Along with four Danish partners, DGE completed in 2016-2017 a Landfill Mining (LFM) project under the Environmental Technology Development and Demonstration Program (in Danish: MUDP) by the Danish Environmental Protection Agency. DGEs partners in the project are contractors Kingo Karlsen and BioRem, the waste disposal firm RenoSyd, and the Danish Waste Council (Dansk Affaldsforening, represented by Danish Waste Solutions).
The LFM project provide insights for the technological and economic benefits and environmental aspects of excavation and sorting of pre-landfilled waste from Skårup Landfill, located in Skanderborg, Denmark. The project develops an application-oriented assessment procedure to plan, select and perform future LFM-projects at different landfills. In the project, an outline of a business model is prepared and a range of factors influencing the economy, and social benefits of LFM projects are discussed.
Initially, a comprehensive literature study was carried out for available knowledge of LFM from Denmark, the EU and abroad. In addition, the EU and Danish legal and regulatory issues affecting the implementation of an LFM project were identified. Finally, environmental impacts and environmental concerns of conducting LFM are considered and described. The regulatory aspects of excavation and recycling of waste are relatively complex, which can have a decisive influence on the economy of an LFM project.
Prior to the physical excavation and management of waste, a detailed pre-characterization of the actual landfill unit was carried out. Both registrations of disposed waste and other historical information regarding the area and the landfill were collected by interviews with employees present during the landfill by evaluation of the environmental status and former investigations. Furthermore, a non-invasive screening of the landfill unit was conducted for a 3D description of the sub-surface material conditions and of the waste. Finally, a test excavation was conducted for additional information regarding the composition of the waste and the conditions during excavation. This pre-characterization of waste is important for correct planning of the main LFM project.
Excavation and sorting of the coarse waste fraction were carried out by an excavator with a sorting grapple. This pre-sorting could separate bulky items from the rest of the waste: e.g. tree roots, tires, lumber, furniture, major foundation bricks, carpets and large, heavy pieces of plastic film. Magnets were mounted at the outlet of the coarse- and mid-size fractions to separate magnetic metal. Moreover, at the outlet from the coarse fraction, a plastic foil suction module was mounted, which blew the light plastic fractions into a separate closed container.
After the mechanical sorting a sample of 500 kg of the mid-size fraction was hand-sorted to make a detailed characterization of the waste in different material types. During the project a total of 2,049 tons of waste was excavated and sorted.
Following the practical implementation and recorded project costs economic calculations were made on implementation of typical LFM projects using the specific methods of excavation and sorting from this project.
One of the objectives of the project was to develop a comprehensive business model for conducting LFM, where individual business factors were assessed and estimated economically. However, as no landfills are identical the content and output of such an assessment will vary. At the same time, the incentives for LFM may be different (e.g. the need for changed land use, or environmental concerns, e.g. no bottom membrane), and therefore it will be unrealistic to make a final business model for a general implementation of all LFM projects. Other important financial factors are the value of land after removal of the waste for better land utilization along with the costs of maintain a controlled waste deposit for 30 or 80 years.
A paradigm was developed for the items to be included in a commercial assessment of an LFM project so that both the administrative and the practical experiences are accounted for, and assessed.
Several different scenarios based on realistic conditions at the Skårup Landfill were described. For each of these scenarios, calculations show the overall economy of LFM implementation. The results of the calculations on the selected scenarios show that, overall, there will be a cost of implementing LFM and very little revenues.
Based on the local conditions at the Skårup Landfill, and depending on the different conditions, the total LFM costs is calculated to ranging from DKK 28 DKK to DKK 775 per ton of waste removed. The calculations will change based om type of waste encountered, different scrap prices, future costs of maintain a landfill and restoration of the area, etc. etc. Other scenarios may even generate revenues.
The developed business model which includes the economic, environmental and social aspects may be a useful tool in the future mapping of landfills and their LFM potential, as requested in the revised EU Landfill Directive.