Research On Network Optimization For Multi-objective Municipal Solid Waste Reverse Logistics

With the acceleration of urbanization,the improvement of living standards and the increase of population,in recent years,the output of municipal solid waste has shown an obvious upward trend.If waste cannot be collected and treated in a timely and effective manner,a large amount of waste piling up will cause serious environmental pollution and resource waste,and endanger the health of urban residents.Therefore,how to construct a scientific and reasonable municipal solid waste reverse logistics network to focuse on environmental protection and social responsibility while reducing economic costs,which has become an urgent problem to be solved.In addition,various facilities and activities in the municipal solid waste reverse logistics network influence and restrict each other,which is limited by factors such as facilities capacity and road traffic conditions.Therefore,it is of great significance to improve the efficiency of municipal solid waste management to study facility location,vehicle routing and flow allocation from an integrated perspective,based on multi-objective optimization considering economic,environmental and social dimensions at the same time.The main research contents are as follows:First of all,considering the changes in the generated amount of waste under economic development and other factors,the problem of multi-period and multi-objective municipal solid waste reverse logistics facility location-flow allocation is studied.In each period,facilities have a certain expansion capacities,and the waste was transported to the transfer station for sorting and then transported to the recycling plant and the waste treatment plant.A multi-period mixed integer nonlinear programming model with minimizing the total cost,minimizing carbon emissions and maximizing the social responsibility index is established.The Epsilon constraint method is used to deal with multi-objective problems.Numerical examples of different scales are designed to verify the effectiveness and applicability of the model and prove that multi-period location and facility expansion is of great help in reducing costs.Furthermore,considering the integrated optimization of the facility location and capacity,vehicle routing and flow allocation for the three-level municipal solid waste reverse logistics,the multi-depot facility location-vehicle routing problem for municipal solid waste reverse logistics is studied.A multi-objective mixed integer nonlinear programming model paying attention to economic,environmental and social factors is developed,and a tabu search hybrid algorithm is designed to solve the model.Simulations of different scales examples are employed to demonstrate that the proposed model and solution algorithm are more effective on large-scale examples.According to the results of sensitivity analysis,some effective methods and recommendations are provided to solve the location and capacity of waste transfer stations,vehicle routing,flow allocation and reverse logistics networks management.