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Long-term field study of nitrate and ammonium remediation using a permeable reactive barrier at a livestock feeding operation
Citation:
Lawrinenko, M., L. Rhea, K. Forshay, T. Lee, M. White, AND R. Wilkin. Long-term field study of nitrate and ammonium remediation using a permeable reactive barrier at a livestock feeding operation. JOURNAL OF ENVIRONMENTAL MANAGEMENT. Elsevier Science Ltd, New York, NY, 380:124962, (2025). https://doi.org/10.1016/j.jenvman.2025.124962
Impact/Purpose:
The selection of groundwater remediation technologies is best supported by a detailed understanding of groundwater geochemistry, hydrologic characteristics, and mechanistic behavior of the remediation technology. The overall goals of the research article described here were to better understand the chemical and microbiological processes that result in nitrate removal in carbon-based permeable reactive barriers (PRBs), to evaluate the effect of the PRB on downgradient aquifer/groundwater chemistry, and to improve and refine the site conceptual hydrogeological model. Researchers at the Groundwater Characterization and Remediation Division have established programs and ongoing interests in the areas of contaminant transport and fate in groundwater, performance and longevity of permeable reactive barriers for groundwater restoration, and microbiological cycling of nitrogen in soils and groundwater. The work is of interest to the international environmental community, including EPA’s regional, program, and local partners.
Description:
Protecting groundwater is a global challenge in modern agriculture. Nutrients from livestock detritus and manure have caused adverse effects on ecosystems, the environment, and posed health risks associated with use of contaminated groundwater. Such occurred at a concentrated animal feeding operation (CAFO) where failed manure containment and buried carcasses led to toxic concentrations of ammonium and nitrate in groundwater. Here we evaluate a two-step approach to remediate ammonium using pump-and-treat technology, and nitrate using a permeable reactive barrier (PRB) composed of local hay as a carbon source to drive denitrification. Long-term monitoring (10-year dataset) revealed that effective mitigation of total nitrogen was accomplished through several mechanisms. Ammonium initially developed in the PRB from mineralization of protein in the hay; however, groundwater conditions permitted the possibility of dissimilatory nitrate reduction. Total nitrogen mitigation is attributed to anaerobic ammonium oxidation and classical denitrification. The reducing environment induced by the PRB caused reduction of iron oxyhydroxides as evidenced by increased dissolved iron and manganese in groundwater. Increased total phosphorus and arsenic mobilization was also locally observed. Some monitoring wells contained high levels of ammonium released from buried detritus. While the PRB effectively removed nitrate, elevated total phosphorus in stream water exceeded recommended limits and placed surface water at risk for eutrophication. Locally sourced carbon sources deployed in a PRB can effectively mitigate nitrogen contamination in groundwater; however, future applications of organic carbon systems should consider the possible mobilization of secondary contaminants including phosphorus, arsenic, iron, and manganese.
URLs/Downloads:
DOI: Long-term field study of nitrate and ammonium remediation using a permeable reactive barrier at a livestock feeding operation