Where do paper shopping bags go when you're done with them?
When you're done using paper shopping bags, for shopping or other household reuses, a couple of things can happen. If minimally-inked (or printed with soy or other veggie-based inks) they can be composted; otherwise, they can be recycled in most mixed-paper recycling schemes, or they can be thrown away (which is not something we recommend).
If you compost them, the bags break down and go from paper to a rich soil nutrient over a period of a couple of months; if you throw them away, they'll eventually break down of the period of many, many years (and without the handy benefits that compost can provide). If you choose to recycle paper bags, then things get a little tricky.
The paper must first be re-pulped, which usually requires a chemical process involving compounds like hydrogen peroxide, sodium silicate and sodium hydroxide, which bleach and separate the pulp fibers. The fibers are then cleaned and screened to be sure they're free of anything that would contaminate the paper-making process, and are then washed to remove any leftover ink before being pressed and rolled into paper, as before.