Food scraps. Okay, those aren’t the first words that come to mind when you think about the environment. But 22 percent of the municipal solid waste dropped into landfills or incincerators in the U.S. is, in fact, food that could be put to better use through composting and soil enrichment.Moreover, food-scrap recycling programs, while still relatively uncommon, are having a growth moment in the U.S.; they’ve roughly doubled in size since 2010. Now, a national study by MIT researchers provides one of the first in-depth looks at the characteristics of places that have adopted food recycling, revealing several new facts in the process.