A pilot Scale Study on a Layered Biofilter System to Control Urban Road Runoff in Korea

Abstract

This study assessed the performance of a pilot-scale biofilter system to control urban road runoff. The field study was performed for four rainfall events, 3 to 32 mm in terms of rainfall depth. A series of correlation analysis were performed to investigate the removal characteristics of various pollutants in the runoff. Excellent removal efficiency was observed for particulate matter (94.1% for turbidity, 93.7% for SS), nutrients (56.2% for TN, 85.1% for TP) and heavy metals (44.8~60.8%). The effluent concentration showed insignificant correlation with influent concentration and flow rate. The initial effluent often showed the lowest concentration due to the retention time in the system (1.85 hr in minimum). The influent concentration of TP and heavy metals had strong relationships with SS concentration, demonstrating the importance of particle capture. Most particles in the runoff were trapped in the mulch layer, rather than in the CSL. A large portion of particles captured in the mulch layer was shown to be smaller than 10 μm.