Surface characteristics of sorptive-filtration storm water media. I: Low-density (rho(s)< 1.0) oxide-coated buoyant media

Control strategies for storm water that combine unit operations and process es can offer distinct advantages for many in situ applications in the built environment. Examples include a variety of control strategies that utilize engineered buoyant media to provide filtration and adsorption for heavy me tals transported by storm water. With the goal of producing such media, met hods were developed to coat iron and manganese oxide onto the surface of co mmon polymeric media. Surface characteristics of coating media were determi ned by powder X-ray diffraction, infrared spectroscopy, and scanning electr on microscopy analyses. Results indicated that oxide coatings ranged from 2 0 to 200 mum in depth, and surface areas were increased from 0.05 m(2)/g fo r uncoated spherical polymeric media to 27 m(2)/g for the same media after oxide coating. All manganese oxide coated media generated a net negative su rface charge in the typical storm water pH range of 6-8. Media specific gra vity (rho (s)) remained less than 0.93 even with oxide coatings. A multiple -layer oxide coating provided surface characteristics that enhance filtrati on and adsorption of heavy metals using coated buoyant polymeric spherical media in storm water treatment systems such as sorptive buoyant media clari fiers.