Optimization of municipal solid waste transportation management with composting plant

The existing municipal solid waste management system in Dar es Salaam particularly in Ilala municipality involves a variety of options including the use of composting plants as complement to the popular landfills in clearing waste. A number of mathematical models have been previously developed to try and optimize the system. However, previous models did not include the concept of composting plant in their formulation. In our study we include the composting plant in order to reduce the amount of solid waste sent to landfill and lower the transportation cost of the solid waste from sources to collection points and from collection points composting plant and landfill in Ilala municipality. Mixed-Integer Programming (MIP) was used to model the problem. Solution is obtained using GNU Linear Programming Kit (GLPK) software. The results shows that the best model solution would include 11 collection points, where we have two cases A and B, for all cases we fix the capacity of collection points at 250 tons and for case A, we choose capacity of composting plant and run the model, for case B, we choose the number of collection points and run the model formulated. Capacity of composting plants varying from 100-500 tons per day and number of collection points chosen from N=5 to N=11. The proposed model results in a least transportation cost of the solid waste from sources to collection points, composting plant and landfill of Tsh. 1,394,944 per day compared to the study done by Lyeme(2011) transportation cost was Tsh.10,969,252 per day. Through constructing composting plant at Buguruni Ilala municipal we must be able to reduce the cost of transportation of solid waste management by selling numbers of plastic bags produced.