Infiltration of Contaminated Stormwater Runoff through Artificial Barriers Carsten Dierkes, Münster
Content Introduction Pollutants in Stormwater Runoff Aims for Infiltration Artificial Barrier Materials Research Projects and Results Conclusions
Urban Water Cycle high evaporation low runoff low evaporation high and fast runoff high groundwaterrecharge low groundwaterrecharge
Endangering Water Resources Photographs: Surholt und Keckevoet (2001)
Flooding
Green Roofs
Infiltration Swales
Problems of Stormwater Treatment High levels of TSS, filter capabilities are reduced Strong rain events, high flow-rates, short contact times with filter material Dissolved substances, mechanical filters can not solve the problem Space consuming systems Maintenance must be cost effective Control possibilities
Pollutants in Runoff inorganic substances heavy metals aluminium arsen cadmium chromium copper iron lead mercury nickel zink organic substances nutrients nitrate, phosphate pesticides phenols PAH benzo(a)pyrene anthracene benzo(g,h,i)perylene salt bacteria, viruses hydrocarbons
Aims 2 BBod Stoff Einheit Dach allgemein Kupferdach Zinkdach Parkplatz, Hauptstraße Gewässer HydroCon Anliegerstraße LAWA 1 TrinkWV SchV System von bis von bis von bis von bis von bis Grenzwert Grenzwert Prüfwert Zielwert Summenparameter elektr. Lf. (us/cm) 25 270 25 270 25 270 50 2400 110 2400-2500 - < 1500 ph-wert (-) 4,7 6,8 4,7 6,8 4,7 6,8 6,4 7,9 6,4 7,9-6,5-9,5-7,0-9,5 Nährstoffe P ges (mg/l) 0,06 0,50 0,06 0,50 0,06 0,50 0,09 0,30 0,23 0,34 - - - - NH 4 (mg/l) 0,1 6,2 0,1 6,2 0,1 6,2 0,0 0,9 0,5 2,3-0,5 - - NO 3 (mg/l) 0,1 4,7 0,1 4,7 0,1 4,7 0,0 16,0 0,0 16,0-50,0 - - Schwermetalle Cd (mg/l) 0,2 2,5 0,2 1,0 0,5 2,0 0,2 1,7 0,3 13,0 1,0 5,0 5,0 < 1,0 Zn (mg/l) 24 4.880 24 877 1.731 43.674 15 1.420 120 2.000 500-500 < 500 Cu (mg/l) 6 3.416 2.200 8.500 11 950 21 140 97 104 20 2000 50 < 50 Pb (mg/l) 2 493 2 493 4 302 98 170 11 525 50 10 25 < 25 Ni (mg/l) 2 7 2 7 2 7 4 70 4 70 50 20 50 < 50 Cr (mg/l) 2 6 2 6 2 6 6 50 6 50 50 50 50 < 50 Org. Summenparameter PAK (EPA) (ug/l) 0,4 0,6 0,4 0,6 0,4 0,6 0,2 17,1 0,2 17,1-0,1 (6 Verb.) 0,2 < 0,2 MKW (mg/l) 0,1 3,1 0,1 3,1 0,1 3,1 0,1 6,5 0,1 6,5 - - 0,2 < 0,2 kritischer Parameter, Reinigung notwendig in der Regel keiner Reinigung notwendig, Einzelfallentscheidung in der Regel unkritischer Parameter noch keine Aussage möglich 1 Zielvorgaben der Länderarbeitsgemeinschaft Wasser für das Schutzgut Oberflächengewässer, Nutzungsart Trinkwasser [LAW98] 2 Grenzwerte der Trinkwasserverordnung [TVO01] 3 Prüfwerte des Wirkungspfades Boden-Grundwasser nach 8 Abs. 1 Satz 2 des BBodSchG [BBG99]
Pollutants in Soils volatisation erosion and transport by water and wind photochemical transformation uptake by soilsolution wash-out pollutants adsorption and chemical precipitation filtration of solid matter chemical transformation microbiological transformation groundwater
Zinc in a swale concentration (μg/l) 800 700 600 500 400 300 200 n=14 n=14 n=23 n=17 5841 Dortmund Gelsenkirchen 100 0 rainwater roof runoff n=17 n=15 n=16 below soil trench outflow
Test Rigs
Test Facilities
Pollutant Removal Sedimentation Precipitation Sorption Filtration Oils
Retention of TSS 6000 5000 4983 4983 4983 4983 TSS (mg/l) 4000 3000 2000 Stormwater Outflow 1000 0 247 213 166 89 1 2 3 4 5 6 7 8 9 10 11 12
Retention of Zinc 6,0 5,0 Konzentration (mg/l) 4,0 3,0 2,0 Carbonate Reactions Zink Vorlage Zink Ablauf 1,0 Permissible Limit 0,0 0,2 0,4 0,6 0,8 1,0 1,2 1,4 1,6 1,8 2,0 2,2 2,4 2,6 2,8 Month
Development of Filters Roof Runoff Metal Roofs Traffic Areas, low traffic density Traffic Areas, high traffic density Separate System Green Roofs Industrial Areas
Zeolite Barrier Materials
Copper Roof Project in Munich Trench 1 Trench 4 Trench 2 Trench 3 Pollution Control Pit Sampling Pit
Pollution Control Pit
Drainage Pipe
Copper Roofs Concentration (μ g/l) 3000 2500 2000 1500 1000 500 Inlet Outlet Filter Outlet Trench Permissible Limit 0 Porous Concrete Zeolite 1 Zeolite 2 Introduction Pollutants Athanasiadis et al. 2006 Aims Projects Conclusions
Removal of Phosphorous
Isotherm for Phosphorous Concentration at solid phase (mg/kg) 1000 100 10 1 0,01 0,10 1,00 Concentration in Solution (mg/l)
Kinetics of Sorption Removal efficiency (%) 100 90 80 70 60 50 40 30 20 10 0 Filter 1 Filter 2 5 min 10 min 15 min 30 min Contact time 60 min 24 h
Phosphorous-Removal Riedel (2006)
Pollution Control Pit
Conclusions Stormwater treatment before infiltration is a complex challenge Treatment trains are necessary to retain all relevant pollutants Efficiencies more than 90 % are possible Contact times, inner surfaces of filter materials must be taken into account Long term studies are necessary Maintenance and control problems must be solved
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