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The Engineering of Landfills

practical.engineering

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Re: The Engineering of Landfills

#71

Post by DylanSp »

nobodyknowin wrote: post #67

I really enjoyed my time working at a medium sized landfill as their surveyor and civil tech. The engineering discussion in the article is spot on. We chose to reinject most of our leachate as that helps with CH4 production, and more CH4 for us meant more micro-turbines running generating us $$$ under our power purchase agreement with the local utility. The well field balancing was crucial as well, we had to not only…

What sort of substances end up in leachate, and how'd that contribute to greater CH4 production in your landfill? I was hoping that the OP post/video went into more detail on the chemistry involved.

Re: The Engineering of Landfills

#72

Post by weaksauce »

_2d30 wrote: post #47
mikojan wrote: post #40

Earlier quoted context omitted.

A single truck requires more energy to operate in a year.

A single truck requires more energy to operate in a year than 70k homes do!? I find this extremely difficult to believe. As far as I can tell, the EIA [1] suggests the average home uses 10,791 kWh a year. A gallon of gasoline contains ~33.7 kWh of energy per the EPA/Wikipedia [2]. This would mean that a single truck would be burning 70,000 * 10,791 / 33.7 = 22,414,540 gallons of gasoline a year or 61,409 gallons a da…

you should note that a gas engine does not convert all that 33kWh of energy into mechanical energy. a gasoline engine has about a 25% conversion into mechanical energy. https://www.fueleconomy.gov/feg/atv.shtml . diesel might be a bit better than a car but it's city driving by nature.

just heat alone is the largest waste product in a car or truck

Re: The Engineering of Landfills

#74

Post by ericd »

mikojan wrote: post #40
darksaints wrote: post #31

Earlier quoted context omitted.

70k homes is about 84MW. You’re gonna have a tough time finding any evidence that running a landfill requires 84MW of electricity.

A single truck requires more energy to operate in a year.

A 500 hp semi truck engine running at peak power is like 350 kw, so 84 megawatts (84,000 kw) is more than 200 of those engines at full throttle at all times.

Re: The Engineering of Landfills

#75

Post by mikojan »

gruez wrote: post #48
mikojan wrote: post #35

Earlier quoted context omitted.

> Putting stuff in a landfill is way better for global warming since its not burned, the carbon is buried. Landfills release gas. Of course it is better than burning plastic but there is no environmentalist on earth demanding for plastic to be burned. > Almost all plastic waste in developed countries ends up in landfills, not the natural environment. This is horrifyingly incorrect! Developed countries process only so…

>This is horrifyingly incorrect! Developed countries process only some of their trash themselves. The rest is shipped into poorer countries. It will end up in the natural environment. No, you're incorrect. https://ourworldindata.org/plastic-waste-trade >Many people think that rich countries ship most of their plastic waste overseas. But is this really true? >The short answer is no: many countries export some of their…

> No, you're incorrect.

Exactly what statement is incorrect?

Adding to that:

Statistics show that developed countries are shipping significant amounts of trash into poorer countries. But there is most likely an even higher number of unrecorded cases. Supply chains can be difficult to monitor even within the OECD, and an estimated third of shipments is illegal.[0]

[0]: https://environment.ec.europa.eu/news/video-how-eu-tackling-...

Re: The Engineering of Landfills

#76

Post by jerf »

breck wrote: post #56
cm2012 wrote: post #9

So many people misunderstand landfills. All the garbage produced in the U.S. for the next 1000 years could fit into a landfill 100 yards deep and 35 miles across on each side. That is, landfills take a trivial amount of space. Putting stuff in a landfill is way better for global warming since its not burned, the carbon is buried. Almost all plastic waste in developed countries ends up in landfills, not the natural en…

> All the garbage produced in the U.S. for the next 1000 years could fit into a landfill 100 yards deep and 35 miles across on each side. > That is, landfills take a trivial amount of space. Damn, I had to think about this for a second, but you are right. How the hell did I not realize this before? Can you please popularize this more? Maybe compress into a pithy phrase.

"How the hell did I not realize this before?"

There was a concentrated effort to blow the problem of landfills massively, massively out of proportion in the 1980s and 1990s. I have not seen in active in a couple of decades, but the cultural detritus of the effort still floats around, and few people are terribly motivated to go correcting it since it's a dead issue.

There have been some legitimate improvements in the space since then. A disturbing amount of Grady is talking about is relatively new, not something we've been doing for a century now.

But the propaganda in the 1980s and 1990s was definitely around running out of space on Earth itself to store garbage itself because we're just generating so much. There's a picture I doubt I could dig up that has been injected into my brain of a field of garbage as seagulls fly over it and a lone backhoe in the distance tries to contend with the field of garbage. And, sure, the actual garbage dump isn't a pleasant place, though to be honest I was always sort of impressed with how little smell they tended to generate even in the 1980s. But there's a lot of unrepresentative places on Planet Earth to plop a camera. Give me a million dollars and I'll make a documentary proving Earth is uninhabited and uninhabitable. Chromecast's default photo screen saver is full of pictures of dozens of square miles of uninhabited wasteland that are very pretty colors due to the local chemical composition. But that's not a great way to understand the world in a proportional manner.

Speaking for the US at the time, in a semi-rural area, the plausibility of this was enhanced by what you would find walking through a forest. People threw a lot more stuff just straight out of their cars on the roadway, dumped cars and mattresses in state forests, all kinds of things like that. Times have changed on that front. But even then, it was really only where the people were. Most land was not full of garbage. But, pretty much by definition, the people are where the people are, so it stood out, made it a lot easier to feel like we were drowning in garbage, when all we really needed to do was take a bit better care of where we actually lived.

(This comment is about land garbage. Oceans are a completely different beast for many reasons and I'm not speaking to the issues of plastic in the ocean.)

Re: The Engineering of Landfills

#77

Post by _2d30 »

weaksauce wrote: post #72
_2d30 wrote: post #47

Earlier quoted context omitted.

A single truck requires more energy to operate in a year than 70k homes do!? I find this extremely difficult to believe. As far as I can tell, the EIA [1] suggests the average home uses 10,791 kWh a year. A gallon of gasoline contains ~33.7 kWh of energy per the EPA/Wikipedia [2]. This would mean that a single truck would be burning 70,000 * 10,791 / 33.7 = 22,414,540 gallons of gasoline a year or 61,409 gallons a da…

you should note that a gas engine does not convert all that 33kWh of energy into mechanical energy. a gasoline engine has about a 25% conversion into mechanical energy. https://www.fueleconomy.gov/feg/atv.shtml . diesel might be a bit better than a car but it's city driving by nature. just heat alone is the largest waste product in a car or truck

That's not relevant to the comparison in any way.

Re: The Engineering of Landfills

#78

Post by sitkack »

renhanxue wrote: post #60
cm2012 wrote: post #9

So many people misunderstand landfills. All the garbage produced in the U.S. for the next 1000 years could fit into a landfill 100 yards deep and 35 miles across on each side. That is, landfills take a trivial amount of space. Putting stuff in a landfill is way better for global warming since its not burned, the carbon is buried. Almost all plastic waste in developed countries ends up in landfills, not the natural en…

> Almost all plastic waste in developed countries ends up in landfills, not the natural environment. Here in Sweden less than 0.5% of household waste goes to landfill. Almost everything is burned in co-generation plants for district heating, with pretty sophisticated exhaust gas treatment. Unfortunately most of the plastic waste that goes into the recycling bins also end up there in the end, with only about 10% curre…

So it goes into the sky instead? That seems more sightly, but the CO2 emissions must be astronomical.

Re: The Engineering of Landfills

#79

Post by simmonmt »

rtkwe wrote: post #68
gruez wrote: post #27

Earlier quoted context omitted.

Is it? Land is dirt cheap in the US. Surely it's cheaper to bury it locally than ship it half way across the world? Even for the plastic that's being shipped half way across the world, they're ostensibly done for recycling purposes (ie. they're buying the plastic waste), and the unrecycleable plastics end up being mismanaged.

Land close enough to cities to be reasonable to truck garbage to is less plentiful though and you have to factor in the costs of properly containing and processing that garbage.

That's true, but NYC still ships trash all over the place: https://storymaps.arcgis.com/stories/8714ca7999a64704b59721c...

At the end of the day it has to go somewhere, and there's no room for it in the five boroughs, so they pay what they need to pay. And it's still cheaper than sending it overseas (otherwise they would).

Re: The Engineering of Landfills

#80

Post by nitwit005 »

ngruhn wrote: post #54
gruez wrote: post #27

Earlier quoted context omitted.

Is it? Land is dirt cheap in the US. Surely it's cheaper to bury it locally than ship it half way across the world? Even for the plastic that's being shipped half way across the world, they're ostensibly done for recycling purposes (ie. they're buying the plastic waste), and the unrecycleable plastics end up being mismanaged.

I’ve heard, shipping a lot of garbage to China was quite common until the Chinese banned it. That was economically viable because China exports so much and many container ships would otherwise return empty to China.

We still ship scrap metal and other recyclables over.

China, and other countries, put limits on such imports, as their recycling industries were not exactly environmentally friendly. Technically you can still import plastic waste into China, but with a very low contamination percentage that's hard to achieve.

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