Characterization of landfilled materials: screening of the enhanced landfill mining potential

The main objective of “Enhanced landfill mining” is the valorization of the excavated waste materials that have been stored in the landfill. Previous landfill mining projects have shown that each landfill site has its own potential with regard to landfill mining. Factors such as the age of the landfill, type of landfill and the country or region where the landfill is located might have an impact on the type of materials stored in the landfill and their valorization potential. In the present article, the valorization options for the materials stored at the REMO site in Houthalen (Belgium) are assessed based on excavation tests done at locations containing either municipal solid waste (MSW) or industrial waste (IW). The results reveal differences in the composition and the characteristics of the waste materials with regard to type of waste (MSW versus IW) and the period during which the waste was stored. Based on the characteristics of the different fractions, an initial assessment was made with regard to their valorization potential. For the plastics, paper/cardboard, wood and textile recovered in this study, waste-to-energy is the most suitable valorization route since the level of contamination was too high to allow high quality material recycling. For metals, glass/ceramics, stones and other inerts in the waste, material valorization might be possible when the materials can adequately be separated. The amount of combustible in the excavated waste varied between 23 and 50% (w/w) with a calorific value of around 18 MJ kg−1 dw and confirm the large potential of waste-to-energy for landfill mining. All waste samples recovered from the landfill contained a large amount (40-60% (w/w)) of a fine grained (<10 mm) mainly mineral waste material. Especially for industrial waste (mainly shredder from ELV), the fines contained high concentrations of heavy metals (Cu, Cr, Ni and Zn) and offer opportunities for metal extraction and recovery. The development of a treatment plant that enables maximum resource recovery remains however one of the technological challenges for further development of enhanced landfill mining.