Thesis
Nitrate and phosphate removal through an optimized bioretention system
Washington State University
Master of Science (MS), Washington State University
2012
Handle:
https://hdl.handle.net/2376/100942
Abstract
Bioretention is an evolving type of Green Stormwater Infrastructure (GSI) now being utilized as a method to clean stormwater runoff and mitigate degradation that has been seen in many aquatic environments. Further regulations enacted by the National Pollution Discharge Elimination System (NPDES) will soon require phase I and phase II communities to reduce stormwater to the maximum extent possible. This imposes an immediate need for further analysis and optimization of bioretention systems to more effectively reduce stormwater pollutants. This thesis examines the capabilities of an optimized bioretention soil mixture to effectively reduce both nutrients and heavy metals from stormwater runoff. Emerging bioretention design features in the forms of saturation, vegetation, and aluminum-based water treatment residuals were utilized to further examine their role to reduce two of the most significant nutrient species in nitrate and ortho-phosphate. Experiments were conducted using 12 large mesocosms constructed following standard bioretention design in Western Washington. Results show that utilization of a saturation zone and aluminum-based water treatment residuals can significantly reduce nitrate and ortho-phosphate, even in a newly constructed system. Nitrate removal was shown at levels up to 71 percent for the mesocosms with a saturation zone and orth-phosphate removal was shown at levels up to 80 percent for the mesocosms without a saturation zone. Early establishment of plants did not significantly improve removal thus showing the need for aluminum based water treatment residuals and a saturation zone during the initial establishment period. Results also show an export of total phosphorus and total nitrogen from the compost amended bioretention soil mixture utilized. While export appears to decrease with an increase in hydraulic loading, this may pose concerns for bioretention systems which utilize an under-drain. Significant removal was also achieved for both zinc and lead, while an export in copper and aluminum was shown.
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Details
- Title
- Nitrate and phosphate removal through an optimized bioretention system
- Creators
- Eric Tyler Palmer
- Contributors
- Cara Poor (Degree Supervisor)
- Awarding Institution
- Washington State University
- Academic Unit
- Civil and Environmental Engineering, Department of
- Theses and Dissertations
- Master of Science (MS), Washington State University
- Publisher
- Washington State University; Pullman, Wash. :
- Identifiers
- 99900525069801842
- Language
- English
- Resource Type
- Thesis