Full-Scale Up-Flo® Filter Field Verification Tests

Yezhao Cai, Robert Pitt, Noboru Togawa, Kevin McGee, Kwabena Osei, and Robert Andoh


The Up-Flo® filter was developed by University of Alabama researchers during EPA supported SBIR research and is commercialized by Hydro International. For typical stormwater conditions, the Up-Flo® Filter has been found to remove at least 80% of the suspended solids concentrations (SSC) during field tests, with variable amounts of treatment for other stormwater pollutants including metals, nutrients, and bacteria. The main advantages of the Up-Flo® Filter includes its high treatment flow rate in a small area, significantly decreased clogging problems compared to downflow filtration, and reduced maintenance requirements.

Full-scale field tests have been conducted at the Bama Belle Riverwalk parking lot test site in Tuscaloosa, Alabama for the past several years. Forty actual storm events have been monitored and sampled, and these field performance results indicate that the Up-Flo® Filter has excellent removals for particulates during a wide-range of hydraulic/rainfall conditions. During these monitored events, the flow-weighted average Total Suspended Solids (TSS) removal was about 82% for influent concentrations ranging from 11 to 571 mg/L (average 101 mg/L), while the SSC flow-weighted removal was about 90%.The flow-weighted turbidity removal was also good at about 61%. The Particle Size Distribution (psd) analysis determined that the influent median particle size (D50) of the 40 sampled storms was about 345 µm and about 33 µm for the effluent. Nutrient reductions were less, being about 37 and 17% for total nitrogen and total phosphorus, respectively. Metal reductions are very good, with flow-weighted removals ranging from about 54 to 76% for total copper, 67 to 98% for total lead, and 79 to 83% for total zinc (removal ranges are due to some of the effluent concentrations being below the detection limits and the two values were calculated substituting 0 and the detection limit for these conditions). Bacteria reductions were also good, at 53% for E. coli. and 57% for Enterococci. Additional event data are being collected and will be further analyzed to examine performance behavior as a function of a wide range of rainfall and runoff conditions.

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