The Landover-based unit of Ahold USA is among a growing number of grocers, restaurants and food makers looking for new ways to tackle the huge amount of waste in the food industry. As much as 40 percent of the food produced in the United States ends up in landfills, where food ranks as the biggest category of waste, according to the Food Waste Reduction Alliance. The groups says waste is generated all along the supply chain, from farms and manufacturers to retailers, restaurants and consumers at home.