Sybil Derrible

It's fascinating to hear about what's happening in Chicago versus New York versus Shanghai versus Paris because they will have a different system partly based on the specificity of the cities themselves and partly based on when the systems were built because things evolve.

I mean, it is amazing for tall buildings, but it's more amazing for entire cities, right? Which is what we do with, again, with Chicago, 12 pumps for all of Chicago. Now for a tall building, what happens is that you also have a pump in the bottom. So usually when you have a pump for an entire city, you want to have enough pressure. The pressure in the system is dictated by the fire department.

they want to make sure that when they connect their fire hose to the hydrant, they can put out a fire. And so that's why usually that pressure is about enough for that water to go up to a five or six-story building. So that's why five or six-story buildings usually don't have a pump in the basement, but tall buildings do.

You have two options, right? One is you look elsewhere, you see what they're doing and you reproduce something similar. And your second option is you see what you have and you try to do the best with what you have. So in the case of telecommunication, one of the things they did is, well, we like fiber optic cables, so we have to lay fiber optic cables there.

And so they went to, in New York, for example, I think they went to a lot of the old Western Union pipes that were there for some cables, and they just replaced all the cables with fiber optics. But usually it's one of those things, you know, where...

It's fascinating to hear about what's happening in Chicago versus New York versus Shanghai versus Paris because they will have a different system partly based on the specificity of the cities themselves and partly based on when the systems were built because things evolve.

Well, you'd assume that that would be the obvious thing that you do, right? But in my experience, usually they don't do that too much just because things evolve so fast. So especially I talk with a lot of people in the transit industry. And when you look at how they handle a system in New York, Boston, D.C., Chicago, often it's going to be pretty different.

So again, you would assume that they get together and that there's a one common system for everywhere, but often it's not the case. Water is another good example because the way that you treat your water really depends on your quality of the raw water that you get. And so there's no way you can have the same system in New York as in Chicago because the quality of the raw water is different.

Wastewater is my favorite infrastructure of all. By training, I'm more of a transportation person, but wastewater is what I prefer because it's incredibly complicated because you don't have one wastewater, you have two. There's the wastewater that we think of, which is the toilet, the showers, whatever we do at home. But there's also the wastewater coming from the rain.

So that's called the stormwater. And so in older cities, you tend to have combined sewer systems. So you have one single pipe in the middle of the road that has to handle the sanitary sewers from people and the stormwater from the rain. And in newer cities, they tend to be separate. And so depending on the type of system, you'll have different strategies.

But usually what you want when you have a separate system is to treat the water that comes from homes, and you don't really treat the water that comes from the storm. But in systems, in cities with the combined sewer, then you treat everything.

And so that's where you have to go to a wastewater treatment plant, you treat all the water that's coming in, and then you put it back into the environment in usually a way that's clean enough where it will not harm anyone or the species or animals downstream, but not clean enough that you can drink readily out of it.

So that's a great question. So the first thing you do is you're going to try to separate some of the solids. So again, screens. Sometimes you might have, again, branches, water bottles, toilet paper all you have. You try to screen everything that you can physically out of it. Then you put some chemicals to favor something called flocculation. So you have all those particles that are there.

Those particles tend to be negatively charged. So essentially, no matter how long you let it sit there, they're like little magnets that just expel one another. So it's never really going to sit to the bottom of a tank. And so you put some chemicals to neutralize that negative charge, and then you just let gravity do its job.

And so that means all those little flocks are going to settle at the bottom of the basin, and then all the greases are going to float at the top. So you skim all those greases from the top, you remove everything from the bottom, and then you're left with clear water, but it's still not good water because it's got a lot of diluted stuff, you know, nasty stuff.

but also detergents and soap and everything. And so then what you do after that is you leverage nature. And by that, I mean that all that disgusting stuff that I just talked about is actually amazing food for microbes. So then you use biofilters and as the water just goes down the biofilters, all those microbes feed on all that stuff.

And then after that, then you tend to have some pretty clear water and you can put some ozone or you can use some UV light to kill whatever is left there. And then you really see it to the environment. And what does that mean?

In the sea, in the river, usually a river, you know. That's why you tend to have water treatment plants upstream of a river and then wastewater treatment plants downstream of a river. One of the things I love to tell people when they fly is when you fly, when you take on a border plane and you start to ascend, look at what's out there. And very often you'll see a wastewater treatment plant.

You'll see huge circles with water. You don't really know what it is, but it's a wastewater treatment plant. And the reason why you see that is because airports tend to be built wherever there was space. And that used to be normally in like low marshland or in a place that used to flood a lot. And that's usually downstream of a river.

And so that's why you have the wastewater treatment plant there and the airport just next door.

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