Forecasting the effects of municipal solid plastic waste generation and streaming using system dynamics: A case study in Dubai

Abstract

To effectively manage municipal solid plastic waste (MSPW), municipalities need to select an appropriate combination of policies and technologies. Numerous policies and technologies are inputs for this selection problem, whereas decision-makers pursue several economic and environmental outcomes. The MSPW flow-controlling variables serve as an intermediary between the inputs and outputs of this selection problem. Examples of the flow-controlling, mediating variables include the source-separated and incinerated MSPW percentages. This study proposes a system dynamics (SD) model that anticipates the influence of these mediating variables on multiple outputs. The outputs include volumes of four MSPW streams and three sustainability-related externalities: GHG emissions reduction, net energy savings, and net profit. Using the SD model, decision-makers can determine the best levels for the mediating variables based on the desired outputs. Consequently, decision-makers can identify the MSPW system stages at which they must choose policies and technologies. Additionally, the values of the mediating variables will help clarify for decision-makers how strict they should be when imposing policies and how much to invest in technologies at the selected MSPW system stages. The SD model is applied to Dubai's MSPW problem. A sensitivity analysis experiment conducted on Dubai's MSPW system demonstrates that the earlier an action is taken, the better the results will be achieved. Consequently, reducing municipal solid waste should take priority, followed by increasing source separation, then post-separation, and finally, incineration with energy recovery. The results of another experiment employing a full factorial design with four mediating variables indicate that recycling would impact GHG emissions and energy reduction values more than incineration with energy recovery. However, these savings are global in nature.