Full-scale Up-Flo^® stormwater filter field performance verification tests

Abstract

The Up-Flo® Filter is an innovative high-rate, small footprint, stormwater treatment device based on upward filtration technology. It was originally developed by environmental engineers at the University of Alabama with grant support from the U.S. EPA-funded Small Business Innovative Research (SBIR) Program and commercialized by Hydro International. Prior data was collected and the performance was evaluated under different conditions and scales during SBIR phase I and phase II testing, pilot-scale field testing, full-scale one module testing, and full-scale six module testing. These data verified the expected Up-Flo® Filter treatability for solids, inorganic nutrients, bacteria, and metals in stormwater runoff. The primary objective of this research was to extend the field performance verification tests of a full-scale six-module Up-Flo® Filter using the Hydro International CPZ Mix TM that were initially conducted by Dr. Noboru Togawa. Hydraulic performance observations through a one-year monitoring period indicated that about 74% of the total flow was completely treated with no bypass. The maximum bypass observed was about 50% under the most intense rains having about 5 in/hr peak rain intensities. The bypassed flows received partial treatment through sedimentation in the filter's sump and floatable control by the siphon bypass. The effluent samples collected blended flows and therefore consider the combined effect of complete treatment and the partial treatment of the bypassed flows. The maximum treatment flow rate (before any bypassing) was about 150 GPM (25 GPM per module) for the first 9 months of the monitoring period (totaling about 34 inches of rainfall) and then dropped to about 50 GPM for the duration of the monitoring period. Therefore, the media bags should be replaced after about 30 inches of rainfall. The flow-weighted TSS removals (for all 50 storms) were about 88%, with an average effluent concentration of about 21 mg/L. The influent median particle size was about 300µm, with a median specific gravity of about 3.0 g/cc, while the effluent median particle size was about 40 um, with a median specific gravity of about 1.6 g/cc. Particles up to about 3 µm had removals of about 35%, increasing to about 70% for particles in the range of 3 to 120 µm, and more than 90% for larger particles. High reductions (58 to 100%) were observed for total Cr, Cu, Pb, and Zn. Moderate reductions (about 50%) were observed for E. coli and enterococci, while low reductions (22 to 34%) were observed for P and N compounds.