Is there a place/way to recycle cans, glass and plastic near Phra Khanong? Used to have the people in the building taking care of it but now it seems like nobody cares.

Bonus question: is there anywhere in Bangkok or Thailand at all to recycle batteries?

Don't worry, if your building staff doesn't separate the trash in order to collect THB 1 for each beer can etc be sure that the guys on the trash trucks will as this is their main source of income... Cans, glass, PET and paper as well as metal is getting sold, not sure with batteries though...