On the effect of annual evolution of rejected and non-rejected rates in the screening process of packaging wastes on meeting target recycling rates

The present work describes a decision supporting tool for managers of municipal solid wastes (MSW) and policy makers. It is analyzed herein the recycling evolution of different packaging wastes from 2002 to 2011 at the management entity of municipal solid wastes (MEMSW) of Lisbon region. For that, a new mathematical model is used together with three different scenarios: scenario 1 is based on the actual situation observed between 2001 and 2002 keeping the recycling trends, whereas scenarios 2 and 3 are designed to ensure the accomplishment of the legally mandated recycling rates. These two scenarios account for the two key variables of recycling: wastes separate collection and their rejected rate at the sorting process. Results from scenario 1 for paper packaging waste demonstrate that the accomplishment of the recycling rates targets is not feasible: 18.6% in 2011, quite below the legally mandated 60%. Although application of scenarios 2 and 3 ensures the accomplishment of the mandated recycling rates they require additional and different efforts. Scenario 2, which exhibits a constant annual growth of the non-rejected rate at 14% in opposition to scenario 3 that exhibits a constant decrease of the rejected rate at 15.7%, is the best one, as additional efforts imposed are always less demanding for all the analyzed packaging wastes. In fact, for paper, a recycling rate of 16.9% in 2005 is obtained, against 25% for scenario 3, although it requires an increase of 135.8% for the separate collection at source from 2002 to 2011.