Many of the Provincial parks in Ontario have collection facilities for disposable canisters. The same with many KOA campgrounds.
 
Ref: http://www.ontarioparks.com/learntocamp/online_gear.html
http://ontarioparks.com/english/index.html
 
"What to do with Empty Propane Tanks and Cylinders?

	* Don’t throw them in the garbage
	* Propane cylinders are not considered ‘recyclable items’ in Ontario
	* Some Ontario Parks have collection sites for propane tanks. If not available, take your used propane tank to your local Orange Drop site. Visit http://www.makethedrop.ca/ to find a collection site near you.
	* Don’t discharge leftover propane into the atmosphere, even if the cylinder is equipped with a device to do this."
Cheers!
Stuart
86 Westfalia GL

________________________________
From: Jeff Palmer <jpalmer@MYMTS.NET>
To: vanagon@GERRY.VANAGON.COM 
Sent: Thursday, July 4, 2013 12:13:41 PM
Subject: Re: Propane Fill Question (Ontario, Canada)

In Ontario, if I recall, provincial park campgrounds treat disposable canisters as hazardous waste i.e. they won't take them.  I guess if they get crushed they could potentially pop?
I try to avoid them because they're wasteful (and expensive) and use a Coleman propane tree connected to a 10 pound tank.  But I still have a propane tank tucked under the back seat.
Jeff