Research On The Selection Of Landfill Leachate Treatment Process

Landfill is widely used in global solid waste treatment.Landfill treatment produces a large amount of landfill leachate,which must be treated before entering the environment to prevent pollution damage to water,land,animals and plants.Due to the complex composition of the landfill leachate and the high concentration of organic pollution,the selection process should be determined by strict comparison.In the feasibility study of landfill leachate treatment project in China,due to the lack of mature process selection methods,the process selection depends on the designer’s subjective understanding of the current popular technology.After a simple technical and economic comparison of selected programs,the process selection lacks scientific basis.This paper is based on the expansion of a landfill leachate treatment plant in Lechang City,Guangdong Province,after studying the water quality characteristics of the landfill leachate,the conventional treatment process and the brief analysis of the treatment of the leachate in the treatment plant,a model of the process comprehensive comparison method based on the Fuzzy-Grey Correlation Analysis Method was established.A number of influencing factors were transformed into 18 single indicators through the establishment of a landfill leachate treatment process selection index system.The system takes“the best comparison process for landfill leachate treatment”as the target layer,and“economic cost,technical performance,operation management,environmental ecology”constitutes four criteria layers,and the criteria layer is subdivided into 18 factor indicators.Among them,The economic cost layer includes four indicators:“engineering cost,energy cost,drug consumption cost,maintenance cost”;the technical performance layer includes six indicators:“the ability to remove COD,the ability to adjust water quality and water volume,the ability to remove heavy metals,the ability to remove ammonia and nitrogen,Pre-treatment dependence,raw material biodegradability requirements.operating management includes four indicators including“degree of facility automation,ease of operation and management,quality requirements for personnel,and process maturity”under the operational management;It includes four indicators:“degree of exhaust pollution,degree of noise pollution,production of concentrated leachate,and floor space”.The Fuzzy Analytic Hierarchy Process is used to determine the weighting coefficients of each indicator.The four indicators of the criteria layer include the“economic cost,technical performance,operational management,environmental ecology”weighting factor₀=[0.294 0.339 0.161 0.206].In addition,the weights of other indicators under the criteria layer were also calculated.A model of process comprehensive comparison method based on Fuzzy-Grey Relational Analysis is constructed.The three alternative processes of A/O+MBR+RO combined process（D1）,UASB+MBR+RO combined process（D2）and BAC+MBR+NF combined process（D3）were compared and verified.The gray correlation method is used to analyze the advantages of single indicators,and the correlation coefficient of each index is determined.After the comprehensive relational degree is obtained₁<₂<₃,the optimal comparison process is finally determined by the comprehensive relational degree.Therefore,the best comparison scheme obtained by Fuzzy-Grey Relational Analysis method is“BAC+MBR+NF process”.