Research On Optimization Model Of Municipal Solid Waste Collection And Transportation System And Its Application

As a part of municipal solid waste (MSW) integrated management system, MSW collection and transportation system holds an important role. Due to lack of systemic guiding theory, MSW collection and transportation is the weak link in the MSW integrated management system. Optimization and perfection of MSW collection and transportation is very important for high efficiency operation of MSW integrated management system.In the paper, based on the deep analysis of all the links in MSW collection and transportation system and combined with the logistic theory, the optimization methods and mathematical models were proposed for the economical optimization goal. The methods were also applied in the actual cases of MSW collection and transportation of western new town and urban area in Chongqing city. The conclusions are as follows:â‘ By analyzing the characteristics of MSW reverse logistics, location of MSW transfer station was divided into two stages. Primarily, the alternative MSW transfer stations were established by setting covering model, then the location of MSW transfer station was optimized again by using inter programming to formulate the minimal expense present value model of the whole MSW collection and transportation system, after that, the optimum combination of MSW transfer stations have been selected from the alternatives. In case study of MSW collection and transportation system of Chongqing western new town, 12 alternative MSW transfer stations were selected from 128 MSW collection points by using setting covering model, the optimum combination of MSW transfer station is 12 by using the minimal expense present value model. The capacity of the selected transfer stations were: 70, 360, 60, 80, 70, 80t/d. The results presented that the method witch dividing the location of MSW transfer station into two stages and avoiding complicated calculations is validated.â‘¡By analyzing the two basic waste collection modes witch were driving container mode and fixed container mode, the vehicle routing model for optimization of waste collection rooting was proposed. By analyzing the characteristic of waste transfer process, the linear programming model for optimization of waste transfer rooting was proposed in logistic perspective for the economical optimization goal. The model for optimization of waste transfer rooting was applied in the MSW collection and transfer system of Chongqing urban area. Especially, the waste transfer rooting of Jiulongpo and Dadukou district has been optimized.â‘¢By analyzing the stochastic dynamic process of waste collection vehicles reaching the MSW transfer station in the waste collection process, the queuing model was introduced, then the cost model of service system in MSW transfer station for optimal allocation of equipment in MSW transfer station was established considering the cost and benefit balance. The models were applied in equipment allocation of MSW transfer station of university town in Chongqing western new town and its capacity is 360t/d. The results presented that the indicators of the service system of MSW transfer station were optimized. For example, comparing 4 waste compactors with 3 waste compactors, the service intensity declined from 0.78 to 0.58, the system queue length declined from 4.47 to 2.70, system cost declined from 494.71 to 457.36. Equipment allocation of MSW transfer station applying queue theory can reach the goal of sharpening the stability, efficiency and anti-risk ability.