A model for the implementation of a two-shift MSW and recyclable materials

17 Separating recyclables from municipal solid waste (MSW) before collection reduces not only the 18 quantity of MSW which needs to be treated, but also the depletion of resources. However, the 19 participation of residents is essential for a successful recycling program, and the level of 20 participation usually depends on the degree of convenience associated with accessing recycling 21 collection points. The residential accessing convenience (RAC) of a collection plan is determined 22 by the proximity of its collection points to all residents and its temporal flexibility in response to 23 resident requirements. The degree of proximity to all residents is determined by using a coverage 24 radius that represents the maximum distance residents need to travel to access a recycling point. 25 The temporal flexibility is assessed by the availability of proximal recycling points at times 26 suitable to the lifestyles of all residents concerned. In Taiwan, the MSW collection is 27 implemented at fixed locations and at fixed times. Residents must deposit their garbage directly 28 into the collection vehicle. To facilitate the assignment of collection vehicles and to encourage 29 residents to separate their recyclables thoroughly, in Taiwan MSW and recyclable materials are 30 usually collected at the same time by different vehicles. A heuristic procedure including an 31 integer programming (IP) model and ant colony optimization (ACO) is explored in this study to 32