Effects of Media and Plant Selection on Biofiltration Performance

Abstract

The goal of this research was to compare the pollutant removal effectiveness of biofiltration systems containing different media and plant species. A laboratory column study was conducted by using three media and two plant species, each with and without a submerged zone intended to promote denitrification. Twenty experiments were run by using synthetic storm water over the course of nine months, and ten of them were analyzed. The three media used were concrete sand, masonry sand, and a medium that meets the City of Austin’s biofiltration specifications. The plant species were Buffalograss 609 and Big Muhly, both commonly found in Texas. The results of this study showed a significant improvement in nutrient removal with the presence of these plants in the filter. The columns without plants were found to export substantial amounts of nitrate/nitrite, whereas the columns with the plants demonstrated a substantial removal of nutrients (59–79% of the total nitrogen and 77–94% of the total phosphorus). Solids removal remained high through the entire set of experiments for all columns (88–97%). Hydraulic conductivity experienced an initial rapid decrease in all columns but then stabilized.