OPTIMAL REGIONAL PLANNING APPROACH IN SOLID WASTE MANAGEMENT

Solid waste consists of all the sol id material that an urban society can no longer useconstructively or economically and must be discarded in a way that is harmful to theenvironment. As a community becomes intensively urbanized, the problem of solid wastemanagement gets more and more aggravated. Cost of providing waste management servicesis rising hoth as a result of scarcity of land and due to the tightening environmentalregulations. An approach of waste management receiving wide attention recently is toreduce the waste disposal costs hy establishing centralized facilities. Centrally operatedfacilities have the advantage of economics of scale that cannot be owned by smallermunicipalities.This paper investigates problems associated with the new approach of rcgionalizauon andwaste diversion. It also investigates the application of linear programming (LP) and mixedinteger programming (MIP) techniques for the optimal allocation of waste stream andfacility scheduling of a regional solid waste management system over a fixed planningperiod. Waste disposal options include landfilling and waste diversion through recyclingand coruposting. The regional system consists of multiple cities. landfills. material recoveryfacilities. cornposting facilities and transfer stations.This paper investigates problems associated with the new approach of rcgionalizauon andwaste diversion. It also investigates the application of linear programming (LP) and mixedinteger programming (MIP) techniques for the optimal allocation of waste stream andfacility scheduling of a regional solid waste management system over a fixed planningperiod. Waste disposal options include landfilling and waste diversion through recyclingand coruposting. The regional system consists of multiple cities. landfills. material recoveryfacilities. cornposting facilities and transfer stations.Mathematical models used for the optimization arc formulated to minimize the net presentvalue of the cost of providing waste management services in a region. The opiimizauonmodel used consists of a set of constraints defining the waste now mass balance andcapacity limitation of the facilities. It is seen that the LP approach is simple and efficient incomputation time hut the usage is limited due LO its inability to handle discrete size forfacilities and mutually exclusive situations. The MIP approach allows for formulating allpossible options into a single model run. However. as the size or the problem increases. MIPapproach may introduce a large number of binary variables into the model, increasing thetime requirement to reach the optimum solution.