Boets, Pieter

Donoso Pantoja, Natalia Carolina

Goethals, Peter

Meers, Erik

English

Ghent University Academic Bibliography

INTEGRATED CONSTRUCTED WETLANDS TO TACKLE DIFFUSE NITRATECONTAMINATION IN SURFACE WATERDonoso N. 1,2, Boets P. 3, Goethals P.L.M. 2, Meers E. 11 Department of Applied Environmental Chemistry, Ghent University, Coupure Links 653, 9000 Ghent, Belgium2 Department of Applied Ecology and Environmental Biology,  Ghent University, J. Plateaustraat 22, B-9000 Gent, Belgium3  Provinciaal Centrum voor Milieuonderzoek, Godshuizenlaan 95 9000 Ghent, Belgium In the current investigation relatively high surface flow and low nitrate removal rates would increase the surface area needed for theimplementation of CWs. A better understanding of these controlling factors as well as the hydrology of small waterways influenced by intenseagriculture, should lead to an appropriate definition of the area and number of CWs needed to decrease nitrate concentrations. Insight flowdynamics of small watercourses would compensate the possible overestimation of the wetland size. ICWs offer an interesting perspective to tackle diffuse nitrate pollution, hence, the importance to further explore the feasibility of thepresented study.1 Bachand, P. A., & Horne, A. J. (1999). Denitrification in constructed free-water surface wetlands: II. Effects of vegetation and temperature. Ecological Engineering , 17-32. 2 Beutel, M. W., Newton, C. D.,Brouillard, E. S., & Watts, R. J. (2009). 3 Nitrate removal in surface-flow constructed wetlands treating dilute agricultural runoff in the lower Yakima Basin, Washington. Ecological Engineering, 35(10), 1538–1546. 4 Flemish Environment Agency (VMM). (2013). Midterm review of the 4th Action Programme of Flanders for the Nitrates Directive. Belgium/Flanders. 5 Tanner, C., & Kadlec, R. H. (2013). Influence ofhydrological regime on wetland attenuation of diffuse agricultural nitrate losses. Ecological Engineering, 79-88. 6 Tonderski, K., Geranmayeh, P., Johannesson, K., Ulén. B., Weisner, S.E.B. (2015). Nitrogenand phosphorus removal in agricultural wetlands. Conference Wetlands in Agricultural Landscapes, 11-16 October, České Budějovice, Czech Republicnataliacarolina.donosopantoja@ugent.beIntroductionThe European Union statistical office, Eurostat, revealed in 2012 thatamongst the members of the EU, Belgium was the first on the list ofcountries with higher nitrate concentrations in groundwater. The FlemishEnvironmental Agency (VMM) reported in 2013 that 26% of the monitoringstations located in small fresh watercourses in Flanders are stillexceeding the maximum allowable limit of 50 mg NO3-/l. Regarding thekey aims of the Water Framework Directive: to achieve “a good status“of all waters by 2027 and to develop water management plans per riverbasin, we investigate whether eco-engineering and installing ConstructedWetlands (CWs) at selected locations alongside small fresh watercoursescould help to diminish diffuse nitrate contamination.MethodologyResultsTable 1: Surface area needed at different experimental nitrate removal rates.Objectives• Examine the effect of the surface flow of watercourses and theenvironmental conditions in the surface area needed for implementingintegrated constructed wetlands (ICW).• Highlight the flaws in the determination of main parameters toconsider, prior the installation of CWs.Conclusions Year Highest NO3- conc.registered in the Broenbeek –StadendrevebeekAverage surface flow (m3/d)13824Experimental nitrate removal rates (g NO3/m2.d)0.2 0.3 0.5 0.6Surface area mg/l ha ha ha ha2003 97.4 27.0 18.7 14.1 10.42005 137.2 49.7 34.5 26.0 19.12007 110.6 34.5 24.0 18.1 13.32009 88.5 21.9 15.2 11.5 8.52011 72.6 12.9 8.9 6.7 5.02013 81.0 17.7 12.2 9.2 6.82015 82.3 18.4 12.8 9.6 7.15 ha 5 to 10 ha 10 to 15 ha > 15 ha1. Site selection: Broenbeek – Stadendrevebeek watercourse, part of theIJzer basin. West Flanders province of Belgium.2. Analysis of monthly NO3- concentrations registered by the VMMbetween November 2002 till November 2015 and determination ofexceeding values above the 50 mgNO3/l.3. Estimation of surface areas needed for implementing CWs able todecrease peak concentrations. Theoretical nitrate removal ratesachieved in full scale CWs systems at similar weather conditions thanBelgium were considered.Where:A= treatment area of the wetland (m2 or ha)Qin= flow rate incoming in the wetland (m3/day)Qout= flow rate outgoing from the wetland (m3/day)Cin = influent concentration (mg NO3/l)Ce = target effluent concentration (mg NO3/l) k = nitrate removal rate (g NO3/m2.d)• Decrease tendency of the highest concentrations recorded in thepast 5 years.• Intense agricultural activities in small water represent elevatedwater use and evapotranspiration rates. The ProbabilityDistributed Moisture (PDM) model used to determine the averagesurface flow does not consider these parameters. Hence, the13824 m3/d could be overestimated.• Land required would be around 9 to 13 ha in order to diminishthe nitrate concentrations for the presented case study.• Peak concentrations expected to be shaved-off• 51% of the measurements exceeded the standard limit

Integrated constructed wetlands to tackle diffuse nitrate contamination in surface water

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Integrated constructed wetlands to tackle diffuse nitrate contamination in surface water

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