2025-OU3 Quantifying the carbon offsetting potential of Enhanced Landfill Mining

Overview

Enhanced Landfill Mining (ELFM) provides an opportunity to reclaim valuable land, recover recyclable materials (e.g. metals, fuels, and construction materials), and reduce the environmental impacts of traditional waste disposal methods (Jain et al., 2023). For example, it is estimated that copper in landfills is equivalent to over 30% of the remaining global reserves (Danthurebandara et al., 2015). In the UK alone, there are 22,000 closed landfills with the potential for ELFM (Wagland et al., 2019). ELFM has social, economic, and long-term environmental benefits, however there are significant environmental challenges associated with excavating landfill sites. Disturbing capped landfill will increase atmosphere-terrestrial greenhouse gas (GHG) exchanges and promote the release of pollutants. Current Life Cycle Assessments of ELFM do not account for the release or fate of GHGs released during excavation. 

Landfills are heterogeneous environments where waste materials decompose anaerobically to produce methane (CH₄) and carbon dioxide (CO₂), both of which are potent GHGs. Landfills account for around 5% of global GHG emissions each year (Zhang et al., 2019). The excavation of landfill sites will result in GHG emissions into the atmosphere. It is anticipated that excavation would initially create a significant pulse of CH4, which would gradually subside as oxygen enters the ground and promotes aerobic decomposition and an associated increase in CO2 emissions. Therefore, GHG emissions from excavation during ELFM may potentially offset carbon savings from resource recovery. 

This research aims to provide insights into the economic viability and sustainability of EFLM by quantifying the recoverable content from excavated material, investigating GHG emissions, and conducting an environmental impact assessment. This study will be relevant to a wide range of stakeholders, including environmental agencies, waste management companies, policymakers, and local communities. By highlighting the potential risks and benefits of ELFM, the research will inform decision-making and promote the adoption of best practices in resource recovery and waste management. Depending on the interests of the candidate, there is also scope to explore the release of additional airborne pollutants (e.g. organic compounds, sulphur dioxide, carbon monoxide, nitrous oxide, and particulate matter) and their impacts on landfill operatives and local residents.  

Figure 1:Landfill mining in action. Source: https://www.geplus.co.uk/features/contaminated-land-ripe-for-remediation-06-05-2021/.