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The Dirty Truth About Turning Seawater into Drinking Water

earther.gizmodo.com

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Re: The Dirty Truth About Turning Seawater into Drinking Water

#31

Post by growlist »

simonh wrote: post #20
xg15 wrote: post #17

Stupid question: Being that a large fraction of the problematic plants seem to exist close to or within desert countries, couldn't you simply pump it into the desert? I figure, if you find an appropriate area, you'll have not much of an ecosystem to destroy anyway and the area could eventually function as an enormous evaporation pond.

If you're wanting to make fresh water there, it's probably because people do actually live there and want to do other stuff there, so any method of polluting the environment is going to have negative consequences. For example if they are extracting fresh water from seawater, they are probably also already using groundwater as well which your proposal would pollute.

Saudi is enormous - no doubt there are vast expanses completely away from civilisation, and I'm guessing there are plenty of remote oil field areas that are already degraded to some extent. However: firstly as you hint at the desert does have an ecosystem, and secondly salt is not the only contaminant in the sea. I could imagine an Aral Sea type scenario where heavy metals, for example, were evaporated out in significant concentrations over time. Then with a little wind blowing the dust towards populated areas, you are in trouble.

Re: The Dirty Truth About Turning Seawater into Drinking Water

#32

Post by nickles »

zaarn wrote: post #29
simonh wrote: post #22

Earlier quoted context omitted.

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.

> 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.

"The primary concern with human health in regards to microplastics is more directed towards the different toxic and carcinogenic chemicals used to make these plastics and what they carry. It has also been thought that microplastics can act as a vector for pathogens as well as heavy metals. More specifically, pregnant women in particular are in danger of causing birth defects to male infants such as anogenital distance, penile width, and testicular descent. This comes from phthalate exposure and DEHP metabolites that interfere with the development of the male reproductive tract."

"Another dangerous ingredient is called Tetrabromobisphenol A (TBBPA) which is a flame retardant in many different types of plastics such as those used in microcircuits. This chemical has been linked to disruptions in thyroid hormones balance, pituitary function, and infertility. The endocrine system is affected by TBBPA through disruption of the natural T3 functions with the nuclear suspension in pituitary and thyroid."

"Many people can expect to come in contact with various types of microplastics on a daily basis in the aforementioned sources (see sources). However, the average citizen is exposed to microplastics through their various types of food included in a normal diet. For instance: Salt. Researchers in China tested three types of table salt samples available in supermarkets and found the presence of microplastics in all of them. Sea salt has the highest amounts of microplastics compared to lake salt and rock/well salt."

Even if we ignore the environmental impact, there's ample evidence to indicate we should not dismiss the dangers of microplastics to human health without further research.

[0] https://en.wikipedia.org/wiki/Microplastics

Re: The Dirty Truth About Turning Seawater into Drinking Water

#33

Post by snowwrestler »

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.

> is just a problem requiring money

Any problem of providing fresh water for human civilization is "just a problem requiring money." It's not like there is a lack of water on the Earth. So it's kind of silly to pick one single particular aspect (diluting brine) to try to hand-wave away as just a money problem.

In general, money is a significant constraint on engineering and can't be hand-waved away.

Re: The Dirty Truth About Turning Seawater into Drinking Water

#34

Post by loudmax »

aphextron wrote: post #28

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.

Carbon emissions is a grave problem with existing desalination infrastructure, but this seems something that can be solved. I'd expect desalination to be well suited for opportunistic use of solar or wind power. Build up reserves of clean water when it's sunny or windy, then deplete those reserves when cheap spare energy isn't available.

Of course this goes for new desalination plants. Whether there's political will to convert existing plants to non-fossil fuel sources is another matter. But at least from an engineering perspective there is a way forward.

What I get out of the article is that disposing of brine is an ecological hazard. This shouldn't really be a surprise since any engineering effort at large scale is going to have some kind of environmental impact, but this is a new consideration for those of us who don't work in the industry and hadn't thought too deeply about the process.

Re: The Dirty Truth About Turning Seawater into Drinking Water

#35

Post by loudmax »

xg15 wrote: post #17

Stupid question: Being that a large fraction of the problematic plants seem to exist close to or within desert countries, couldn't you simply pump it into the desert? I figure, if you find an appropriate area, you'll have not much of an ecosystem to destroy anyway and the area could eventually function as an enormous evaporation pond.

I think the issue is the scale of the operation. It's not that the desert doesn't have the capacity to absorb brine, it's that pumping all that brine into one spot creates a local ecological catastrophe. To avoid a concentration of toxins you need to spread it around, which is expensive.

My expectation is that the brine will have to go back into the ocean. The deserts a big, but the ocean is bigger. What the paper mentioned in the article points out is that you can't dump this all in one place.

Re: The Dirty Truth About Turning Seawater into Drinking Water

#36

Post by snowwrestler »

zaarn wrote: post #29
simonh wrote: post #22

Earlier quoted context omitted.

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.

Things can get weird at very small sizes because of the huge ratio of surface area to mass. An amount of plastic that is safe to place against your skin as one object, might have more significant chemical interactions as a collection of particles in your digestive system--which specializes in leaching complex chemicals out the materials that pass through it.

Re: The Dirty Truth About Turning Seawater into Drinking Water

#37

Post by beagle3 »

loudmax wrote: post #34
aphextron wrote: post #28

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.

Carbon emissions is a grave problem with existing desalination infrastructure, but this seems something that can be solved. I'd expect desalination to be well suited for opportunistic use of solar or wind power. Build up reserves of clean water when it's sunny or windy, then deplete those reserves when cheap spare energy isn't available. Of course this goes for new desalination plants. Whether there's political will…

Most desalination plants around the world are operating at 100% capacity all of the time, because that's what needed to avoid depletion of the reservoirs.

To be able to "build up reserves" means that you have to build much higher capacity, but only use as much of it as clean energy allows - in today's world, this is highly uneconomical.

If anything, the reserves to be built are energy reserves that allow water to be desalinated continuously -- and that's something which makes sense in general, possibly grid scale as storage technology improves, regardless of the specifics of water desalination.

Re: The Dirty Truth About Turning Seawater into Drinking Water

#38

Post by sunstone »

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. >…

Yes, just like exhaled breath is a waste product full of C02 and containing very little oxygen. If other people had to breath that they would become very sick or even die.

Re: The Dirty Truth About Turning Seawater into Drinking Water

#39

Post by Jeff_Brown »

endorphone wrote: post #30
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…

Diluting it with ... fresh water?

Re: The Dirty Truth About Turning Seawater into Drinking Water

#40

Post by [deleted] »

loudmax wrote: post #35
xg15 wrote: post #17

Stupid question: Being that a large fraction of the problematic plants seem to exist close to or within desert countries, couldn't you simply pump it into the desert? I figure, if you find an appropriate area, you'll have not much of an ecosystem to destroy anyway and the area could eventually function as an enormous evaporation pond.

I think the issue is the scale of the operation. It's not that the desert doesn't have the capacity to absorb brine, it's that pumping all that brine into one spot creates a local ecological catastrophe. To avoid a concentration of toxins you need to spread it around, which is expensive. My expectation is that the brine will have to go back into the ocean. The deserts a big, but the ocean is bigger. What the paper me…

[deleted]
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