So all the industrial producers should do is get massive amounts of water, mix their acid whey with it, then use that mixture to irrigate the larger area around their plants? Maybe just inject their whey into irrigation systems at the point they pump up their water? (hint: no that is not a solution)
Of course the whey is not the pollutant, it's the acids in it. Low concentrations of anything are harmless.
That is a true and useless statement. By the same token high concentrations of anything are harmful but nobody is going to call water a pollutant. The question is about why and how something is harmful and whether it builds up. First off, why are you saying the acid is the problem? From my reading, talking about decomposition sapping oxygen, it sounds like it's the sugar and the fact that it's a food. And food isn't a pollutant. You leave it alone, it rots, nobody is harmed unless you dump large amounts of it in one spot. Now let's contrast with an actual pollutant like smoke. A whole lot of people emitting small amounts of smoke does build up, and it lingers. It causes direct harmful effects.
Of course the whey is not the pollutant, it's the acids in it. Low concentrations of anything are harmless.