Recycling of aged refuse from a closed landfill

Abstract

In this study, refuse excavated from a typical refuse landfill in Shanghai after 8-10 years of placement was characterized in terms of particle size, total nitrogen, total phosphorus, and biodegradable matter. The refuse contained a large and diverse population of micro-organisms with a high capacity for decomposing refractory organic matter present in some wastewaters, including leachate. It was found that the aged refuse was quite stable after about a decade of decomposition in the warm, humid climate of southern China. The fine fractions resembled and had the properties of black soil, a medium that is suitable for green construction, organic fertilizer, or as bioreactor media for biological treatment of organic wastewaters. Excavation of the aged refuse would make about 50% of the space available for fresh refuse. The plastics, glass, textiles, and cans can be readily mechanically separated and recycled after cleaning. It is estimated that at least 200 millions tonnes of such aged refuse are available in China alone, and at least 10 times that much is buried worldwide. Hence, the evaluation of mined landfill waste and consideration of its potential uses is of great significance.

Characterization of Fine Fractions From Landfill Mining: A Review of Previous Investigations

“…Previous investigations made by Krook et al, 2012;Cossu, Motzo, & Laudadio, 1995, Kaartinen et al, 2013Prechthai, Padmasri, & Visvanathan, 2008;Quaghebeur et al, 2013;Zhao, Song, Huang, Song, & Li, 2007 report that landfill-mined waste normally consists of 20-30 wt.% combustible materials, 50-60 wt.% fine-grained degraded matter, 10 wt.% inert materials and a small percentage of metals. For further references predating year 2011, a broad worldwide overview of over 60 LFM projects and the rough composition of landfilled waste from over 20 landfill dismantling and exploratory drilling projects can be consulted in the work made by Bockreis & Knapp, 2011. A more detailed material composition (Van Vossen & Prent, 2011), obtained from information found in literature of 60 landfill mining projects, plus the outcomes of most recent investigations (after year 2011) are presented in Table 1.…”

A cost-benefit analysis of landfill mining and material recycling in China

“…The heavy metal contents of soil-like materials were as follows: Pb, 21.53 ± 22.89 mg kg À1 ; Cd, 0.14 ± 0.11 mg kg À1 ; Cr, 9.99 ± 10.89 mg kg À1 ; As, 29.61 ± 9.57 mg kg À1 ; Hg, 0.17 ± 0.11 mg kg À1 , while the Chinese National Standard for Urban Wastes for Agricultural Use (GB 8172-87) specifies the following upper limits for these heavy metals: As (30 mg kg À1 ), Pb (100 mg kg À1 ), Cd (3 mg kg À1 ), Cr (300 mg kg À1 ), Hg (5 mg kg À1 ). It indicated that the soil-like materials (seems like natural black soils) could be applied as substrates or fertilizers to ornamental plants and garden plants (Zhao et al, 2007).…”

“…incineration, gasification, pyrolysis, plasma technologies, combinations) for energetic valorization and material recovery (Krook et al, 2012;Bosmans et al, 2013;Jones et al, 2013). Landfill mining is considered if the environmental pollution is urgent, land is scarce, or combustible waste treatment and energy recovery facilities are available (Zhao et al, 2007;Jain et al, 2013;Jones et al, 2013). Recent researches mostly focuse on the components and characteristics of stored waste and http://dx.doi.org/10.1016/j.wasman.2014.09.029 0956-053X/Ó 2014 Elsevier Ltd. All rights reserved.…”

Characteristics and the recovery potential of plastic wastes obtained from landfill mining

“…According to recent researches, the municipal solid waste stored in landfills normally consists of 20e30% combustible materials (the primary component is plastic wastes), 50e60% soil-type materials, 10% inorganic substances (mainly including concrete, stones and glass) and a small percentage of metals (Cossu et al, 1995;Zhao et al, 2007;Prechthai et al, 2008;Kaartinen et al, 2013;Quaghebeur et al, 2013). After the stored waste being excavated and screened from the old landfill, metals and construction wastes can be easily recycled, soil-type materials can be applied to green spaces and gardens as fertilizers , but how to recover more energy from the plastic wastes in landfill mining were still in discussing (Bosmans et al, 2013), and the potential of recovering plastic wastes is the major factor to assess the economic feasibility of a landfill mining project (van der Zee et al, 2004;van Passel et al, 2013).…”