Fractionation of the organic matter of a landfill leachate before and after aerobic or anaerobic biological treatment

Abstract Membrane ultrafiltration, gel permeation and high performance liquid chromatography were used to separate the soluble organics of a leachate collected from a mixed industrial and urban wastes tip. The organic load of the leachate was low and consisted mainly of compounds below 500 MW (over 95% of the TOC), although volatile fatty acids were not present. The fractionation of the organic matter was performed before and after aerobic or anaerobic treatment so as to compare the aerobic and anaerobic biodegradabilities. It was found that a large majority of the organics initially present in the leachate were very well degraded under both aerobic and anaerobic conditions, and that the organic matter resistant to aerobic or anaerobic biodegradation consisted of the same molecules. All these recalcitrant molecules but one were below 500 MW and probably consisted of industrial chemicals. These organics were almost non-biodegradable in anaerobiosis, whereas they were biodegraded to about 50% in aerobic conditions.