Sewage Sludge Becomes Rich Compost

Oct 7, 2014

The City of Coeur d'Alene is greening up its newly renovated McEuen Park using tons of a home-brewed compost. The stuff is made from sludge at the city's wastewater treatment plant. They call it Coeur d'Green. The city carefully describes it as made from "de-watered biosolids."

In plain English, that means the raw material is sewage plant sludge.

The city's been making the unusual compost since 1990, using it on city projects and even selling it commercially. It's been popular for years for greening up area golf courses, and landscapers use it widely as a moisture retainer and soil amendment.

The stuff has already been put through a primary treatment process by the time it's trucked over to the Coeur d' Green plant where it's mixed with wood chips and then left for microbes to do their work of eating up pathogens.

The resulting compost is black and fluffy, redolent more of humus than of Honey Bucket. The compost is safe to use on vegetable gardens - it meets all EPA regulations for use in agriculture and horticulture. And Coeur d'Green beats steer-manure for nitrogen content because human diets are richer in protein than cattle diets.