Decision support framework for solid waste management based on sustainability criteria: A case study of tailings pond cover systems

Abstract

Abstract Tailings are one of the major categories of industrial waste, the disposal of which is problematic from an environmental viewpoint. The weathering of sulfide bearing waste materials commonly generates acidity and dissolved metals in the environment creating acid mine drainage (AMD). Typically, the chosen reclamation solutions emphasize low construction costs over environmental and technical sustainability challenging decision making. The aim of this work was to develop a framework for analysis of alternative cover scenarios with multiple-criteria decision analysis (MCDA) applied for the purpose. The case study comprised totally 10 criteria and five different cover structure options: moraine-based cover, biofuel fly ash/steel slag cover, stabilization with ordinary Portland cement or with composite binder, and use of an advanced hardpan cover liner (AHCL) system. The proposed methodological approach provides the structural steps of MCDA process to compare and contextually evaluate the economic, technical and social-ecological implications of cover alternatives. Modified Analytical Hierarchy Process (AHP) was applied as a MCDA approach for structuring complex problems and assisting decision makers to choose the best alternative among a discrete set of scenarios. Differing preferences of the stakeholders were resolved by synthetizing the conflicting weightings in the beginning of the analysis. Life-Cycle Assessment (LCA) was used to evaluate the social-ecological impacts of emissions, energy demand and impact to human health. Overall, the results from this study show that when considering total sustainability, the AHCL was preferred over the other alternatives when the weighting of the main technical, social-ecological and economic criteria was equal (33%). The weighting of main criteria and consequently sub-criteria impacts the ranking order of compared solutions. Decision making comprising viewpoints of different stakeholders is important when evaluating sustainability criteria. Higher weighting of social-ecological and technical criteria (50%) favored stabilization with composite binder while higher weighting (50%) of costs favored moraine cover. The proposed framework can process competing and conflicting objectives in addition to quantitative and qualitative criteria, hence providing a holistic and interdisciplinary approach to complex problems. The results from this project can help to develop sustainable remediation strategies to reduce the environmental risks associated with mine wastes.