Landfills present a host of environmental problems, such as methane emissions and groundwater contamination, often resulting in health-related issues for nearby residents. They’re also noisy, smelly, and ridden with vermin.
But what if we could transform these waste dumps from an environmental and health threat into an opportunity for resource recovery? Enhanced landfill mining could do just that.
For more than a century, the human race has been discarding its waste in landfills. The U.S. alone currently has about 2,000 active landfills and as many as 10,000 more inactive landfills. Many of the closed landfills pre-date the EPA’s 1976 Resource Conservation and Recovery Act. In other words, they have little or no environmental protections in place.
Without protections, methane emissions and groundwater contamination can reach threatening levels. For instance, as biodegradable organic matter decomposes in the landfill, methane gas is released. Methane is a highly potent greenhouse gas. Which makes landfills a serious global warming problem.
Likewise, whenever rain falls on the landfill, both organic and inorganic materials begin to dissolve. This forms toxic “leachate,” which can result in serious contamination of the local groundwater.
Consequently, the EPA requires closed landfills to be monitored for at least 30 years after waste placement ceases.
Landfill remediation — the process of cleaning up toxic landfills and introducing environmental protections — is necessary, but costly. For instance, it cost one Belgian public waste agency more than $105 million to excavate and move hazardous waste to state-of-the-art sanitary landfills over an eight-year period.
Costs like that are prohibitive to many countries. Particularly the developing nations — the very places that have the greatest need for remediation.
Going a step beyond remediation is the concept of landfill mining (sometimes referred to as “urban mining”). Landfill mining involves the excavation and processing of solid wastes from the landfill. As part of the process, of course, hazardous materials are removed and protective measures are taken. But that’s only part of it.
Landfill mining also recovers:
The concept of landfill mining was first introduced back in 1953 at the Hiriya landfill near the city of Tel Aviv, Israel. (See related article, “Clean Energy…From Garbage Dumps!”) Similar to other types of mining operations, the process of landfill mining basically uses a system of excavators, screens and conveyors to separate and transport the various types of waste.
Odor control sprayers may also be used to neutralize the smell of exposed wastes.
Limited information is available on landfill mining projects that have been carried out on a worldwide basis. But in the United States, only six landfills have been mined, most of which are located in the Northeast.
In the US, however, the term “landfill mining” has increasingly become a misnomer. The primary motivation for landfill mining in this country has been to redevelop the landfill to meet current EPA standards and gain valuable additional space for active waste filling. Any reclamation of recyclable materials has been considered secondary.
Which is why organizations like the World Economic Forum are advocating what they call “enhanced landfill mining.” The idea behind enhanced mining is to recycle 100% of landfill materials. The following video clip depicts this European concept:
As indicated in the film clip above, plasma gasification technology can now be used to transform traditionally non-recyclable landfill material into the green, low-carbon “plasma rock.” This rock can be used in the production of various consumer goods, such as building materials. Apparently, 45 lbs of plasma rock can be created out of about 220 lbs of landfill waste.
This enhanced approach to landfill mining is currently being demonstrated in two flagship projects, NEW-MINE (for municipal solid waste) and METGROW+ (for industrial waste). Both are funded by the European Commission’s Horizon 2020 Programme.
Will the U.S. follow suit? That remains to be seen.
But as resource recovery technology improves, and raw resource reserves deplete, the possibilities for landfill mining are likely to increase.
Experts agree. According to waste industry magazine Waste Management World, “As resources become scarcer and demands on land for development increase, so the pull factors for landfill mining will strengthen.”