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Comment by rascul | Hacker News Reader

> After the soda lime is maxed out, it's tossed. At least so far as I understand you can't meaningfully re-use it for scrubbing, though there are other industrial uses where it can be re-purposed.

Does it get re-purposed? Is there an issue to "tossing" it out of the sub while submerged?

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The soda lime solution is only used for shipboard casualties. The normal service system on a submarine uses a regenerative fluid to scrub the air of CO2.

This fluid smells like cat piss.

Interesting. I did more research and there isn't a ton out in the public domain, but it looks to be that the USN and others are using MonoEthanolAmine (MEA) as a regenerative CO2 scrubber. MEA

>Weeks et al. (1960) reported that volunteers who smelled MEA vapor described the odor as ammoniacal, musty, or foreign; some volunteers were unable to characterize the odor.

> Ethanolamine is a colorless, viscous liquid with an odor reminiscent of ammonia.

Ammonia is a lot of what "cat piss" smells of, so that tracks. Thanks! That was really interesting to read about!

* https://en.wikipedia.org/wiki/Ethanolamine

* https://apps.dtic.mil/sti/citations/ADA389253

* https://www.sonistics.com/wp-content/uploads/01-KEY-DEVELOPM...

* https://nap.nationalacademies.org/read/11170/chapter/10#197

If I remember my chemistry correctly Soda lime + CO2 results in Sodium Bicarbonate (baking soda) and Calcium Carbonate. I'm not a submariner, so I have no idea if they have re-purposes use for it onboard. I would assume it is stored, like all trash/waste, onboard until the sub is resupplied.

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