>This is simply a choice of not diluting it enough.
If that choice were up to engineers, it's fine.
In practice that choice is actually made by MBA types, a field where harmful short-termism is almost a religion.
It's made by practical money and people who don't want to consume local resources.
This is dishonest: toxicity, dosage are fundamental properties.
You can't just wave a word at it like dilution and think you're solving an engineering problem.
If you got 1 gallon out of sea water, what do you think you need to dilute it to be safe? Typically, it's 99%∆.
You don’t need to dilute a gallon of sea water at all, it is perfectly safe to dump it back into sea as is.
For you, locally, sure.
It'll kill however, plenty of things.
It won't kill anything. The surface of the ocean has natural fluctuations of salinity all the time due to evaporation, and it doesn't cause mass die offs. It's literally a necessary part of the ecosystem (and in fact discharging freshwater can cause problems to the ecosystem). But if your discharged water is within the natural 30 to 40 grams of salt per liter range, there's no ecological problem here.
It's not waving a word around. There's natural variations of salinity of oceanwater, roughly 30 to 40 grams of salt per liter. So diluting the discharged brine so it's within that natural evaporation-driven band would be perfectly safe as it's in the natural variation of salinity.
This is false and somewhat dishonest. This is simply a choice of not diluting it enough. There is nothing about the discharge from reverse osmosis that is any more fundamentally toxic than the natural process of evaporation.
Proper dilution is essential, and treating the discharge as fundamentally toxic actually undermines the engineering to do this proper dilution because people will figure “oh well, I guess there’s nothing we can do as it’s going to tend to kill no matter what.”
People need to stop misleading about discharge toxicity.