Technical BRIEF INNOVATIVE RESEARCH FOR A SUSTAINABLE FUTURE Treatment of Chemical, Biological, and Radiological (GBR) Contaminants in Storm water Runoff Results from testing different media in a pilot-scale stormwater drainage system inlet Introduction Testing treatment technologies prior to spills of hazardous or infectious materials is critical so that the impact of such disasters can be quickly minimized, and environmental resources and human health preserved, A better understanding of distributed stormwater treatment options for homeland security contaminants is critical to protect against immediate discharge to nearby waterways, spatial spread of contamination, sorption onto pipe material that can cause persistent releases, and/or protection of wastewater treatment plant unit processes. The use of media-based catch basin inserts in separate or combined sewer networks for removing conventional contaminants such as solids, metals, nutrients, and oil and grease from stormwater runoff has been previously studied [1-6]. The products demonstrated mixed success depending on factors such as hydraulic retention time, installation geometry, and stormwater quality. However, there is a lack of data focused on homeland security contaminants of concern (i.e., chemical, biological, and radiological (CBR) contaminants). This study investigated the feasibility to reduce CBR contaminant concentrations entering the conveyance system by installing treatment media in a pilot-scale inlet. Capability To conduct this research, a pilot-scale storm inlet was built and characterized at EPA's Test and Evaluation (T&E) Facility in Cincinnati, OH (Figure 1). The system is comprised of a feed tank, flow distributor arm, flow table, piping, and inlet. The polyethylene feed tank (VT0850-54, Ace Roto- Mold, Den Hartog Industries Inc., Hospers, IA) has U.S. Environmental Protection Agency's Homeland Security Research Program (HSRP) develops scientific products based on research and technology evaluations. Our products and expertise are widely used in preventing, preparing for, and recovering from public health and environmental emergencies that arise from terrorist attacks or natural disasters. Our research and products address biological, radiological, chemical, and oil contaminants that could affect indoor areas, outdoor areas, and water infrastructure. The HSRP provides these products, technical assistance, and expertise to support EPA's roles and responsibilities under the National Response Framework, statutory requirements, and Presidential Directives. a capacity of 850 gallons. The distributor is constructed from 3 in. diameter polyvinyl chloride (PVC) pipe and sends water onto a 6.5-foot-long flow table constructed from PVC sheets, which in turn directs water to a box with a discharge pipe located 7 in. from its' bottom. The on-grade box is a commercially available high-density polyethylene insert (2400 BLKIT, NDS, Woodland Hills, CA) with dimensions of 2 ft. wide x 2 ft. long x 2 ft. deep and comes with a grate divided into four sections with 13 rows of 1-in. x 5-in. slots. The system can generate flows from approximately 1- 50 gpm. For this study, its' interception capacity was 100% as the bypass was kept closed. Flows were measured using electromagnetic flowmeters (#335-379, Toshiba America Inc., Irvine, CA). Note, this design is considered a "simple" inlet since there is no solids storage under the effluent pipe once the media is inserted such as in a conventional catch basin design, but it does replicate the upper portion of a catch basin where an insert would be installed. U.S. Environmental Protection Agency - Office of Research and Development EPA/600/S-25/-028 2025 ------- 78" 4.5" o * ~ 11.5" * 47" A 11.5" 2.5" * * It 1.5"| Bypass Drain 6" Flowmeter Effluent Sample Oistri butor (1/I6"x42" long) To Drain ~ Figure 1. Pilot-scale stormwater inlet top-view schematic and pictures U.S. Environmental Protection Agency - Office of Research and Development EPA/600/S-25/-028 2025 ------- Experimental Methods To-date, switchgrass (Big Switch, BEG Group LLC, Cambridge, OH), a coal-based granular activated carbon (GAC) (FILTRASORB 400, Calgon Carbon Corporation, Pittsburgh, PA), and a coconut-based GAC (OLS Plus 12x30, Calgon Carbon Corporation, Pittsburgh, PA) have been tested. These media were selected due to their high availability and low cost. Prior to testing the media for treatment efficacy, hydraulic performance tests were conducted that determined a 5-gpm flowrate avoided flooding the table for all media types, although switchgrass could accommodate higher flowrates. Treatment efficacy tests were then conducted by filling the inlet with 1-3 mesh bags containing the media according to Figure 2. The placement of the bags was selected to minimize short-circuiting of the water and/or expedite contaminant breakthrough testing. Simulated stormwater was used for the testing according to the recipe in Table 1. Figure 2. Media Configuration for A) Coal & Coconut GAC 800-gallon tests, B) Switchgrass, and C) Coal & Coconut GAC breakthrough tests For these tests, malathion (ORTHO Max Malathion, The Scotts Company LLC, Marysville, OH) was used as a simulant for the nerve agent Venomous Agent X (VX), Bacillus globigii (Bg) for the bioagent Bacillus anthracis, and stable (non- radioactive) cesium chloride (CsCI) for the radionuclide Cs-137. Table 2 summarizes the testing matrix. Contaminants were quantified using EPA method 622 for malathion, ICP-MS for cesium, and membrane filtration and culture for Bg. The CsCI, Bg, and 0.2-0.3 mg/L malathion experiments were conducted using 800 gallons of water and the media configurations in Figure 2A/2B. The average weight of media used was 83 lbs (37.6 kg), for GAC and 16 lbs. for switchgrass. Higher concentration malathion-GAC experiments were conducted to discern contaminant breakthrough. A cinder block was added to the inlet (Figure 2C) so less GAC could be used (approximately 28 lbs.) without short-circuiting. Table 1. Simulated Stormwater Recipe Chemical Amount mg/L Source Product Code Magnesium Sulfate Heptahydrate 15 Fisher Chemical M63-3 Potassium Chloride 125 Fisher Bioreagent s BP366-1 Potassium Nitrate 90 Sigma Aldrich P8394-2.5KB Sodium Nitrate 90 Fisher Chemical S342-3 Calcium Chloride Dihydrate 47 Fisher Chemical C79-3 Sodium Chloride 302.6 Fisher Chemical S271-10 Copper (II) sulfate pentahydrate 0.16 Acros Organics 197722500 Zinc Sulfate Heptahydrate 0.41 Fisher Chemical Z76-500 Soil Humic Acid 1 mg/L Total Organic Carbon GS Plant Food Not Applicable Table 2. Testing Matrix Media Contaminant Average Influent Replicates Switchgrass CsCI 3.2 mg/L 2 Coal GAC Bg 4.9 x 105 CFU/100 mL 2 Coal GAC CsCI 3.0 mg/L 2 Coal GAC Malathion 0.2 mg/L 4 Coal GAC Malathion 13 mg/L 3 Coconut GAC Malathion 0.3 3 Coconut GAC Malathion 7.2 mg/L 1 U.S. Environmental Protection Agency - Office of Research and Development EPA/600/S-25/-028 2025 ------- Results Out of the combinations tested, malathion removal was the most successful (Figure 3). The media were ineffective at removing Bg spores (Figure 3A) and cesium (Figure 3B) during 800-gallon experiments and therefore not investigated further. Across all sampled effluent points (100, 200, 400, 600, and 800 gallons), the coal GAC averaged 86% removal of malathion and the coconut GAC averaged 91% removal of malathion. This variation was within the range of standard deviation for both media types (Figure 3C). 800 gallons of Treated Water Coal GAC Coal GAC Switchgrass Media Coal GAC Coconut GAC Figure 3. Average treatment efficacy by media type for A) Bg spores, B) cesium, and C) malathion Data from 800-gallon testing indicated steady removal of malathion in which breakthrough had not yet been achieved (Figure 4A). Further testing was performed to determine how long the media would last. During these experiments with 55 times higher malathion concentrations, 3 times less media, and 6 times more water, breakthrough was achieved for both media types (Figure 4B). Timeseries Samp ing Data 200 400 600 Cumulative Volume (gal) Media ~ Coal GAC Coconut GAC 800 1000 2000 3000 4000 Cumulative Volume (gal) Media ¦+¦ Coal GAC Coconut GAC 5000 Figure 4. Treatment efficacy at sampled timepoints for GAC media and malathion- contaminated simulated stormwater A) 800-gallon tests, B) breakthrough tests (n = 1 Coconut GAC and n =3 Coal GAC) U.S. Environmental Protection Agency - Office of Research and Development EPA/600/S-25/-028 ------- To estimate an approximate sorption capacity, the breakthrough data was averaged on each cumulative volume data point in Figure 4B. An average percent reduction was applied to the averaged influent malathion concentration to estimate the total malathion removed between sample points. This resulted in an estimated sorption capacity of 7.46 mg malathion / g of carbon. Freundlich isotherm coefficients for malathion from the literature[7] of k = 1.6 and 1/n of 0.60 were also applied to the average influent malathion data and resulted in an estimated theoretical sorption capacity of 6.54 mg malathion / g of carbon for the breakthrough experiments. The difference is reasonable considering the averaging of the data, granularity of sample points, and different carbons in the experiments vs. literature study. The collected data indicate that for preliminary design of a GAC inlet capture system, the use of the Freundlich isotherm is a reasonable starting point. Discussion Due to a limited testing budget and historical projects showing low removal for some test combinations only a limited number of combinations of contaminant-media pairings were tested. Switchgrass and GAC were selected as the test media because of their availability and low cost. Not unexpectedly, their large grain size and lack of ion exchange capacity led to poor treatment efficacy of stormwater contaminated with Bg and CsCI. Further evaluation of media for catch basin inserts is needed to document treatment options for biological and radiological contaminants under storm drain hydraulics. On the other hand, GAC has a proven history of successfully treating pesticides [8, 9] and malathion, an organo-phosphate pesticide, performed well under the pilot-scale stormwater inlet hydraulic conditions. Still, the feasibility of inlet treatment with GAC requires further site- specific analysis to determine its suitability. For example, determining a media use rate is crucial for a utility or emergency responder to understand implementation logistics. A use rate is dependent on the amount of malathion spilled, the surface that is contaminated, and the climate (e.g., when precipitation occurs and temperature). To put the malathion data in perspective, consider a 1-acre asphalt parking lot with a 5% slope in Research Triangle Park, North Carolina that experienced a nerve agent attack of 100 mg/ft2. Assuming a 5% washoff rate and using the experimental sorption capacity of 7.45 mg/g, a minimum of 65.5 lbs. of GAC would be needed in the inlet to treat the stormwater runoff. This is congruent with what was feasible in pilot-scale experiments. Next, a hydraulic understanding of the capture efficiency of the inlet + media is necessary to evaluate how much water would be treated and if surface flooding would occur. For the RTP parking lot, a total runoff volume of 1.06 x 106gallons is estimated using EPA's Storm Water Management Model (SWMM) and 2024 precipitation data. Further, peak runoff was estimated at 801 gpm (from a 1.77-inch event) and an average runoff of 23 gpm. This indicates that many storm events would have a portion of water bypass the carbon treatment at the current 5 gpm testing conditions and that surface flooding might occur. As such, holding tanks or a different configuration of the media would need to be considered. Performing modeling to estimate the exceedances and bypasses at the specific location is a key component to developing a disaster management protocol involving the deployment of media in stormwater inlets and helps answer if this technology is suitable in a specific location. This work demonstrates the stormwater inlet capability at EPA's T&E facility that is available to test novel media and/or flow regimes to continue providing data to assist responders in preparing for disaster. Contact Information Technical Contacts Anne Mikelonis, mikelonis.anne@epa.gov Jeff Szabo, szabo.ieff@epa.gov Jim Goodrich, goodrich.iames@epa.gov Josh Steenbock, steenbock.ioshua@epa.gov General Feedback CESER@epa.gov U.S. Environmental Protection Agency - Office of Research and Development EPA/600/S-25/-028 2025 ------- Disclaimer: This document has been reviewed in accordance with U.S. Environmental Protection Agency, Office of Research and Development, and approved for publication. Mention of trade names or commercial products does not constitute endorsement or recommendation for use. References 1. Pitt, R. and R. Field. An evaluation of storm drainage inlet devices for stormwater quality treatment. in Water Environment Federation Technical Exposition and Conference. 1998. Orlando, FL. 2. Morgan, R.A., et al. An evaluation of the urban stormwater pollutant removal efficiency of catch basin inserts. Water environment research, 2005. 77(5): p. 500-510. 3. Kostarelos, K., et al. Field study of catch basin inserts for the removal of pollutants from urban runoff. Water resources management, 2011. 25(4): p. 1205-1217. 4. Basham, D., et al. Design and construction of full-scale testing apparatus for evaluating performance of catch basin inserts. Journal of Sustainable Water in the Built Environment, 2019. 5(1): p. 04018013. 5. Alam, M.Z., et al. Characterising stormwater gross pollutants captured in catch basin inserts. Science of The Total Environment, 2017. 586: p. 76-86. 6. Alam, M.Z., et al. Improving stormwater quality at source using catch basin inserts. Journal of Environmental Management, 2018. 228: p. 393-404. 7. Sharma, S., H. Rathore, and S. Ahmed. Studies on removal of malathion from water by means of activated charcoal. Ecotoxicology and environmental safety, 1987. 14(1): p. 22-29. 8. Jusoh, H.H.W., et al. Granular activated carbon optimization for enhanced environmental disaster resilience and malathion removal from agricultural effluent, in E3S web of conferences, 2023. EDP Sciences. 9. Kearns, J., E. Dickenson, and D. Knappe. Enabling organic micropollutant removal from water by full- scale biochar and activated carbon adsorbers using predictions from bench-scale column data. Environmental Engineering Science, 2020. 37(7): p. 459-471. U.S. Environmental Protection Agency - Office of Research and Development EPA/600/S-25/-028 2025 ------- |