| When the waste classification becomes a new trend,food waste is separated from the original mixed collection and transportation system of domestic waste,and it is urgent to establish a relatively independent and complete collection and transportation system.The collection routes of vehicles and the locations of treatment plants directly affect the operation efficiency and cost of the whole collection and transportation system.Based on graph theory and linear programming,the optimization model of food waste collection route was constructed,and the corresponding algorithm was established.Qiandeng Town of Kunshan was taken as a case to verify the feasibility of the route optimization method.Combined with analytic hierarchy process,GIS spatial analysis and cluster analysis,the location optimization model of food waste treatment plants was established.Kunshan was taken as a case,and the practical application of the model was studied.On the basis of network diagram,the route optimization model with the shortest total collection distance was constructed by linear programming method.The genetic algorithm with strong search ability and high robustness was selected as the basic algorithm for model solving.Because genetic algorithm is easy to fall into local optimum,which could lead to poor solution quality,an improved method combining multiple mutation method and neighborhood search was proposed,and a solution program based on MATLAB was developed.Compared with the results obtained by the basic genetic algorithm,the minimum and average total distances of the optimized routes obtained by the improved genetic algorithm were reduced by 16.6% and19.4% respectively.The optimization of food waste collection and transportation route in Qiandeng Town of Kunshan was taken as a case.57 collection points and 4 transfer stations in the study area were divided into 4 areas,and the database of geographic coordinates,waste quantity and real road length between points in each area was established.The improved genetic algorithm was used to optimize the collection routes of food waste in each area.Compared with the existing collection routes,the total length of the optimized collection routes was reduced by 22.35%,and the number of vehicles was reduced by 15.38%.The analytic hierarchy process was used to establish the hierarchical structure of the influencing factors of the locations of food waste treatment plants.The judgment matrix of the influencing factors was determined according to the expert estimation,and the weight of the influencing factors was obtained.Arc GIS was used to analyze the data layers of each influencing factor,and the location suitability of 30 m * 30 m grid was obtained by weighted overlay analysis.According to the reclassification results,the regions with high suitability were selected as candidate sites;According to the geographical coordinates of the transfer stations,the k-means algorithm of cluster analysis was used to divide the service area of the treatment plants,and the centroid of each service area was taken as the theoretical sites of the treatment plants,and the nearest candidate sites were selected.The optimization of locations of food waste treatment plants in Kunshan was taken as a case,according to the results of GIS spatial analysis,11 regions with high suitability were selected as candidate sites.Based on the cluster analysis of 88 existing transfer stations in Kunshan,the transfer stations were divided into five districts and five theoretical plants were determined.Combined with the field investigation,the paper analyzes the candidate sites and theoretical sites of the treatment plants,and put forward the site selection scheme of Kunshan food waste treatment plants.The optimization method of collection and transportation route and treatment plant layout established in this paper provides a valuable reference for scientific decision-making of food waste collection and transportation system under the background of waste classification. |
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