4 ms·

> while salt can't pass But will not the separated salt clog the membrane? Separated salt is an issue, e.g. in distillation - you have to remove it to remain d

by mdp2021 3y ago

> while salt can't pass But will not the separated salt clog the membrane? Separated salt is an issue, e.g. in distillation - you have to remove it to remain decently efficient. And speaking of efficiency: do energy costs make mass desalinization with this technology feasible?

freshpots 3y ago
Salt doesn't pass through RO membranes and these appear to have the same pore size. However, they all foul and you perform maintenance like backwashing and chemical cleaning as the flow rate goes down. Here is an overview: https://www.suezwaterhandbook.com/water-and-generalities/fundamental-physical-chemical-engineering-processes-applicable-to-water-treatment/membrane-separation/desalination-membranes https://www.suezwaterhandbook.com/water-and-generalities/fun... In terms of efficiency, it is cost dependent. Making drinking water is not cost prohibitive at this time but for large scale agriculture it would typically be considered too expensive to irrigate with RO desalinated water. This technology appears to lower the energy requirements but more research and scaling it up is needed.
- Gibbon1 3y ago
  When I've looked into RO for irrigation it seems that cost is a problem but it's tantalizingly close to economic. I think you need to get the cost down by 2/3rds. However boron is a problem, most RO water has more boron than is healthy for plants. Though I saw one press release talking about a membrane that unexpectedly produces water with low levels of boron.
  - freshpots 3y ago
    Interesting, TIL. I wasn't aware of boron issues with RO. Is this for seawater RO to irrigation water? This link is interesting: https://www.globalwaterintel.com/sponsored-content/boron-a-key-challenge-for-reverse-osmosis-systems-successfully-treated-with-lg-chem-tfn-membranes-lg-chem https://www.globalwaterintel.com/sponsored-content/boron-a-k...
- sacnoradhq 3y ago
  RO membranes typically include a waste path so they're self-cleaning for their lifecycle, but some manufacturers may have flushing procedures to extend service life. Saudi Arabia, Kuwait, UAE, Qatar, Bahrain, and Libya are almost completely dependent on RO for water. The Carlsbad plant in San Diego was $1B and costs $80M/y (@ 40 MW) to operate while producing 56k acre-ft/y (7% of demand), enough for about 400k people or 20k acres of farmland with average crops. What would cut water use greatly would be the elimination of meat agriculture which depends on crops such as hay, alfalfa, and cow corn. 2/3 of Utah's water goes to irrigating crops to feed cows.
sacnoradhq 3y ago
Unlikely. At scale, will likely be setup like an RO membrane with 3 lines.

freshpots 3y ago

Salt doesn't pass through RO membranes and these appear to have the same pore size. However, they all foul and you perform maintenance like backwashing and chemical cleaning as the flow rate goes down. Here is an overview: https://www.suezwaterhandbook.com/water-and-generalities/fundamental-physical-chemical-engineering-processes-applicable-to-water-treatment/membrane-separation/desalination-membranes https://www.suezwaterhandbook.com/water-and-generalities/fun... In terms of efficiency, it is cost dependent. Making drinking water is not cost prohibitive at this time but for large scale agriculture it would typically be considered too expensive to irrigate with RO desalinated water. This technology appears to lower the energy requirements but more research and scaling it up is needed.

Gibbon1 3y ago
When I've looked into RO for irrigation it seems that cost is a problem but it's tantalizingly close to economic. I think you need to get the cost down by 2/3rds. However boron is a problem, most RO water has more boron than is healthy for plants. Though I saw one press release talking about a membrane that unexpectedly produces water with low levels of boron.
- freshpots 3y ago
  Interesting, TIL. I wasn't aware of boron issues with RO. Is this for seawater RO to irrigation water? This link is interesting: https://www.globalwaterintel.com/sponsored-content/boron-a-key-challenge-for-reverse-osmosis-systems-successfully-treated-with-lg-chem-tfn-membranes-lg-chem https://www.globalwaterintel.com/sponsored-content/boron-a-k...
sacnoradhq 3y ago
RO membranes typically include a waste path so they're self-cleaning for their lifecycle, but some manufacturers may have flushing procedures to extend service life. Saudi Arabia, Kuwait, UAE, Qatar, Bahrain, and Libya are almost completely dependent on RO for water. The Carlsbad plant in San Diego was $1B and costs $80M/y (@ 40 MW) to operate while producing 56k acre-ft/y (7% of demand), enough for about 400k people or 20k acres of farmland with average crops. What would cut water use greatly would be the elimination of meat agriculture which depends on crops such as hay, alfalfa, and cow corn. 2/3 of Utah's water goes to irrigating crops to feed cows.

sacnoradhq 3y ago

Unlikely. At scale, will likely be setup like an RO membrane with 3 lines.