Here are two guys who are thinking out of the box. We know that used coffee grounds make good compost and we know that you can grow mushrooms on all sorts of matter, including paper. They made a deal with a coffee shop to take their used grounds & now they grow mushrooms to sell on the grounds. Not such a leap of insight, but they actually did it.
You might want to try it on a smaller scale. They sell mushroom growing kits, but once you get started, your business could, er, mushroom.
Click title for link at PlanetGreen.