Standard for Used Toner Cartridges?

I found today that the library has quite a stash of old toner cartridges and drum kits for the copy machine. Is there a recommended (or a standard) way to dispose of these? I just took over the ordering responsibilities for our building this year and the previous clerk didn't know what to do with them so they just accumulated in a closet in the library.

[Moderator note: Topic moved to a more suitable forum.]
You might want to check out the discussion below for some helpful ideas on how to recycle spent cartridges.

Disposing of toner cartridges

Excellent! Thanks for the link.