ABSTRACT
Various studies have indicated that the collection phase of solid wastes, which comprises of the initial col-
lection at the source of generation and the transportation to the disposal sites, is by far the most expensive.
Two fundamental issues of concern in solid waste collection are the locations of initial collection and the
period of collection by the dedicated vehicles. However, considering the prevailing conditions of adhoc lo-
cation of waste containers and the faulty roads in many developing countries, this research was conducted
to develop two e_ective models for solid waste collection and disposal such that new parameters measuring
the capacity of waste ow from each source unit and road accessibility were introduced and incorporated
in the mathematical formulations of the models. To formulate the problems, two classes of integer pro-
gramming problems namely, Facility Location Problem (FLP) and the Vehicle Routing Problem (VRP),
were used for the collection and disposal respectively. The clustering process involved in the model for the
collection phase was based on the Euclidean distance relationship among the various entities within the
study area. In this model, the study area was considered as a universal set and simply partitioned with each
element representing a cluster. At this stage, a threshold distance was de_ned as the maximum allowable
distance between a cluster and the potential collection sites. In the VRP formulation of the disposal model,
two new parameters, called the accessibility ratio and road attribute, were introduced and included in
the formulation. The inclusion of these parameters ensure that a waste collection vehicle uses only roads
with high attributes. The solution to the model on the collection phase was based on the Lagrangian re-
laxation of the set of constraints where decision variables are linked, while in the model on waste vehicle
routing, the assignment constraints were relaxed. Both resulting Lagrangian dual problems were solved
using sub-gradient optimization algorithm. It was shown that the resulting Lagrangian dual functions were
non-di_erentiable concave functions and thus the application of the sub-gradient optimization method was
justi_ed. By applying these techniques, strong lower bounds on the optimal values of the decision variables
were obtained. All model implementations were based on randomly generated data that mimic real-life
experience of the study area (Eti-Osa Local Government Area of Lagos State, Nigeria), as well as large-scale
standard benchmark data instances in literature. These computational experiments were carried out using
the CPLEX and MINOS optimization solvers on AIMMS and AMPL modeling environments. Results from
the computational experiments revealed that the models are capable of addressing the challenge of solid
waste collection and disposal. For instance, more than 60% reductions were obtained for the number of
collection points to be activated and the container allocations for the di_erent wastes considered. Numerical
results from the disposal model showed that there is a general reduction in the total distance covered by a
vehicle and a slight improvement in the number of customers visited. Result comparison with those found in literature suggested that our models are very encient.
JOSHUA, A (2021). Location-Allocation-Routing Approach To Solid Waste Collection And Disposal. Afribary. Retrieved from https://afribary.com/works/location-allocation-routing-approach-to-solid-waste-collection-and-disposal
JOSHUA, ADELEKE "Location-Allocation-Routing Approach To Solid Waste Collection And Disposal" Afribary. Afribary, 20 May. 2021, https://afribary.com/works/location-allocation-routing-approach-to-solid-waste-collection-and-disposal. Accessed 22 Nov. 2024.
JOSHUA, ADELEKE . "Location-Allocation-Routing Approach To Solid Waste Collection And Disposal". Afribary, Afribary, 20 May. 2021. Web. 22 Nov. 2024. < https://afribary.com/works/location-allocation-routing-approach-to-solid-waste-collection-and-disposal >.
JOSHUA, ADELEKE . "Location-Allocation-Routing Approach To Solid Waste Collection And Disposal" Afribary (2021). Accessed November 22, 2024. https://afribary.com/works/location-allocation-routing-approach-to-solid-waste-collection-and-disposal