Accelerated Stabilization of Waste Landfill by Activation of Microbial Functions

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Experimental studies were carried out to evaluate the feasibility of application of bioventing techniques, which is one of the in situ bioremediation techniques for clean-up of contaminated soil, to accelerate the stabilization of waste disposal landfill. Pilot- and/or lab-scale landfill reactor studies indicated that the application of bioventing, i.e. feeding of air to the waste pile, successfully transformed the condition of the waste pile to aerobic/microaerobic from anaerobic, considerably stimulated indigenous aerobic bacterial populations, and enhanced aerobic degradation of the wastes. The necessity of proper control of the moisture content of the waste pile (approx. 50 %) by circulating the leachate was suggested in order to stimulate the metabolic activities of aerobic bacterial populations. The aerobic degradation of wastes enhanced the waste settlement and also effectively improved quality of the leachate and the landfill gas. Especially degradation of the volatile matter in the waste pile, removal of COD, and nitrification of ammonium in the leachate were improved by the application of bioventing coupled with circulation of the leachate. Ecotoxicological assays of the leachate clarified that the application of bioventing could considerably reduce the mutagenicity and estrogenicity of the leachate compared with the traditional anaerobic landfill. The bioventing was also effective for accelerating the biodegradation of some degradable plastics including PHB and starch-blend plastics. It may be concluded that the application of bioventing to the waste landfill can enhance the landfill stabilization and greatly shoten the period that is required for the landfill management. It may also contribute to the reduction of the possible risks cause by the waste landfill. Aerobic landfill operation like bioventing application could be an attractive counter measure for overcoming major problems of the existing landfill sites.