基于降解-渗流-温度耦合模型的渗滤液回灌数值模拟

Numerical simulation of leachate recirculation based on biological-hydro-thermo coupled model

渗滤液回灌能加速生化反应器填埋场的稳定,而回灌参数决定了回灌加速效果.为研究不同回灌条件下填埋场的稳定化进程以选择最佳回灌参数,在考虑含水率、VFA浓度和温度对垃圾降解影响的条件下,基于COMSOL Multiphysics 5.0建立了二维降解-渗流-温度耦合回灌模型并进行了验证;并采用本模型模拟单次回灌量为4 L的点源回灌,回灌频率分别为1、2、3 d·次-1,结果显示2 d·次-1的回灌条件下填埋场最先达到相对稳定状态;对比分析VFA浓度、垃圾降解速率、甲烷菌浓度的变化趋势,结果表明高回灌频率更有利于填埋场加速进入甲烷化阶段,而在确保含水率低影响的情况下低回灌频率更有利于进入稳定化阶段,因此实际工程中要综合考虑以选择合适的回灌参数.

Leachate recirculation can accelerate the stabilization of bioreactor landfill,and the parameters of recirculation determine the quality. In order to study the stabilization process of the landfill under different recirculation conditions and to select the optimum parameters,a two-dimensional biologicalhydro-thermo coupling model was established based on COMSOL Multiphysics 5. 0 in consideration of the influences of water content,VFA and temperature on degradation. This model was then adopted to simulate the stabilization process of landfill with recirculation mode of point source,volume of4 L,frequency of 1,2,3 d per time,and that landfill of 2 d per time achieve stability firstly. The variations of VFA concentration,degradation rate of solid waste and methanogens concentration were comparably analyzed,and the result indicated that high recirculation frequency is more favorable for landfill to accelerate into the methane phase whereas low frequency has more advantages from the stage of methane to stabilization under the condition of low impact by water content. Therefore,appropriate parameters should be selected after comprehensive consideration in the actual application.