5 ms·

Nanofiber membrane makes seawater drinkable in minutes

76 points by starkd 5y ago

awestroke 5y ago
Looking forward to reading about the effects of strands of these nano fibers ending up in the environment and in our cells
- fredfoobar 5y ago
  It's not a consumer product, you can achieve 100% recycling by defining a process for it.
  - jvanderbot 5y ago
    If you don't make laws about it, I'm skeptical anyone would recycle unless theres a magic rare occasion where it's abaolutely necessary to keep profitable.
scott_paul 5y ago
Article is gibberish. Link to the actual study: https://www.sciencedirect.com/science/article/abs/pii/S0376738820316008 https://www.sciencedirect.com/science/article/abs/pii/S03767...
nayuki 5y ago
> They used a new nanofiber membrane distillation process that could desalinate water with 99.99% efficiency. The article doesn't say much about the process, but it seems like membrane distillation does involve water vapor in some way: https://en.wikipedia.org/wiki/Membrane_distillation https://en.wikipedia.org/wiki/Membrane_distillation > Unfortunately, reverse osmosis uses a tremendous amount of energy, and in the process of desalting water in this way, harmful waste is generated, which is usually discharged back into the sea or ocean. I believe every desalination process, including this one, inherently needs to discharge salty wastewater back to the ocean.
- thisrod 5y ago
  Every desalination process uses a lot of energy, too! However fancy a membrane they're using, they need to force the salt water through it, and push hard enough to beat the osmotic pressure. This is a reversible process, as you can get the energy back by using the osmotic pressure to drive a piston. A desalination process that used a lot less energy would let you build a perpetual motion machine, and is seriously against the laws of physics.
  - yazaddaruvala 5y ago
    I was thinking about this today, What if we use the oceans water pressure in our benefit? For example, deploy this membrane 100m under the ocean, and have a pipe from the membrane going into a tank on the beach nearby. As we pump fresh water out of the tank on the beach, the oceans own water pressure, pushes water through the membrane and up into the tank on the beach. That way the pump on the beach requires “very little” energy to move the water horizontally on the surface. The excess brine build up would still be an issue but that’s always an issue.
    - thisrod 5y ago
      > the oceans own water pressure, pushes water through the membrane and up into the tank on the beach Unfortunately, that's not how pressure works. There's a 100m column of water above the salt side of the membrane, but there's also a 100m column of water in the pipe on the fresh side. Those columns generate an enormous pressure, but it's pushing from both sides, which doesn't help you get water through the membrane.
      - yazaddaruvala 5y ago
        That’s why you have a pump to move the water horizontally into different tanks. Then there is a 100m column and a 95m column forcing the water through the membrane. So the pumps still need energy by “very little” energy because they are doing relatively little work.

76 points by starkd 5y ago

Looking forward to reading about the effects of strands of these nano fibers ending up in the environment and in our cells

fredfoobar 5y ago
It's not a consumer product, you can achieve 100% recycling by defining a process for it.
- jvanderbot 5y ago
  If you don't make laws about it, I'm skeptical anyone would recycle unless theres a magic rare occasion where it's abaolutely necessary to keep profitable.

scott_paul 5y ago

Article is gibberish. Link to the actual study: https://www.sciencedirect.com/science/article/abs/pii/S0376738820316008 https://www.sciencedirect.com/science/article/abs/pii/S03767...

nayuki 5y ago

> They used a new nanofiber membrane distillation process that could desalinate water with 99.99% efficiency. The article doesn't say much about the process, but it seems like membrane distillation does involve water vapor in some way: https://en.wikipedia.org/wiki/Membrane_distillation https://en.wikipedia.org/wiki/Membrane_distillation > Unfortunately, reverse osmosis uses a tremendous amount of energy, and in the process of desalting water in this way, harmful waste is generated, which is usually discharged back into the sea or ocean. I believe every desalination process, including this one, inherently needs to discharge salty wastewater back to the ocean.

thisrod 5y ago
Every desalination process uses a lot of energy, too! However fancy a membrane they're using, they need to force the salt water through it, and push hard enough to beat the osmotic pressure. This is a reversible process, as you can get the energy back by using the osmotic pressure to drive a piston. A desalination process that used a lot less energy would let you build a perpetual motion machine, and is seriously against the laws of physics.
- yazaddaruvala 5y ago
  I was thinking about this today, What if we use the oceans water pressure in our benefit? For example, deploy this membrane 100m under the ocean, and have a pipe from the membrane going into a tank on the beach nearby. As we pump fresh water out of the tank on the beach, the oceans own water pressure, pushes water through the membrane and up into the tank on the beach. That way the pump on the beach requires “very little” energy to move the water horizontally on the surface. The excess brine build up would still be an issue but that’s always an issue.
  - thisrod 5y ago
    > the oceans own water pressure, pushes water through the membrane and up into the tank on the beach Unfortunately, that's not how pressure works. There's a 100m column of water above the salt side of the membrane, but there's also a 100m column of water in the pipe on the fresh side. Those columns generate an enormous pressure, but it's pushing from both sides, which doesn't help you get water through the membrane.
    - yazaddaruvala 5y ago
      That’s why you have a pump to move the water horizontally into different tanks. Then there is a 100m column and a 95m column forcing the water through the membrane. So the pumps still need energy by “very little” energy because they are doing relatively little work.