3 ms·

Only if the discharge is not diluted sufficiently. There is nothing about reverse osmosis that is fundamentally more toxic or harmful than the typical evaporat

Only if the discharge is not diluted sufficiently. There is nothing about reverse osmosis that is fundamentally more toxic or harmful than the typical evaporation that takes place naturally in the ocean. And it’s pretty dishonest to claim otherwise. If there’s a problem with too high salinity of discharge, that’s an engineering problem that should be fixed with greater dilution.

xenadu02 3y ago
I almost addressed this point in my original post... you need a diffusion system that runs the brine out into the ocean and mixes it with seawater to a certain concentration... as long as it isn't super concentrated or at a very different temperature it won't create a brine pool and the salt will diffuse harmlessly.
strken 3y ago
If you're drawing water from a bay and not putting all that water back in, then the salinity of the bay must depend on the rate it mixes with the outside ocean, since you're removing water from the system. I assume that in practice the amount of water taken by a desal plan is tiny and most bays have high tidal inflow and outflow, but it's obvious that more than just dilution should be considered.
8n4vidtmkvmk 3y ago
What would you dilute it with? Surely not the water we just extracted?
- Robotbeat 3y ago
  You dilute it with more seawater. The salinity of the ocean changes significantly just due to evaporation. The band of variability is roughly 30 to 40 grams of salts per liter for sea surface salinity. So if your discharge is within that band, it's not going to be a significant ecological problem (especially if the discharge is at the right location). It's no more a "mass ecological problem" than surface evaporation of seawater is.
  - rtkwe 3y ago
    Mass dilution is going to be fairly expensive because you have to move a significant multiple of the water you actually process. The brine waste water is roughly double the salinity of normal sea water at 70 ppt so to get back to the 33-37 ppt that's the real average band you're looking at moving a lot of sea water to dilute the output. If you run the numbers you're looking at 15:1 of volume to get 70ppt to 37ppt using 35ppt water all while ensuring you're at a place with enough natural mixing that your inputs and outputs don't start feeding back into each other.
rtkwe 3y ago
Of course but read the comment I was replying to, to my reading they're saying the regular water cycle would take care of the excess salinity which is drastically wrong in the human scale and a complete misread of the issue. The problem isn't that we'll over salinate the whole ocean but that locally the released brine will kill some, potentially large, area of underwater life before it diffuses back down to the rough background levels.

xenadu02 3y ago

I almost addressed this point in my original post... you need a diffusion system that runs the brine out into the ocean and mixes it with seawater to a certain concentration... as long as it isn't super concentrated or at a very different temperature it won't create a brine pool and the salt will diffuse harmlessly.

strken 3y ago

If you're drawing water from a bay and not putting all that water back in, then the salinity of the bay must depend on the rate it mixes with the outside ocean, since you're removing water from the system. I assume that in practice the amount of water taken by a desal plan is tiny and most bays have high tidal inflow and outflow, but it's obvious that more than just dilution should be considered.

8n4vidtmkvmk 3y ago

What would you dilute it with? Surely not the water we just extracted?

Robotbeat 3y ago
You dilute it with more seawater. The salinity of the ocean changes significantly just due to evaporation. The band of variability is roughly 30 to 40 grams of salts per liter for sea surface salinity. So if your discharge is within that band, it's not going to be a significant ecological problem (especially if the discharge is at the right location). It's no more a "mass ecological problem" than surface evaporation of seawater is.
- rtkwe 3y ago
  Mass dilution is going to be fairly expensive because you have to move a significant multiple of the water you actually process. The brine waste water is roughly double the salinity of normal sea water at 70 ppt so to get back to the 33-37 ppt that's the real average band you're looking at moving a lot of sea water to dilute the output. If you run the numbers you're looking at 15:1 of volume to get 70ppt to 37ppt using 35ppt water all while ensuring you're at a place with enough natural mixing that your inputs and outputs don't start feeding back into each other.

rtkwe 3y ago

Of course but read the comment I was replying to, to my reading they're saying the regular water cycle would take care of the excess salinity which is drastically wrong in the human scale and a complete misread of the issue. The problem isn't that we'll over salinate the whole ocean but that locally the released brine will kill some, potentially large, area of underwater life before it diffuses back down to the rough background levels.