PCBs and many PAHs are highly toxic persistent organic pollutants (POPs) that accumulate in the food chain due to their hydrophobic characteristics, whereas copper is one of the more challenging heavy metals in stormwater due to its toxicity to aquatic life (particularly salmon in the Pacific Northwest) and strong affinity to organic matter. 

The goal for this project is to develop new and innovative treatment media or mixes of media to provide optimum removal of POPs and metals, with a focus on PCBs, PAHs and copper from stormwater runoff originating from Department of Defense (DoD) sites. Emphasis will be placed on removal of contaminants of concern (COCs) that are associated with particulate matter as well as remaining dissolved fractions of COCs. Removal by microbial degradation of the adsorbed POPs and immobilization of copper organized in a “treatment train” best management practices will be examined. A passive sampling approach will be employed for monitoring breakthrough of the geomedia. Furthermore, implementation, scale-up, and commercialization aspects will be considered for the developed treatment solutions.

Capture of stormwater COCs at the source, before they are dispersed in the aquatic environment, provides many treatment advantages due to higher concentrations of COCs and easier accessibility for capture. This work will provide information on COC affiliations with stormwater particulate matter (PM), with a specific focus on variations of COC concentrations and mass loads with PM sizes. The research and data collection will initially take place using research-level stormwater monitoring. The collected data will guide subsequent project tasks toward development of technologies for removal of COC affiliated with PM, which can be coupled with established PM removal technologies.

Various types of geomedia will be developed for capture of dissolved-phase COCs. Several types of geomedia or amended geomedia may result, each with defined characteristics for capture of specific COCs (PCBs, PAHs and copper). An inexpensive natural media will be developed for use in bioretention facilities and similar technologies for treatment of stormwater, along with a more efficient “engineered” media. Possible sources of geomedia include locally-sourced “standard” bioretention media and amendments such as compost (yard waste), wood chips, activated carbon (AC), biochar, aluminum and/or iron oxide. The criteria for selection of media will include high sorption capacity, rapid rates of uptake, no leaching of captured COC or other undesired substances, promotion of biodegradation of organic COC and/or long-term immobilization of copper.

In situ biodegradation will be examined via biomolecular tools for PCB and PAH degrading microorganism and detection of degradation products; strength of affiliations of copper in the geomedia will be determined. A passive sampling approach will be employed for monitoring breakthrough of the geomedia. Scale-up to pilot-scale will be employed for these studies and the scale-up and implementation cost and requirements will be assessed throughout the project to ensure that the geomedia can be effectively implemented in situ.

Stormwater runoff has been implicated as a major cause of contamination and recontamination of sediment near stormwater discharge points at or close to DoD sites. Addressing and removing COCs such as PCBs, PAHs and copper near their sources, where concentrations are higher and they are less dispersed, will keep these pollutants isolated near their source, where they can be managed more effectively and in a more sustainable manner. A “treatment train” approach is envisioned, with layers or modules that specifically target PM and affiliated COCs, followed by layers that may separately or collectively target dissolved COC. Ease of maintenance and long-term COC management will drive these approaches, where passive sampling will be employed for testing of geomedia breakthrough. Layers or modules can be easily replaced when needed. The results from this project will assist in the development of the next generation of stormwater management tools, to effectively prevent release of COCs into local water bodies and (re)contaminating sediments. An overall DoD benefit is a more efficient reduction of environmental risk at lower costs. (Anticipated Project Completion - 2023)

Cao, S., A. Davis, and B.V. Kjellerup. 2022. Presence of Bacteria Capable of PCB Biotransformation in Stormwater Bioretention Cells. FEMS Microbiology Ecology, 97(12):fiab159. doi.org/10.1093/femsec/fiab159.

Cao, S., M. Bensi, A.P. Davis, and B.V. Kjellerup. 2023. Polychlorinated Biphenyls (PCBs) in Dissolved and Particulate Phases of Urban Stormwater Before and After Bioretention Treatment. ES&T – Water, 3(10): 3235-3243. doi.org/10.1021/acsestwater.3c00214.

Kaya, D., K. Croft, S.T. Pamuru, C. Yuan, A.P. Davis, and B.V. Kjellerup. 2022. Considerations for Evaluating Innovative Stormwater Treatment Media for Removal of Dissolved Contaminants of Concern with Focus on Biochar. Chemosphere, 307(4):135753. doi.org/10.1016/j.chemosphere.2022.135753.

Pamuru, S.T., E. Forgione, K. Croft, B.V. Kjellerup, and A.P. Davis. 2022. Chemical Characterization of Urban Stormwater: Traditional and Emerging Contaminants. Science of the Total Environment, 813:151887. doi.org/10.1016/j.scitotenv.2021.151887.

Theses and Dissertations

Cao, S. 2020. Occurrence and Removal of Polychlorinated Biphenyls (PCBs) in Urban Stormwater (partial Ph.D. Dissertation). University of Maryland, College Park.

Croft, K. 2023. Interactions and Treatment of Metals in Urban Stormwater (Ph.D. Dissertation). University of Maryland, College Park.

Yuan, C. 2020. Polycyclic Aromatic Hydrocarbons (PAHs) Degrading Bacteria in Media of a Stormwater Bioretention Cell (Master’s Thesis). University of Maryland, College Park.

Yuan, C. 2023. Prevention and Treatment of Persistent Organic Pollutants in Stormwater and Sediment (Ph.D. Dissertation). University of Maryland, College Park.