Performance comparison of two hybrid stormwater treatment systems having different filter media configuration

Stormwater best management practices (BMPs) commonly employ only one function that is sometimes insufficient to achieve its necessary efficiency. The method of integrating several functions of BMP technologies and incorporating them in one treatment system is referred to as hybrid BMP. This study developed, investigated, and compared the efficiency of two laboratory-scale hybrid BMP in reducing stormwater pollutants and runoff volume. The laboratory-scale hybrid BMPs developed were composed of treatment tanks arranged in series referred to as infiltration, storage or retention and final tanks that have different media configuration. Based on the results, both hybrid types were effectual in pollutant removal and flow volume reduction since both hybrid types significantly reduced the inflow volume and all pollutants including total suspended solids, chemical oxygen demand and total metals (p < 0.05). Hybrid type A was more advantageous for designs considering greater volume for groundwater recharge, less pollutant discharged to sewer systems and good removal efficiency for shorter hydraulic retention time. Meanwhile, hybrid type B was more appropriate for designs considering greater volume for stormwater reuse and less cost in terms of filter media usage. Depending on the design consideration, either one of the hybrid BMP types may be applicable.