a b s t r a c tLandfill mining is an environmentally-friendly technology that combines the concepts of material recycling and sustainable waste management, and it has received a great deal of worldwide attention because of its significant environmental and economic potential in material recycling, energy recovery, land reclamation and pollution prevention. This work applied a cost-benefit analysis model for assessing the economic feasibility, which is important for promoting landfill mining. The model includes eight indicators of costs and nine indicators of benefits. Four landfill mining scenarios were designed and analyzed based on field data. The economic feasibility of landfill mining was then evaluated by the indicator of net present value (NPV). According to our case study of a typical old landfill mining project in China (Yingchun landfill), rental of excavation and hauling equipment, waste processing and material transportation were the top three costs of landfill mining, accounting for 88.2% of the total cost, and the average cost per unit of stored waste was 12.7 USD ton À1 . The top three benefits of landfill mining were electricity generation by incineration, land reclamation and recycling soil-like materials. The NPV analysis of the four different scenarios indicated that the Yingchun landfill mining project could obtain a net positive benefit varying from 1.92 million USD to 16.63 million USD. However, the NPV was sensitive to the mode of land reuse, the availability of energy recovery facilities and the possibility of obtaining financial support by avoiding post-closure care.

Landfills stock massive amounts of minerals and materials, where soil-like material is the primary component of stored waste in old landfills. A typical old landfill (Yingchun landfill) in China was taken as a study case. The stored wastes were sampled from different depths of the landfill, and then the soil-like materials were screened for further analysis. Physicochemical characteristics and the fertilizer quality of the soillike materials were analyzed and the fertilizer effects were studied by cultivating Impatiens balsamina L. with different mixed ratios of soil-like materials and natural soils. According to the results, soil-like materials accounted for 75.02% of the total stored wastes and were in an advanced state of decomposition. Soil-like materials displayed a cation exchange capacity of 84.53 cmol(þ) kg À1 , pH 8.14, and an electrical conductivity of 1190.55 mS cm À1, and were also characterized by high levels of organic carbon and nutrient contents compared to natural soils. The total organic carbon, total nitrogen, total phosphorus, and total potassium of soil-like materials were 9.06, 0.16, 0.21, and 1.48%, respectively. Most of the heavy metal content was relatively lower than the law limits in China. However, As and Zn may have an environmental contamination risk. It could be shown that soil-like materials could significantly promote growing and flowering of I. balsamina L., and were proved to be a valuable bio-resource with utility as soil amendment, cultivating substrate, and raw materials for producing organicinorganic compound fertilizers.