Field-portable X-ray fluorescence spectrometry as rapid measurement tool for landfill mining operations: comparison of field data vs. laboratory analysis

Abstract

Landfill mining applied in reclamation at the territories of old dump sites and landfills is a known approach tended to global economic and environmental benefits as recovery of metals and energy is an important challenge. The aim of this study was to analyse the concentration of several metallic elements (Ca, Cu, Cr, Fe, K, Mn, Pb, Zn) in the fine fraction of waste derived in the landfill and to compare the results of measurements obtained by field-portable equipment with the data gained by advanced analytical tools. Atomic absorption spectrometry (AAS) and inductively coupled plasma mass spectrometry (ICP-MS) were used for the quantitative detection of metallic elements at the laboratory; whereas field-portable X-ray fluorescence spectrometry (FPXRF) was applied for rapid sample characterisation in the field (on-site). Wet digestion of samples (fine fraction of waste at landfill) was done prior analytical procedures at the laboratory conditions, but FPXRF analysis was performed using raw solid samples of waste fine fraction derived in the Kudjape Landfill in Estonia. Although the use of AAS and ICP-MS for the measurements of metals achieves more precise results, it was concluded that precision and accuracy of the measurements obtained by FPXRF is acceptable for fast approximate evaluation of quantities of metallic elements in fine fraction samples excavated from the waste at landfills. Precision and accuracy of the results provided by express method is acceptable for quick analysis or screening of the concentration of major and trace metallic elements in field projects; however, data correction can be applied by calculating moisture and organic matter content dependent on sample matrix as well as special attention must be paid on sample selection and homogenisation and number of analysed samples.