Optimizing the Municipal Solid Waste Collection and Transportation Practice Using Integer Programming Model: A Case Study of Hawassa City

Abstract

Abstract: Municipal solid waste (MSW) describes the stream of solid waste generated by households, commercial establishments, industries and institutions which consists of everyday items such as product packaging, grass clippings, furniture, clothing, bottles, food scraps, newspapers, appliances, paint and batteries. Municipal solid waste management involves collection, storage, transportation and recycling. The process of collecting and transporting solid waste includes storing the waste at the generating and pick-up sites, collecting it, driving trucks around the neighbourhoods, and transporting to a transfer or disposal site. The transportation part of Hawassa City's solid waste management was the main focus of this study. In the city, waste is loaded onto collection trucks at each home's gate. This practice results higher transportation cost due to longer vehicle routing distance and absence of appropriate transfer areas. Therefore, determining the appropriate and number of transfer areas was the goal of this study to minimize the transportation cost. In order to achieve this objective an integer programming model was used as optimization technique particularly in Tabor sub city. This sub city was selected among eight sub cities of Hawassa since it constitutes largest population. Tabor sub city has five administrative Kebeles (Hogane Wacho, Tilte, Dume, Hiteta & Fara) and a population of 93,625. Hawassa city have a capacity of generating 0.43 kg waste per day per capita and Tabor sub city generates 28,181 kg per day. A 0-1 integer programming model gives two intermediate transfer areas in Hogane Wacho and Fara kebeles. The transportation cost per cargo was calculated for road transport mode which composed of costs for Cargo investment, operation & maintenance and fuel & lubricant from each collection points to the landfill and transfer areas. The transportation model is formulated and solved using POM software and the minimized cost is 267,982.6 ETB which is less than the existing system transportation cost 298,703.38 ETB.

Keywords: Municipal Solid waste, Transportation cost, Integer programming, Transfer area