Welcome to this month’s issue. I am delighted to be writing this editorial and hope that the articles contained within this issue provoke scientific debate in the exciting field of landfill science! Having worked in the waste and resource sector for over 20 years, I am still excited about the challenges which lie ahead in developing new approaches contributing to the sector achieving a circular economy and net zero goals. The fast-evolving waste and resource management sector now places greater emphasis on sustainable waste management, especially as population grows, waste becomes more complex and global goals on climate change become increasingly ambitious. However, it is important that we don’t lose sight of tackling waste that will be/has been landfilled, by ensuring that pollutants are contained and managed effectively, energy is recovered and, potentially, the valuable resources are recovered through landfill mining. This issue broadly covers the theme of sustainable landfill management, whereby control of emissions and maximising the recovery of energy and other resources remains an ongoing global challenge.
Waste management has developed dramatically over the last 20 years. Mechanical processes to sort recyclable materials from residual wastes are becoming common throughout the world along with energy recovery. Energy from waste includes biochemical and thermochemical routes, mostly anaerobic digestion and combustion, respectively. Recycling rates on a global scale have increased significantly in recent years. This is all good, however, landfill disposal remains the most common means of managing waste. As long as this remains the case, we need to ensure that this is done in the most sustainable manner with minimised environmental impacts.
Landfills and dumpsites pose long-term environmental challenges alongside concerns that valuable resources are lost. Globally, we have a legacy of managing waste in this way, with up to 500,000 closed landfill sites across Europe alone (Särkkä et al., 2018) Extraction of resources from these sites has been discussed at length (Jones et al., 2013), however the benefits extend beyond simply recovering the resources. The land can be repurposed for housing or industrial development and the long-term environmental concerns are reduced. This is a significant opportunity in this sector; however, the process of landfill disposal isn’t going to stop anytime soon. The articles within this issue of Environmental Geotechnics cover the engineering of landfill sites, the collection and management of gaseous and liquid emissions and how the composition of landfilled waste impacts these emissions.
Arguably the first step in managing the emissions of a landfill site is to engineer the site to ensure that pollutants are kept within the site and that gases will be collected effectively. The first two articles by Ke et al. (2023) and Devarangadi and Masilamani (2023) address the important matter of liner materials and the landfill structure in terms of leachate containment. The corrosion resistance of the liner material helps us to understand which waste materials might pose greater problems, ensuring that this scientific knowledge can impact how the site is utilised long term. The use of slag mixtures blended with clay is an innovative approach to use another waste source in the containment of another waste’s leachate.
Waste properties and the influence of composition on biogas is covered in our next paper by Datta and Zekkos (2023). Modelling biogas production within a landfill is a significant challenge due to the multifarious biochemical processes occurring in parallel. This article complements our next two articles, which tackle the issues of structural integrity of a site due to the settlement waste undergoes during biodegradation (Hanson et al., 2023; Shu et al., 2023).
The next two papers present the use of waste-derived products in landfill management to deal with gas and leachate production. Using food waste compost as a biocover material to mitigate methane emissions (Rayhani et al., 2023) and the application of tyre-derived aggregate for leachate collection (Adesokan et al., 2023) are novel and could have cost-effective impacts on emission control.
The final paper discusses metal recovery from incinerator bottom ash and the need for ongoing landfill monitoring (Paleologos et al., 2023). Reserves for critical metals are diminishing and critical metal demand has significantly increased due to rapid technological growth, with many critical metals being vital for low-carbon energy technologies (Huntington et al., 2023).
The future of resource management will need to include a joined-up approach involving multiple waste management technologies to ensure maximised resource recovery and minimised environmental and human health impacts. This is a significant challenge, but also a very exciting opportunity.
