There are a number of "lockers" where you can leave bags in the lounge, right behind reception. But here's the catch: they don't have a lock, so it's entirely at your own risk. In my experience I have left bags in there all day and not had a problem, but then again I have only ever left bags containing things I could replace at minimal cost - clothes etc.

Edited to add: these are right behind reception in the Schengen lounge (C pier) and right opposite reception in the non-Schengen lounges (E/F pier).