By Lauren Rosenblatt From Pittsburgh Post-Gazette PITTSBURGH—Ecotone Renewables, a startup by students and graduates of Carnegie Mellon University and the University of Pittsburgh, wants to change the way the world thinks about food waste—and it wants to use a seahorse to do so. It’s not talking about the underwater critter but it is paying homage both to a horse’s stomach and the ocean. Founded about five years ago, the startup wants to “close the food loop” by turning food waste into something that isn’t wasteful. Its system, dubbed the “Seahorse,” uses recycled rain water (hence the sea) and works in the same way a horse’s stomach would when digesting all that hay (hence the horse.) Using a technical process called anaerobic digestion, it takes the “digested” food waste and turns it into something more useful, specifically fertilizer and energy that can then be reused to create more food. The pandemic …