This has to be one of the most frequently asked questions on this forum, doesn't it! A perennial problem.
I've heard whey can even be used to clean floors!
It is a delicious drink. The green might make you a bit queasy but, I dunno, maybe imagine it's a radioactive drink that will turn you into a superhero.
It's great in bread (whey bread is *delicious*, google around for the recipe - it involves a bit of butter and sugar in addition to the flour, water, yeast, and salt), is a good starter for lacto-fermentation, and I even keep some to use as flavouring in my beers. (Whey contains lactose, which is a sugar yeast is not able to ferment, so it will sweeten beers and other brews).
I give a lot to the chooks too, and of course pour it in the garden