Grantee Research Project Results
Soil Amendments for Enhanced Phosphorus Retention: Implications forGreen Infrastructure Design
EPA Grant Number: SU839456Title: Soil Amendments for Enhanced Phosphorus Retention: Implications forGreen Infrastructure Design
Investigators: Small, Gaston E , Salzl, Michael
Current Investigators: Small, Gaston E , Wihlm, Spencer E , Wallace, Hannah R , Abrahamson, Jenna N , Deile, Madison P , Mahre, Erin K , Fischer, John PH , Jimenez, Ivan J , Shrestha, Paliza , Salzl, Michael T
Institution: University of Saint Thomas
Current Institution: University of St Thomas
EPA Project Officer: Page, Angela
Phase: I
Project Period: December 1, 2018 through November 30, 2019
Project Amount: $14,997
RFA: P3 Awards: A National Student Design Competition Focusing on People, Prosperity and the Planet (2018) RFA Text | Recipients Lists
Research Category: P3 Challenge Area - Safe and Sustainable Water Resources , P3 Awards
Objective:
Green stormwater infrastructure (GSI) such as bioretention is a national stormwater focus and offers promising solution to control nutrient losses (of phosphorus; P, and nitrogen; N) from urban storm runoff as a way to combat eutrophication and harmful algal blooms (i.e., toxic cyanobacteria and Microcystis) in the receiving waters. They are commonly being implemented in cities as part of their stormwater management strategy. The paradigm has been that these bioretention systems remove all or nearly all of P and N from stormwater runoff, but increasing number of studies has shown that a significant amount of P and N is being leached and exported to the effluent from these systems. Especially in light of predicted increases in rainfall volumes and intensity in many areas in the U.S., we need to have a better understanding of how soil media in bioretention systems retains and releases nutrients in response, and improves bioretention performance. The soil media is one of the critical design elements of a bioretention, which filters and "treats" runoff, attenuates flows, and provides a medium for plant growth. For P specifically, the composition of the soil media is of utmost importance as P removal is heavily reliant on sorption mechanisms in soils. Managing P in the watersheds to combat eutrophication for clean drinking water and healthy aquatic ecosystems will be increasingly challenging at the face of climate change projected to make some areas warmer and wetter. The ultimate goal of this Phase I project is to identify the most effective soil amendments for P, and possibly N retention, in bioretention filter systems through a combination of laboratory and field experiments.
Approach:
An interdisciplinary team of undergraduate students from the University of St. Thomas supervised by postdoc (Paliza Shrestha) and the PI will conduct a series of experiments to test the effectiveness of different waste materials, as soil treatments, to remove P from compost leachate under variable flows. N will also be monitored simultaneously. The waste materials examined will be Aluminum-based water treatment residuals (Al-WTR), coconut coir, and high carbon (C) wood-ash, as soil treatments in a laboratory based column study. The team will also test the three amendments in small-scale field trials at the University of St. Thomas Research Garden to confirm laboratory research results. Field confirmation is valuable as the treatments are exposed to natural environmental variations not easily replicated in the lab. The team will model the lifespan of the individual filter media substrates to reach P saturation under variable P loads as in a watershed scenario, and generate a comparative cost benefit analysis. In the cost-benefit analysis, we will also compare the costs of P removed from these amendments against the cost of implementing these materials per unit land surface area.
Results will be used to inform municipal stormwater managers and water planners the attributes that enhance soil filter media's capacity for nutrient removal, as they consider responding to P and N water quality hazards associated with harmful algal blooms by retrofitting stormwater infrastructure. The project will benefit people by improving health and quality of local waterways by keeping nutrients out of surface waters, thereby improving their ecological, cultural and recreation values. With respect to prosperity, improved water quality can strengthen local economy from recreation, tourism and agriculture, while decreasing the cost for drinking water treatment and combating harmful algal blooms. With respect to the planet, this project will be promoting waste recycling, eco-technology and eutrophication control for healthy ecosystems.
Expected Results:
Performance results from the laboratory column experiment will be evaluated against those from the small-scale urban garden trials at University of St. Thomas. All results will be disseminated to collaborators at the Freshwater Society, Mississippi Watershed Management Organization, and University of Minnesota Stormwater Education Program. The output from this project is land-application of waste materials as soil treatments for innovative and ecological treatment of stormwater for P, and possible N reduction. Project outcomes include: reduction of P and N transport and mobilization downstream; improved quality of local waters; diversion of waste materials from landfills; hands-on opportunity for students to get involved in designing of engineered media filters; training students to be leaders in environmental monitoring and problem solving; communicating design recommendations to urban planners, which will aid in the search for tools to mitigate water quality hazards and adapt to extreme precipitation events in a watershed by strengthening stormwater infrastructure.
Contribution to Pollution Prevention or Control: This project explores a novel application of different waste materials targeted at removing P and N from runoff to combat problems of harmful algal blooms that endanger local surface water quality (in freshwater and coastal ecosystems) and pose aquatic and public health threat.
Publications and Presentations:
Publications have been submitted on this project: View all 7 publications for this projectJournal Articles:
Journal Articles have been submitted on this project: View all 1 journal articles for this projectSupplemental Keywords:
stormwater management, phosphorus, nitrogen, green infrastructure, bioretention, urban water planning, water treatment, waste recycling, agricultural wastewater treatmentProgress and Final Reports:
The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.