TitleReductive dehalogenation potential in a leachate recirculating bioreactor landfill and its affect on leachate toxicity
NameLoudon, Jennifer Ann (author), Fennell, Donna (chair), Cooper, Keith (internal member), White, Lori (internal member), Rutgers University, Graduate School - New Brunswick,
DescriptionHalogenated organic compounds may enter landfills through emplacement of various types of waste and are often detected in leachate. While leachate is a complex mixture of both organic and inorganic contaminants, the overall toxicity may be influenced by the presence of halogenated organic compounds. Leachate recirculating bioreactor landfills are generally anaerobic and support a diverse microbial community. The major hypothesis of this study was that leachate recirculating bioreactor landfill microorganisms can biotransform halogenated organic compounds and thus increase or decrease the toxicity of landfill leachate. To test the hypothesis, anaerobic microcosms were developed using elutriated landfill solids or leachate solids collected from the Burlington County Resource Recovery Center (BCRRC) leachate recirculating bioreactor landfill. The microcosms were amended with tetrachloroethene (PCE) as a model halogenated compound. In the landfill solids microcosms PCE dechlorination to cis-1,2-dichloroethene was observed, and in the leachate solids microcosms PCE dechlorination to ethene was observed, indicating the presence of dechlorinating microorganisms in the landfill system. The bacterial communities present in the raw landfill materials and the microcosms were compared using polymerase chain reaction amplification of 16S rRNA genes followed by denaturing gradient gel electrophoresis. There were distinct phylogenic differences between the communities, and phylotypes of the known dehalogenating bacterial genus, Dehalobacter, were detected in transfer enrichments of the leachate and solids microcosms. A Zebrafish embryo larval assay (ELA) was used to evaluate the toxicity of landfill leachate. One hundred percent mortality occurred when the embryos were exposed to solutions containing 16% leachate by volume over an exposure period of 24 hours. Various sublethal lesions were observed at lower concentrations. ELAs performed on microcosm supernatant yielded similar results. Minimal change in supernatant toxicity occurred as a result of incubating the material under conditions enhancing reductive dechlorination in the microcosms. Fractionation of the leachate suggested that most of the lethal toxicity could be attributed to the inorganic/metal fraction of the landfill leachate as opposed to the fraction containing the organic contaminants. Our results suggested that dehalogenating microorganisms are present in the BCRRC leachate recirculating bioreactor landfill and that landfill leachate toxicity can be assessed using the Zebrafish ELA approach.
NoteIncludes bibliographical references
Noteby Jennifer Ann Loudon
CollectionGraduate School - New Brunswick Electronic Theses and Dissertations
Organization NameRutgers, The State University of New Jersey
RightsThe author owns the copyright to this work.