Landfill Leachate Biodegradation

Fortuitous or co-metabolic biodegradation may account for a significant portion of the removal of xenobiotics in the environment.24 Numerous examples of co-metabolic activity have been described for pure substrates,22 but co-metabolism has been very difficult to demonstrate in mixed-substrate, mixed-culture systems, because products of the co-metabolic reactions of one species may be degraded by another.24 To encourage co-metabolism, easily degradable co-substrates should be included in the leachate prior to biological treatment. Fatty acids, which often occur in landfill leachates, may fulfill this requirement. 

Inoculation of landfill for faster biodegradation. Biotreatment of landfill leachate. 

When aquifers were amended with nitrate in order to stimulate biodegradation, the results were generally consistent with those obtained in laboratory investigations. In a field injection experiment at Seal Beach, California, Ball et al. (1994) demonstrated complete removal of w-xylene and the m-,/-xylene fraction decreased significantly in parallel bioreactor experiments. A Canadian study showed a decrease in m- and /-xylene of 14% and 15%, respectively, over aim flowpath in the Borden aquifer (Barbara et al., 1992). Very little degradation was observed beyond that point, presumably due to the availability of preferred electron donors in the landfill leachate impacted aquifer. 

Berwanger, D. J. Barker, J. F. (1988). Aerobic biodegradation of aromatic and chlorinated hydrocarbons commonly detected in landfill leachates. Water Pollution Research Journal of Canada, 23(3), 460—75. 

The entry of strongly reduced landfill leachate into a pristine, often oxidized, aquifer, leads to the creation of very complex redox environments. Important processes include organic matter biodegradation, biotic and abiotic redox processes, dissolution/precipitation of minerals, complexa-tion, ion exchange, and sorption. The resulting... 

Scholl M. A., CozzareUi I. M., Christenson S. C., Istok J., Jaeschke J., Ferree D. M., and Senko J. (2001) Measuring variability of in-situ biodegradation rates in a heterogeneous aquifer contaminated by landfill leachate. EOS, Trans., AGU 82(20), 146. 

Sources can only be generally linked to specific chemical or microbial contaminants and their potential effects on human and environmental health. The picture at local, regional, and national scales may be blurred by chemical contaminants, which appear in several categories (e.g., benzene or trichloroethylene which have been associated both with landfill leachates and leaking storage tanks). Also, natural biodegradation processes act on primaiy contaminants to yield transformation products (e.g., vinyl chloride and dichloroethylene from trichloroethylene or perchloroethylene). 

J. Lopes de Morals and P. Peralta Zamora. Use of advanced oxidation processes to improve the biodegradability of mature landfill leachates. J. Hazard. Mater., 1236 181-186, 2005. 

Richnow H. H., MeckenstockR. U., AskL., Baun A., Ledin A., and Christensen T. H. (2003) In situ biodegradation determined by carbon isotope fractionation of aromatic hydrocarbons in an anaerobic landfill leachate plume (Vejen, Denmark). J. Contamin. Hydrol. 64, 59—72. 

For highly chlorinated solvents to biodegrade, anaerobic conditions must prevail within the contaminant plume. Anaerobic conditions are typical at sites contaminated with fuel hydrocarbons, landfill leachate, or other anthropogenic carbon because these organics exert a tremendous electron-acceptor demand on the system. This condition is referred to... 

Anaerobic. Moisture is added to the waste mass in the form of recirculated leachate and from other sources to obtain optimal moisture levels. Biodegradation occurs in the absence of oxygen (anaerobically) and produces landfill gas. Landfill gas, primarily methane, can be captured to minimize greenhouse gas emissions and for energy projects. 

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