EAPSI: Managing Stormwater Runoff and Nitrogen in Urbanizing Cities Through the Use of Bioretention Systems

Lopez Emma V, Lutz FL

Investigators

Abstract

Stormwater and nutrient management are becoming increasingly important as urbanization in coastal cities continues to increase. Stormwater runoff carries pollutants that are discharged in natural waterbodies. One pollutant of concern for water quality in coastal cities is reactive nitrogen. Although a nutrient and vital for life on Earth, when found in excess in aquatic environments nitrogen may lead to algal blooms, negatively impacting surface water bodies which are sources for drinking water, recreation and the fishing industry. A technology used to treat stormwater runoff is bioretention, which consists of a shallow depression with native plants and a series of permeable layers including sand and gravel where the water is filtered and pollutants are degraded. Additional advantages of bioretention are reduced flooding, improved groundwater recharge and increases green space. The purpose of this project is to study bioretention systems for nitrogen removal in an urban coastal city. The researcher will be working at the National University of Singapore, where research on the development of bioretention systems for sustainable stormwater management is being conducted. The research will be carried out under the guidance of Dr. Hu Jiangyong, an expert on water technologies. Singapore is the third most densely populated nation in the world and flashfloods are common during the rainy season and stormwater and nutrient management is crucial for their livelihood and water quality. Nitrogen is a highly mobile nutrient and therefore challenging to fully remove from the aqueous phase. Biological, physical, and chemical processes that take place in bioretention systems can contribute to the removal of nitrogen. Moreover, bioretention systems need to be designed to promote nitrification and denitrification to successfully remove nitrogen from the aqueous phase and return it to the atmosphere as dinitrogen, N2 (g). The researcher will study how the geographical context of different precipitation events and local materials found in Singapore contribute to nitrogen removal in bioretention compared to systems being studied in the U.S. Storm events that were performed in Tampa, FL in a denitrifying bioretention system will be replicated in a bioretention system in Singapore. Total nitrogen removal data will be compared for both systems. These comparison studies will provide a deeper insight on how the media type and environmental parameters of precipitation impact nitrogen removal. The new knowledge gained will contribute to improvements in bioretention design and overall water quality for coastal cities around the world. This award, under the East Asia and Pacific Summer Institutes program, supports summer research by a U.S. graduate student is jointly funded by NSF and the National Research Foundation of Singapore.