Least cost management of solid waste collection

Most developing countries have to grapple with the problem of efficient solid waste management in the face of increasing waste generation rate, high collection cost and dwindling financial resources. In some cities wastes are dumped indiscriminately and littered on the streets. This is the case with Onitsha, a heavy commercial city in Eastern Nigeria. This study is aimed at least cost solid waste collection in Onitsha through mixed integer programming. Actual transportation cost was estimated based on 1999 salaries and fuel prices. Optimum cost of collection via transfer stations to two disposal sites were compared with the existing situation of having no transfer station and only one disposal site. Post-optimality analysis was performed for several scenarios, investigating the sensitivities of the optimal cost to varying capacities of the transfer stations, investments and operating cost of the transfer stations, generation rates and unit collection costs via transfer stations that were each operated at a capacity of 300 tons per day. The introduction of transfer stations resulted in $463.75 (38.9%) savings in the collection cost per day. Implementation of the program will facilitate regular collection of solid wastes by reducing the operation cost.