Solid Waste Disposal Assignment Problem: A Lagrangian Relaxation Approach

Abstract

Solid waste removal and disposal are expensive day to day activities that affect the quality of life and the environment in cities throughout the world. Indiscriminate dumping of refuse along road pavement (side walk), gutter and other unwanted sites, constitute an environmental hazard or degradation and nuisance. To facilitate traffic flow in urban regions, solid waste is first ploughed from streets and sidewalks and then hauled to disposal sites. A city is typically divided into many collection points that are cleared of waste every day. This research work describes Kaduna metropolis solid waste removal and disposal operations and analyzed the Solid Waste Disposal Assignment Problem for assigning solid waste removal collection points to disposal sites. The Solid Waste Disposal Assignment Problem (SWDAP) is formulated as a multi-resource generalized assignment problem. A heuristic solution procedure is developed; solutions and sensitivity analyses are presented using data for Kaduna metropolis. A Mathematical Programming Language (AMPL) was used to model the problem and solver CPLEX was employed to solve the modeled problem. The results show that disposal site 1 will receive wastes from 20 centroids and disposal site 2 will receive wastes from 18 centroids having optimal integer cost solution of N7012360. After the creation of two dummy sites, the result shows that disposal site 1 and 2 will receive waste from 2 centroids, disposal site 3 will receive wastes from 18 centroids and disposal site 4 will receive wastes from 16 centroids having optimal integer cost solution of N 9710488.