Fecal Indicator Removal in Enhanced Biofilters: Role of Biochar and Field Conditioning
Biofilters are engineered, small-scale, depressed areas that capture, reduce, and infiltrate or filter stormwater runoff from the surrounding area. Contaminant removal performance of a biofilter largely depends on its biofilter soil media (BSM) composition and outlet design. Recent research has reported promising performance of biochar as a BSM amendment for removing microbes and nutrient from stormwater in a laboratory-setting. Studies have also identified the importance of biochar’s hydrophobicity for contaminant removal which implied reduced performance in the presence of biological aging in the field. In this year-long pilot-scale study, we have investigated how the presence of biofilm and an internal water storage (IWS) zone influences the hydraulic and contaminant removal performance of biochar-augmented biofilters. Considering the performance of sand biofilters are known to improve with biofilm growth, we compared the performance of biochar-amended biofilters with the sand only biofilters under similar field conditions. Our results provide insights into BSM and IWS selection for enhanced performance of bioretention systems.