If you use these propane tanks for camping, grilling or for other purposes, please don't throw them in the trash when they are empty. They can and should be recycled. However, because they are considered hazardous waste, they can't go into your recycling bin. They usually have a trace amount of propane gas left in them and when they are compressed they can explode, creating a dangerous situation. They must be dropped off for recycling. Recycling the propane tanks is a free service, so you will into incur any charges.
In Volusia County, drop propane tanks off for recycling at either of these two places:
1990 Tomoka Farms Road
Volusia Transfer Station
located at 3151 E New York Ave