Problems in traditional landfilling and proposals for solutions based on sustainability

In recent years, the Circular Economy has become the key lynchpin underlying the waste management system. However, the emphasis placed on recycling has led, on one hand, to an underestimation of the critical issues that are currently emerging so dramatically (i.e. limited recyclability of materials, instability of markets for secondary raw materials, and accumulation of contaminants present in the recycled materials), whilst on the other to neglect the inescapable role of landfill in waste management. In many cases, landfills are seen as a simple and economical means of disposing of waste, and from a political, legislative and technical viewpoint they are frequently denied the attention devoted to other engineering works, lacking ade-quate financial investment to cover the costs required to ensure a sustainable landfill system. Landfill should be designed and constructed in line with the principle of environmental sustainability, by adopting technical measures aimed at guaranteeing waste stability and immobilisation of contaminants over a period of less than one generation and ensuring a Final Storage Quality in equilibrium with the environment. This article summarises the concept of sustainable landfilling, identifies the technical strategies that characterise this system, describes the critical issues frequently encountered after decades of operation and proposes a series of solutions aimed to control long-term behavior.