With suitable pulleys or links could you make a spraycan shaker? Moby Duck's idea is a good one. I feed everything to the dogs , seagulls or compost so I've never seen a waste disposal unit but if they reverse each time they are turned on as hemmjo said I would be interested to know how the blades are arranged. To reverse like that the moter must have an electronic control or a mechanical switch like a car windscreen wiper gearbox surley? If so I'd pull it down just to see how it worked, the fun value alone would be worthwhile aye?
Then you could post how it works and that would open up more possibilities for use.