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Comment by amelius | Hacker News Reader

> So I wonder how many drones this volcano has eaten so far?

Perhaps it's a good way to deal with our e-waste?

Ignoring the logistics what are the downsides of dumping toxic waste into lava considering how long the lava would be stable once it has cooled?

Toxic waste getting vaporized would be my biggest concern.

That's actually how its often gotten rid of - https://frtr.gov/matrix2/section4/4-23.html

> temperatures, 870 to 1,200 °C (1,400 to 2,200 °F), are used to volatilize and combust (in the presence of oxygen) halogenated and other refractory organics in hazardous wastes. Often auxiliary fuels are employed to initiate and sustain combustion. The destruction and removal efficiency (DRE) for properly operated incinerators exceeds the 99.99% requirement for hazardous waste and can be operated to meet the 99.9999% requirement for PCBs and dioxins. Off gases and combustion residuals generally require treatment.

And lava is in the range of 700 °C to 1300 °C. So... that could work.

With regular waste incinerators, the issue is the treatment of the gas... which... well... they already have issues with - https://www.usgs.gov/natural-hazards/volcano-hazards/volcani...

That said...

https://www.forbes.com/sites/robinandrews/2017/09/28/this-is...

> I was recently asked by a fairly small and young human why we don't just throw a lot of our waste into volcanoes – specifically, into the ones that have lava lakes, like Hawaii's Kilauea or the Democratic Republic of Congo's Nyiragongo.

> ...

> It's certainly a question that deserves an answer. Well, sadly, that answer probably isn’t the one you’re hoping for. As I've explained in a previous Forbes piece, lava lakes are complex things. They're extremely hot, and can melt plenty of things, that's for sure. However, they can't melt everything, and humanity has invented plenty of materials that would simply float atop the surface.

I read an article that proposed burying nuclear waste in the fracture zone of the Mid-Atlantic Ridge.

https://link.springer.com/article/10.1007%2FBF02430666

Wouldn't you rather want to bury it in a subduction zone? Dumping it where new crust is being created seems like a strange solution...

I think that Sauron has voiced objection.

The first problem is there's not enough lava. Per a few sources there have been about 6 billion tons/tonnes of solid plastic waste since the mid-20th century; assuming the density of PVC, .05 g/cm^3, my napkin math says this is over 100 cubic kilometers of plastic waste, or enough to build a small volcano on its own.

(edit) You said "ignoring the logistics" so I agree with the other commenter, the outgassing of the burning would be environmentally devastating. Lava doesn't instantly vaporize things: https://www.youtube.com/watch?v=cXJfg_JIUZA

Nitpick: PVC sinks in water. That would make it over 1g/cm³.

Polypropylene and polyethylene do float, but don’t come near 0.05g/cm³. They’re closer to 0.9g/cm³ (https://www.plasticseurope.org/en/about-plastics/what-are-pl...). That’s close to icebergs.

You are right, seems I had a bad source—density is closer to 1.1-1.5 g/cm^3 than the 0.5 I used. So only 50 cubic km...

In your post you mentioned 0.05, so that's not a factor of 3 off of 1.5, but instead a factor of 30...

A little more formally, with sources:

Density of plastic: https://omnexus.specialchem.com/polymer-properties/propertie... - Eyeballed at 1.2 g/cm^3

Plastic waste, lifetime: https://advances.sciencemag.org/content/3/7/e1700782 - 6.3 megatonnes (2017)

6.3 Mt / (1.2 g/cm^3) = 5250000 (5.25 million) m^3 = 0.00525 km^3

You were right! My math was way off. Thanks for noticing. This is a great demonstration of peer review :)

There is certainly enough lava. The eruption that occurred in 2018 in my home town produced 1 billion cubic yards or 914402.757839 cubic kilometers.

https://volcanoes.usgs.gov/vsc/file_mngr/file-224/OVERVIEW_K...

I imaging the outgassing of the plastic would be pretty terrible but the volcanic gas is pretty damaging too. But yes, I imagine there are a hundred different reasons this wouldn't really work out.

I don’t think that math is right. 1 billion cubic yards is like less than 1 cubic km.

You are correct. I messed that up bad and forgot how dimensions worked.

Yet even ignoring those two issues, you included 12 significant figures on a number that was likely 10% off in the first place.

If you dump something radioactive into a volcano, now you have a radioactive volcano, which is not better

The vast majority of "toxic waste" is chemically toxic not radioactive.

I wonder if at least some volcanos might be radioactive ? The stuff is comming from deep below & there are theories the core is being kept molten thanks to decay of radioactive elements, so I wonder if some of that might get up occasionally ?

Or is that nonsense as core is much much deeper and there is hardly any mixibg goin on between the layers?

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