Preliminary Assessment of Heavy Metals in Refuse Derived Fuel (RDF) for Thermochemical Conversion

Abstract

Thermochemical conversion of raw municipal solid waste (MSW) is continuously growing in the context of contemporary technology. The quality of MSW needs an improved analysis to enhance the choice of energy exploitation and environmental assessment of fly and bottom ashes associated with thermochemical conversion. MSW was collected from solid waste disposal facilities (SWDF) in Cape Town in order to investigate heavy metal distributions in MSW obtained from SWDF. The MSW was pre-treated to improve its quality. The 7700 Series quadrupole ICP-MS solution method was used to determine the concentrations and distributions of some heavy metals from SWDF in Cape Town. This study assessed and quantified the distributions of heavy metal in MSW in the city of Cape Town. The accumulation of high concentrations of heavy metals in bottom ash residue from thermochemical conversion could be a good remedy for heavy metals control. High transfer coefficients of heavy metals were observed, and the heavy metals were mainly transferred to the bottom ash. Heavy metals such as Cd, Cu, Pb, and Zn in bottom ash are regarded as relatively unstable with the highest concentrations of Cu and Zn 1295 mg/Kg and 3347 mg/Kg, respectively. The heavy metals (especially Pb, Zn and Hg) emissions were technically monitored and controlled from escaping into the urban air-sheds atmosphere and prevented from their consequential secondary environmental and health implications.