Enhancing the Efficiency of Plastic Recovery Facilities: Systematically Integrating Seasonal and Regional Variations...

Plastic Recovery Facilities are typically designed to process a specific, predetermined mix of plastic in the infeed. However, in many cases, the composition of the infeed varies seasonally and regionally. These variations may result in bottlenecks within sorting machines, thereby causing inconsistencies in the quality and quantity of recovered material. While most recovery facilities attempt to mix different bales before feeding them into the sorting line, relying on trial and error based on the material compositions of those bales, there is a lack of a systematic approach to this process. This paper introduces a systematic approach to plastic sorting within a plastic recovery facility, where the entire recovery process flow is dynamically modelled and validated. By identifying bottleneck regions within the system, infeed bales can be premixed to achieve the designed proportions, ensuring that machines and process lines are optimised for maximum efficiency. A pre-waste survey is necessary to achieve premixing, and the cost is justified by the benefits of the final return. To enhance the efficiency, it is crucial to implement a dynamic mixing model adaptable to daily variations in infeed. In this study, the dynamic optimisation model is designed in the form of simple mixing charts, allowing for on-site premix adjustments to bales without the need for additional equipment or tools. The proposed design chart based mixing methodology can be adopted across the globe to increase the output of established plastic recovery facilities.