More than 170 volunteers in the Brattleboro, Vt., area have contributed urine to the Rich Earth Institute field trials. Mike Earley/Courtesy of Rich Earth Institute hide caption

itoggle caption Mike Earley/Courtesy of Rich Earth Institute

The digester eggs at Newtown Creek Wastewater Treatment Plant in Brooklyn contain millions of gallons of black sludge. Courtesy of New York City Department of Environmental Protection hide caption

itoggle caption Courtesy of New York City Department of Environmental Protection

Worker Charles Lee sorts through clothes at Mac Recycling near Baltimore. Textile recycling is a huge international business, and a small facility like Mac ships about 80 tons of clothes each week to buyers around the world. Jackie Northam/NPR hide caption

itoggle caption Jackie Northam/NPR

Portland recycling handlers say they've seen more diapers in recycling bins after the city switched to biweekly trash pickups. A file photo shows bags of diapers in a container at a California recycling facility. David McNew/Getty Images hide caption

itoggle caption David McNew/Getty Images

A 1,000-pound butter sculpture is unveiled at the 97th Pennsylvania Farm Show in Harrisburg last week. Bradley C. Bower/AP hide caption

itoggle caption Bradley C. Bower/AP

Charlotte Douglas International Airport has deployed an army of 1.9 million worms to eat through its organic waste. The airport has reduced the trash it sends to the landfill by 70 percent. Julie Rose hide caption

itoggle caption Julie Rose