The findings of a series of studies investigating the clogging of leachate collection and drainage systems for municipal landfill sites are described. Batch tests, column studies, and field-scale “mesocosm” test cells were used to study the development of a thick microbial biofilm covering the surfaces and filling the pore space of the granular drainage media. Within this biofilm, anaerobic microbial consortia effect the stabilization of the organic load (expressed as chemical oxygen demand), with the concurrent precipitation within the granular drainage system of various minerals dominated by calcite. Key words:
