A LABORATORY INVESTIGATION OF ANAEROBIC MICROBIAL CLOGGING IN GRANULAR LANDFILL DRAINAGE MEDIA

A laboratory investigation was made of the clogging of landfill draina ge systems due to microbial growth in anaerobic conditions. The factor s addressed included the flowrate and composition of the leachate, the saturation conditions, and the mineralogy and particle size of the dr ainage material. Reductions in drainable porosity of 1-12% occurred in columns modelling anaerobic landfill drainage systems following perio ds of 400-800 days of continuous operation. Within the range of parame ters covered by the investigation, the principal factor governing the rate and degree of this reduction in pore volume was the typical parti cle size of the drainage material: a D-10 size of at least 10 mm may b e necessary to guard against long-term microbial clogging, The rate of clogging was also influenced by both the biological load and the hydr aulic conditions (i,e, saturated, unsaturated or varying) within the c olumn, probably because of their potentially limiting effect on the di stribution and rate of nutrient supply. The impact of aggregate minera logy on the clogging rate was not significant.