I'm SICK of all your crap.

I make no apologies for my potentially offensive blog title.

Simply because it's entirely true. Though not in the sense you probably assumed. This blog post is a public service announcement! And also part of a quest, but hey, I'm not spamming like everyone else! I have a purpose!
 I am here to educate you all about a subject near and dear to my own heart: 

Where does the poo go?

 This is actually a real book.

That's right. Poo. Crap. Shit. Big brown bombs. Turds. Ass candy. Cornhole gold. Or as we in engineering call it: "biosolids". 
I bet you never ever thought about this before, huh? You just take a seat on your toilet, let 'er rip on out, and then flush the little magic lever that whisks away your 8-hour breakfast to a magical, unknown place. Those holes in the street? Who KNOWS what they're for, right? Who CARES?

 This guy has one of the worst jobs in the world. Trust me.

Well, I'm here to break it down for you, kiddos. Here's a nice, brief overview of what happens to your crap. And hopefully, by the end of this, you'll be a little less prone to knee-jerk reactions against the hard-workin' guys and gals at your local sanitary district. All right, let's get started.
STEP 1: You crap, you flush, and it begins.
I was considering putting an image in for the crapping step, but (wisely) decided against it. Most home toilets hook into the sewer mains via lateral pipes as shown in my totally awesome Paint image below. [Yes, yes, okay, some people have septic tanks, but let's ignore them for the sake of brevity.]

 Megabowl: THE Toilet for the Hefty Gentleman

And away it goes! If you care, lateral pipes are usually about 4 inches in diameter, while sewer mains can range up to several feet across (I've stood upright inside 8-foot mains before, it's pretty crazy.)
STEP 2: Snakes and Ladders 
Protip for anybody who is thinking about designing a sanitary collection system: water (and shit) flows downhill. That's why, most of the time, you'll find wastewater treatment plants (WWTPs) located at the lowest possible elevation. In valleys, in canyons, etc. That way, the majority of the flow simply comes straight to the plant! Sometimes, though, there's stupid hills or mountains in the way, and that's when you need pumping stations. You might see some of these pumping stations throughout your neighborhood. They're usually pretty clearly labeled with big "PUMP STATION" signs and "STAY THE HELL OUT" signs.

 If we cannot pass over the mountain, let us go under it! Let us go through the halls of MORIA.

 You gotta give credit to the guys that maintain the pipelines that run throughout our cities. These underground pipes are very difficult to install, very difficult to repair (impossible, really), and pretty dangerous to work with. Most older pipelines in the U.S. are made from concrete, and many of our older systems are suffering from terrible corrosion issues nowadays. Newer pipes tend to be PVC (or some other plastic) which are far more corrosion resistant. Usually, when a concrete segment fails, the district goes in and just replaces it with a PVC segment, rather than trying to repair the concrete.
 This is what the inside of a typical pumping station looks like. Those long, gray, cylindrical things are the pumps themselves, and they pump away 24/7 pushing your shit up and over the elevations in your district, so that it can ultimately get to the WWTP.

 Key variables in pump design are "shaft work" and "head". Again, not kidding. You know you're an engineer when these terms no longer make you laugh.

Step 3: The Plant
Understanding a wastewater treatment plant is.......well, it's fucking complicated, and I'm sure as hell not going to explain every aspect of it. Look at the picture below if you're curious. (And yes, I COULD explain every single one of those damn things, I just don't wanna). Plants range vastly in size. A "moderate" plant will handle about 45 million gallons per day of incoming sewage, and that can quadruple (or more) in big wet weather events. 
Let's pause for a second and consider that. Say the "average" flow is 45 million gallons per day (MGD). But the peak flow, during a huge storm, might be 250 MGD. You have to design your plant to operate at that WHOLE range. From, say, a 30 MGD minimum to the 250 MGD maximum. That's a goddamn HUGE design range. That's nuts. That means that, on average, 80% of your plant will be unused. But you need that capacity there to handle the wet weather events! And if you don't have it, you get fined, sued, and fired when overflows start happening. (An overflow is simply a backup in the sewage line, usually resulting in manholes popping off and sewage spraying into people's homes and so forth. The EPA simply loves overflows because it gets to fine the sewage district shit-tons of money any time one happens).

 A pretty typical plant. The trickling filter thing is a little uncommon, but whatever, you can design these plants in like a million ways.

All you really need to know is the following order for how a WWTP works:
1) You take the heavy things out of the flow (tree branches, skateboards, you name it)
2) You take smaller things out of the flow (sand, grit, pebbles, etc.)
3) You separate the flow into two components: sludge (biosolids) and liquor (stinky brown water)
4) The sludge goes one way, and the liquor goes another.
What we're going to talk about is the sludge. Sludge is a generic term for the concentrated flows of biosolids that you start seeing at the end of the plant process. You see that thing called the "sludge thickener" in the picture above? That's right about where we're going to start paying attention. That device is taking all the sludge lines that have been created so far (there's a couple which come from different parts of the plant) and it mixes them all together into one, uniform flow.
Yes, this is exactly as disgusting as it sounds.  It's stinky, pathogenic, disgusting, slimy, and horrible. Sludge is the third-worst thing you can imagine at a WWTP.  Don't worry, we'll get to the other two.

 This is a "light" sludge. It's one of the LESS offensive sludge flows you'll see at a WWTP.

Step 4: Killing the Sludge
How do you get rid of all this horrible sludge? Well, there's two ways: burning it and digesting it. I'm deliberately omitting a step here, that step being DRYING the sludge, because I have a great/horrible story about that that I'm saving for the end. 

I absolutely love incineration. In most places (especially here in California) it gets a bad rap because people are idiots and don't know the first thing about engineering. The common belief is that it's not "green" because it has fire and smoke, so it MUST be dirty. The truth is it has almost exactly the same greenhouse gas emissions as the "green" way of destroying biosolids, digestion (which we'll cover in a second). The best kind of incinerator is called a Fluidized Bed Incinerator, and you can see it below. It's basically a huge can full of sand. You heat it up with natural gas, then throw some sludge in there. The sludge burns, and as long as you keep adding more sludge, the temperature stays high enough to maintain combustion (that means you can cut the natural gas feeds, it will keep running with just sludge). You also make a LOT OF HEAT which you can use to make steam, which can be used to spin turbines, which make electric power that you can use around the plant. So that's pretty cool.

 Another protip: Don't touch the sides of these furnaces with your bare hands.

You gotta marvel at the majesty of Creation, because sure enough, there are some microorganisms ("bugs", as we say) out there that just can't wait to eat your shit. That's exactly what an anaerobic digester tank takes advantage of. It's a huge, "bug" rich, stomach tank. You pump in sludge, the "bugs" inside eat it up and fart out methane gas, and then you take the methane gas and burn it. You can get energy out of burning that methane, which is a big draw for plants to use digestion.

And that's pretty much how you destroy crap. There's more to it, of course. A LOT more. But I think this is a pretty good quick and dirty (ha) overview.  Read on if you wish to hear a truly sad, disgusting story about the fall of a noble man.

The Legend of Gary
Remember how I said I omitted a step? Drying the sludge? Well, it turns out that you don't want to incinerate really wet sludge. Go figure. Most mixed sludge lines are about 5% actual sludge and 95% water. Protip: Don't try to burn water, it doesn't fucking work. 
So you want to dry that out somewhat. A good incineration value is 22% sludge and 78% water. (That sounds like it's still a lot of water, but this is really as far as you can dewater most sludges in common practice.) This 22% sludge is called the "cake". Because it has pretty much the same consistency of a nice, soft cake. A cake made of shit. Hyper-compressed, concentrated, compacted, warm, gooey, shit.
 This is some cake. This looks like it's more than 22%, probably more than 30%. A standard 22% cake is much....gooier.

So how do you dry the cake? You don't want to do it thermally. Again, like I said, it's stupid to heat water. So you use mechanical means. A nice big belt press, or in Gary's case, a centrifuge.
 I want you to realize that industrial centrifuges are big. Really big. These ain't your pansy little high school centrifuges.
Poor Gary was a WWTP operator. His centrifuges were running just fine until one day there was a high pressure alarm on Centrifuge #4. Gary, being a fresh new hire, eagerly jumped on the chance to prove himself. He turned off the centrifuge from the control room, ran downstairs to the plant floor, and looked at the now-off centrifuge. What ever could be wrong? Knowing that he turned it off, Gary proceeded to crawl under the centrifuge and find the access hatch that permitted a look inside the machine.

 This is a chili dog. I'll leave the rest up to you.

Gary, from that day forward, would be forever known as "Chili Dog" among his fellow plant workers. Upon opening that hatch, a veritable flood of rich, creamy cake covered Gary from head to toe. He cried out for help, and suffice it to say that his situation did not improve. After being hosed down outside the building, Gary went home early that day. About two weeks later, Gary's skin color returned to its normal hue.
That's all, folks. Thanks for reading, and maybe next time you take a fat dump, think about all the poor schmucks that it might traumatize.
Oh and hey, if any mods feel like checking me out, you know, that would rock.
84 Comments Refresh
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Posted by natetodamax

I couldn't keep reading after the picture of the dude and the manhole.

Posted by BraveToaster
@Everyones_A_Critic said:
Posted by emkeighcameron
@shrig32 said:
"Some of the pictures were a bit shitty, though.  Good luck getting your next job by the way! I'd hire you to deal with my toxic waste if it was my choice. "
Perhaps this is because it's 4AM here and I haven't yet slept, but I honestly went back through my pictures and was like "which ones are shittty  :(  "  before I saw what you did there. I already got the job, but thanks for the vote of confidence, at this stage I'm  just waiting to finish up my last semester in grad school   :D
Posted by Sweep

That was an emotional read. Also educational.
But mainly emotional.

Posted by nail1080
@SumDeus said:
" That's...that's a lot of text. "
it takes 2 minutes max to read
Posted by Tiwi

I knew much of this from before (thank god for national geographic), but i found the amount of water in "cake" surprising.

Posted by Jeffery
@Everyones_A_Critic said:

Posted by ZenaxPure

I'd love to make a shit pun but all the best ones have been done. That said this topic was actually an awesome read. I love learning/listening about random things most people (myself slightly included) don't think about on a daily basis. Good shit.

Posted by pekoe212

Wow, that was very informative. Every time read about WWTPs I feel slightly sick because of an article I read that I always remember. A 30-year-long employee at my city's local plant was attempting to repair a tank of some kind filled with waste. He fell in. And he DROWNED. To work there for thirty years, and then go out like that. I'd laugh except it seems like such a horrible, horrible, HORRIBLE way to die. So that's what i associate with waste water treatment!

Posted by ryanwho

You talk a lot of shit. 
badum chh 
I better have been like the 5th person to make that shitty joke. 
badum chh

Posted by SinGulaR

This is one great blog post :)
Posted by Taborlin

Lol, surprisingly good to read? >< 

Posted by AjayRaz

this is the best thing i have ever read

Posted by RelentlessKnight

great allusion

Posted by xyzygy

Is it possible to purify the water we pee into clean water? 

Edited by emkeighcameron
@xyzygy said:

" Is it possible to purify the water we pee into clean water?  "

Yup, it's entirely possible. It costs a little bit more money, but the leap from "clean and treated wastewater" to "clean and drinkable drinking water" is NOT a very large one. It certainly could be done with more frequency.
A) The water districts (not the sanitary districts, but the actual drinking/bathing water supply districts) have RIGHTS TO SELL. This means that they can muscle out wastewater recyclers. They are literally given priority in the eyes of the law. This is total bullshit for a couple of reasons. One, recycled drinking water is cheaper (once you add it all up) and two, drinking water districts sell perfectly good drinking water to companies that use it for industrial processes. Like refineries. Cooling water and cleaning water used in most refineries is DRINKING water. There's no need for it to be drinking water. It could be recycled water from a WWTP just as easily. And it would cost about 1/10 the price. But again, the water districts have right to sell, and so they get to charge the refineries tons of money and steal income from the wastewater districts.
B) Most people have an instant knee-jerk reaction against drinking recycled water. The idea that it came from crap water is just unacceptable to most public bodies. Which is stupid, but there's really nothing you can do about it.
EDIT: Also, it's kind of funny, water treatment is WAY EASIER than wastewater treatment. It's much less equipment intensive, much cheaper, and overall child's play compared to treating wastewater. This is why many wastewater engineers look down on water engineers with derision, because the water guys get all this preferential treatment and good press for doing pretty much nothing.  

This, of course, isn't entirely warranted; they do a lot of good work, but clean water work doesn't compare to the difficulties of running a sanitary system.
Posted by xyzygy
@emkeighcameron: I find that all so fascinating... it's like the apex of self-preservation!
Posted by emkeighcameron
@xyzygy said:
" @emkeighcameron: I find that all so fascinating... it's like the apex of self-preservation! "
The impact of recycled water is SLOWLY being realized, but it will take many, many years (or a serious crisis, like a MAJOR drought) for us to stop being idiots about it. I agree that it would be a really awesome thing, if we could get it working. There are several legal and infrastructure issues outside of engineering that would be huge hurdles to overcome.
Just as an example, the plant I worked at was a 45 MGD (average) plant. And they had a filter plant that took a small percentage of the final effluent (the treated water, most of which got shot out to the Bay). The filter plant was designed to create 10 MGD of recycled water. Meaning it could, in theory, take about 20% of the final effluent and make recycled water out of it. But the plant operated at MUCH lower capacity; it made maybe 1MGD, or 800,000 GD tops. And that was because the WWTP literally could not SELL the water. Nobody could buy it. 
The refineries up the street couldn't buy it (because the drinking water guys had rights to sell) and the golf courses that used thousands of gallons a day for irrigation couldn't but it (because the drinking water guys had rights to sell) and the car washes couldn't buy it (because the drinking water guys had rights to sell) and so forth. These weren't even drinking water applications! They were fucking industrial! It's madness, I tell you. 
Keep in mind, that we here in North California are sending a huge amount of our water every day down to South California via pipelines, because they're in the middle of a big drought (plus there's no water there anyway). Think of all the money it takes to do that? Think of how much we could save (both in money and resources) if we didn't fucking WASTE water like this.
Posted by CornontheCobbe

Now... where does all the Pee go?

Posted by eroticfishcake
@CornontheCobbe said:
" Now... where does all the Pee go? "
Water sports.
Posted by cuzintheboss
@Everyones_A_Critic:  lmao
Posted by Virago

Dude, you just covered a 2 hour lecture in one forum post. who the hell needs college education when you got shit like this. no pun intended. Well done, i feel smarter.

Posted by Systech

Easily one of the best threads I have seen in a long time.

Posted by Alphazero

YOU'RE a fluidizing air blower! 
No, you are!

Posted by PenguinDust
People like you are the reason Giant Bomb is such a kick-ass website.  That was fuckin' brilliant!  Educational and funny.  Really excellent work.
heh-heh, "ass-candy".
Posted by Butano

Fantastic read! Good to know there are other educated Nor-Cal folks here.

Posted by Wrect

Dude, yes.
Posted by luce

I learned something on Giantbomb....wtf is going on!?!?

Posted by ATrevelan

This would be great toilet reading.

Posted by fwylo
@emkeighcameron:  I'm a programmer for PLC's that run WWTP's, and I can confirm all of that.
Edited by Tireyo

You know, water can be the same way. Who knows, if your drinking water right now, you might be drinking someone elses pee!! Of course the water would be purified first and such. Perhaps there is a purification process with chili. I know some old restaurant I used to go to as a kid made their chili from dog food. Once the people found out about that, the restaurant changed their recipe so they could stay in business.

Posted by AndrooD2

Awesome. Came for the video games, stayed for the poop.

Posted by Godlyawesomeguy

uhhhhhhhhh.......ok I guess? Thats pretty fucking gross.

Posted by emkeighcameron
@Godlyawesomeguy said:
" uhhhhhhhhh.......ok I guess? Thats pretty fucking gross. "
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