Helium tanks require proper disposal. It is not correct procedure to simply put a helium tank out with the trash when you are finished with it. It is actually an easy process to properly dispose of a helium tank.
Completely Use The Helium Tank Either use all of the helium in the tank or release all of the helium so that the tank is completely empty.
Properly Secure The Helium Tank Roll the helium tank outdoors, if it is not outdoors already and close the valve as tight as possible.
Disassemble The Helium Tank Unscrew the nozzle on the tank and remove it completely. You can do this by hand or a ¾ wrench usually works. Once you do this any residual helium left in the tank can be released by opening the valve.
Label The Helium Tank Write EMPTY on the tank so that it can be distinguished from other helium tanks.
Prepare The Tank To Be Removed You can either take the tank to a steel recycling center or place it with your other recyclables for pickup. Also check with the place you purchased the helium tank from, sometimes they will accept the empty tanks.