The Dirty Truth About Turning Seawater into Drinking Water • Hacker News Board

Re: The Dirty Truth About Turning Seawater into Drinking Water

#21

Post by geofft » Wed, Jan 16, 2019, 2:03 PM UTC

bryanlarsen wrote: post #18

geofft wrote: post #15

Earlier quoted context omitted.

This isn't absurd at all. Sea water contains lots of components, not just salt. Many are non-toxic at their current concentration ; if you remove the water and pump in the rest into the ocean, you're potentially increasing the concentration enough to make it toxic. It is quite literally toxic waste. And the journalist did you the favor of linking to scientific research that says the same thing.

"at their current concentration" So the solution is obvious. Mix 1 part brine with X parts seawater before releasing. Oceans are big, so X can be a very large number, if that is necessary.

I wonder why that never occurred to the researchers who spend their professional lives studying how to safely dispose of brine?

As the article points out, desalinization produces "37.5 billion gallons (142 billion liters) of this salty-ass junk every day." What's your plan for pumping in X times that from the oceans, diluting it, and then pumping it out?

Re: The Dirty Truth About Turning Seawater into Drinking Water

#22

Post by simonh » Wed, Jan 16, 2019, 2:08 PM UTC

wlll wrote: post #3

> At the very least, we should be treating the brine so it’s safe to discharge into the ocean. This amused me as I pictured people mixing newly produced fresh water with the brine and releasing this "new" seawater back. Seriously though, I guess I assumed people were at least turning this stuff into salt. I watched a documentary on salt production (Italy I think) and they just got sea water and evaporated it in huge…

Sea salt has it's own problems due to it's microplastics content. Around 90% of domestic sea salt contains microplastics and the average adult consumes around 2,000 microplastic particles as a result every year. People who go out of their way to buy sea salt presumably ingest significantly more on average.

My mother used to love sea salt, but recently switched to rock salt.

Re: The Dirty Truth About Turning Seawater into Drinking Water

#23

Post by bryanlarsen » Wed, Jan 16, 2019, 2:09 PM UTC

geofft wrote: post #21

bryanlarsen wrote: post #18

Earlier quoted context omitted.

"at their current concentration" So the solution is obvious. Mix 1 part brine with X parts seawater before releasing. Oceans are big, so X can be a very large number, if that is necessary.

I wonder why that never occurred to the researchers who spend their professional lives studying how to safely dispose of brine? As the article points out, desalinization produces "37.5 billion gallons (142 billion liters) of this salty-ass junk every day." What's your plan for pumping in X times that from the oceans, diluting it, and then pumping it out?

I'm fairly confident that the plant designers and researchers know this and that journalists have messed it up.

They're already pumping in 37.5B + 37.5*2.5/1.5B gallons of it, so pumping in a multiple of that is just a problem requiring money.

But getting the money to do so requires scaring the public into giving it to them, thus the scare articles like this one in the press.

Re: The Dirty Truth About Turning Seawater into Drinking Water

#24

Post by cagenut » Wed, Jan 16, 2019, 2:11 PM UTC

abalone wrote: post #19

It’s saying for every 2.5L of seawater only 1L of freshwater is recovered and the rest is brine, which also includes chemical byproducts. Why is this ratio so bad? What would it take to recover more water and produce more concentrated waste that could be managed differently?

energy

Re: The Dirty Truth About Turning Seawater into Drinking Water

#25

Post by kaybe » Wed, Jan 16, 2019, 2:15 PM UTC

wlll wrote: post #3

> At the very least, we should be treating the brine so it’s safe to discharge into the ocean. This amused me as I pictured people mixing newly produced fresh water with the brine and releasing this "new" seawater back. Seriously though, I guess I assumed people were at least turning this stuff into salt. I watched a documentary on salt production (Italy I think) and they just got sea water and evaporated it in huge…

Well you could probably run an osmosis power station off it. I'm not sure about the efficiency, but it's a viable way to store energy.

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

Re: The Dirty Truth About Turning Seawater into Drinking Water

#26

Post by geofft » Wed, Jan 16, 2019, 2:16 PM UTC

bryanlarsen wrote: post #23

geofft wrote: post #21

Earlier quoted context omitted.

I wonder why that never occurred to the researchers who spend their professional lives studying how to safely dispose of brine? As the article points out, desalinization produces "37.5 billion gallons (142 billion liters) of this salty-ass junk every day." What's your plan for pumping in X times that from the oceans, diluting it, and then pumping it out?

I'm fairly confident that the plant designers and researchers know this and that journalists have messed it up. They're already pumping in 37.5B + 37.5*2.5/1.5B gallons of it, so pumping in a multiple of that is just a problem requiring money. But getting the money to do so requires scaring the public into giving it to them, thus the scare articles like this one in the press.

Interesting. Why do you think this article will help scare the public into giving "them" the money? According to the paper linked in the article (Jones et al. 2019), many of these desalinization plants are in the Middle East and North Africa: "Brine production in Saudi Arabia, UAE, Kuwait and Qatar accounts for 55% of the total global share." Do you think that the general public in those countries reads Gizmodo and also has voting power to adjust the budgets for desalinization plants?

Also, why do you think that paper does not address the option of pumping in more ocean water and diluting it? (It's paywalled - if you'd like a PDF I can get you one.)

Re: The Dirty Truth About Turning Seawater into Drinking Water

#27

Post by nickthemagicman » Wed, Jan 16, 2019, 2:27 PM UTC

arkades wrote: post #6

Just to be clear, "brine" isn't "salty water." > This untreated salt water can’t just hang around in ponds—or, in worst-case scenarios, go into oceans or sewers. Disposal depends on geography, but typically the waste does go into oceans or sewers, if not injected into wells or kept in evaporation ponds. The high concentrations of salt, as well as chemicals like copper and chlorine, can make it toxic to marine life. >…

Is there any use for it at all?

Re: The Dirty Truth About Turning Seawater into Drinking Water

#28

Post by aphextron » Wed, Jan 16, 2019, 2:36 PM UTC

I’m surprised this article mentions nothing about energy. Practically all desalination in existence is powered by fossil fuels, with Israel and Saudi Arabia being the worst offenders. The only reason it’s even economically viable is the externalized cost of carbon emission. It’s simply not a long term tenable solution until this is addressed.

Re: The Dirty Truth About Turning Seawater into Drinking Water

#29

Post by zaarn » Wed, Jan 16, 2019, 2:37 PM UTC

simonh wrote: post #22

wlll wrote: post #3

> At the very least, we should be treating the brine so it’s safe to discharge into the ocean. This amused me as I pictured people mixing newly produced fresh water with the brine and releasing this "new" seawater back. Seriously though, I guess I assumed people were at least turning this stuff into salt. I watched a documentary on salt production (Italy I think) and they just got sea water and evaporated it in huge…

Sea salt has it's own problems due to it's microplastics content. Around 90% of domestic sea salt contains microplastics and the average adult consumes around 2,000 microplastic particles as a result every year. People who go out of their way to buy sea salt presumably ingest significantly more on average. My mother used to love sea salt, but recently switched to rock salt.

I don't think microplastic particles in the human digestive system are that big of a problem; most of it is fairly inert and will just pass through, the other stuff is in low enough quantities that our stomach should be able to deal with it.

Re: The Dirty Truth About Turning Seawater into Drinking Water

#30

Post by endorphone » Wed, Jan 16, 2019, 2:50 PM UTC

arkades wrote: post #6

Just to be clear, "brine" isn't "salty water." > This untreated salt water can’t just hang around in ponds—or, in worst-case scenarios, go into oceans or sewers. Disposal depends on geography, but typically the waste does go into oceans or sewers, if not injected into wells or kept in evaporation ponds. The high concentrations of salt, as well as chemicals like copper and chlorine, can make it toxic to marine life. >…

Just to be clear, "brine" isn't "salty water."

It mostly is, and the additional chemicals they mention are already in the sea water, not that were added somehow in the process. It's just concentrated.

That it's concentrated is a problem, obviously -- very high-saline water (e.g. brine) and concentrated toxins are a problem, and would cause environmental problems if just dumped. The most common way to deal with brine is simply diluting it before discharge, ensuring that the salt content isn't high enough that it sinks and forms a brine pool.