Research Of In-situ Aerobic Stabilization Acceleration Technology For Municipal Solid Waste Landfill

In-situ aerobic stabilization acceleration technology for municipal solid waste(MSW) landfill can reduce or eliminate waste pollutant release from the source in arelatively short period, through control of oxygen concentration and moisture content inwaste to accelerate the process of waste stabilization. The technology is effective andlow cost, which is significant to the development of MSW sustainable landfill andtreatment of waste stacking yard. In this paper, on support of self-developedtwo-parameter (oxygen concentration and moisture content) feedback joint controlsystem, a series of landfill simulation experiments in different landfill situation andvarious initial waste characteristics were conducted. The variation characteristics ofoxygen concentration and moisture content in aerobic control process were studied. Thestabilization acceleration effect under optimal control was cpompared with other controlmeasures. The impact of initial waste characteristics to stabilization acceleration effectwas analysed. In addition, characteristic index for waste stabilization process wasscreened out from various parameters of leachate quality and organic waste, on basis oftheir scientific meaning and correlation. The main conclusions were as follows:The upper layer of waste was determined as target of moisture control, while fieldwater-holding rate of waste as control value. Time domain reflectometer (TDR)readings corresponding to moisture control values for waste of zero,1year,3years and7years of landfill age were80%,70%,63%and61%, respectively. The inner wall ofreactor (farthest from the center ventilation pipe) in the bottom layer of waste wasdetermined as target of oxygen control. The control ranges for waste of zero,1year,3years and7years of landfill age were11%to14%,8%to14%,7%to15%and6%to17%, respectively.The correlation analysis of TDR readings and volumetric moisture content basedon water balance calculation showed that for waste of zero,1year,3years and7yearsof landfill age, deviations did not exceed±5%,±2%,±1%and±1%, respectively.Through aerobic control period, auto recirculation happened in initial stage (hightemperature phase) of zero landfill age waste and in later period of7years of landfillage waste due to low moisture content. This two potential water shortage should becared in control process. Fluctuation frequency (ventilation frequency) of oxygen concentration in wastereduced along with aerobic control proceeding and waste landfill age increasing. Incontrol process, ventilation frequency should be gradually reduced to achieve thepurpose of cost saving, ensuring adequate oxygen concentration at the same time. Thevariation characteristic of oxygen comsumption rate was similar between zero and1year of landfill age waste. The whole control period could be divided into three stages.In the first stage, oxygen consumption rate has high value and significantchange,reflecting the rapid degradation of waste. In the second stage, oxygen consumption ratewas moderate and keeping stable, reflecting the transition period of waste. In the thirdstage, oxygen consumption rate was very low and continuing declining, reflecting theslow degradation of waste. Oxygen consumption rate of3and7years of landfill agewaste showed single reduction trend, which indicated that waste was in slowdegradation stage from the beginning.B/C and BDM were screened out as characteristic indices for waste stabilizationprocess from various parameters of leachate quality and organic waste, on basis of theirscientific meaning and correlation. According to index trend in control process, wastestabilization end value were B/C<0.1，BDM<4%.