Posted on 07/09/2021 1:41:29 PM PDT by blam
Could the holy grail of turning salt water to drinkable water finally be upon us?
A new report from Interesting Engineering seems to suggest that could be the case – detailing a new nanofiber membrane, developed by Yunchul Woo and his team at the Korea Institute of Civil Engineering and Building Technology, that appears to be “stable in the long term” for desalinization. And it can be done “in minutes”, the report says.
Membranes had been used in the past, but there is often a challenge in keeping them dry for long periods of time. When they become wet, their filtration characteristics become ineffective and large amounts of salt can pass through.
Woo’s team has created a membrane “made of nanofibres that have been fabricated into a three-dimensional hierarchical structure” by using a technology called “electrospinning”. This new membrane is said to be highly water repellant.
Water from one side is heated and allows water vapor to pass through the membrane, which is then condensed on the other side. The process is called membrane distillation.
“Since the salt particles are not converted to the gaseous state, they are left out on one side of the membrane, giving highly purified water on the other side,” the report says.
It also notes that the researchers used silica aerogel in their membrane fabrication process.
Upon testing the technology for 30 days continuously, they found the membrane filtered out 99.9% of salt without wetting problems.
Desalinization is the obvious answer to the global issue of over 785 million people lacking clean drinking water. Up until now, scientists have been unable to figure out a quick, cost-efficient and effective way to turn salt water into drinkable water.
Fresh water only accounts for 2.5% of the total water available on Earth, the report notes.
Returning sea salt to the sea shouldn’t be too destructive to the “environment.”
Doesn’t say anything about steam.
You made that up.
The Israelis are using it to build a rampart to slow the invaders who want to eventually overrun Israel.. Nice thread about it here a few weeks ago. Lots of pictures, too.
“Doesn’t this process bypass the vaporization phasechange?”
How do you convert liquid to vapor without vaporization phase change?
“Yes but consider what is in that brine from the ocean...many usable and extractable minerals and metals in a concentrated form...economical? Perhaps the researchers will discover.”
Oh, I agree. But making the brine useful and discarding what of it is not, has been a major cost factor when it comes to decisions to build or not to build desalinization plants.
Thanks. Now you have proven a source of fake knowledge.
So you are saying water does not naturally evaporate at ambient temperature?
But you get some vapor with even ambient temperatures. So the energy does not all have to come from external heat sources.
You’re talking about a very, very gradual return to the oceans and at various points. The current process most often means effectively dumping the brine back into the ocean in one place, vastly increasing local salinity. It takes a long time without further brine dumping for that to dissipate and return to normal conditions. In the meantime, a dead zone has been created where the entire food chain is wiped out. It takes a long time for that to recover and it can only begin that long process after the salinity levels have returned to normal. Which never happens so long as brine is continually dumped back to that point.
Imagine a clear lake that’s pretty large, but still small enough to see across. If you dump a bunch of mud in one part, it’s not clear in that part for a while. If you wait long enough, it’ll clear up again. But if you keep dumping more mud there, it’ll just stay that way indefinitely. As time goes on, if you continue this process, you’ll affected a larger area and more severely affect the local area (perhaps changing the shoreline from mud build-up).
The answer here would be to store the brine and combine it with filtered waste water, then distribute it across a larger area where it rapidly dissipates. This is a more costly way of going about it, but you avoid the destruction of the local area.
I don’t trust any writer who doesn’t know there is no “z” in desalination.
“So you are saying water does not naturally evaporate at ambient temperature?”
Never said that. Like your sweat evaporates heat is absorbed cooling your skin.
Latent heat of vaporization.
In the very long term, you’re right. Earth is a closed system, water and all. But in the shorter term returning the highly concentrated salty sludge to the sea (or wherever) is devastating to the immediate environment.
“But you get some vapor with even ambient temperatures. So the energy does not all have to come from external heat sources”
True. Evaporation can draw on internal heat cooling the liquid.
“Water from one side is heated and allows water vapor to pass through the membrane, which is then condensed on the other side. The process is called membrane distillation.”
I don’t get it. Why do you need a membrane if you’re collecting water vapor, which is already distilled (no salt)?
The Saudis and Israelis get a large chunk of their water from desalination. What do they do with the leftover brine?
That's exactly my question.
Eat more pickles?
More Kimchee?
“The Saudis and Israelis get a large chunk of their water from desalination. What do they do with the leftover brine?”
The answer is in two parts. 1. The first part is in the cost vs benefit in specifics in locales with fewer water choices than many other places - like Israel and Saudi Arabia. 2. The second part is that I think they do not do allot of economic recapture of the brine from their plants, that they are mostly discharging it, and some environmental studies have suggested the results in their coastal waters is negative - increased local water salinity and temperature.
All I said was that they may add some heat but evidently it was a lot less than required to bring it to a boil.
What offends you about that?
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