Is it possible to recycle or refill small (disposable 😉) propane cannisters?
In the US you cannot refill the small tank at a propane distributor, at least not in any state that I am aware of. In general, the small tanks are classed as not refillable. There is small risk of fire and explosion refilling the tank on your own. If you chose to do it be careful and keep the refilled tanks outsidea in well ventilated area away from flames and heat sources.
Partially refilling a small tank is quite easy. There are lots of how to videos on the web. With the proper adaptor, you can connect the small tank to a 20lb tank. These adaptors are readily available at propan shops, the Web and some big stores like Walmart. You simply connect the tanks and open the valve of the big tank. You will be able to hear the gas stops flowing. It is unlikely you will get it to be 100% full, but you can do a pretty good job. Once it stops, close the valve and disconnect the tanks.
You recycle them the same way you'd recycle an isobutane canister. You puncture the sidewall (once empty) and then recycle anyplace that recycles the metal. See What's the best way to use up (and dispose of) almost-empty butane canisters?