Landfill mining is a method for recovering valuable materials, reclaiming land, and mitigating air and water pollution. It is similar to surface mining, in which valuable minerals are recovered from the earth by removing (excavating) soil and ore, followed by processing to concentrate the ore. In landfill mining, the excavated soil is processed to recover valuable recyclable materials, such as metals (aluminum, copper, etc.) as well as combustible materials (wood and other bio-based materials) for producing energy from waste. See also: Air pollution; Aluminum; Copper; Energy sources; Industrial ecology; Land reclamation; Land-use classes; Mining; Recycling technology; Surface mining; Waste-to-energy; Water pollution
The process of landfill mining requires heavy construction equipment for excavating, conveyors for transporting the excavated materials, and screening equipment for separating and recovering the useable materials. In addition, soils must be decontaminated and hazardous wastes contained for disposal. Finally, the reclaimed land must be regraded and covered with topsoil. See also: Construction equipment; Conveyor; Hazardous waste; Screening
In addition to the rewards, landfill mining entails some environmental risks. Excavation and separation processes can emit methane and volatile organic compounds; operation of the production equipment can release carbon dioxide; and the handling of toxic materials and medical waste (including pharmaceutical residues) poses hazards to human health and the environment. Nevertheless, landfill mining also offers the great environmental benefit of cleaning up old, unsound landfills that contaminate the soil and groundwater through leaching and runoff that contains toxic materials (including heavy metals such as lead and mercury), minerals such as asbestos, organic chemicals such as polychlorinated biphenyls, and pathogens such as bacteria and viruses. See also: Asbestos; Environmental engineering; Environmental toxicology; Greenhouse effect; Groundwater hydrology; Hazardous waste engineering; Lead; Medical waste; Mercury (element); Pathogen; Polychlorinated biphenyls
At present, mining landfills for their metal content is not economically viable. However, landfill mining is expected to become more cost-effective in the future, as concentrations of recoverable minerals in the earth decrease and the technology for mining and processing landfill materials advances. See also: Mineral resources; Precious element resources
