Environmental Impact Assessment of Resource Recovery Through Enhanced Landfill Mining - Addressing Uncertainties via Life Cycle Assessment and Integrated Approaches

Due to the vast amount of landfills in Europe, and in the world, and the limited availability of primary raw materials and land space, new waste management concepts are being developed. The focus is on the reduction of risks to human health and the environment (HHE) and on a more integrated recovery of resources. In this context, the concept of landfill mining (LFM), and the more integrated approach of enhanced landfill mining (ELFM), are gaining increasing attention, especially in the academic world. As the long-term emissions of landfill sites, and related risks to HHE, call for more sustainable landfill management approaches, (E)LFM seems to represent a valid solution, addressing site remediation together with the recovery of materials and energy, land and landfill space. Furthermore, (E)LFM may also yield environmental, economic and societal benefits. However, (E)LFM projects are complex and entail different processes for the excavation, separation and sorting, and treatment of the waste streams for material and energy recovery. Site-specific, technological, organizational, but also regulative and market-related factors, influence their feasibility. Multi-criteria assessments of (E)LFM have therefore gained increasing attention and importance. The aim of such assessments is to analyze under which conditions and settings LFM could be economically, environmentally, and socially justified. In particular, environmental assessments, focus of this research, are of great importance to support stakeholders' engagement and policy implementation. However, methodological and empirical challenges still exist due to the limited knowledge on the processes, as well as their complexity. These factors are inherently variable, geographically and temporally. To understand under what conditions LFM could be environmentally beneficial, it is necessary to take into account the parameters that influence the processes, as well as to address the uncertainties that arise. Life cycle assessment (LCA) is the commonly used tool for the environmental impact assessment of products or services. However, the inclusion of critical performance factors and their spatial and temporal variability in LCA is limited. Addressing different types of uncertainties at different levels calls for new approaches. The thesis aims at identifying and address the critical factors, and their variability, from a methodological perspective, to provide the tools for more valid assessments. In particular, the research aims at addressing different uncertainties that arise due to both the lack of knowledge and the inherent variability of conditions in order to improve the assessment of the impacts of LFM and of the landfill reference case. Three main approaches are adopted and/or developed to address different levels of uncertainties. Scenario analysis in LCA is used to address the variability of site-specific factors, such as waste composition, environmental and technological conditions, on the impacts of landfills. An integrated LCA and quantitative risk assessment (QRA) approach is then developed to integrate spatial and temporal information in the LCA of the landfill reference case. The general aim of the approach is to address model uncertainties by integrating the probability of occurrence of the events that define the scenarios, and their impacts. This is in order to understand the relevance of the modelled scenarios for the system under study. An integrated environmental and economic framework for the ex-ante assessment of emerging technologies is further developed. The integrated framework, based on multiple scenario analysis, addresses factor variability at site, project, and system-level in the economic and environmental performance of emerging technologies. The use of multiple scenarios allows in fact to explore the plausible performance of the systems under varying local/regional conditions. Global sensitivity analysis applied to the integrated results allows a deeper knowledge of the factors that drive its performance. The integrated framework is developed and applied to the case of plasma gasification of excavated landfill waste, and to the whole ELFM process chain. Overall, the developed and applied approaches allow increasing the spatial and temporal representativeness of the assessments. By applying these approaches it is therefore possible to better understand, on the one hand the implications of the landfill reference case, and on the other hand under what conditions LFM could be viable and how to support project implementation. The first two approaches enable a deeper understanding of the environmental implications of the landfill "business as usual" scenario. Site-specific factors, and their variability in time, are addressed to have a broader perspective on the landfill impacts under different conditions. The integrated ex-ante environmental and economic approach addresses the temporal and geographical variation of site-, project-, and system level conditions on the performance of emerging technologies and concepts. This allows to better support the development of the concept and technologies, as well as project implementation, taking into account varying local/regional conditions. Moreover, granular understanding of what builds the economic and environmental performance of LFM contributes to improve the know-how on LFM, and therefore understand under what conditions LFM could be a viable landfill management option. In particular, the research highlights the importance of considering factors at different levels for a more strategic selection of landfills, as well as the development of tailored project set-ups, promoting a more adaptable and sustainable system design. The results of the case studies show the environmental potential of LFM and the added value of advanced technologies for the treatment of excavated waste. Nevertheless, this depends on the regional availability of the technologies, as well as on site and system-level factors, such as the waste composition, the background energy system, surrounding market and policy conditions. These factors have proved to be of critical importance in project development and project set-up. At a system level, market and policy conditions have a significant influence on the potential implementation of certain technologies and on the recovery and marketability of resources.

Publication year:2021

Accessibility:Closed