I just discovered the most wonderful thing

The university where I teach part time has a fabrication lab that recently acquired an extruder/printer waste recycler! Apparently I can bring in all my excess PLA now and they'll turn it into filament for use by the engineering department.

I'm sharing this because you might have a school near you that does this -- I'd imaging it's going to get more common. I never would have known if a student who worked there didn't fill me in. I'm not sharing the school for privacy reasons and because they're not currently available to the public.