A Case Study Of Comprehensive Benefit Evaluation Of Disposal Methods For Old Landfill Sites

The disposal of old landfill sites includes three methods of in-situ anaerobic closure,in-situ aerobic remediation,and ectopic mining.Nobody had studied how to make the benefit of landfill disposal projects maximize.In this paper,the characteristics of the Guoqiaowo landfill were analyzed,which to gain the process and technical methods of the three disposal methods.Meanwhile,direct assessment of cost-benefit analysis,life cycle cost evaluation and contingent value method were conducted to evaluate its comprehensive benefits.Based on this,comprehensive benefit evaluation index system was built under different disposal methods.This paper took the Guoqiaowo landfill as an example,applying the established system,the cost value and benefit value under different disposal methods of the landfill were calculated,the distribution of its cost and benefits were analyzed,and comprehensive benefit values of the different disposal methods were obtained and compared.The results showed as follow:（1）The characteristics of Guoqiao landfill were studied and the stability of the landfill site was evaluated.The results showed that the year of closure,the content of organic matter,and the stability of the slope all met the requirements for a high degree of stability.The methane content in the landfill gas had not yet reached the high degree of utilization requirements in the landfill.（2）A comprehensive benefit evaluation index system was established for different disposal methods of landfills.Through the study of the characteristics of landfills,two overall indicators of cost-benefit for three disposal methods in landfills have been established.For different disposal methods,their project contents are different,and corresponding cost indicators and benefit indicators are constructed.（3）The three disposal methods with anaerobic closure,aerobic remediation,and ectopic mining and disposal for the net present values are-0.98 million yuan,-3.05 million yuan,and-1.20 million yuan respectively,and NBV₁>NBV₃>NBV₂.The benefit cost rate was0.89,0.84,and 0.96,respectively,and BCR₃>BCR₁>BCR₂.The net benefit cost rate was-0.11,-0.16,and-0.04,respectively,andα3>α1>α2.The results of the study indicate that the overall benefit of using ectopic mining is the best for the Guoqiaowo landfill,followed by in-situ anaerobic closure and the overall benefit of in-situ aerobic remediation is the worst.