A System Dynamics analysis of the causes of Australian recycling rates plateauing below full potential

Abstract

As Australia enters the 21st century, there is increasing discussion around waste and circular economies. The mindset of landfilling waste is becoming more difficult to justify and as natural resources are depleting is it increasingly necessary to move toward a circular economy. An existing option to improve sustainability is the recycling of waste materials, a process that has a long history in Australia. However, we are now seeing Australian Municipal Solid Waste (MSW) and certain material recycling rates plateauing below their full capacity. To continue recycling momentum, it is necessary to identify barriers preventing improvement in recycling rates. Existing research on recycling has commonly concentrated upon a part of the recycling system, but ignored the whole. This thesis uses System Dynamics (SD) to address the MSW recycling plateau problem and to resolve the following issues: (a) how do MSW recycling plateaus relate to material recycling plateaus, (b) what role do recycling influences play with MSW recycling plateaus and bin contamination, and (c) are the forces driving MSW recycling rates exogenous or endogenous to the waste control system? A case study on Old Newspaper (ONP) recycling plateaus addressed the link between a material experiencing plateauing recycling rates and its relationship to MSW plateauing recycling rates. The intention of this study was to determine whether the barrier to higher ONP recycling rates was the capture of ONP in the MSW recycling system (supply) or the demand for ONP as a raw material for remanufacture. The key limiting factor in ONP recycling rates was found to be supply, predominantly from MSW, thus emphasising the importance of MSW recycling systems in material recovery and leading to the analysis of MSW to better understand recycling plateaus. The role of recycling influences on MSW recycling plateaus and bin contamination was investigated via a local government case study. Recycling influences refers to the ten variables found via the literature review that could possibly act as barriers to recycling rates; demographics, policy, disposal knowledge, waste collection service quality, dwelling type, attitude toward recycling, time devoted to recycling, recycling social norms, MRF sorting quality and household consumption trends. These variables were investigated using Australian census data, a household survey and a waste audit. It was determined that the level of plateau was primarily caused by consumption trends. If a higher proportion of recyclables was in the waste stream, then the recycling plateaus would also rise. MSW bin contamination was also an important factor in determining recycling rate levels, with incorrectly disposed waste showing potential to inflate or deflate recycling rates. Household disposal knowledge and biases when making uncertain decisions were found to be the key influences on bin contamination levels. When using System Dynamics to model the municipal waste system, a purely endogenous explanation for plateauing recycling rates could not be found. Recycling rate plateau level was largely determined by exogenous waste stream proportions, which could also be described as residential consumption trends. The only endogenous feedback was in the form of council education campaigns, responding to increased recycling bin contamination. When this feedback loop was active it resulted in significant decreases in bin contamination and a small increase in the recycling rate plateau. From this research, two potential endogenous pathways for increasing MSW recycling rates were identified and recommended for further research; (a) councils influencing consumption habits, and (b) council influencing retail packaging types. Both feedback loops represented a means for Australian local government to influence their recycling rates through behaviour change.