The brine came from the ocean. So just dilute it back to close to ambient salinity using municipal waste water that you are discharging anyway.

> The brine came from the ocean.

Sure, and enriched uranium comes from the ground, but that doesn't mean it's safe to dump it back in after the enrichment process!

> So just dilute it back to close to ambient salinity using municipal waste water…

Wouldn't it generally be easier to process that municipal waste water, as is already fairly common?

The analogy would be if you "un-enrich" it. Then it's safe. Or at least no worse than when you took it out of the ground.

> The analogy would be if you "un-enrich" it.

But you're doing that with the same water you're trying to make in the first place!

You could just dilute it using fresh seawater, if you used enough and (maybe) spread it over a wider area. The amount of water people need for drinking is a relative drop in the ocean.

Brine doesn't necessarily behave the way you imagine.

https://en.wikipedia.org/wiki/Brinicle

https://en.wikipedia.org/wiki/Brine_pool

Blue Planet video of a brinicle, content warning for kind of horrifying death of sea creatures: https://www.youtube.com/watch?v=lAupJzH31tc

And a Blue Planet II video of a brine pool, stronger content warning for much more horrifying death: https://www.youtube.com/watch?v=ZwuVpNYrKPY

You can dilute the brine in a facility before disposing.

With fresh water, we’ll get it from desalinization! Hey wait a second…

Sarcasm aside, your comment actually works: you can use the freshwater from desalination!

Just wait for the saltwater to come back around in the sewer.

Globally about 70% of freshwater is used for agriculture so less than a third of it will come back around, if it's exclusively for residential/commercial use you might do better but overall not a strategy that balances out

70% of desalinated water wont ever go to agriculture because its too expensive to use for corn. Only very high value crops need apply.

But, so what? 30% sewage is still a strong dilluant... especially when mixed with more seawater

Im shocked how many people cannot grasp that you can dilute brine's salinity arbitrarily close to seawater's with energetically cheap pumps.

Go on. With what?

Seems like you could just dilute it with seawater at like 100:1 ratio and it would be negligible done offshore. We already dump our shit 5 miles out.

100:1 is overkill and energetically very wasteful. It's a fairly straightforward chemical engineering problem.

gasoline

...sea water. You take 10 units of sea water for every unit processed and you'll get a slight increase in salinity.

A phase diagram tells you exactly how far you need to go.

You know this makes more thermodynamic sense than carbon capture, right?

> Sure, and enriched uranium comes from the ground

Uranium can also come from the ocean water (there is, apparently, quite a lot of it in there, relatively speaking). Japan experimented with the technology in the nineties, but it really was much cheaper to just mine it from the ground, so they abandoned it.

Japan is also barred from doing own enrichment, being a non-nuclear state. Though, there nevertheless is a dormant set of requisite facilities.

You're wrong. Japan does do their own enrichment, 150k SWUs at Rokkasho with plans to bring that up to 500k SWUs a year soon. If they chose to make.bombs instead of fuel, they could make dozens a year.

That's the dormant plant. Rokkasho-mura plant is officially incomplete for decades, doing tests and upgrades without actual production.

If you think otherwise and you're not wrong, and I think you ARE not mistaken since this isn't the first time someone other than myself mentioned it here, that means they're making bombs because we in Japanese public aren't told about it. There has only been just some routine commentaries from local mayors at most.

I think you might be confusing the Rokkasho Reprocessing Plant (not yet operational, intended for plutonium extraction from spent fuel) and the Rokkasho Uranium Enrichment plant, which has been running at 75 tSWU/year (I think that should be kSWU or tSW) since 2023-08-24 https://www.jnfl.co.jp/ja/business/about/uran/daily/enrichme... 112.5 tSWU/year since 2025-06-26 https://www.jnfl.co.jp/ja/business/about/uran/daily/enrichme... and 150 tSWU/year since 2025-11-20 https://www.jnfl.co.jp/ja/business/about/uran/daily/enrichme...

It's a bit weird though that they have a graph of tons of uranium hexafluoride shipped that shows the last shipment in 2018 and nothing since then.

They also have a large stockpile of reactor grade plutonium. Not the best material for bombs, but workable.

It's about 3 parts per billion. Uranium is about $85/pound, so you'd need to be able to completely process/extract about 40 million gallons of saltwater for $85 to break even. The real cost there is orders of magnitude higher. It's one reason the claim about the Earth having vast amounts of uranium is quite disingenuous. The amount of cost efficient accessible uranium is only enough to last ~1 century at current consumption rates. If nuclear energy scaled up significantly, we'd run out in a matter of decades if not less, or we send the price of uranium skyrocketing and the price arguments would need to be significantly adjusted.

Enriched uranium is perfectly safe to dump but it would be stupid to do so. Fission products are nasty but uranium itself is not, comparatively.

Municipal waste water is a much cheaper way to get desalinated water in the first place though.

except for the pharmaceuticals anyway

Hey, it's free viagra, prozac, progesterone and multivitamin supplements, all in a glass.

There’s some fat fish out there, I hope we can get those guys some Ozempic too

Democrats intentionally killing the fishing industry by giving fish free glp1s and cocaine with your tax dollars!

That’s been a solved problem, engineering-wise, for a while.

The advanced treatment stages take care of it. Between UV, ozone, and nanofiltration, etc. we can remove the pharmaceuticals.

Actually the problem is the water comes out too pure out of a well designed water reuse system, to the point where the mineral content can be too low and you need to add some back in.

Cite for it being solved? All the articles I can find have it as ‘active and growing problem with some potential mitigations which are not universally applied’.

All the recycled water systems I’m aware of still have PCC issues and excess ion contamination problems too still.

Admittedly my knowledge was based on work I did in academia, and I now work in transportation, so I suppose it’s possible I’m in error, but I’d be surprised if much survives the RO stage, and isn’t eaten up by the oxidation stage. My understanding was that the water needs to actually get remineralized to protect the distribution system. And that it’s very devoid of pharmaceutical contaminants by that point. I was unaware of this being an issue in real world potable reuse systems. Though, I suppose different jurisdictions may have different standards. My state was pretty strict.

Maybe, but dumping crystalline salt is even worse to the spot you’re dumping it on.

I wonder. It would have to dissolve, a big block of salt would take a while, kind of like the erosion of cliffs where the salt comes from in the first place. Eh, I guess you're right though, the fish wouldn't like that at all.

It doesn't need to be crystalline salt. Just mix the brine with seawater at a really high ratio of sea water to brine then dump that out. 100:1 ratio should be fine I would guess. Quick search suggests seawater salinity variance is already like 10%-15% or so. Even better if you pipe it offshore where currents will take it and not somewhere that doesn't circulate.

Yes, that's my point: if you're next to the ocean, disposing of brine is extremely easy.

You could put it back into old salt mines.

Even better, just package it up and eat it instead of digging underground and creating more pollution.

It's not every day that industrial waste happens to be not only edible but also tasty. Too tasty, in fact. Salt is addictive.

It’s not going to be pure NaCl though; making Morton salt with it would make sense only if it wouldn’t cost more to process it (net of its resale value) than just disposing of it somewhere not particularly sensitive. I’d propose the Utah salt flats or indeed, kinda love the idea of just sticking them in a salt mine that is all tapped out. If it used to be chock full of salt it seems pretty environmentally fair to make it salty again.

The impurities are exactly what give sea salt from various regions their distinctive flavors and mineral profiles. The salt should be edible as long as it wasn't pulled from seriously polluted waters. It might even sell for a premium.

If you use fat pipes that go a decent distance from shore, diluting your brine with ocean water, you’ll have a negligible impact on the ocean. The problem is if you dump lots of brine in shallow waters. Old designs did have that flaw, but it’s not that difficult to design around this constraint now that we know about it.

IMO this is an issue where NIMBYs are using environmental concerns as a smokescreen to block new desal plants from ruining the vibe at their beachfront property. Rhymes with the opposition against offshore wind farms.

Yeah. Worrying about salt in the sea is like worrying about oxygen in the air. Can too much oxygen in the air sometimes be a problem? Yeah, in some corner cases. Is it a major problem that we can't solve? Not at all.

That makes sense to me. At the same time I know the mediterranean sea is heating up more because it cannot move heat out quick enough. I dont know of any mediterranean air, so I believe more closed water zones would behave different than, lets say, the atlantic ocean.

Isn't it more akin in this case to worrying about too much carbon dioxide in the air?

Why is it akin to that? Doesn't the salt come from the sea in the first place?

A more apt comparison than you realize.

Most of the carbon we spew into the atmosphere came from the air. Ancient plants took it in via respiration.

That still doesn't make it a good comparison. The salt emitted by desalination plants is already in the sea now, it's not salt that went somewhere else.

And the water we take out eventually goes back.

I can probably be convinced pretty easily with some evidence of that, but you’ll never convince the contingent who is convinced it’ll kill sea life at any concentration or location, so, being able to shut them up by saying “we have no wastewater, we load rail cars with crunchy salt and use it for stuff” still has value.

The goalposts will just shift to attack that excess salt instead. It’s like all of the FUD about datacenter water usage while people shove almonds in their mouths.

In Germany, it's the water usage of a Tesla plant vs. the neighboring asparagus farm.

I wish we could reimagine carbon credits to that degree of stringency. You offset a kg of carbon emissions? Let's see that kg.

> The problem is if you dump lots of brine in shallow waters. Old designs did have that flaw, but it’s not that difficult to design around this constraint now that we know about it.

I think that problem was known (and discarded as not important) when the first serious water desalination plants were built.

The city of Corpus Christi, TX is currently considering options for desalination plants—all of which pump their brine into the shallow water inside the bay or the ship channel.

Sounds on brand for Texas.

Actually it's easy and ok. Just mix it with the treated sewage right before it returns. Simple mass action implies the salinity hasn't changed.

But wait! There's water mass loss due to leaky pipes and outdoor pools!

Mixing salt water and brine is perfectly ok. Just use a phase diagram.

that's 200% bullshits. Countries that invested into desalination plants are known to create death zones right where brine is sent back - even if miles from the coast

Someone tell me why this is stupid, which it probably is: Put the desalination plant on a tanker ship and let it do its duty out in the middle of the ocean, then cruise back to port and dispense the water.