The presence and leachability of antimony in different wastes and waste handling facilities in Norway

Abstract

The environmental behaviour of antimony (Sb) is gathering attention due to its increasingly extensive use in various products, particularly in plastics. Because of this it may be expected that plastic waste is an emission source for Sb in the environment. This study presents a comprehensive field investigation of Sb concentrations in diverse types of waste from waste handling facilities in Norway. The wastes included waste electrical and electronic equipment (WEEE), glass, vehicle fluff, combustibles, bottom ash, fly ash and digested sludge. The highest solid Sb concentrations were found in WEEE and vehicle plastic (from 1238 to 1715 mg kg⁻¹) and vehicle fluff (from 34 to 4565 mg kg⁻¹). The type of acid used to digest the diverse solid waste materials was also tested. It was found that HNO₃:HCl extraction gave substantially lower, non-quantitative yields compared to HNO₃:HF. The highest water-leachable concentration for wastes when mixed with water at a 1 : 10 ratio were observed for plastic (from 0.6 to 2.0 mg kg⁻¹) and bottom ash (from 0.4 to 0.8 mg kg⁻¹). For all of the considered waste fractions, Sb(V) was the dominant species in the leachates, even though Sb(III) as Sb₂O₃ is mainly used in plastics and other products, indicating rapid oxidation in water. This study also presents for the first time a comparison of Sb concentrations in leachate at waste handling facilities using both active grab samples and DGT passive samples. Grab samples target the total suspended Sb, whereas DGT targets the sum of free- and other chemically labile species. The grab sample concentrations (from 0.5 to 50 μg L⁻¹) were lower than the predicted no-effect concentration (PNEC) of 113 μg L⁻¹. The DGT concentrations were substantially lower (from 0.05 to 9.93 μg L⁻¹) than the grab samples, indicating much of the Sb is present in a non-available colloidal form. In addition, air samples were taken from the chimney and areas within combustible waste incinerators, as well as from the vent of WEEE sorting facility. The WEEE vent had the highest Sb concentration (from <100 to 2200 ng m⁻³), which were orders of magnitude higher than the air surrounding the combustible shredder (from 25 to 217 ng m⁻³), and the incinerator chimney (from <30 to 100 ng m⁻³). From these results, it seems evident that Sb from waste is not an environmental concern in Norway, and that Sb is mostly readily recovered from plastic and bottom ash.