Friday, May 20, 2022

Preventing Flint – Environmental Engineering: Crash Course Engineering #29

Thanks to CuriosityStream for supporting PBSDigital Studios. Our world isn’t just some big rock we liveon. It’s an ever-changing environment, withcountless creatures – us included – justtrying to survive. That’s why as an engineer, you have to thinkabout how you affect the world and how theworld affects us. If we want to try and live in harmony withnature, we need environmental engineering. [Theme Music] Environmental engineering combines natural scienceslike chemistry and biology with engineering principles tocome up with solutions to environmental problems. It boils down to three main things:protecting people from the environment, protecting the environment from people,and improving the overall quality of theworld around us. .

As an environmental engineer, you’ll belooking into issues such as public healthand sustainability. You’ll be especially concerned with controllingair and water quality. The air we breathe and the water we drinkare crucial to life itself, and even simplechanges can lead to serious problems. Take, for instance, what happened in Flint,Michigan. After switching the city’s water sourceto the Flint River back in 2014, Flint’sdrinking water became dangerous. Untreated river water corroded the pipes,contaminating the water with lead. Lead consumption affects everything from yourheart to your brain, leading to cardiovascular problemslike elevated blood pressure and hypertension, as well as neurological issues likeincreased aggression or difficulty thinking. The contamination was also tied to an outbreakof Legionnaires’ diseases that caused at least12 deaths. .

One study even found that fertility ratesdecreased by 12% and fetal death rates wentup by more than half. Solving the problem isn’t just about switchingFlint’s drinking water back to a better source. All of the city’s damaged pipes need tobe replaced before the water will truly besafe to drink again. It will take years to fix what could’vebeen avoided. The lesson here is that you need to make surewhatever water source you’re using, it isn’t goingto mess up any systems already in place. We now know that water from the Flint Rivershould’ve been treated with alkaline chemicals toreduce corrosivity before being fed into the city’s pipes. It’s not just drinking water – you need to be concerned with water qualitywhenever you’re dealing with an aquatic environment,like a natural water supply that houses fish. Flint’s problem was rooted in human safety,but just as often it’s the safety of other organismsyou need to be worried about. .

It’s critical that your work doesn’t dramaticallyalter the local water’s natural characteristics. Like, for instance, its dissolved oxygen content. Fish and other aquatic creatures need to consumeoxygen from the water around them in order to survive. It’s impossible to perfectly predict theamount of dissolved oxygen needed, but in general, a level of about 4-5 parts per millionis usually the bare minimum necessary to supportan underwater population. Get up to 9 parts per million and you have athriving community, but drop below 3 and eventhe toughest fish won’t be able to survive. Cold water can hold more dissolved oxygenthan warm water, so cooling off a lake canhelp to correct low levels. Photosynthesis from the water’s plants willalso produce oxygen, so it might not be abad idea to add some greenery, too. Another thing to worry about is the pH level:how acidic or basic is it? .

Pure water has a pH level of 7. Below 7 is acidic and above 7 is basic. Generally, a pH range of about 6 to 8 supportslife. But go too far outside of these levels andyou’ll start running into trouble, especiallyon the lower end. Fish will usually start to die at pH levelsunder 5. More acidic water can also leachmetals from your pipes, such as copper,zinc, or lead – like in Flint. Drinking water with a higher pH level isn’tas dangerous, but it can cause drinks to taste bitter andlead to mineral build-up in your plumbing,which makes it harder for water to flow. You can try to correct out-of-range pH levelsby adding other chemicals to the water, but thoseneed to be supportive of your overall system. .

For instance, if you’re adding salt to try and correctout-of-range pH levels, you could throw off the water’ssalinity, or the amount of dissolved salt. That definitely won’t taste the best, butit reduces the dissolved oxygen; in environmentalengineering, everything is connected. You can tell how much salt is in the waterby measuring its conductivity, or how wellelectricity flows through it. The more salt, the more ions, and the betterthe water will conduct electricity. And any hormones that make their way into awater supply can have pretty substantial effects. Many of the medicines you take end up inyour sewage and can affect entire aquaticpopulations. Estrogen is especially important because it’shard to filter out. When released at the right concentrations,scientists have seen it change the sex ofentire schools of fish! There are many other factors that affect water quality,like how clear the water is, what nutrients are in it, andif it has any viruses or bacteria swimming around. .

But no matter the problem, you need to treatit. And you don’t just want to play clean-upafter a disaster – you want to try to snuffout the problem at the source. One way to remove unwanted material is througha process called coagulation. It works by adding a chemical like aluminumsulfate that causes small particles to sticktogether, or coagulate. As they clump, they become larger and easierto remove with something like a filter. You can clean water by focusing on thingslike rivers and sewers. It’s a whole different problem to cleansomething that’s all around us, like the air. From exhaust fumes to smokestacks and insecticides,there are countless forms of airborne pollution. Factories are among the largest culprits, producingchemicals like carbon monoxide and sulfur dioxideas byproducts of the combustion process. .

Breathing in too much carbon monoxide canlead to flu-like symptoms, such as dizziness,weakness, and vomiting. Enough exposure can even be fatal. Every year, more than 20,000 people in the US end upin the emergency room, due to non-fire related carbonmonoxide poisoning, so this is a pretty big problem. When pollutants like these get in the air,you need to find out not just how they got there,but how far they’re going to travel. High wind speeds and storms will be able tocarry the pollutants farther than a light breeze. But probably the biggest thing you need tobe concerned about is the size of the pollutants. The smaller they are, the harder it is tofilter them out. For example, bacteria are typically biggerthan viruses. If your friend has a cold that they don’twant to spread, they should wear a face maskwith extremely small pores. .

Remember, the common cold is a virus, so thepores need to be smaller than if they were justtrying to stop the spread of everyday bacteria. Filters can remove many pollutants from theair, but they come with some limitations. Some of the smallest particles can slip throughand larger ones clog things up, so they need to bereplaced even when working properly. That’s where absorption towers come in. They combine liquid falling from above withair rising from below to remove many kindsof particles. Another way to remove pollutants is by usingan electrostatic air filter. These are made up of multiple layers of vented metaland essentially work like a magnet for any unwantedparticles floating in the air, such as dust, mold, or pollen. As air passes through the first layer of metal,the molecules in the air are positively charged bythe friction between the air and the filter. With their new positive charge, the molecules will attach themselves to the next couple of layers as they try to pass through the rest of the filter, essentially getting trapped inside. .

So not only will a good air filtration systemhelp block out deadly pollutants, but it canalso help save you from a runny nose! Air and water quality are just two of theproblems addressed by environmental engineering, but others include things like noise pollutionand waste management. Loud noises may not sound that important, but spendsome time trying to think next to a construction site,and you’ll realize how harmful noise pollution can be. And many of the things that we make, makenoise. Cars are a big one. Left unattended, highways can be a major sourceof noise pollution. That’s why you’ll see those wall-likesound barriers on the side of the road. Factories and places with a lot of loud machinerycan also disrupt their neighbors. .

Earplugs may be enough for the workers inside,but if a factory is making too much noise, it might need a more sound-proof buildingor to be put in a less residential area. You also have to find a way manage all ofthe trash you create, whether that’s piling it upin landfills or finding ways to recycle. Recycling isn’t just about reducing pollution – it alsohelps conserve natural resources like timber and savesenergy, which might come from fossil fuels. It’s not only small things like soda cans,either. Computers, cars, and even abandoned buildingscan all be recycled. Many of the chemical reactions involved withengineering also produce waste, so you need to getrid of that too, especially if it’s hazardous. Sometimes you can treat the hazardous materialsand eliminate the danger outright, but other times you might have to settle for simplystoring it as best as possible. .

If you have to do that, you need to make surethat the waste won’t react with, weaken, ordissolve whatever container you put it in. All of these things – and so much more – mustbe considered when approaching problems froman environmental engineering perspective. But as long as you take the proper precautions,you’ll be on the right path to keeping this world spinning. Today we learned all about environmental engineeringand the work that goes into managing our impact onthe environment, and its impact on us. We found out the importance of water qualityand how differing levels of dissolved oxygen,pH, and salinity can affect it. Then we saw how air quality matters and thedifferent types of pollution we have to deal with. Finally, we went into other issues, like noisepollution and waste management, and saw howthey can affect us too. I’ll see you next time, when we’ll learnabout alternative energy. Thank you to CuriosityStream for supportingPBS Digital Studios. .

CuriosityStream is a subscription streaming service that offers documentaries and non-fiction titles from a variety of filmmakers, including CuriosityStream originals. For instance, CuriosityStream has “Nature’sMathematics,” a series about patterns andsymmetry in nature. Nature’s Mathematics explores the rulesthat shape trees and river estuaries alike, and that continue to baffle scientists bytheir often unfathomable ubiquity. You can learn more at curiositystream.com/crashcourseand use the code crashcourse during the sign-up process. Crash Course Engineering is produced in associationwith PBS Digital Studios, which also produces Hot Mess, a show about how climate changeimpacts all of us, and what we can do about it. Head to the link in the description to findout how we can create a better future forour planet and ourselves. Crash Course is a Complexly production and thisepisode was filmed in the Doctor Cheryl C. KinneyStudio with the help of these wonderful people. .

And our amazing graphics team is Thought Cafe.

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