Unit processes of stormwater treatment techniques for filtration practices (Adapted from WEF, 2008)
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Control Dry swale or step pool Wet swale Biofiltration Permeable pavement Tree box/tree trench Green roof
Peak flow attenuation X X X X X
Runoff volume reduction X X X X X
Infiltration X X X X
Dispersion X
Evapotranspiration X X X X X
Runoff collection and usage X X
Sedimentation X X X
Flotation X
Laminar separation
Swirl concentration
Sorption X X X X X
Precipitation X X
Coagulation X X
Filtration X X X X X X
Plant metabolism X X X
Nitrification/denitrification X X
Organic compound degradation X X X X X
Pathogen die off X
Temperature reduction X X X X X
Disinfection X X