Development of an Open-Air Laboratory to Test Nitrate Removal in Bioswales
C.E. Martin (TU Delft - Civil Engineering & Geosciences)
Job van der Werf – Mentor (TU Delft - Sanitary Engineering)
T.A. Bogaard – Graduation committee member (TU Delft - Water Resources)
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Abstract
The implementation of Sustainable Urban Drainage Systems (SUDS) is increasingly adopted to address stormwater management challenges in urban environments. Among these, bioswales – vegetated channels with bioretention media – are designed to mitigate urban flooding while improving runoff quality through physical and chemical pollutant removal. Despite their widespread application in the Netherlands, especially as climate adaptation measures, limited research has assessed their water treatment performance, particularly with respect to nitrate removal. Existing studies are either insufficiently monitored at full scale or confined to controlled lab settings that fail to represent field heterogeneity. Additionally, municipal bioswale monitoring remains limited due to the high resource requirements of standard sensing equipment.
This study introduced MeSUDa (Managed experimental Sustainable Urban Drainage area), an open-air lab developed to support research in bioswale development and monitoring. The setup was equipped with both low-cost and industry standard sensors, evaluated using a set of performance indicators to assess their suitability for municipal implementation. Tracer testing was conducted to characterise MeSUDa’s hydrological behaviour, and a 1D advection-dispersion model was developed to investigate nitrate removal via woodchip-enhanced denitrification.
Results indicated that low-cost sensors may be appropriate for short-term monitoring but lack the reliability required for long-term municipal use. Hydrological testing revealed excessively slow infiltration and extended residence times, reducing MeSUDa’s representativeness of actual bioswale conditions; however, design modifications could address these limitations. The nitrate removal model projected up to 42% removal, with further improvements possible by optimising woodchip mass and placement.
Overall, MeSUDa proved to be a flexible and adaptable research platform for bioswale development and monitoring. The study provides a foundation for continued investigation into enhanced denitrification and offers design and monitoring recommendations for future research.