Assessment of bioretention pilot-scale systems for urban stormwater management

ABSTRACT Currently, bioretention was applied in many developed countries because it was considered as a solution for reducing the impacts of climate change and urbanization. Bioretention is mainly composed of engineered soil and plants, wherein several pollutant treatment mechanisms and stormwater regulation capabilities were integrated within the system. In this research, 2 bioretention pilot scales were developed to treat urban runoff in which the Type A has Rhododendron indicum Linnaeus plant species and the Type B has Spiraea japonica plant species. Both pilot scales attained high pollutant removal efficiencies for TSS and COD by having a removal of approximately 90%. However, for other pollutants such as nitrogen, phosphorus and metals, the type-A system shows high removal efficiencies compared to type-B. In order to determine the suitable design characteristics, the pollutant removal of each system were analyzed with varying length and depth. The results show that more than 50% of TSS, TP, Total Zn and Total Pb were reduced at the distance of 50% and 60% of total length and depth respectively. Lastly, it was found out that the obtained nitrogen removal was caused by the soil microbial activities, nitrification, de-nitrification and bioremediation.