Lan Ji-Wu, Zhan Liang-Tong, Li Yu-Chao, Chen Yun-Min
Key Laboratory of Soft Soils and Geoenviromental Engineering, Ministry of Education, Zhejiang University, Hangzhou 310058, China.
Huan Jing Ke Xue. 2012 Apr;33(4):1389-96.
The amount of leachate generation rate in MSW landfills is often underestimated during design phase in China. A water balance model of a valley landfill, whose size is 400 m long, 500 m wide and 50 m thick, is created to investigate the influences of initial moisture content of waste on source and production of leachate. The 50 m thick waste mass is assumed to be 5 layers. Each layer is 10 m thick with a filling period of 2 years. The leachate mainly comes from precipitation and from squeezed pore water of waste. It is found that higher initial moisture content of waste leads to higher amounts of squeezed leachate and total leachate generation rate, and also results in a high ratio of squeezed leachate to total leachate generation rate. For the cases that the initial moisture contents of waste are 27%, 40%, 50%, and 60%, the amounts of total leachate generation rate are 272, 583, 823 and 1 063 m3 x d(-1), respectively, and the amounts of squeezed leachate are--144, 168, 408, and 647 m3 x d(-1), respectively. It is also found that when the initial moisture content of waste is greater than 50%, the squeezed leachate becomes the primary source of total leachate generation rate. However, the formula for predicting leachate generation rate used in the national code could not consider the contribution of squeezed leachate, this may cause a significant underestimation of leachate generation rate for the case having a high initial moisture content of waste. Based on the water balance analyses, a modified formula for predicting leachate generation rate, which includes the contribution of squeezed leachate is proposed. It is verified by consideration of the operational practices of two large-scale landfills in southern China.
在中国，城市生活垃圾填埋场渗滤液产生速率在设计阶段常常被低估。建立了一个山谷型填埋场的水平衡模型，该填埋场长400米、宽500米、厚50米，以研究垃圾初始含水量对渗滤液来源及产生量的影响。50米厚的垃圾体假定分为5层，每层厚10米，填埋周期为2年。渗滤液主要来源于降水和垃圾挤压出的孔隙水。研究发现，较高的垃圾初始含水量会导致挤压出的渗滤液量和总渗滤液产生速率增加，同时也会使挤压出的渗滤液占总渗滤液产生速率的比例升高。对于垃圾初始含水量分别为27%、40%、50%和60%的情况，总渗滤液产生速率分别为272、583、823和1063立方米/天，挤压出的渗滤液量分别为144、168、408和647立方米/天。还发现，当垃圾初始含水量大于50%时，挤压出的渗滤液成为总渗滤液产生速率的主要来源。然而，国家规范中用于预测渗滤液产生速率的公式未考虑挤压出渗滤液的贡献，这可能导致对垃圾初始含水量较高情况的渗滤液产生速率严重低估。基于水平衡分析，提出了一个修正的渗滤液产生速率预测公式，该公式考虑了挤压出渗滤液的贡献。通过对中国南方两个大型填埋场运行实践的考量进行了验证。
