In an urban setting, rainwater flows over rooftops and concrete surfaces picking contaminants including bacteria, oil & grease, metals and pesticides before entering the sewer systems. These pollutants will eventually end up in the surrounding waterways contributing water pollution and increasing the treatment load to municipal wastewater treatment plants. Green infrastructure such as green rooftops, roadside plants and landscaped parks can potentially reduce the amount of polluted stormwater runoff, hence, reducing the reliance on wastewater treatment plants.
Bioretention systems comprising of a novel engineered filter media and various types of plants were developed to mitigate the negative effects of urban stormwater runoff. This novel modular bioretention system process consists of detention, conveyance, sedimentation, filtration and biological denitrification. Compared to conventional media, the modular system is more cost-effective and customizable in managing the non-point source pollution.
This technology can be implemented near development sites and impervious areas containing pollutants and suspended solids. The bioretention system can be constructed near carparks, farms and housing areas. For sites with high inorganic nitrogen contamination, bioretenton with saturated anoxic zones (the bottom media remains continuously submerged) can be installed.