Mr. Baumgaertel is director of the Massachusetts Alternative Septic System Test Center, a county organization that does pretty much what its name suggests: He and his staff run sewage through a variety of contraptions, and see what comes out the other end. Septic systems work well where homes are too sparse to justify expensive sewers and water treatment plants. About 95 percent of the Cape’s properties use them. But they don’t filter out nitrogen or phosphorus, which seeps into the groundwater and, eventually, bodies of water.
Enter Mr. Baumgaertel’s outdoor laboratory of sewage management.
On a recent December afternoon, Mr. Baumgaertel removed the cover leading to an underground chamber. Inside, nitrate-heavy liquid waste flowed into a space filled with wood chips and bacteria. The carbon in the chips fuel the bacteria that turns the nitrogen into gas, a reaction manifested by small bubbles hissing on the surface of the subterranean goo. The nitrogen gas is released into the atmosphere.A Toxic Stew on Cape Cod: Human Waste and Warming Water – The New York Times