Startups, bolstered by revved-up government policies to cut down on food waste in landfills, are selling kitchen devices that turn food scraps into a substance that they say can be used on farms or in gardens.

Startups, bolstered by revved-up government policies to cut down on food waste in landfills, are selling kitchen devices that turn food scraps into a substance that they say can be used on farms or in gardens.