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New method turns ocean water into drinking water, without waste

rochester.edu

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Re: New method turns ocean water into drinking water, without waste

#21

Post by Jblx2 »

eimrine wrote: post #17
mkl wrote: post #15

> without waste ...except for the huge piles of salt. If the salt was not waste, surely people would already be extracting it from the brine and the existing methods would also be "without waste".

Persian Gulf has 20% more salt in water because of the humans which are throwing the oversalinated waste back into the sea. Dehidrated salt may be a big deal for some areas because of no waste into input.

>Persian Gulf has 20% more salt in water because of the humans

I would like to read more about this from an authoritative source.

Re: New method turns ocean water into drinking water, without waste

#24

Post by gausswho »

kaonwarb wrote: post #3

This reads like hyperbole: > The brine byproduct wreaks havoc on sea life when it’s deposited back into the ocean by raising the salt level and lowering oxygen in the water. Managing return of concentrated brine should be entirely tractable in the literal ocean.

It kinda depends where it's deposited, right? The expected AMOC collapse is fundamentally about salt imbalance.

Re: New method turns ocean water into drinking water, without waste

#25

Post by tdb7893 »

Jblx2 wrote: post #21
eimrine wrote: post #17

Earlier quoted context omitted.

Persian Gulf has 20% more salt in water because of the humans which are throwing the oversalinated waste back into the sea. Dehidrated salt may be a big deal for some areas because of no waste into input.

>Persian Gulf has 20% more salt in water because of the humans I would like to read more about this from an authoritative source.

Through the magic of Googling "Persian Gulf salinity" it seems like it's more that it's a shallow Gulf in a dry area so it has significant evaporation. Desalination does effect it but it's only a few percent of the total evaporation (which is still surprisingly big) and doesn't sound like the main driving factor or an imminent ecological concern.

https://www.frontiersin.org/journals/marine-science/articles...

https://www.sciencedirect.com/science/article/abs/pii/S14635...

Re: New method turns ocean water into drinking water, without waste

#26

Post by scythe »

They are talking about lithium recovery, but there is a less exotic byproduct I'm interested in. One tonne (≈ 1 m^3) of seawater contains about 1.3 kilograms of magnesium, equivalent to about 4 kg of magnesite ore. Typical desal prices are on the order of $1 per tonne. Magnesite ore goes for about $100 per tonne, so the crude magnesium in a tonne of seawater is worth about $0.40, which could account for a substantial fraction of the desalination cost. (These numbers are very rough.)

Now you ask: why don't we just recover magnesium from brines if it's so great? Magnesium recovery from seawater isn't that easy: typically you have to treat it with some kind of alkali (often Ca(OH)2), so the cost is dominated by the extraction process (your alkali is consumed!), and you're competing with a pretty cheap ore. But if you have a solid byproduct, instead of a liquid, the options for magnesium recovery might be a lot more efficient, potentially offsetting the cost.

The fourth-most-prevalent ion, sulfate, might also be interesting, at least in a hypothetical post-petroleum future where sulfur as a byproduct of fossil fuel extraction is no longer "free". Sulfate is also annoying to extract from seawater, but again if we have a solid, the rules change.

As for the "table" salt itself, I think we'd quickly saturate (!) the market.

Re: New method turns ocean water into drinking water, without waste

#27

Post by [deleted] »

eimrine wrote: post #17
mkl wrote: post #15

> without waste ...except for the huge piles of salt. If the salt was not waste, surely people would already be extracting it from the brine and the existing methods would also be "without waste".

Persian Gulf has 20% more salt in water because of the humans which are throwing the oversalinated waste back into the sea. Dehidrated salt may be a big deal for some areas because of no waste into input.

[deleted]

Re: New method turns ocean water into drinking water, without waste

#28

Post by gibspaulding »

scythe wrote: post #19
dylan604 wrote: post #11

Earlier quoted context omitted.

I liked the idea of loading it up on a ship that sails out releasing as it goes out and back. Make it solar powered or even go old school with literal sails.

If you want to be really clever about it, maybe the ship is powered by the brine. https://en.wikipedia.org/wiki/Osmotic_power

I like this! Though I’m not sure the math works. That page says ideal efficiency for that system would be something like 0.75 kWh/m^3. Compared to 4000 to 5000 kWh/m^3 of diesel. Now we don’t need to be efficient since the point is to use up our “fuel” and we don’t need to cary cargo for this to make sense but with numbers like that, I don’t think our boat will be able to make enough power to move at all.

Re: New method turns ocean water into drinking water, without waste

#29

Post by Animats »

The paper: [1]

They're still at lab scale in glass. They haven't built a usable system, even a small one. The big claim here is that it doesn't clog; capillary action moves the salt out of the active area to another area, where some yet to be developed mechanism removes it. That needs to be demonstrated. If they can come up with something that runs for years without clogging or replacing the active material, that's a real advance.

Laser surface preparation is known.[2] It's useful for roughening smooth surfaces in a very structured way, in preparation for painting. The result is a smooth paint surface. If you sandblast to roughen, the first paint layer is somewhat irregular. Then you need to sand and paint again to get a smooth surface. Laser roughening has been tried for auto painting, but didn't go mainstream. A good question here is whether commercial laser surface prep systems can make the material this new process uses.

[1] https://www.nature.com/articles/s41377-026-02315-4

[2] https://www.youtube.com/watch?v=BKYOglHYo_Y

Re: New method turns ocean water into drinking water, without waste

#30

Post by mmmBacon »

b0rbb wrote: post #22

Awesome, love seeing stuff out of Rochester - RIT or UofR or any of the nearby schools. Totally underrated area for academic pursuits.

UofR physic grad that also worked at the LLE here. Agree Rochester schools are underrated (although admittedly a little biased).

At least in the sciences you have access to lots of opportunities you don’t have at bigger name schools.

They set me up in life in a way that I don’t think would have happened elsewhere.

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