Introduction to Water - Technologies for Water and Wastewater Treatment

So. We've talked about water quality issues, and things, in the water that can be of concern and so, this leads to the next. Step, which would be how do we treat the water to make that water is safe to drink and, as, we begin to move into that discussion may be a good question to think about is where. Is the safest water on earth, when. You think about naturally, occurring water on earth where do you think about as the. Safest water and. Different. Answers, come to mind you, might think about, groundwater. And that would be a good answer you. Might think about, rainwater. Water coming down from, the sky and that would be a good answer you might think about mountain. Streams, up, in the Rocky. Mountains, that pristine, water coming, down from the snowmelt, and. You might think about well, what about glaciers and, maybe the Arctic, ice and those, would all be good answers but, let, me share. With you some, issues. That might come up with each, of those sources of water while we would think of them as being the safest water on earth each, of them can have issues associated with them and so, this helps, us to realize we need to be aware. And cautious well. Let's start with the groundwater the, groundwater is safer than the surface water because. The surface water may have pathogens. In it that may cause the spread of disease and. We talked about London, and Chicago. In the 1800s, in, Milwaukee. In 1993. And so, we might think all the groundwater is the water flows through the ground those. Pathogens, die off and that water is safer and that's. Assuming that there's not surface. Influences. On the groundwater that might be introducing, pathogens, directly, into the groundwater and that'd be exactly true but. We can, think about naturally, occurring arsenic, that might be in that ground water like in Norman, Oklahoma and so. We need to think about that groundwater what. About the rain water it's, not coming in contact with the geology so it's not dissolving, things out of the geologic, materials. Well. It turns out as that rain falls through the sky, we. Can get acid rain now. What does acid rain well, you may have nitrogen. Oxides, you may have sulfur oxides, in the atmosphere. To call combustion, and other activities, and as, the rain falls through that it may dissolve those compounds. Into the rain and you, may get acid, rain and, so that's something we need to worry about think, about and the. Black Forest in Germany, the, trees started dying because of the acid rain what. About the mountain stream water there your snowmelt. Up in the Rockies. Or. If you talked to a backpacker, people, that go backpacking up, in the mountains, that. Have experience. They know not to trust that water they, know that you need to boil the water you need to add on tablets, you need some. Special, filter, to. Make that water safe it turns out the deer and the Beavers, that, are living up in those mountains that can excrete, Giardia. And Cryptosporidium into. The water you get deathly ill from, that water well. What about the the, arctic ice the. Glaciers. Well. Interestingly enough we find that, chlorofluorocarbons. Freon. And other, types of compounds that have gotten in the atmosphere, can move through the atmosphere, up, to the Arctic ice, and partitioning. The ice and so we actually find these chemicals, in that that, ice and so. All of these waters, that we think about as being the safest may actually have water, quality issues associated with them so. Because of water quality issues that we may have we, think about treating the water we. Treat water for, several different reasons and we. Have several different what. We call regulations. Or standards, we, have primary, standards, and these. Standards are, focused on human health. Preventing. The spread of disease. Like cholera, typhoid. Fever. Preventing. The exposure, to compounds, that may cause cancer and. So these are primary, standards, to protect the water that we drink we, also have secondary standards. These. Secondary, standards, aren't. Designed. To protect human health they're. More for a esthetic reasons how, the water appears, and so. Maybe the water for example like Thunderbird east, of Norman if you, take a glass of water if like Thunderbird water and you hold it up you'll. See a lot of fine. Particles. We call that turbidity, in the, water, and it almost has a little bit of a red reddish, color to it that's because the iron particles, in those fine particles, give that color to it now. Those. Solids. And in the water may or may not be health issues but they're certainly not very pleasing to look at iron. In the water you. May if. Your ground water has. Reducing, conditions in the absence of oxygen you may get iron dissolved, in the water, now. I remember a time when. My wife was on an iron supplement diet, adding. More iron into, her diet at the same time the city of Memphis, was taking iron out of the drinking water so. That wasn't a health standard, that, was because that iron that was in the water if it comes into the home and gets.

In Your washing machine and that iron precipitates, your white shirts or your white tablecloths, become, pink, so. That's more of an aesthetic, concern, a visual. Concern, so. These are a couple of the reasons that we treat water for. Health concerns that's the number one to, prevent the spread of disease to prevent the. Episodes, of cholera and typhoid fever that we know from our history but, then there are also things that we do to make the water more pleasing for the consumer, well, the type of treatment we consider is a function, of the source of the water, we. Can have river. Water can be our source, our. Source could be a lake like. Like thunder bird for Norman or. It could be ground water in Norman, historically. Used ground water was its source of water but when Mike Thunderbird, was built in the late. 60s, early 70s, in, that timeframe that. Became a source of water and so, you have different types of treatment processes as. A function, of what's in the water as, a function, of the source of the water so, let's talk about treating. Water that's like, a river water or lake. Water that has these fine particles this turbidity, in the water and one, of the first things we want to do is to remove that turbidity, to clear up that water so that it's more, aesthetically. Pleasing it. Turns out these particles, are so fine that they won't settle out very, quickly if you have a river water like the Mississippi River you, have sand, that, will be in the water because of the the. Turbulence, the energy, in the water will even be able to suspend sand and that'll settle the sand will set very quickly but. These fine clay particles, settle. Much slower. And so, one of the first steps we do is to take that water and to make those fine particles, so, that they'll come together and become larger particles. So, that they will settle out by gravity. Now. The process that we use to get these fine particles to come together we.

Call Them to aggregate or agglomerate, it's. Called coagulation. And. Coagulation, is a process, whereby we take these particles, that normally, don't want to attach and. We add some chemicals that, change the nature of the surfaces, of these particles, so that they will attach, and. When they come together they attach and they become larger, and they'll, settle out by gravity, and so, that we call that coagulation. And the process, of the particles coming together and, colliding. And aggregating, we call flocculation, here's. A picture from the, draper, water treatment, plant in Oklahoma City and in. The left. Side of the picture what, we see is this, turbid, water but, kind of brownish in nature and we're, doing the coagulation, and flocculation and as you look to the right part of the figure you see the water is clear in, the basin we have these these boards. And. They look kind of like a paddle, wheel on the back of a paddlewheel boat and, these. Paddles, rotate. Very slowly and encourage. Those particles, to collide and aggregate, so they become large enough and so, if you look beyond you see the water is clear because the larger particles, that we've helped create now settle out of the water and the, water is much clearer. So. The next step after coagulation. Flocculation, and, settling, gravity, settling is we, go into a filter, and here. What we mean by a filter is a sand filter of a bed of sand that the water flows through it. Helps to further remove, these fine particles that haven't settled out by, gravity, actually. This is from Bangkok, Thailand and, they take water from the shafa'ah river and then, coagulate flocculate it and then they put it in the sand filter you might say well where is the sand, what. We're seeing in this picture is the water, as. It's, flowing. Downwards, we can't tell that it's flowing downwards, because it's doing it at a very slow rate but, it's flowing down through sand that's below the water surface. So looking, now at the next picture we see what we've done is we've drained the water down in this Basin to, where now we're seeing the top of the sand and. We're doing this because we're getting ready to clean, the filter we've been using this filter long enough it's become very clogged, with. All the material that's been removed in the sand and so. In this next picture we see what we've done is we begin. To flush, water back, up through, the filter in the opposite direction and we're displacing all this trapped material. And we, see the color of the water in this case is kind of brownish and that. Reflects, the brown particles. That were in the surface water that were trapped, by the sand filter but, now we're cleaning that sand filter, removing. All that dirt. That had accumulated in it so, that we can continue to use the sand filter, for. Additional treatment of water so that was a sand filter for. Bangkok, Thailand which, was treating, a surface, water, now. If, we look at the next picture we see a sand filter and this is from Memphis Tennessee, now. We see the color of this water is different instead of being brownish. I kind, of like a chocolate. Milk or a weak chocolate, milk color we see it's reddish, and this. Reflects the fact that in Memphis, it's, not the Mississippi River water that they're treating it's the ground water and, they're, pumping the water up from the ground and that water, has iron in it and. So what they're doing is they're precipitating. The iron and then. They're filtering, out that iron in their sand filter so what we're seeing in this picture is they're running water back through that filter in the opposite direction and, the, iron is becoming displaced, from, the sand. And now. We're. Regenerating. That sand filter so it can be used to treat additional, water so. This would be the steps of coagulation. Flocculation. Sedimentation. Gravity. Settling and now filtration. The sand filter to help polish. Or further improve the quality, of the water but, what's the most important. Reason that we treat water, is. To prevent the spread of disease. Cholera. Typhoid. Fever and, so. The next picture we're looking at this is a disinfection, process and. Here. What do we see our tanks, and these tanks, have chlorine, in them. And this, chlorine is being added into the water at just the right concentration, to help disinfect that water to, kill any pathogens that, might be in the water and, remember, this is the most important, reason we.

Treat The water you should prevent the spread of disease, to prevent the, epidemics. From. Cholera typhoid, fever, removing. The iron removing. The turbidity of the solids, that makes. The water more pleasant, but, treating, it with the disinfectant. That makes it safe. And, prevents. The spread of disease, so. In this example I showed in Memphis, it, was chlorine, what's a disinfectant. Chlorine. Gas added. Into the water to. Give. A residual, chlorine to, make the water safe to drink and you want to make sure that chlorine residual stays in the water distribution system. So, the water coming out of the tap still has that so, the water can't be recontaminate. 'add by, pathogens in, the distribution system this is why I don't drink the water in a developing country in, Bangkok. I've seen the water treatment plan I trust. The water at the water treatment plant but I don't trust it at my hotel because. I'm concerned that it might have been recontaminate. 'add in the distribution system and so in the US and Europe, developed. Countries we make sure there's a certain residual, level of chlorine or our disinfectant. At the tap to, keep that water safe we. Can use other disinfectants. Like ozone, or UV, light these. Can help to disinfect the water in UV light and ozone are better for Cryptosporidium. And certain pathogens but. They don't leave a residual, they. Won't stay in the water all the way to the tap so, even if we use them we need to add another chemical, to. Keep that, residual. Disinfectant, in the distribution system, and, just. One. More picture I shown you a couple of very large water, treatment, plants here's. A very, small water treatment, plant and this is from. A rural community in, Central. Missouri we were just driving by and I saw this and stuff and took the picture of it and this, is a system, where they're removing, iron and what you're seeing are a, series, of trades they, pump this water up it has a higher named it and they put it in these trays and as the water flows from the top down, through these trays. It gets air ready to get supposed to oxygen, the iron precipitates, and then, they're able to remove the iron and so this is a small, plant for a small community as opposed to the large plants, that I've shown you before well. Having talked about water treatment once. We use the water in a home the, water goes down the drain and it goes to the wastewater treatment plant, and, we need to make sure that water is safe before it goes into the river or lake of, the receiving, stream and so next let's talk about wastewater, treatment so, we treat this wastewater to make it safe. To discharge, into the river of the stream and one, of the major concerns if this wastewater, isn't treated as that, waste goes into the river and stream it, will consume all the oxygen as the. Microorganisms. Consume, those organics, they'll use up the oxygen and, what. Happens to a river if, it doesn't have oxygen in it, well. What. Happens to the fish if there's no oxygen in, the fish tank, well the fish died and so. Fish, and other many other organisms require oxygen. To, be able to live in these streams and lakes and so, what we want to do is we want to get, these organics, that are in these wastewater we. Want to degrade that and, we want to provide all the options that's necessary, in a treatment plant so. When that wastewater goes into the river it, doesn't, deplete, the oxygen in, the river and. So. The, way we do that is through a series of processes in, wastewater treatment, so. This next picture you're seeing is a picture of the shafa'ah, River in Bangkok. Thailand. My. First trip to Bangkok in, 1992. I wanted. To go see a wastewater treatment plant the. Only thing is in 1992. Bangkok, had no wastewater, treatment plants, the, human waste went. Into the ditches into the creeks and into the shafa'ah, River untreated. And the. Dissolved oxygen level, in the river was virtually, zero which. Meant no, fish no aquatic, life could live in that water I'm, happy, to report since night 1992. Bangkok, has implemented, wastewater, treatment and the, Chao, Phraya River, now does support fish life again but this is an example of what can happen in, the absence and we, in the United States we were in that same position in the nineteen 50s, and 1960s, before. We started implementing the, wastewater treatment that, we is. So common, today when. We look at a wastewater treatment plant what's, the first process, that we might encounter at the plant and the, first process could, be a filter, as green to, remove large materials.

That Come in to the plant and so that's what we see in this next picture is, just. A screen kind, of like a screen. Door if you will a screen, that. Helps. To remove the larger, materials. From that water and then we'd next go into a, process. That just allows. Time for heavy, things to settle out and they say that. One of the things that shows up in this settling, Basin initially, coffee. Grounds, sometimes. People will flush that down the toilet and it makes it to the wastewater treatment plant and so that gets settled out and so, we have simple physical, processes, of screening, and then gravity settling and that. Removes those types of materials, but now we're starting to talk about those dissolved. Materials. We, put some food down our food grinder, or down, the garbage, disposal that, goes down the drain we, could take those things and put them out in the compost pile and we. Have a compost, pile at our house and so, those things where those organics, would break down in a compost pile but sometimes we use. Our, garbage. Disposal, it goes down the drain and if that goes into the river it'll consume the oxygen in the river just, like it consumes oxygen in, our compost, pile as it, degrades and so. Now we need to think about how can we design processes. To, help remove those organic, compounds, that won't be removed with the screens or won't, be removed by settling. So. What we do to remove these organics, is actually somewhat similar, to what we do in a compost pile do, you've ever worked with a compost, pile you put, the organics, you always. Like to have. Compost. That's. Already been composted, because you can put that in and that brings the microorganisms. And you. Need some moisture, you need water and you. Turn your compost pile and that's to keep it aerated, so. These are some of the important ingredients when we're thinking about trying to do biological, degradation of, organic. Pounds and so how do we do this in a wastewater treatment plan and I always like it when I go to a wastewater treatment plant and they, have, several.

Basins, And one is in operation but, ones down because, they're doing maintenance because. You can see what it looks like when, it has water in it but you can see what it looks like when it's empty and that's very nice in this picture this is a wastewater treatment plant from Memphis Tennessee and, to, the left we see a. Unit, that's in operation, the wastewater is flowing through it and we see the basin. Filled with water in the, center we see a basin, that's dry and if, you notice down at the bottom of that basin, you see a pipe and. That. Pipe has, little, diffusers. Coming out of it's very similar to what you do in a fish tank in. A fish tank at the bottom of the tank you put a little diffuser and you pump air in and that, provides the air that the fish need to stay alive, what. We're doing in this Basin is we're bringing the wastewater and we're, providing air, and we're, also bringing, in microorganisms we're, taking settled sludge and returning, it and, we're bringing all these ingredients together so. That the, organics. Can break down in this Basin in this. Engineered, treatment, system rather. Than happening in the river itself so. What happens in this basin is you have, microorganisms. They see food and they eat that food to them what to us is the wastewater to them it's food they say pizza get excited and start eating and they. Break down these organics, and they multiply in a process, and, so we produce lots. Of. Microorganisms. Or what we call, sludge. We go into the next basin which, is shown here and this is a settling basin and we allow that sludge, those microorganisms to settle out to the bottom and the, water that comes off the top is devoid. Of the organics, but also we've. Settled out the sludge the solids, the microorganisms. And so. Now we're ready to discharge this, water to the river you see often horizon. It's a Mississippi, River and so, now Memphis, is treated this wastewater and it's, removed the solids, it's remove the organics, and, settled out the microorganisms. And it's ready to send this water on to the Mississippi, River and the, oxygen level in the Mississippi River won't be depleted because, we satisfied, that oxygen. In this engineered, treatment, system so, we've protected the receiving, body, we've also protected, people downstream, that, might pull out Mississippi. River water because. We've removed. Potential. Pathogens that, were in the water. To, protect the. Downstream, users. So. He now talked about treating the wastewater to remove the solid. Particles, and to. Remove the organics, that dissolved organics, depending. Upon the where the wastewater, is going into if that wastewater is going into a lake we. May need to remove nitrogen. And phosphorous. From, the wastewater as well because. Those may be limiting, factors, that.

Are Preventing, growth, of large amounts, of algae and that. Algae can potentially, consume oxygen in the water and, have. A negative impact on the water so, there's certain situations, where we need to go beyond just simply removing, the organics, and remove the nitrogen the phosphorus as, well so. We've talked now about water treatment wastewater, treatment and, in. Looking at these processes, we found the combination of physics. Gravity, settling, chemistry. Adding, chemicals to achieve certain, removal. Processes. Microbiology. We. See math. We. See Public Health and so, hopefully get a sense of how all these different disciplines come, together to. Help us achieve our goal of making our water safe our wastewater. Safe, for the environment and human health but, just as a final thing let's think about what might this look like in a developing country. Where. People are in. A village a hundred, families in a village living on less than a dollar per day don't. Have the resources, to build these sophisticated types, of processes, that we're talking about in those, applications, we. Might be thinking about instead of a wastewater treatment plant we might be thinking about a little tree but. Interestingly enough we may be think of a latrine of being, at a state park or a campground, but. There's actually some technology, that can go into improving latrines, and so, we talked about ventilated. Improved pit VIP. Latrines. And. We, talked about eco latrines or composting. Latrines and. So, there's some technology, that can go into making the management of. The wastewater more, effective, even in these developing, countries in terms of water treatment we. Can think about simple things instead of a large water. Treatment, plant we. Might be looking at a bottle. Of, chlorine. Where we add a capful of the chlorine into a certain amount of the water, we. Might be looking at taking. Water and putting it in a, coke. Bottle and putting it on the roof and the, UV light in the sunlight can, disinfect that water so. We might be looking at very simple we might be looking at ceramic water filters or.

BioSand. Filters so. Very simple technologies, that use the same concepts. But, are more appropriate, for that setting, so. In this lesson we talked about the importance, of water treatment, the importance, of wastewater treatment and some. Of the different concepts, and processes that we can use trying. To make the waters safer, for healing consumption, more. Pleasant, for human consumption, safer. To discharge, into the environment, safer. For people that might be using the water downstream. After, we discharge it into the environment and we're. Hopefully. You, see now the importance, of water treatment and wastewater treatment to. Public health and to society, as we know it.

2019-03-19 07:59

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