I send mine to LP Sharp and buy new blades from them. Works great for me.

I love my Tru Sharp electric sharpener. Got it from joann.com. If its not on sale you can use a coupon

I have one of those sharpeners that you run your rotary cutter through like a knife sharpener, I guess you'd say. It works for a few times and gets you a lot farther than you'd get w/o it. But I recently found the Titanium blades and they really are longer lasting. You eventually have to sharpen/replace them but it takes a LOT longer to dull them. Then I usually just keep them in the plastic case they came in. I guess I haven't gotten to the point that I had one full yet and had to decide what to do w/it from there. Someday soon I will, I'm sure.

I got one of those sharpeners that you leave the blade in and run it across it. It's read... can't remember the brand. It works AWESOME! I get 10 times the life out of a blade... matter of fact unless it gets really nicked from hitting the ruler or something it seems to last forever.

red, not "read"... ooops... and the brand is TrueCut. Got it from Nancy's Notions.

I have used the blade sharpener, it works okay for a little while. I save the old blades to cut paper, until they no longer cut paper, then take them to the dump.

Check the archives. There was a good discussion on this a few weeks back with the address of the place where you could send your old blades and get new ones terrifically reasonable. I don't have the address, sorry. Maybe someone else will see this and give the address again.

Used machine needles and rotary blades disposal
 

I have a plastic container that I put my used needles /blades into. When I fill it up, I put the container in my reycle bin. It is labeled. If you have a recyling program in your area this is where things like this can be disposed of. In the landfill does no one any good. But recyling does.
jc

I bought one of those orbital sharpeners but did not have any luck with it. I sharpen better running the blade through folded aluminum foil. At first it sounds rough but eventually cuts very well.

I put mine back in an old blade container, and when it's full, I tape it shut- really tape it good - and throw it out. I know some quilters use round containers, like a small Pringles can to put used blades until you can tape it shut and throw it out.