Life cycle assessment of the management of residual waste from material recovery facilities by landfill, incineration and gasification-pyrolysis in Victoria.
Creators: name: Demetrious, Alexis
Publisher: name: RMIT University
Year: 2024
Subjects: classificationCode: 400410
subject: Wastewater treatment processes
classificationCode: 410101
subject: Carbon sequestration science
classificationCode: 410402
subject: Environmental assessment and monitoring

description: Excessive waste generation caused by exponential growth in resource use for the production of consumer goods, electronics and packaging has placed a growing burden on waste management globally. In addition, commodity prices for materials including virgin paper and crude oil have slumped, lowering the value of recyclate, and presenting new challenges for the Australian waste and recycling industries. In Victoria, total waste generation is approximately 9.3 million tonne per annum, with approximately 23% from municipal solid waste (MSW), 33% from commercial and industrial, and 32% from construction and demolition. Diminishing landfill capacity adds to the pressure faced by government to consider alternative waste management put forward by industry. The Victorian Government are currently deliberating their position to incorporate thermal treatments for its MSW management, and are expected announce a position in 2018. The Western Australian Government position supports the use of thermal treatments, and there are three plants are under construction to manage MSW and residual waste from material recovery facilities (MRFs) instead of landfilling. MRF residual waste is not currently economically feasible to be efficiently separated for further processing and is neither re-used nor recycled. Therefore, it is considered an appropriate feedstock for thermal treatments in respect to the waste management hierarchy. Interpretations of the waste management hierarchy mean thermal treatments can even be considered as resource recovery, rather than disposal. The classification of thermal treatments (with energy recovery) as resource recovery rather than disposal is an area of debate. In the context of this thesis, the analysis of results found that the waste management hierarchy is not a valid tool to predict environmental performance for MRF residual waste. The management of MRF residual waste in landfill, incineration and gasification-pyrolysis in Victoria, Australia, was assessed using a life cycle assessment (LCA). In the LCA model, the Victorian electricity grid was avoided by electricity produced by landfill gas combustion, thermal turbine and synthetic gas engine, and found incineration of MRF residual waste to have the highest electricity production potential, followed by gasification-pyrolysis, and lastly landfill. The LCA model was used to calculate the potential environmental impacts of acidification (AP), climate change (CCP), eutrophication (EP) and photochemical oxidation (POP). The LCA results show that landfilling of MRF residual waste minimises AP and CCP, whilst incineration minimises EP and POP. When comparing just the thermal treatments, incineration outperforms gasification-pyrolysis for all potential impacts. A dimensionless, weighted, normalised, single-score result is lowest for landfill, followed by incineration, and lastly gasification-pyrolysis. The baseline results were compared to scenarios developed for sensitivity analyses, and in some circumstances the directional outcomes change. For instance, landfilling no longer has the lowest AP, when the incineration system includes a credit from recovered heat as thermal energy. Additionally, landfilling no longer has the lowest CCP, when MRF residual waste has very high fractions biomass-based waste (e.g., food, paper, garden etc.). However, landfilling of the baseline MRF residual waste was found to have the lowest GHG emissions regardless of the exclusion of electricity credits, and of the GHG accounting methods used to measure biogenic carbon dioxide. This research is significant because waste management in Victoria is now considering thermal treatment options, due to perceived environmental benefits. Policy changes to waste management systems will benefit from this independent and evidence-based research.