All of my sawdust and wood chips usually becomes mulch, unless it is from walnut or treated lumber. These go in the trash. Last year I was making outside shutters and planning a lot of fir to make them. When I told the lady at the lumber yard what I was doing, she asked if she could have some of the planer chips (not sawdust) to cover the play area of her backyard for her children. I took her 8 large size lawn/leaf bags packed as full as I could make them (a whole pick-up load). Fir chips have a sweet smell and a pretty pink/tan color, so it likely was a very pleasant surface for the kids to play in/on, for a while. At the cost of the select fir I was wishing that I could somehow glue it all back together and re-use it as lumber. Machinists can recycle precious metal shavings. It's a real shame that we can't do the same.
Charley