Is it safe to drink the whey?
Whey is an excellent source of protein and whey protein in particular is used in many body-building supplements. 

Please see the excerpt below from  FARMcurious .


  Drink Up! – The acidic tang of whey may be a bit of an acquired tasted but I actually find it refreshing.  Cultured whey has pro-biotics that can help balance the microflora in your gut as an extra bonus to the protein.


The web page gives a lot of information about whey and the many other uses for it as well as a great tip for storing.

Hope this helps!