The real answer is to dilute the salt back into the ocean, but even the cost of transport - whether by truck or rail or pipeline - a hundred miles and +3000’ of elevation is likely less than building and maintaining a system that distributes that salt widely enough in the ocean to have negligible ecological impact at the points of dispersal.
A thousand smaller desalination plants spread along a hundred miles of coastline each distributing 87 thousand pounds of salt per day (basically: one pound per second) would be more feasible for ocean discharge than anything you might try to do from a single point. The system would also be much more robust / less prone to critical failures. ~10% of the plants might be offline at any given time while still providing full required capacity.
Looking at those numbers, I would propose something like 500 plants, no two closer than 1000’ from each other along the coastline, each distributing up to three pounds of salt per second in a 6" outflow pipe at least 500’ offshore that’s carrying 100 gallons per minute of water with that salt dissolved therein. The discharge could be through a series of 100 1" holes spread 1’ apart. I’m sure there would be local ecological effects, but in most areas they should be minimal by the time you’re 200’ or more down-current from the outflow.
Compared to treated wastewater discharge, I think the salty water discharge would be much less impactful. There’s probably some opportunity to combine treated wastewater with the salty discharge to further treat the wastewater, though I wouldn’t want to do that in ALL the salt discharge plants (you’d want some to study the salt impact alone.)
The real answer is to dilute the salt back into the ocean, but even the cost of transport - whether by truck or rail or pipeline - a hundred miles and +3000’ of elevation is likely less than building and maintaining a system that distributes that salt widely enough in the ocean to have negligible ecological impact at the points of dispersal.
A thousand smaller desalination plants spread along a hundred miles of coastline each distributing 87 thousand pounds of salt per day (basically: one pound per second) would be more feasible for ocean discharge than anything you might try to do from a single point. The system would also be much more robust / less prone to critical failures. ~10% of the plants might be offline at any given time while still providing full required capacity.
Looking at those numbers, I would propose something like 500 plants, no two closer than 1000’ from each other along the coastline, each distributing up to three pounds of salt per second in a 6" outflow pipe at least 500’ offshore that’s carrying 100 gallons per minute of water with that salt dissolved therein. The discharge could be through a series of 100 1" holes spread 1’ apart. I’m sure there would be local ecological effects, but in most areas they should be minimal by the time you’re 200’ or more down-current from the outflow.
Compared to treated wastewater discharge, I think the salty water discharge would be much less impactful. There’s probably some opportunity to combine treated wastewater with the salty discharge to further treat the wastewater, though I wouldn’t want to do that in ALL the salt discharge plants (you’d want some to study the salt impact alone.)