Removing Dissolved Phosphorus from Stormwater

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Bethanie Nicholson
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1 Removing Dissolved Phosphorus from Stormwater Peter T. Weiss, Associate Professor Department of Civil Engineering Valparaiso University (USA) International Conference on Urban Drainage Porto Alegre, Brazil 15 September 2011

Engineering Valparaiso University (USA) International

2 Outline Dissolved Pollutants Experiments and Model Applications of Dissolved Phosphorus Removal Conclusions Photo Courtesy: A. Erickson

3 Total Phosphorus Concentration (mg/l) Total Phosphorus Load (kg/event) Percent of Data (%) Dissolved Pollutants: Distribution of Phosphorus 0% 5% 10% 15% 20% 1000 Concentration Load % 10% 20% 30% 40% 50% 60% 70% 80% 90% 100% Dissolved Percent (of total phosphorus) Adapted from Brezonik and Stadelmann (2004)

Concentration Load 1000 100 10 1 0.1 100 10 1 0.1 0.01 0.

4 Dissolved Pollutants: Rationale Most urban watersheds need: 80+% capture of solids and pollutants, including dissolved component Precipitation and adsorption are two unit processes that have not been used to treat urban runoff.

dissolved component Precipitation and adsorption are two

5 Dissolved Pollutants: Enhanced Sand Filter Sand Filtration Particulate capture > 80% - Dissolved capture < 2% Enhanced Sand Photo Courtesy: A. Erickson Addition of elements that would precipitate or adsorb dissolved phosphorus

6 Experiments and Model: Experimental Setup Column Study (10) 5% iron (3) A,B,C 2% iron (3) D,E,F 0.3% iron (3) G,H,I 100% sand (1) J Reservoir mixed with dissolved phosphorus Mass balance model Photo Courtesy: A. Erickson

7 Experiments and Model: Model Attributes: Model Derivation Mass balance model between iron and phosphorus in water Predict phosphorus capture of ironenhanced sand filtration Data observed in column experiments Function of contact time (t c ) and total mass of adsorbed phosphorus (SM)

of ironenhanced sand filtration Data observed in column experiments

8 dc dt Experiments and Model: = -ka(c -C*) Model Derivation C C out in dc C C * t contact 0 kadt After integration: C in out kat C C * e c C 1 in and assuming: C* C in 1 e 0 1 M C in 0 C in C* S Mass Removed

9 dc dt Experiments and Model: = -ka(c -C*) Model Derivation C C out in dc C C * t contact 0 kadt After integration: C in out kat C C * e c C 1 in and assuming: C* C in 1 e 0 1 M by substitution yields: C C M t e e c 1 1 in out 2 Fraction Captured 0 C in

kat C C * e c C 1 in and assuming: C* C in 1 e 0 1 M by

10 Phosphorus Fraction Retained Experiments and Model: Experimental Results 1.2 5% iron 2% iron 0.3% iron 100% Sand Depth Treated (m)

2 5% iron 2% iron 0.3% iron 100% Sand 1 0.8 0.

11 Phosphorus Fraction Retained Experiments and Model: Experimental Results 1.2 5% iron 2% iron 0.3% iron 100% Sand Depth Treated (m)

12 Phosphorus Fraction Retained Experiments and Model: Experimental Results % sand 5% iron filings 2% iron filings 0.3% iron filings Depth Years of Treated Service(m) HLR = 5.6 m/yr

2 0 100% sand 5% iron filings 2% iron filings 0.

13 Applications: Sand with 5% iron filings Volume Treated by Filter Overflow Grate Drain tile Sand + Iron Filings

14 Applications: Sand with 5% iron filings, Maplewood, MN Photo Courtesy: A. Erickson

15 Applications: Enhanced Sand Filter Trenches around wet detention ponds Volume Treated by Trenches (Filter Volume) Overflow Grate Normal Water Surface Elevation Water Level Control Weir Drain tile Minnesota Filter Drain tile

Volume) Overflow Grate Normal Water Surface Elevation

16 Prior Lake, MN, Filter Trenches around wet detention ponds Photo Courtesy: A. Erickson

17 Enhanced Sand Permeable Weir Permeable Weir: Minnesota Filter Coarse Aggregate Natural Soil

18 Applications: Enhanced Sand Permeable Weir Photo Courtesy: VLAWMO and EOR

19 Applications: Enhanced Sand to reduce PO4 Release with Bioretention Compost-Amended Sand Iron-Enhanced Sand Gravel Subbase and underdrain Drain tile Natural Soil

20 Conclusions Dissolved Stormwater Pollutants are important Approx. 45% of total concentration is dissolved Physical methods are not enough Chemical mechanisms (adsorption) can be used to capture dissolved fractions. There are solutions! Minnesota Filter (iron-enhanced sand) adsorb phosphorus onto iron. Dissolved nitrogen is next.

$mechanisms (adsorption) can be used to capture dissolved fractions.$

21 Acknowledgements Collaborators: Andy Erickson (U of MN) John Gulliver (U of MN) Brian J. Huser (Sveriges Lantbruksuniversitet and Barr Engineering Co.) Ross Bintner (City of Prior Lake) Contributors: Global Material Technology, Inc. (Steel wool) Connelly GPM, Inc. (Iron filings) Funding Partners: RWMWD, LRRB, City of Prior Lake, PLSLWD, Scott WMO, VLAWMO, EPA/MPCA

For more information, contact: Andy Erickson (eric0706@umn.

22 For more information, contact: Andy Erickson Iron Enhanced Sand Filter, Maplewood, MN (photo courtesy A. Erickson)

DESCRIPTION OF STORMWATER STRUCTURAL CONTROLS IN MS4 PERMITS

DESCRIPTION OF STORMWATER STRUCTURAL CONTROLS IN MS4 PERMITS Phase I MS4 permits require continuous updating of the stormwater system inventory owned and operated by the MS4. They also include inspection