The attenuation of the organic component of landfill leachate in the unsaturated zone: a review

Current philosophies for the landfill disposal of wastes are reviewed. A survey of research and operating experience suggests that in some geological environments biodegradation of organic components is occurring within the unsaturated zone whereas little attenuation occurs elsewhere. The most important factor controlling this biodegradation is the buffering capacity of the strata. Aquifers with a significant carbonate content are able to buffer acid leachates favouring the development of microbial populations and leachate attenuation. The lack of buffering capacity within many Permo-Triassic Sandstones maintains acid conditions and limits the development of biodegradation reactions.