, Lenormand E. , BoisP. 1 , Laurent J. , Wanko A....
Transcript of , Lenormand E. , BoisP. 1 , Laurent J. , Wanko A....
Walaszek M. 1, Lenormand E. 1, Bois P. 1, Laurent J. 1, Wanko A.1 1 Ecole Nationale du Génie de l’Eau et de l’Environnement de Strasbourg (ENGEES)
Laboratoire des Sciences de l’Ingénieur, de l’Informatique et de l’Imagerie (Icube), 2 rue Boussingault, 67000 Strasbourg, France
Urban stormwater constructed wetland : Micropollutants removal linked to rain events characteristics and
accumulation
Context and objectives
Material and methods
Stormwater quality
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MicroP removal efficiencies
Micropollutants storage
Conclusion
Urban stormwater: a micropollutants source
Atmosphere Heating, oil industry
PCB (0.015 ng/L) Polycyclic Aromatic
Hydrocarbures (PAHs: 0.26 µg/L)
Roadway Traffic, road signs
Metals (Zn: 407 µg/L; Pb: 170 µg/L ; Cu: 97 µg/L)
PAHs (1.65 µg/L)
Green areas Gardening, crop
Pesticides Glyphosate (3.24 µg/L) Diuron (0.21 µg/L)
Buildings (roof, gutter, walls) Atmospheric deposition,
corrosion Metals (Zn: 370-1851
µg/L; Pb: 69 µg/L ; Cu: 153 µg/L)
PAHs (0.7 µg/L)
(References: Bressy, 2011; Göbel, 2006; Lamprea, 2009)
• Stormwater runoff collected by storm sewer system
• Directly discharged in stream
Context and objectives
Material and methods
Stormwater quality
The Ostwaldergraben: a poor quality stream
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Ostwaldergraben: bad status - presence of micropollutants (pesticides, hydrocarbons, metals) Stormwater runoff discharges
The European Water Framework Directive: good status before 2027 Necessity to improve the stream quality
Ostwaldergraben
Watershed
Old tannery
Ill & Ostwaldergraben confluence
MicroP removal efficiencies
Micropollutants storage
Conclusion
Solution:
2011 – Construction of a stormwater treatment system (settling pond + constructed wetland)
Aim: to reduce the micropollution in stormwater before discharging into the stream
Context and objectives
Material and methods
Stormwater quality
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MicroP removal efficiencies
Micropollutants storage
Conclusion
Objectives of the study
Link between rain event characteristics and stormwater micropollution ?
Removal efficiency of the system ?
Fate of micropollutants in the system ?
Context and objectives
Material and methods
Stormwater quality
Experimental site
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MicroP removal efficiencies
Micropollutants storage
Conclusion
Manhole
Runoff
Catchment area
Total area (m²)
27,000
Active area (m²)
9,000
Type Residential
Artificial pond Volume (m3) 28 to 56
Dimensions (m x m)
11 x 9
Constructed wetland
Area (m²)
90
Hydraulic conductivity (m/s)
2.61e-4
Hydraulic load (m3/m²/h)
0.5 to 1
% of active area (m²)
1%
Context and objectives
Material and methods
Stormwater quality
Water quality evaluation
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MicroP removal efficiencies
Micropollutants storage
Conclusion
Parameter Analytical method Sample
7 Metals (Cd, Cr, Co, Cu, Ni, Pb, Zn)
ICP/AES (NF EN ISO 11885)
Raw and filtered
16 PAHs GC/MS after hexane extraction (NF EN ISO 17993)
Raw
Context and objectives
Material and methods
Stormwater quality
Soils quality and storage evaluation
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MicroP removal efficiencies
Micropollutants storage
Conclusion
Pond sediments: 1 sampling point
CW soil:
• 2 sampling areas (highly/poorly fed in water)
• 3 random sampling points in each area
• 3 depth (organic deposit/sand close to the organic deposit/ deep sand) at each sampling point
• Composite sample by mixing together layers from the same depth and the same area
Context and objectives
Material and methods
Stormwater quality
Rainfall characteristics of 13 sampling sessions
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MicroP removal efficiencies
Micropollutants storage
Conclusion
Event Date Dry period (day)
Duration (hour)
Maximum intensity for
15min (mm/h)
Depth (mm) Return period
1 10/4/2015 10.1 4.5 4 6.2 3 to 6 months
2 12/9/2015 7.7 3.3 4.8 5 3 to 6 months
3 2/23/2016 2.9 5.3 2.4 8 3 to 6 months
4 3/25/2016 1.6 10.3 1.6 2.8 1.5 to 3 months
5 4/26/2016 1.4 4.8 0.8 2.4 1.5 to 3 months
6 5/23/2016 3.8 21.8 2.4 11 1.5 to 3 months
7 10/21/2016 2.5 0.3 0.8 0.2 2 weeks to 1 month
8 2/28/2017 0.2 0.5 3.2 1 1.5 to 3 months
9 3/21/2017 3.1 17.0 1.6 11 6 months to 1.5 year 10 4/26/2017 6.4 10.8 0.8 4.6 1.5 to 3 months
11 5/4/2017 2.6 6.5 3.2 3.8 1.5 to 3 months
12 5/13/2017 1.6 4.3 20.8 13.2 1.5 year to 2 years 13 6/3/2017 2.6 19 5.6 16.4 3 to 6 months
Group #1 : low rainfall depth (N=8) Group #2 : high rainfall durations + rainfall depth (N=3) Group #3 : large dry periods (N=2) Group #4 : high maximum intensity (N=1)
Context and objectives
Material and methods
Stormwater quality
Stormwater quality
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MicroP removal efficiencies
Micropollutants storage
Conclusion
Detection frequency > 50%
High concentrations of metals
Zn >> Cu > Pb > Cr 12 PAHs
Fractions repartition: • Zn particulate • Cu, Pb, Cr dissolved
(n=13) LOQ (µg/L) Stormwater
(µg/L)
ND
Chromium-D 0.5 7 1 Chromium-P 0.5 0-5 [1.84] 13
Cobalt-D 0.2 <LOQ 0
Cobalt-P 0.2 0.22 1 Copper-D 0.5 <LOQ 0
Copper-P 0.5 4.11-9.7 [6.44] 13 Lead-D 0.5 6 1 Lead-P 0.5 1.95-4.15 [3.11] 13
Zinc-D 5 70-300 [146.5] 13
Zinc-P 5 20-281 [90.1] 13
Acenaphtene 0.01 0.01 1 Benzo(a)pyrene 0.01 0.0533 1 Fluorene 0.01 0.01-0.02 [0.013] 13
Phenanthrene 0.01 0.01-0.06 [0.028] 12
Anthracene 0.01 <LOQ 0
Fluoranthene 0.01 0.01-0.17 [0.036] 9
Pyrene 0.01 0.01-0.12 [0.033] 7
Benzo(a)anthracene 0.01 0.06 1 Chrysene 0.01 0.05 1 Benzo(b)fluoranthene 0.01 0.01-0.06 [0.035] 7
Benzo(k)fluoranthene 0.01 0.03 1 Naphtalene 0.01 0.01-0.06 [0.02] 7
Context and objectives
Material and methods
Stormwater quality
Link between hydrology and stormwater quality
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MicroP removal efficiencies
Micropollutants storage
Conclusion
ACP Variables
• rainfall duration (tp) • depth (h) • dry period (dts) • dissolved metals
particulate metals • PHAs
Individuals • rainfalls 1 to 13
• Particulate Cu, dissolved Zn, benzo(a)anthracene positively influenced by
rainfall duration (tp) and depth (h)
• Particulate Zn, acenaphtene
negatively influenced by rainfall duration and depth
• 3 PAHs
negatively influenced by dry periods (dts)
Context and objectives
Material and methods
Stormwater quality
Removal efficiencies (RE)
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MicroP removal efficiencies
Micropollutants storage
Conclusion
Min-Max [Mean] Pond RE (%) Filter RE (%) Treatment system RE (%)
Chromium-D - 96 96
Chromium-P 0-54 [27] 0-76 [38] 0-54 [27] Cobalt-D - - - Cobalt-P -77 21 -41 Copper-D - - - Copper-P 19-56 [6] 49-91 [70] 47-96 [70] Lead-D 0 96 96
Lead-P -74-10 [-38] 86-95 [91] 87-94 [90] Zinc-D -20-67 [37] 94-98 [97] 96-99 [98] Zinc-P -200-57 [-6] 75-99 [93] 88-99 [93] Acenaphtene 50 - 50
Benzo(a)pyrene 91 - 91 Fluorene 0-50 [38] 50-75 [56] 50-75 [56] Phenanthrene -100-75 [2] 50-92 [74] 50-92 [68] Anthracene - 90 - Fluoranthene -100-76 [8] 50-88 [71] 50-88 [71] Pyrene 0-75 [11] 67-75 [74] 75-92 [77]
Benzo(a)anthracene 92 - 92
Chrysene 90 - 90
Benzo(b)fluoranthene 0-92 [46] 50 50-92 [71]
RE≥70% 40<RE<70% RE≤40%
• Major part of dissolved and particulate µpollution catched by the filter
• RE (Particulate Pb and Zn) <0 in the pond
Pond RE Suspended solids = -100%
[SS], [Zn] and [Pb] correlated
Resuspension of SS and combined metals by incoming flow
Context and objectives
Material and methods
Stormwater quality
Metals contents along the system
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Micropollutants storage
Conclusion
L1=organic deposit
L2 = Intermediate sand
L3 = Deep sand
Z
Pond
Highly water fed area
Poorly water fed area
Pond Highly water fed area
Poorly water fed area
Ni and Co detected Zn >> Pb > Cu > Cr > Ni > Co [Pond] >> [highly fed area] > [poorly fed area]
(except for Cr, Ni and Co)
• Ni and Co detected • Zn >> Pb > Cu > Cr > Ni > Co • [2017]>>[2016] metals accumulation • [Pond] >> [highly fed area] > [poorly fed area] (except for
Cr, Ni and Co) • All concentrations decrease with CW depth
Context and objectives
Material and methods
Stormwater quality
Metals contents along the system
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MicroP removal efficiencies
Micropollutants storage
Conclusion
[Pond] >> [CW] No significant difference between highly and poorly fed area
(Highly water fed area)
(Poorly water fed area)
L1=organic deposit
Z
Context and objectives
Material and methods
Stormwater quality
Conclusion
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MicroP removal efficiencies
Micropollutants storage
Conclusion
Conclusion
• Link between rain event characteristics and stormwater micropollution ?
Stormwaters characterized by high metal loads Zn >> Cu > Pb > Cr [µpollutants] influenced by rainfall duration,
rainfall depth and dry period • Removal efficiency of the system ? RE>70% for all µpollutants, except 3 PAHs
(RE<70%) , Cr and Co (RE<40%) Filter catches most part of µpollution (rain
event scale) • Fate of micropollutants in the system ? [Pond] >> [CW] for metals and PAHs Opposite of removal efficiencies results Mobility of µpollutants in CW ? (Physico-chemical changes in the CW during extended dry periods)
Perspectives
• Study of the CW sorption capacities for metals Saturation of the CW substrate after 6 years of functionning ?