Grantee Research Project Results

Final Report: Vermicompost from Phytoremediation of Stormwater

EPA Grant Number: SU839453
Title: Vermicompost from Phytoremediation of Stormwater
Investigators: Malcolm, Elizabeth , Wang, Xixi , McConnell, William , Howard, Maury , Reese, Margaret , Rock, Philip , Henry, Katrina , Ewell, Paul , McCorty, Mayanni , Bateman, Kelly , Wang, Leyi , Brett, Arika , Craft, Noah , Marosi, Arika , Canady, Warren , Steel, Gavin , Class, Michael , Venanzi, Philip , Hipple, Elizabeth , Hendricks, Christy , Purdin, Emily , Murrell, Phoebe , Fernandez, Allison , Xie, Jinyuan
Institution: Virginia Wesleyan College
EPA Project Officer: Page, Angela
Phase: I
Project Period: December 1, 2018 through November 30, 2019 (Extended to May 30, 2020)
Project Amount: $15,000
RFA: P3 Awards: A National Student Design Competition Focusing on People, Prosperity and the Planet (2018) RFA Text |  Recipients Lists
Research Category: P3 Awards , P3 Challenge Area - Safe and Sustainable Water Resources

Objective:

Constructed wetlands (CWs) and stormwater management ponds (SWMPs) are a popular best management practice for reducing flood risk and removing pollution from stormwater runoff in rural, urban, and suburban areas. SWMPs and CWs are often a sink for heavy metal pollution from sources including automotive wear and atmospheric deposition. However, some CWs have been found to be 
“hotspots” of methylmercury production, thus increasing downstream methylmercury. Another challenge is that excess nutrients in SWMPs cause algal blooms, often considered a nuisance by adjacent landowners and thus detrimental to property values. These algal blooms are sometimes controlled by application of algaecides. 
The research and design goals of this project are to 1) evaluate the potential for reducing nutrients, mercury and metals within stormwater ponds and CWs by algae removal, and 2) design and demonstrate a novel, value-added vermicomposting method for freshwater algae.  

Summary/Accomplishments (Outputs/Outcomes):

A mesocosm experiment was conducted first, which evaluated the uptake of metals by a natural consortium of filamentous algae. It was demonstrated that the algae in the mesocosms that had been spiked with heavy metals (Cu, Cd, Hg, Pb and Zn) retained higher concentrations of said metals than
the algae in mesocosms without spikes. The concentrations of metals in the water decreased more in the tanks with algae, a 150-185% improved reduction. A vermicompost experiment was then initiated using these algae samples. There were three treatments: vermicompost bins with high-metal algae, low-metal algae or no algae. The worms successfully decomposed filamentous algae, which was mixed with food waste and cardboard, demonstrating that filamentous freshwater algae can be used as a vermicompost feedstock. The metal concentrations in the finished compost, including that with the high-metal algae treatment, were well within limits laid out by European compost rules, except for mercury, which was high in compost created both with and without algae, with a likely source coming from the food. A second vermicomposting experiment was conducted using filamentous algae from three different stormwater ponds. Algae from two of the ponds contained high concentrations of copper, resulting in vermicompost with copper content above the typical regulatory limit. The source of the copper may have been copper-based algaecide, a popular treatment for stormwater ponds. Thus we recommend that the level of heavy metals should be measured in algae feedstock, particularly if it is possible that copper sulfate has been used in the pond as an algaecide, or if there are other potential sources of heavy metals to the pond such as highway runoff. The vermicompost created with algae did not differ significantly in percentage of total nitrogen, phosphorus, or potassium relative to the no algae treatments.

A conceptual framework for modeling hydrologic processes in bioretention ponds was created and evaluated, which included refined nomographs, and was determined to be a cost-effective tool for assessing treatment efficiency of bioretention ponds in removing nitrogen and phosphorus. Further, the
applicability of the Monold model for predicting algal blooms in shallow lakes or ponds, which share the hydrodynamic and physiological characteristics with the constructed wetland on the VWU campus was evaluated. The fluctuations of nitrogen and phosphorus concentrations in an urban stormwater pond located in Virginia Beach, Virginia were measured and visualized. These measured concentrations may be extrapolated or scaled up to formulate a broad picture of water quality in the stormwater ponds in coastal Virginia and beyond.

An inquiry-based lesson on phycoremediation and stormwater pollution was created and shared with over four hundred elementary students and around fifty elementary students' parents, through field trips onto our campus, summer camps, and from presenting the lesson at area schools and organizations. The lesson has also been presented to around twenty practicing teachers through state and national teaching conferences. At least forty teaching candidates in teacher education classes have participated in learning about this lesson. Additionally, over sixty undergraduate students conducted course research projects based on this research.

Conclusions:

To our knowledge this is the first study to evaluate phycoremediation for nutrients and metals in stormwater ponds and the first study to use algae as a vermicompost amendment.​  This research suggests that the removal of filamentous algae from surface water is an effective, easily-implemented and eco-friendly means to reduce toxic metals in water bodies and that freshwater filamentous algae can be used to create nutrient rich vermicompost. 

Journal Articles:

No journal articles submitted with this report: View all 7 publications for this project

Relevant Websites:

VWU receives second grant from the Environmental Protection Agency Exit

Progress and Final Reports:

Original Abstract

2019 Progress Report