Rain gardens are increasingly popular with homeowners and municipalities and are mandatory for many communities nationally. U.S. Department of Agriculture (USDA) scientists are finding ways to improve rain gardens so they not only reduce runoff, but also keep toxic metals out of storm drains. Rain gardens are plantings in depressions that catch stormwater runoff from sidewalks, parking lots, roads and roofs. Rain gardens come in various shapes and sizes, from large basins carved by front-end loaders to small artificial streambed-like formations complete with pebbles. Rain gardens not only slow water down to give it time to soak into the ground and be used by plants, but also filter out sediment and chemical pollutants.
The scientists at the SRRC found that poultry litter biochar-activated carbons created from the charred remains of poultry litter-is a powerful pollutant magnet. It can attract heavy metals such as copper, cadmium and zinc, which are ordinarily tough to snag from wastewater. They created the biochar by subjecting poultry litter -- bedding materials such as sawdust, wood shavings and peanut shells, as well as droppings and feathers -- to pyrolysis, a high-temperature process that takes place in the absence of oxygen.
http://www.sciencedaily.com/releases/2010/12/101201151908.htm
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