Experimental Study On Settlement And Temperature Characteristics Of Waste Dumps Under Aerobic Ventilation

Mastering the internal settlement and temperature changes caused by the ventilation process during the ventilation process has important practical significance for the operation and management of aerobic landfill restoration projects.The main reason for controlling sedimentation and temperature change is the biochemical degradation of organic matter in the landfill,and the aerobic reaction is more severe than the anaerobic reaction.In order to further explore the law of aerobic ventilation on the settlement and temperature evolution of refuse soil,this paper uses a combination of experiments and theoretical analysis,a combination of indoor simulation and parameter analogy,and selects the typical working conditions in the aerobic ventilation process as the background.Settling and temperature monitoring tests,and simulations of temperature evolution.Using aerobic ventilation and sedimentation test equipment developed by Wuhan Institute of Rock and Soil Mechanics,Chinese Academy of Sciences-Key Laboratory of Contaminated Soil Science and Engineering of Hubei Province,an experiment was conducted on the effect of aerobic degradation on the settlement characteristics of refuse soil under the effect of vertical pressure.It shows that aerobic degradation has little effect on the primary compression settlement during the primary compression settlement phase;during the secondary compression settlement phase,the first 90 days of settlement accounted for an average of 96.37% of the total settlement.Applying a vertical load can shorten the time to complete the secondary compression settlement;The primary compression index is closer to the anaerobic reactor,but the upper limit of the modified secondary compression index is higher(0.425-1.0);during the degradation process,the methane concentration is less than 2.5%,the hydrogen sulfide is less than 20 ppm,and the leachate p H is alkaline.CODCr,BOD5,and NH3-N all increased first and then decreased.After the degradation was stable,the concentration of NH3-N reached the emission standard specified by the specification,indicating that the test process completed the aerobic degradation reaction well.The aerobic ventilation simulation test system of waste soil developed by the Wuhan Institute of Rock and Soil Mechanics of the Chinese Academy of Sciences-Hong Kong Polytechnic University(IRSM-CAS / HK Poly U Joint Laboratory on Solid Waste Science)was used to carry out different ventilation intensities Monitoring tests on the temperature evolution characteristics of waste dumps,the test results show that the average temperature change trend is the same under different ventilation intensity;the greater the ventilation intensity,the shorter the time for the waste to reach the peak temperature,the peak temperature difference can reach 15.1°C,the temperature drops and reaches The faster the stabilization time,the longer the stabilization time is 16 days.The ambient temperature has a small effect on the temperature of the waste soil.The temperature of the intermediate layer is the highest.Under high ventilation intensity,the maximum temperature difference of waste at each depth can reach 5.1°C.A two-stage oxygen consumption rate model in the aerobic reaction process was constructed,and the heat release rate equation in the aerobic degradation process was modified based on the model.Using COMSOL software to simulate the effects of factors such as recharge conditions,ventilation methods and equivalent thermal conductivity coefficients on the temperature change of waste dumps under aerobic ventilation.The simulation results show that the prediction results obtained by using this model better reflect the temperature change process during the experiment,and the reliability of the model is initially verified;the initial temperature of leachate and the intensity of reinjection have a significant effect on the temperature of the waste,and it is well used In the oxygen ventilated landfill technology,the influence of the initial temperature of the backfilled leachate on the temperature of the reactor should be considered.When the heat capacity parameters of the waste soil skeleton,leachate,and gas are equivalently treated,specific internal environmental conditions of the landfill site need to be considered.