Use of organic amendments derived from biosolids for groundwater remediation of TCE

Authors: SAFFARI GHANDEHARI, S. - University Of Maryland; BOYER, J. - University Of Maryland; RONIN, D. - University Of Maryland; WHITE, J. - Collaborator; Hapeman, Cathleen; JACKSON, D. - Former ARS Employee; KAYA, D. - Oregon State University; TORRENTS, A. - University Of Maryland; KJELLERUP, B. - University Of Maryland

Submitted to: Chemosphere
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/3/2023
Publication Date: 2/18/2023
Citation: Saffari Ghandehari, S., Boyer, J., Ronin, D., White, J., Hapeman, C.J., Jackson, D., Kaya, D., Torrents, A., Kjellerup, B.V. 2023. Use of organic amendments derived from biosolids for groundwater remediation of TCE. Chemosphere. 323. Article 138059. https://doi.org/10.1016/j.chemosphere.2023.138059.
DOI: https://doi.org/10.1016/j.chemosphere.2023.138059

Interpretive Summary: Trichloroethylene (TCE) is a highly-effective industrial degreasing agent and known carcinogen. It was frequently buried improperly in landfills and has subsequently become one of the most common groundwater and soil contaminants in the United States and in industrial areas globally. A common strategy to remediate TCE-contaminated sites and to prevent movement of the TCE plumes into waterways is to construct a permeable reactive barrier, often referred to as a biowall, which consists of biomaterials and amendments to enhance biodegradation. Biowalls, however, need to be refreshed periodically with new organic matter and amendments. We conducted in-depth laboratory studies where we examined the use of biosolids that provide a source of carbon and nutrients for the organisms that can degrade pollutants that contain chlorine atoms. A vexing problem is that biosolids can also encourage growth of other naturally occurring organisms that can out-compete the organisms needed to degrade the pollutants. We found that although the biosolids did encourage growth of many organisms, the TCE-degrading organisms performed better with the biosolids than when no biosolids were added. This work has provided insight into how to enhance degradation and has led to additional studies. This information will be useful to policy makers and land managers who need effective, long-term mitigation strategies.

Technical Abstract: Many groundwater aquifers around the world are contaminated with trichloroethene (TCE), which can be harmful to human and ecosystem health. Permeable Reactive Barriers (PRB) are commonly used to remediate TCE-contaminated groundwaters especially when a point source is ill defined. Using biosolids from wastewater treatment plants as a PRB filling material can provide a source of carbon and nutrients for dechlorinating bacterial activity. However, under the anaerobic conditions of the PRB, methanogenesis can also occur which can adversely affect reductive dechlorination. We conducted bench scale experiments to evaluate the effect of biosolids on TCE reductive dechlorination and found that methanogenesis was significantly higher in the reactors amended with biosolids, but that reductive dechlorination did not decrease. Furthermore, the microbial communities in the biosolid-enhanced reactors were more abundant with obligate dechlorinators, such as Dehalobacter and Dehalogenimonas, than the reactors amended only with the dechlorinating culture. The biosolids enhanced the presence and abundance of methanogens and acetogens, which had a positive effect on maintaining an efficient dechlorinating microbial community and provided the necessary enzymes, cofactors, and electron donors. These results indicate that waste materials such as biosolids can be turned into a valuable resource for bioremediation of TCE and likely other contaminants.