Bioindication and bioremediation of landfill emissions
Abstract: This thesis investigates the use of plants, fungi, and microorganisms to assess and treat landfill gas, leachate and contaminated soils. As landfill emissions can occur over extended time periods, it is a practical strategy to develop passive and economical methods for emission control i.e., requiring little human involvement. Organisms can play an important role in such methods if their living requirements can be met, e.g., adequate temperature or moisture content. A broader understanding of how organisms respond to and are affected by pollution may be used to develop landfill design strategies and engineering technologies that favour bioremediation. A secondary benefit is that a greater knowledge of organism response may be used to determine the pollution state of a site. Methanotrophic bacteria in the soil can be used to identify methane emission areas. An assay method was developed, based on the pressure change induced by methane oxidation. The fungus Telephora caryophyllea accumulates arsenic.The method could be sufficient to delimit arsenic contaminated areas. Landfill vegetation is exposed to pollutants and can indicate their presence. Despite high species diversity, no damages to the vegetation, due to the presence of pollutants,could be observed. The oxidation capacity of the studied soil is sufficient to completely oxidise the methane emissions at old and small landfill sites. Even though the oxidising capacity is sufficient, non-optimal conditions result in methane emission peaks. Wetlands can reduce the nitrate concentration in leachates. In the cold climate regions studied at least four years are needed to have a fully established vegetation cover and degraded organic material. A 30% reduction of nitrate was attributed to denitrification. However a precise mass balance is needed to accurately evaluate the treatment capacity. Vegetation at the investigated site may used to immobilise soil contaminants such as Cu, Zn, Pb, and As. However, the application of soil amendments is recommended to reduce foliar accumulation of contaminants.
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