Prioritizing Landfill Contaminants for Environmental Remediation

Landfills in the United States represent an important potential source of environmental pollution, generating millions of liters of leachate or contaminated groundwater every day. Such pollution can negatively impact human health if leached offsite. Therefore, many actions, from preventative measures to remediation activities, are implemented to decrease the risks associated with landfill pollution. In recent years, increased interest in sustainability has led to a greater focus on on-site remediation, which can involve activities such as microbial remediation, in situ injection treatments, or the “green liver” approach of phytoremediation. However, the composition of landfill leachate is dynamic, changing over time and space due to chemical, physical, and societal factors. Thousands of potentially harmful contaminants can exist within leachate, though traditionally, only a limited number of contaminants are monitored. Therefore, decision-support tools which provide objective, quantitative means for identifying which contaminants at a site to target with remediation activities, are critical. 

Key Findings

• Researchers developed and used a pollutant prioritization approach to prioritize over 300 landfill leachate contaminants reported in the literature.
• Over 60% of the top 40 most-toxic contaminants identified in a review are not included in regulatory lists for landfill leachate.
• Not only is this flexible approach customizable according to community priorities, but it also is versatile, and can be used to identify priority contaminants across diverse site types. 
   

To address this need, researchers developed a pollutant prioritization approach that systematically prioritizes contaminants according to reported toxicity values. The approach incorporates publicly available toxicity data to quantitatively rank contaminants. In addition, the approach is easily customizable to address community-specific health concerns, such as cancer or endocrine disruption. While pollutants are typically selected for remediation based on regulatory lists for landfill leachate monitoring, this approach doesn’t consider all possible contaminants, especially newer classes of pollutants that were recognized after the lists were created (e.g., pharmaceuticals, personal care products, contaminants from electronic wastes and plastics). As such, remediation activities based on regulatory lists may not address all the most harmful contaminants produced by landfills. This comprehensive approach takes into account a much broader range of pollutants that can exist at contaminated sites. 

To date, the tool has been used to prioritize landfill leachate contaminants reported in the literature. Researchers are currently using this tool to prioritize pollutants in leachate and groundwater from two landfill sites in southeastern Wisconsin where the team established phytoremediation buffer systems to reduce pollutant transport. These phytoremediation systems are included in the regional phytotechnologies network in the Great Lakes Basin. 

Expected Outcomes

This approach can be utilized by researchers, engineers, site managers, and other industry professionals to systematically prioritize landfill contaminants for remediation activities and other environmental applications. The approach can be easily integrated with global metabolomics profiling to establish a comprehensive understanding of contaminants at the site level. Further, this approach may help to identify newer classes of contaminants at landfills that have yet to be included on regulatory lists. The approach is highly flexible, and can be used for pollutant prioritization beyond landfills, such as indoor air pollutants, and pollutants in stormwater.