What do water desalinating plants dilute brine with before returning it back to the ocean?

Question

I read in an article that it takes two gallons of sea water to make one gallon of fresh water. My question is the left over water or brine is twice as salty as regular sea water. Plants say the dilute before returning it back to the ocean. My question is, dilute it with what? If obtaining fresh water is the goal, are they just taking that fresh water back and mixing it with the brine?

Answer 1

No, the desalinating plants will dilute the brine with more salt water because the brine is sometime more salt than water and hard to pass thru the pipes back to the ocean.  Hope this clears up the confusion.

Answer 2

A straight answer to the first question is that there is no need for the de-salanation plants to do anything with the brine before returning it to the sea and it would be surprising if they did. I agree that if they had to dilute it there would be less overall effect of the de-salanation process, which would make this process less worth-while.

Answer 3

my plant makes 1 gallon of fresh from 3 gallons of sea water; the brine is no where near 2x as salty; the US EPA allows us to dump it right back in the ocean after allowing it to cool to ambient temperature, which essentially means running it through a long length of pipe before it hits the sea.

Very large output de-sal plants will mix their "brine" with sea water, to reduce the concentration and cool it before it goes back into Mother Ocean.

Hope this helps.