Mobility of Metals and Valorization of Sorted Fine Fraction of Waste After Landfill Excavation

Reclamation of landfills and dumpsites requires detailed technical and economic evaluation of actual and potential pollution at the site, including detection of the main contaminants, their concentration, chemical stability and mobility in the environment. Contamination with metallic elements and metalloids is among the most important problems that limits recultivation of landfills and dumpsites and reuse of landfilled materials. This study was implemented at the Kudjape Municipal Landfill, located on Saaremaa Island in Estonia. The Kudjape Landfill is a partly closed landfill recultivated by covering it with a layer of a fine fraction of landfill material after the landfill mining operations. The fine fraction was derived at the site by sorting the landfill material (i.e., disposed waste) using mechanical screening, manual sorting and sieving. Obtained relatively homogeneous material, consisting of particles smaller than 10 mm, was defined as a fine fraction of waste. Samples from the fine fraction at different depth were collected and analyzed. Metal mobility was assessed after the sequential extraction. Results revealed that such elements as Zn, Mn, Mg are found in various fractions; Fe, Cd, Cr—mainly in residual fraction; Cu, Pb, Ni, Ba, Co and Rb mostly in fractions of residuals and reduced compounds, but they are presented in larger proportion of acid and water soluble fractions. Slight interconnection of detected parameters and sampling depth was revealed. Sequential extraction of elements in the fine fraction suggested the valorization of waste and confirmed that such landfill material can be successfully used as a landfill-covering layer under the specific engineering circumstances.