salt per liter. Nevertheless, we can observe regions, especially in the Middle East, where the salinity of the sea water can increase up to 45,000 mg per liter. In the figure on the left, we can see the map of ocean salinity, and we can see here that the salinity of sea water depends on the location. It depends on the water bodies that are discharging in the sea, the amount of fresh water rainfall, etc. One of the oldest technologies for desalination of sea water is distillation. Perhaps the oldest technology available for sea water desalination is mainly used by the sailors when they have to travel many miles deep into the sea. In this process, the dissolved salts remain behind a fresh water, and vapor as energy is boiled away. Then we have a condensation with heat loss via air or water cooling to produce pure water. In this case, we have three products. We have the feed water, we have the distilled water, and of course, we have a highly concentrated also solution, which is the brine that can be discharged perhaps back into the sea. Nowadays, we have no sufficient processes, learning from the experiences in the past, and this is called a multi-effect distillation process, in which we have, for instance, starting from the left to the right, we will have a sea water feed that is introduced into the first effect. Into the first effect, we have a steam that is coming from a boiler that is going to be in charge of increasing the temperature of the sea water that is being fed to this first effect. The steam water is going to be produced, is going to be evaporated, and this vapor is going to be passed into a second mix effect, the second effect. And we can see here also that the brine of the first effect, which is with high temperature, is going to pass to the second effect, and we are making use of the temperature of the sea water in the first effect. We are going to make use of the vapor that was produced in the first effect to generate a second batch of vapor in the second effect, and so on. So, we will also have here a condensation happening in each effect. In the case of the first effect, the condensate is returned to the boiler side. The second effect, the condensation will be produced as freshwater product into this manifold, which is going to collect the condense freshwater of all the effects that could be present in this multi-effect distillation unit. In practice, we could have up to seven, eight effects to make use of this residual heat of previous effects. Another technology that is available for desalination, and perhaps is the dominant in the market, is reverse osmosis. In this process, we make use of membranes that have various mold pores that could have basically two configurations. As flat sheets or as capillaries. In reverse osmosis, the water is forced to flow through the pores of the membranes with the help of high pressure. So, we need a lot of energy, and we will discuss about this later. And we apply this high pressure to overcome the salinity of the water, so this is overcoming the osmotic pressure of the water, and also to overcome the hydraulic resistance of the membrane itself. And eventually, the pressure required to overcome the fouling development on the membranes. In these reverse osmosis membranes, salts cannot pass the small pores. So, they are rejected. In practice, we are talking about 99.7, 99.8 rejection of salts present in the water. In this table, we can see a comparative removal by different technologies, depending if you are talking about inorganic compounds, organic microorganisms or suspended and colloidal matter. So, for instance, reverse osmosis is a technology that is able to remove monovalent ions, divalent ions, organic compounds, microorganisms, suspended colloidal matter. Nonofiltration is also very effective for divalent ions, organic compounds, microorganisms, suspended matter, but not so much for monovalent ions. So, it's very specific, for instance, for removal of hardness in water, removal of color. Ultra-filtration, microfiltration, they are membrane processes, demand low pressure, and they are specific for removal of microorganisms and suspended and colloidal matter. And electrolysis, very specific, very efficient in the removal of ions present in the water. Nowadays, more and more, besides quantity for the production of water, we are talking about removal of specific micro pollutants. And in this case, reverse osmosis has proven to be a very robust technology, not only for producing water in quantity, but also in very high-quality product water. Briefly, and grossly, we can talk about the components in a seawater desalination plant. And we will have, from left to right, the ocean, the seawater source. We will have an intake that is going to be the first step to bring the water to the pretreatment. There is a lot of discussion about what is the best type of pretreatment for different conditions and different locations in the world. We can talk about media filtration versus membrane technology. And more and more, in case of alderblum events, the introduction of dissolved air flotation as a strategy to cope with difficult waters. After pretreatment, which is in charge of guaranteeing a certain quality, specific for the reverse osmosis membranes, we will have a high pressure pump operating at pressures from 50 up to 90 bars in charge of forcing the water to pass through the reverse osmosis membranes. In the reverse osmosis, we will have on the left side the feed water. On the right side, the fresh water. And here at the bottom, the concentrated stream for the brain discharge. We will talk about this later when we talk about environmental concerns. The fresh water quality after reverse osmosis membrane is aggressive in nature. So we need to remineralize. We need to bring back minerals. So let's remember these reverse osmosis membranes have decreased the salinity content by up to 99.7%. So the fresh water, the product water needs to be post-treated. And here we are going to correct the pH and we are going to bring back minerals like calcium, like magnesium to improve the hardness, the buffer capacity of the water, before it can be transferred into the distribution or later consumption in our houses. An example here of one of the famous plants in the United Arab Emirates, Fujairi too, is a combined power plant with a total production of energy of about 2,000 megawatts. And it makes use of two of both technologies. A multi-effect distillation with a capacity of 460,000 cubic meters per day. And the reverse osmosis capacity of about 136,000 cubic meters per day. In this plant, we have a steam that is going to be produced in the power plant and is going to be used by the multi-effect distillation. And we can see in the photo here that the large area actually is mostly used for the multi-effect distillation in comparison in the bottom left with the reverse osmosis membranes that are much more compact in the land use that they required. Another example is a plant located in Ashkelon in Israel. It was a commission in 2005 and at the time was the largest seawater reverse osmosis plant in the world. With a capacity of 330,000 cubic meters per day, it has been expanded to about 400,000 cubic meters per day. And the type of contract or this plant was a built-on operate transfer type, which is still applied. The footprint of this plant is about 70,000 square meters of an area of about 350 meters times 200 meters. The third part of my presentation is about the desalination trend worldwide. And actually there is a database accompanying in the UK called Global Water Intelligent and they compile every year a report about the desalination industry. In 2020, they reported about 25,000 desalination plants all over the world in over 180 countries with capacity over 100 million cubic meters per day. If we talk about drinking water production with reverse osmosis, we are talking about 24 million cubic meters per day produced from seawater, from brackish water about 9 million cubic meters per day, and about 3 million cubic meters per day produced from freshwater. This is an equivalent to serving over 330 million persons in the world but rendering water supplied by desalination plants at a rate of 120 liters per person per day, which perhaps is not significant but is growing more and more per year. This world map is illustrating the world desalination capacity for the three main sources that are seawater in blue color, brackish water in brown color, and wastewater with water reuse in green color. And we can see here that the region that mostly demands desalination is in the Middle East with a capacity of about 47 million cubic meters per day. Then we have North America with United States basically desalinating brackish water with a capacity of 10 million cubic meters per day. And we have other regions like Latin America with a capacity of about 4.2 million cubic meters per day. The Caribbean 1.5 cubic meters per day mainly seawater. In Europe we may use about 65% from seawater desalination. North Africa Middle East the regions that mostly demand the application and use of desalination. Sub-Saharan Africa about 2 million cubic meters per day also mainly seawater desalination. And in Asia we have more a combination of the three water sources. Seawater is present but they are also making use of wastewater for wastewater reuse. And a very good example of that is Singapore with a total capacity of about 2.1 million cubic meters per day of desalination of which 55% is seawater desalination, 43% is wastewater desalination. In the case of Australia about 3 million cubic meters per day, 60% desalination of seawater, 22% wastewater use, 15% brackish water. Japan is one of the countries that is also rapidly growing in their economy and in their use of desalination. And in this case they mainly use desalination for industry not so much for municipal or agriculture. And Japan, Korea, Taiwan, these islands or these countries make use also of desalination will equal with equal parts of seawater, brackish water and wastewater reuse. The highest capacity desalination countries in the world are presented in the table on the right. Saudi Arabia is the number one country about 19 million cubic meters per day followed by the United States, the Arab Emirates, China, Spain, Kuwait, India, etc. Other countries that are relevant or that are not in the Middle East are for instance, Mexico is growing. In their next five years they are planning to implement five desalination plants in the northern area of the country. Indonesia is also depending, Japan, Brazil, Chile is also investing a lot on desalination for industry, for the copper industry. And in the figure on the left we can see here the uses that these countries are making use. In light blue color we have for drinking water, light blue or dark blue color for industry and we can see in green color some countries, not all of them make use of desalination for irrigation like for instance Spain, Kuwait, Morocco, etc. So the main application is either production of drinking water or the use of desalination for industry. The total desalination capacity is over 100,000 cubic meters per day and soon as this year projected they expect that by 2030 the capacity all over the world is going to reach about 200 million cubic meters per day at an estimated growth rate of 6% per year for mainly use in the municipal and industry. Two-thirds of the capacity is depending on membrane-based desalination and one-third is depending on thermal processes like multi-stage flash desalation or multi-effect desalation. Reverse osmosis is dominating the market because the investment costs and energy costs are lower than for desalination. 70% of the desalination is happening in the Middle East and North Africa and in the other regions of the world they are growing more and more because of water stress, drought, climate change as catalyzers of alternative sources for alleviating scarcity. 60% of the desalination depends on seawater, 8% depends on wastewater, 20% of the world depends on brackish water but also freshwater and pure water can be further treated with desalination for instance for industry applications. The trend in desalination plants over time is that they are growing in size. In this figure we can see here the reverse osmosis plant capacity versus the time history and we can see here that the capacity is increasing over time. This is becoming relevant and critical because for these desalination processes, pretreatment plays a very important role and pretreatment is going to influence how frequent the reverse osmosis membranes for instance need to be cleaned. This is critical when you have thousands of elements that need to be put on hold for stopping the production because of cleaning with high risk of damaging them in the process. Okay, let's start and talk about the energy consumption in these desalination processes. In this table we can see different technologies that are applied in the production of drinking water. In the second column we can talk about the pressure that they apply in the process. The third column, the energy demand per produce cubic meter in kilowatts hour and in the case of thermal processes, the heat that they demand in the process. In the case of conventional drinking water, they demand very low energy consumption, 0.1 to 0.2. If we talk about membrane filtration with ultra-micro filtration, the pressure range between 0.5 to 2 bars with a comparable energy consumption. Normal filtration with smaller pores do demand a higher pressure to push the water through the membranes with a slightly higher energy demand, 0.3 to 0.5 kilowatts hour per cubic meter. And then we have brackage water reverse osmosis in which the pressure can be actually from 5 up to 20 bars with an energy consumption in the range 0.5 to 1 kilowatt hour per cubic meter. And in the case of seed water desalination with reverse osmosis, the pressure range that is applied is between 50 to 90 bars with an average energy consumption nowadays between 3 to 4 kilowatts hour per cubic meter. In the case of distillation, we need both electrical energy and heat. In distillation, the consumption of energy will range between 1 to 4 kilowatts hour per cubic meter, but we also need heat. Because of energy, it depends on where you are. It depends, yeah, perhaps incentives that you have for industry. Typically in the range 0.05 to 0.1 dollars per kilowatt hour. And in the case of heat, 5 to 15 dollars per giga joule. About cost, we have here in the first column technologies versus the cost in euros per cubic meter. So in the case of seed water reverse osmosis desalination, the production cost is between 0.5 to 1 dollar, 1 euro per cubic meter. Brackage water, the costs are lower, 0.25 up to 0.5. Electrodialysis comparable to brackage water, nanofiltration slightly lower, and ultrafiltration, microfiltration 0.05, 0.1 dollars per cubic meter. But ultramicofiltration do not remove salts, they will only remove microorganisms suspended colloidal matter in comparison with seed water reverse osmosis. Energy is a major cost component in seed water reversal osmosis. Now, let's put in context the cost of producing one cubic meter of drinking water from the sea. For instance, when we go to our kiosk and we buy a bottle of water or a bottle of Coca-Cola, we can pay in the Netherlands from 1 euro up to perhaps 3 euros, which is just 1 liter or even half a liter. Nowadays, of course, large-scale desalination plants have lower costs, but still the production of 1,000 liters of drinking water from the sea is less than 1 dollar, less than 1 euro. But still there is potential to optimize the energy consumption in this desalination process and in this way also reducing the cost of production. This is a representation of the consumption of energy in a seed water reversal osmosis process. And for instance, if the production cost is 1 dollar, about 40 cents of the production come from the amortization, so the payment to the bank of the loan or the construction of the plant. Another 40 cents will be spent in the energy consumption, and about 20 remaining cents will be used for the staff working in the plant, the consumption of chemicals, replacing the membranes in the plant, the cleaning of the reverse osmosis membranes and maintenance. So energy plays a major role in the cost of desalination processes. Here we can see an example of a seawater reverse osmosis plant located in Perth. It's called the southern seawater desalination plant with an average consumption of 3.6 kilowatts hour per cubic meter. This plant receives the supply of energy from a wind farm and also from a solar farm. About 55 megawatts are produced with a wind farm and about 10 megawatts are produced by a solar farm close by in the region. This is a photo of the solar plant located in the region of Perth. It's called the Moon Vida Wind Farm, and they have 22 wind towers producing each about 2.5 megawatts generated by these windmills. And of course the windmills, the solar panels do not produce energy the 24 hours of the day, but they can be used to offset the energy consumption or the energy take from the grid by the reverse osmosis plant. The use of solar parks is growing more and more all over the world. One of the first ones was in Gujarat in India, and it's the Charanka Solar Park with making use of photovoltaic cells. In the table on the right we can see, well I just took it from Wikipedia, but in the last two years there has been a very large investment, development on the implementation of solar parks for energy production all over the world. Not all these examples in this table are going to supply desalination plants, but more and more I think the industry is focusing on the need and the use of renewable energies for desalination. A very perhaps simple example of the potential of solar photovoltaic energy for decentralized desalination processes. And we can see here a photo of a photovoltaic cell at the roof of a house in the Netherlands. There are many solar panels here. In this house as an example they generated 3700 kilowatts hour over a period of one year. This amount of energy is equivalent to the energy needed for desalting about 1000 cubic meters. This considering the total energy produced divided by the average consumption to desalinate sea water. The yearly consumption of drinking water from the tap in this house equals about 120 cubic meters. So of course there is an investment cost, but the application of renewable energies can be applied at different scales from large desalination plants to also decentralized systems. Now briefly some of the environmental concerns that are related to desalination. So desalination, I quote a definition from a paper from 2008 that says, desalination is a water treatment method that is often chemically, energetically and operationally intensive, focus on large systems and thus requires considerable infusion of capital and generating expertise and infrastructure. So what are the main environmental concerns in desalination? There are many actually, starting with the concentrated discharge, marine pollution, the influence of sea water intake in marine life, the use of chemicals in the treatment of drinking water, the disposal of materials in desalination plants, land use, the impact on climate change to the energy use and the greenhouse gases emissions. So there are many concerns, but there are also many sustainable solutions that are technically feasible. If we talk about the greenhouses, we can minimize and compensate the energy use. If we talk about the concentrate disposals, we can minimize the impact through this person, concentrate through multiple diffusers in a suitable marine site. We can treat all the backwashing and cleaning waste to reduce the marine production. We can use a surface of submerged intakes with low intake velocities. We can implement low, we can minimize the consumption of chemicals, or we can just avoid the use of chemicals in the treatment of sea water. We can improve the recyclability and reuse of the materials. And we can also minimize the land use and landscape to a specific site location and perhaps by making use of technologies that are also compact in their engineering. Finally, I'd like to present to you what IHE DELF is working on and is busy in the field of desalination. We do research in desalination and membrane technology, mainly in reverse osmosis systems, and we are focusing on the problem-focused solution-oriented demand-driven research questions with the interest to translate practical problems into research projects. And we work with water quality methods and tools to quantify the folding potential of water to optimize pre-treatment efficiency. We work with the modeling of folding and scaling. We are interested in the removal of micropollutants, personal care products, medicines that are present in water, assessment of pre-treatment, and also dealing with post-treatment for the reverse osmosis permeates, working also on the development of licycle assessment, environmental impact assessment, or concentrate disposal, etc. Our Institute IHE DELF has three main pillars, working on desalination on education, institutional strengthening, and also research and innovation. And we are also busy in these three pillars in the group of desalination. We have our PhD program that is specialized in the field of desalination and membrane technology. Our Master of Science on Water Supply Engineering has a specific module on desalination, and we are also contributing to the Graduate Professional Diploma Program on Water Supply Engineering and Ways Water Treatment Technology. This year we will start our online course on desalination and membrane technology. This presentation perhaps is an introduction to what is coming ahead, the basic principles, application, design of this type of systems. We offer tailor-made training. So wherever you are, if you're working in the water sector, and you're interested in having a training for your colleagues, for your company, we are available, so please contact us. All our research is also open access, and so everybody can benefit from that. We are interested in strategic partnerships with governments, with universities, research centers, water utilities. So the aim is that our research should have an impact, should be problem-driven. And with the aiming at reducing the impact on environment, promoting circularity, et cetera. So concluding, desalination by itself cannot deliver the promise of improved water supply unless underlying weaknesses are addressed, like the reduction of non-revenue water, appropriate cold recovery, environmental impact assessment before implemented these kind of processes, the need for expertise on these technologies for a sustainable implementation of them. And it's very important to have an integrated water resources management involving all the water cycle. With that, I would like to thank you all for your attention, and I'll be happy to contribute with some answers to the many questions you may have. And if not possible during this webinar, please reach out to me through this email, and please visit our website, www.um-ihe.org, for information of all our educational capacity-building offer in all the water cycle. Thank you very much. Thank you very much, Jio, for your great presentation. We have to take a lot of questions, so let's start. First of all, WikiF asks if microplastics are a concern in reverse osmosis of seawater. I think microplastics are a concern more and more in all water bodies. Not so much a concern in the production of drinking water, because results, at least in the Netherlands, have demonstrated that water treatment is able to remove microplastics. But you all are aware, I think, of the plastic pollution in the oceans, which is a big deal of a problem. In this regard, let's say, we should be concerned with pollution of our water sources, like seawater. But I think in the drinking water production process, we will be able to deal with the removal of these microplastics if they are present in the seawater. But I think it's an issue for all of us. The next question is from Dr. Sudeep Pal, who asks, how frequently reverse osmosis needs replacement? RO is the only option, or do you believe there are alternatives? That's an interesting question. Thank you very much. In practice, it is said that the replacement rate of reverse osmosis membranes is about 20% per year. So let's say in about five years, you will replace all your membranes in the plant. Nevertheless, this is just an indication. There are plants that have a lifetime of their membranes up to eight years, even cases of 10 years. What influences? It will depend very much on the type of intake. It will depend very much on the type of treatment you have in your system. And in this way, you will influence the frequency of cleaning of your membranes, which will relate to the lifetime of them. As we have seen at the moment, the two main technologies for this alienation are reverse osmosis and also thermal processes like multi-effect distillation or multi-stage flash distillation. More and more, as you might recall, the figure with the growth over time, reverse osmosis is dominating the market because of the investment costs and the lower energy consumption. There is more potential of making use of renewable energy sources that will further decrease the cost in the process. And reverse osmosis has also the advantage that has a high productivity in comparison with other membrane processes that have niche application areas like forward osmosis, microbial desalination cells, and other configurations of reverse osmosis like pressure retardant osmosis and reverse osmosis. So there is a lot of research going on, but in practice, we have these two main technologies. The next question is from Jean Lindsey, who asks if continuous drinking of freshwater produced from desalination represents a health threat in the long run. Let's talk about two things. First one, we don't drink directly the water that is produced by reverse osmosis. There is the need for post-treatment. And in this post-treatment, we correct for the aggressivity of the water, so we bring back some hardness, and we also bring back some minerals that are essential, like calcium and magnesium. And as a last stage before distribution, we will also disinfect the water, so it's free of any microorganism that could be a pathogenic nature. So in the long term, I don't think it's going to be a threat. There are many reports on this. The water quality will satisfy WHO considerations before it's used for drinking purposes. Next, I would like to put up two questions together. I just read them quickly, and I reckon they were kind of related. Let's see. First question is, would there be a table comparing capital costs, O&M costs per cubic meter treated of existing treatment plants? How does this affect water tariffs? And the second question is, any comparison of production costs between usual water treatment plants and desalination plants? So I guess the two questions are related. How does a cost compare to existing sort of regular treatment plants? And what kind of effects does it have on water tariffs? I think the first question was answered in two of the slides that I presented. So desalination is, of course, demanding a higher energy consumption in comparison with fresh water or conventional drinking water production. The average consumption is 3 to 4 kilowatts per cubic meter, while in conventional drinking water, it will be 1.2 kilowatts per cubic meter. And the second part of the question was, could you repeat the other hand, please? How does this affect water tariffs? Oh, yes. In order to achieve the lower costs that are reported in desalination plants, less than 1 euro per cubic meter, I think the record is about 50 cents dollars per cubic meter. It depends very much on the cost engineering that you have in your plant. Because the cost of energy may not be the same in nighttime that, for instance, in daytime. So depending where you are, for instance, you will want to produce most of the water during the nighttime than during the daytime. So the energy policies depend per country, depend per supply, et cetera. This will also influence the final cost. We have been getting a lot of questions on costs, and that seems to be a central concern, a central point of curiosity for a lot of the audience members, including the next question, which is from Bijimal Jose, who asks, what is the cost-effect ratio of desalination, the saline water, I suppose, is being used for irrigation? I don't think that there is most of the cost in a desalination process comes from the energy component, as you may recall. So 40% comes from the payment de-amortization cost, 40% comes from the energy cost. And the rest is staff, consumption of chemical, replacements, et cetera. So this energy consumption is not going to change if you are producing water for municipal use or if you are going to use it for agriculture. Perhaps the difference is going to be you don't need to disinfect the water for irrigation, and perhaps the requirements for post-treatment are not going to be the same as for municipal use. I don't think the cost difference is going to be significant. The next question is from Fozul Rizka, who asks, what is the best desalination technology for a small community, let's say 100 people in coastal areas, is reverse osmosis the one? There are many examples. There are many companies from many countries that deliver solutions to these kind of problems. There are decentralized reverse osmosis systems that are making use of solar energy and also wind mills, wind energy to produce the energy for the reverse osmosis desalination. The challenge in these situations is the storage of the energy for application or for continuous production of desalination, but also the frequent start and stop of these kind of systems. That's a challenge. In the Netherlands there is a company called Elemental Water Makers. It's also based in Dalt and they produce these kind of solutions. I've seen in their website, in many presentations, that they have examples for islands and in the Caribbean or in the Pacific Ocean, et cetera. So there are examples. Sorry. I thought the next three questions were kind of similar, so I grouped them together and they concerned sourcing the energy that is needed for desalination from alternative sources. So the first question is, do you see the energy from waves a possibility? The second question is, can we use thermal power plant steam to use in distillation technology to vaporize? And the third is, if brine can be utilized in the production of energy to offset the energy requirements for reverse osmosis? I think the answer to the last question says yes. More or more, we are trying to be creative with making use of the renewable energy sources that we have at hand. It much depends on the efficiency of the processes for them to be attractive. And it depends on the scale of the project. But yes, we can generate energy from the wave movement. I think there are some examples, but I don't know if there are desalination plants that are making use of this kind of energy source. In the Netherlands, there is an example of mixing two streams with different salinity content to also generate electricity. And the second question is, I think that is the basis of why desalination plants are located next to power plants. Basically, to take advantage of the steam or the heat that these power plants are producing. And the third one, can the brine be utilized? For instance, there is a process called formal osmosis. The opposite to reverse osmosis. In this case, we use the driving force, a high concentrated stream to desalinate the water. And brine could be used, but I think there are other, what they call draw solutions that could be more efficient than brine. The next question is from Rafa, who asks what do you think about eutectic freeze crystallization methods? That's a very difficult question to Rafa. Rafa is our student at IHE. And for desalination, it cannot compete in scale. For instance, with reverse osmosis or thermal processes. But it's an option, mainly used for industry. Also a company based in the Netherlands in Delft, I start up of the two Delfts, has this product as commercial product. I think it's an interesting solution. I don't know much about it, more than I already mentioned, but I would say it cannot compete with reverse osmosis or thermal processes. The next question is from Savagroup Lebanon, who asks what kind of contaminates are not allowed during the desalination processes mentioned? That is while using heat and while using RO technologies. In the case of thermal processes, scaling is one of the main limitations. So there is a lot of consumption of anti-ascaling to prevent the scaling of sparing lean soluble compounds like calcium carbonate in the process. That will decrease the efficiency in the process. So we need to control the scaling potential of the water. In the case of reverse osmosis desalination, we want to remove of course the salt to make it potable. Patsy water also contains microorganisms, it contains algae, it contains clay particles, it contains exopolymer particles, substances, etc. That will influence the lifetime, the performance of the reverse osmosis system. So for this, pre-treatment is very relevant. And it's very relevant not only because of the quality we need to produce in front of the reverse osmosis, but also the quantity that needs to treat. Reverse osmosis systems operate at about 40 to 50 percent what we call recovery or conversion. So this means that 100 percent feed water is going to produce only 50 percent product water and 50 percent will be about the brine or concentrated stream. But the pre-treatment needs to treat the 100 percent that the reverse osmosis is going to treat. So it's a high volume of water that needs to be treated. The next question is from Victoria who asks what happens to the brine produced during the desalination, knowing that depending on the source of water the brine might be polluting. I think you addressed that in some of your slides but would you like to add something to what you've already discussed? Sure, this is a very perhaps important concern when we think about desalination and perhaps two points related to that. One is the visual pollution, mainly because the brines will have a higher concentration than the water that we are discharging back. But let's analyze, we are taking seawater from the sea and then we are bringing back the same feed water with more self-concentration back into the sea. In the process of desalination the only thing that is changing is perhaps the addition of some chemicals like for coagulation process. We are talking about only cells like iron chloride, aluminum sulfate or some additives that are polyalkalite to improve the coagulation process. But these are compounds that are not foreigners to water itself. And we can minimize the environmental pollution by having diffusers that are strategically located with rapid diffusion etc. There are sustainable alternatives to control this. Thank you. And the next question which will have to be our last question which is we have gone over time is from Vishradu Mohapatra who asks whether any study has been conducted to assess the impact of reject brine disposal from desalination plants which is mostly directly disposed into surface impoundments. It's impact on groundwater quality. If there have been any studies on the impact of disposed brine on groundwater quality? I'm sure that there are studies. I think that there is scientific literature that is dealing with these specific issues. It doesn't come to my mind in this precise moment. Sorry for that. No problems. Thank you Sergio. Thanks a lot for sharing your work with us and for sharing your insights on this very important topic and a very popular topic it seems. For me personally a very valuable take away was that there is an access to desalination countries. Desalination technology varies a lot from country to country. We should not look at it as a silver bullet as we say towards in the fight to reduce water scarcity globally. For me that was a very important take away. With this we would like to close the webinar. Thank you again Sergio for your great presentation and thanks to the audience for turning up and for your great questions and comments. As I have mentioned before a recording of the webinar will be available shortly. Later today in a few hours time on www.thewaterchannel.tv slash webinars that is the page that you will be redirected to when we close the webinar. A small announcement I would like to pre-announce the next webinar that will be on September 8th. At the webinar Mr. Benson Karimba from Kenya will discuss the possibilities of small holder irrigation using sand river aquifers and semi-arid lands. So I guess we will be discussing technologies like sand dams and such. We will be posting details of that very soon on the water channel. So thanks again and see you the next time. Thank you.