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Retrofitting urban watersheds with wireless sensing and control technologies will enable the next generation of autonomous water systems. While many studies have highlighted the benefits of real-time controlled gray infrastructure, few have evaluated real-time controlled green infrastructure. Motivated by a controlled bioretention site where phosphorus is a major runoff pollutant, phosphorus removal was simulated over a range of influent concentrations and storm conditions for three scenarios: a passive, uncontrolled bioretention cell (baseline), a real-time controlled cell (autonomous upgrade), and a cell with soil amendments (passive upgrade). Results suggest the autonomous upgrade matched the pollutant treatment performance of the baseline scenario in half the spatial footprint. The autonomous upgrade also matched the performance of the passive upgrade; suggesting real-time control may provide a ‘digital’ alternative to existing, passive upgrades. These findings may help site- and cost-constrained stormwater managers meet their water quality goals.
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Real time control schemes for improving water quality from bioretention cells
Abstract Extreme weather and the proliferation of impervious areas in urban watersheds increases the frequency of flood events and deepens water quality concerns. Bioretention is a type of green infrastructure practice developed to mitigate these impacts by reducing peak flows, runoff volume, and nutrient loads in stormwater. However, studies have shown inconsistency in the ability of bioretention to manage some pollutants, particularly some forms of nitrogen. Innovative sensor and control technologies are being tested to actively manage urban stormwater, primarily in open water stormwater systems such as wet ponds. Through these cyber-physical controls, it may be possible to optimize storage time and/or soil moisture dynamics within bioretention cells to create more favorable conditions for water quality improvements. A column study testing the influence of active control on bioretention system performance was conducted over a nine-week period. Active control columns were regulated based on either maintaining a specific water level or soil moisture content and were compared to free draining (FD) and internal water storage standards. Actively controlled bioretention columns performed similarly, with the soil moisture-based control showing the best performance with over 86% removal of metals and TSS while also exhibiting the highest ammonium removal (43%) and second highest nitrate removal (74%). While all column types showed mostly similar TSS and metal removal trends (median 94 and 98%, respectively), traditionally FD and internal water storage configurations promoted aerobic and anaerobic processes, respectively, which suggests that actively controlled systems have greater potential for targeting both processes. The results suggest that active controls can improve upon standard bioretention designs, but further optimization is required to balance the water quality benefits gained by retention time against storage needs for impending storms.
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- Award ID(s):
- 1737432
- PAR ID:
- 10112532
- Date Published:
- Journal Name:
- Blue-Green Systems
- ISSN:
- 2617-4782
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.2166/bgs.2019.924
