[kaonwarb]

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.

[rconti]

Sure, but typically desalination plants are located in a single physical place, so a discharge pipe dumping brine 24x7 is bad for all of the things around it, as the local concentration is extremely high.

[joshred]

Seems like you could run a long perforated tube to diminish that effect.

[XorNot]

The short version is brine is weird: it's surprisingly resistant to diffusing and tends to flow more like an immisicible fluid. So you have to put quite a lot of effort into getting it to actually disperse rather then just fall to the seafloor.

[fc417fc802]

That's silly, you'd mechanically mix it with seawater rather than wait for it to diffuse. The concern would be the volume of desalinated water extracted from the local region versus the flux from ocean current. As long as that ratio is acceptable there won't be any long term problem.

Alternatively, in the absence of sensible regulations a cutthroat operator devoid of ethics constructs a plant that dumps concentrated brine in the immediate vicinity because that's the cheapest approach. Then reactionary elements raise talking points about environmental damage and pretend that it's a difficult problem to solve. Business as usual.

[dieselgate]

I wonder what the linear diffusion gradient would look like for that. Like the perforated garden hoses or whatever for soaking soil. Aquatic organisms grow so quick though very curious on the constraints for something like this.

[dylan604]

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.

[sgc]

I thought they tend to pipe far out and discharge as far below the surface as possible, since there is a lot of surface life and it is less damaging this way.

Ships (with long submerged pipes) would be prone to weather events and generally less reliable than an installed pipe. Perforation would be prone to clogging from build up so a nonstarter I would expect. Adding flex tubing and a relocation robot would be a maintenance headache as well. Not sure there is an easy optimization.

[dylan604]

Ships wouldn't need a long submerged pipe. It'd just need a small hole like a bilge drain or maybe a live well on a fishing boat. Just let the boat cruise around slowly draining back into the ocean.

As for surface life, I'm no oceanographer, but is that really the most vulnerable place? The surface is where fresh water rain meets the ocean, so that would dilute the salinity during storms. However, there's nothing to say that another pump couldn't be pulling from the ocean and mixing the brine into that so it's diluted before and not just pouring brine straight into the ocean

[sgc]

I think your sense of scale is off. 90% of sea life is on the surface. 0.029% of ocean water is replenished from rainfall annually. Desalination concentrates are absolutely toxic to life. The current daily volume of brine discharge would require more than half the tankers in the world to be filled and discharged every single day. They would of course not last long with such a routine.

[scythe]

If you want to be really clever about it, maybe the ship is powered by the brine.

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

[gibspaulding]

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.

[01100011]

And it doesn't even need to be a rigid pipe. A flexible pipe made out of, say, waterproof fabric, could be cheaply made to extend miles while remaining open due to the pressure of the water pumped into it.

[dylan604]

Things left underwater tend to collect things on it which would make this much less porous over time.

[dizhn]

Then they should become salt producers too. Win win (win).

[bilsbie]

The brine thing is just a way to shut down conversation and let people feel superior for claiming there are no solutions to our problems except to reduce our standard of living.

It’s obvious you can safely put salt back into the ocean with enough dilution. I bet a middle schooler could design a system to do it.

[rplnt]

Yeah, middle schooler with middle school understanding can design anything. There are plenty of middle school solutions in the comments around. The problem is when they meet real world, beyond their high school level understanding of the issue.

[gausswho]

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

[wolfi1]

depends of course, how easy does the brine dissolve, how long does it take that it is so diluted that it can't do any harm, without that information it's not easy to tell

[dylan604]

These are often built near shallower parts along the coast where changes are more pronounced.

[boxed]

I mean.. we really want to permanently desalinate the ocean somewhat too so putting the brine back seems kinda stupid. Put it on land, let it dry, sell some as table salt and dump the rest into abandoned mines.

[wizzwizz4]

Excellent idea! The largest abandoned mines I'm aware of are salt mines, which… hang on.

[boxed]

Yea, that's one of the problems. We're literally digging up salt AND the mountains are being eroded to add more salt. The Earth is getting anti-terraformed and we're speeding it up. (Although obviously the fossil fuel situation is a much closer and worse problem)