I've thought quite a lot about municipal solid waste. Here in Seattle the dumps contain something like 80% construction debris. Of that, probably half is stuff like gypsum board. What is not construction debris is very low grade. I don't know if there are areas with "better" garbage, so to speak, but it really seems to me that garbage is hard to deal with.

Any kind of fresh vegetative biomass with high water content is hard to transport even very short distances, so we are sort of down to wood byproducts (sawdust, mill scraps, perhaps some direct line on sorted construction debris, and paper).

What about tree services? Does anyone know how many tons of wood chips are removed per day from a large city? Where do they go? Do they get paid for the chips, or are they a disposal problem? Large infrastructure projects always rip out large numbers of trees - where do they go?

Big construction firms pay huge dump fees. They can recycle clean wood, but perhpas if one were to allow free dumping of non-clean wood it might encourage them to supply you, but then how could you deal with it? How can one grind up a big timber that is full of bolts, drift pins, steel brackets, and is covered with lead paint?

One thing that has crossed my mind several times is whether there are specialty institutions that have better waste streams? Prisons? Postal service? Old phone books? Somewhere there is the ticket, but the trick is to find it.