Application of Drinking Water Treatment Residuals in Green Stormwater Infrastructure for Enhanced Phosphorus Removal
June 3, 2018 to August 31, 2021
Researchers will develop, demonstrate, and advance the science to improve water quality through reducing nutrient input to Lake Champlain. Currently, Lake Champlain is impaired due to excess phosphorus loadings from a variety of sources, dominated by “nonpoint sources,” which are generated by runoff and erosion across agricultural and urban landscapes. This has resulted in severe eutrophication in many lakes.
To reduce phosphorus losses from urban landscape, stormwater management requires installation of infrastructure to treat runoff from existing impervious cover and this presents significant technical and economic challenges. Improved efficiencies in Green Stormwater Infrastructure (GSI) performances to capture nutrients can result in substantial water quality improvements and costs savings. Many forms of GSI, including bioretention/biofiltration, raingardens and gravel-bed wetlands, utilize filter media to trap pollutants. Some research suggests that media designed for enhanced phosphorus absorption could result in cost reductions of 10 to 50 million dollars per 1000 lbs captured from stormwater runoff from developed landscapes.
Aluminum-based drinking water treatment residuals (DWTR) have been suggested as an amendment to stormwater filter media to reduce phosphorus loads from developed landscapes. Previous research, at the lab bench and pilot scale, has demonstrated promising results. Unlike other additives available on the market, including proprietary products, industrial byproducts, etc., DWTR materials are locally available in the Lake Champlain basin and elsewhere in New England and New York. Using DWTRs in stormwater filters has the potential to provide beneficial use of a waste product in addition to restoring watershed functions and water quality of nutrient impaired waterbodies.
- investigate the variability of key constituent content (e.g., aluminum and iron) of drinking water treatment residuals (DWTRs) from various sources;
- quantify the capacity of DWTR to continue phosphorus removal over time in stormwater filters;
- investigate the potential for DWTRs to have unintended adverse consequences on water quality over time; and
- communicate the results of this research.
The research team is using laboratory analyses to characterize the composition of DWTR, a laboratory column study to evaluate phosphorus adsorption with various DWTR material, and a field study at the outdoor University of Vermont Bioretention Laboratory runoff for approximately 20 storm events over two years to develop and incorporate performance curves into water quality models. The project allows for more credible quantified estimates of long-term cumulative reductions in nutrient loads from developed landscapes using collected field data from this study. Finally, the team is sharing research findings with stakeholders via Extension outreach efforts for both professional and lay audiences.