Optimal routing for infectious waste collection

Most small to medium-sized hospitals and clinics in Taiwan do not have on-site treatment facilities for their medical and infectious wastes and must rely on outside agencies for its collection and treatment. The problem of optimally planning and scheduling the collection of medical wastes from a disperse group of facilities is formulated as a periodic vehicle routing problem. Special attention is paid to the requirement that waste pickup be made on at least a weekly basis. A two-phased approach is used to solve the resulting optimization model. The first phase solves a standard vehicle routing problem to determine a set of individual routes for the collection vehicles. The second phase uses mixed-integer programming to assign routes to particular days of the week. An illustrative example for 38 hospitals in the Taipei city area demonstrates the effectiveness of the approach.