Dry screening - Assessing the effectiveness of contaminant reduction in recovered landfill soils

作者：Hoelzle Ingo

来源：Journal of Cleaner Production, 2018, 172: 1998-2008.

DOI：10.1016/j.jclepro.2017.11.225

• Landfill mining
• Substance flows
• Dry screening
• Processing technology
• Reuse of soils

Landfill mining - an alternative to landfill closure - is designed to recover resources. As landfills consist mainly of soils, the soil quality and possible reuse options are crucial for the economical assessment. The objective of this study is to redistribute contaminants - primarily chemical - in excavated landfill soils for off-site reuse using exclusively mechanical processing equipment. The waste from two full-scale landfill remediation projects were processed in four different processing plants. The efficiency of contaminant redistribution in soils at each processing plant was investigated using statistical methods.
At all four processing plants considerable lower concentrations of heavy metals, polycyclic aromatic hydrocarbons (PAH), total organic carbon (TOC) and sulphate were observed in the coarse-grained soils appropriate for off-site use. In contrast, the differences in leachate analyses (pH, electrical conductivity, chloride, fluoride, barium, dissolved organic carbon) proved to be heterogeneous, less pronounced between fines and coarse-grained soils. Fluoride and chloride sometimes even showed higher concentrations in the coarse-grained. Screens with a mesh size of 50 mm performed more efficiently in terms of contaminant reduction and proportion of material flows (unders and overs) compared to openings of 35 mm or of 70 mm and larger. However, the results indicated an optimum between 35 mm and 50 mm. To ensure the reuse of soils, the determination of contaminants and the grain size distribution should be established in preliminary investigations which are an indispensable requirement for selecting optimal processing equipment and appropriate screen openings.

• 出版日期2018-1-20