, Lenormand E. , BoisP. 1 , Laurent J. , Wanko A. 1wems.dk/wp-content/uploads/2018/01/walaszek.pdf · Walaszek M. 1, Lenormand E. , BoisP. 1, Laurent J. , Wanko A.1 1 Ecole Nationale

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

[email protected] WETPOL 2017 2

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



Stormwater quality

The Ostwaldergraben: a poor quality stream


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



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



Stormwater quality




Conclusion

Objectives of the study

Link between rain event characteristics and stormwater micropollution ?

Removal efficiency of the system ?

Fate of micropollutants in the system ?



Stormwater quality

Experimental site




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%



Stormwater quality

Water quality evaluation




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



Stormwater quality

Soils quality and storage evaluation




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



Stormwater quality

Rainfall characteristics of 13 sampling sessions




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)



Stormwater quality

Stormwater quality




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



Stormwater quality

Link between hydrology and stormwater quality




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)



Stormwater quality

Removal efficiencies (RE)




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



Stormwater quality

Metals contents along the system




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



Stormwater quality

Metals contents along the system




Conclusion

[Pond] >> [CW] No significant difference between highly and poorly fed area

(Highly water fed area)

(Poorly water fed area)

L1=organic deposit

Z



Stormwater quality

Conclusion




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 ?

Thank you for your attention !


Documents

, Lenormand E. , BoisP. 1 , Laurent J. , Wanko A. 1wems.dk/wp-content/uploads/2018/01/walaszek.pdf · Walaszek M. 1, Lenormand E. , BoisP. 1, Laurent J. , Wanko A.1 1 Ecole Nationale