Sand Filtration Enhanced By Various Reactive Materials For Bioretention Cell Design Considerations

Various reactive treatment materials were evaluated to enhance sand filtration of dissolved species common in stormwater runoff: NO3- , PO43- , Cu2+, Pb2+, and Zn2+. Fly ash and iron oxyhydroxide mine drainage residuals were blended with sand at 5% (FA5.0) and 7.5% (MDR7.5) by mass and packed into laboratory columns. Additionally, minus 30 mesh particle sizes of proprietary peat products APTsorb and bioAPT were each packed without blending with a succeeding sand layer (APT-S and BIO-S). Pollutant removal performance was evaluated by pumping synthetic stormwater (SS) through packed up-flow columns without recirculation. The control material was 100% sand (SAND). Target SS concentrations included 1.5 mg/LNO3- as N, 0.5 mg/LPO43- as P, 25 mu g/LCu2+, 30 mu g/LPb2+, and 100 mu g/LZn2+. FA5.0 and MDR7.5 both removed over 84% of P. SAND, APT-S, and BIO-S removed limited total P and total dissolved P, while BIO showed a net export of up to 30% P. All columns removed greater than 75% and 89% of Cu2+ and Zn2+, respectively. APT-S removed the greatest Pb2+, at over 84%. None of the columns exhibited consistent NO3 (-) removal greater than 10%. (C) 2021 American Society of Civil Engineers.