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Soil Amendments for Removing Phosphorus, Metals, and Hydrocarbons. Andy Erickson, Research Fellow St. Anthony Falls Laboratory April 1, 2014. Acknowledgements. Collaborators: John S. Gulliver ( UMN ) Peter T. Weiss (Valparaiso University) Multidisciplinary Technical Advisory Committee
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Soil Amendments for Removing Phosphorus, Metals, and Hydrocarbons Andy Erickson, Research FellowSt. Anthony Falls Laboratory April 1, 2014
Acknowledgements • Collaborators: • John S. Gulliver (UMN) • Peter T. Weiss (Valparaiso University) • Multidisciplinary Technical Advisory Committee • Partners: • UMN, LRRB, EPA/MPCA, CWL, BWSR, RWMWD, City of Prior Lake, PLSLWD, Scott WMO, Carver County, Dakota County, Wright County, VLAWMO, CLFLWD, CRWD, and others!
What’s in Urban Stormwater? • Solids • inorganic, organic • Nutrients • nitrogen, phosphorus, etc. • Metals • copper, cadmium, zinc, etc. • Deicing Agents • chloride, salts, etc. • Hydrocarbons • Bacteria/Pathogens • Others
Phosphorus Sorption with Iron Photo Courtesy: A. Erickson • Sand Filtration • Particulate capture > 80% • Enhanced Sand Filtration • Steel wool increases dissolved phosphorus capture via surface sorption to iron oxide Source: Erickson, A.J., Gulliver, J.S. and Weiss, P.T. (2007) Enhanced sand filtration for storm water phosphorus removal. Journal of Environmental Engineering-ASCE 133(5), 485-497.
Experimental Results(Iron Enhanced Sand Filtration, SAFL) n = 112 n = 336 n = 336 n = 336 n = 112 Detection limit
Iron Enhanced Filter (5% iron filings, Maplewood, MN) Photo Courtesy: A. Erickson
MN (Iron Enhanced) Filter(5% iron filings, Maplewood, MN) Photo Courtesy: A. Erickson
Iron Enhanced Filter Trenches wet detention ponds (Prior Lake, MN) Photos Courtesy: A. Erickson
Filter Trenches around wet detention ponds (Prior Lake, MN) Volume Treated by Trenches (Filter Volume) Overflow Grate Water Level Control Weir Normal Water Surface Elevation Drain tile Iron Enhanced Filter Drain tile
MN Filter Trenches wet detention ponds (Prior Lake, MN) 2010 Testing Data: Average Inflow Phosphate = 69.7 μg/L (ppb) Average Outflow Phosphate = 18.7 μg/L (ppb) Average Reduction = 73.1% Photos Courtesy: A. Erickson
MN Filter Bioretention (Carver County, MN) MN Filter Trenches (Prior Lake MN) Photo Courtesy: W. Forbord Photo Courtesy: A. Erickson MN Filter Bioretention(Maplewood, MN) MN Filter Weir (Vadnais Heights, MN) Photo Courtesy: Barr Engineering Company Photo Courtesy: VLAWMO and EOR
Designing for Phosphorus Capture with Iron • As iron rusts, sorption sites for phosphorus are created, therefore: • Design Iron Enhanced Filter systems for watersheds with significant dissolved phosphorus fraction • Ensure the system is oxygenated to ensure iron oxides remain aerobic • Design systems with 8% or less iron by weight to prevent clogging
Metals sorption to Compost Source: Morgan, J. G., Paus, K. A., Hozalski, R. M., and Gulliver , J. S. (2011). "Sorption and Release of Dissolved Pollutants Via Bioretention Media." Project Report 559. St. Anthony Falls Laboratory, University of Minnesota, Minneapolis, MN.
Expected Lifespan (Zinc at 10%) Longer for Cadmium 12 inches Source: Morgan, J. G., Paus, K. A., Hozalski, R. M., and Gulliver , J. S. (2011). "Sorption and Release of Dissolved Pollutants Via Bioretention Media." Project Report 559. St. Anthony Falls Laboratory, University of Minnesota, Minneapolis, MN.
Rain gardens sustainably treat petroleum hydrocarbons in stormwater • Petroleum Hydrocarbons are captured by sorption to organic matter • Biodegradation prevents accumulation of petroleum hydrocarbons Source: LeFevre, G.H., Hozalski, R.M., and Novak, P.J. (2012). "The Role of Biodegradation in Limiting the Accumulation of Petroleum Hydrocarbons in Raingarden Soils." Water Research, 46(20), 6753–6762.
Phosphorus Leaching from Compost Source: Morgan, J. G., Paus, K. A., Hozalski, R. M., and Gulliver , J. S. (2011). "Sorption and Release of Dissolved Pollutants Via Bioretention Media." Project Report 559. St. Anthony Falls Laboratory, University of Minnesota, Minneapolis, MN.
Other Amendments • Alum (water treatment residual) & Hardwood Bark Mulch – Phosphorus sorption (A. Davis, Univ. of Maryland) • Commercial products (various) • Internal Submerged Zone for denitrification (W. Hunt, North Carolina State University)
Conclusions • Dissolved Stormwater Pollutants are important • Approx. 45% of total concentration is dissolved • Physical methods are not enough • Chemical and biological mechanisms can be used to capture dissolved fractions • There are field-tested solutions! • Minnesota Filter (iron-enhanced sand) phosphorus • Compost-amended bioretention metals & petroleum hydrocarbons
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Thank you for your attention!Questions? Photo Courtesy: A. Erickson For more information, contact: Andy Erickson (eric0706@umn.edu)