Characterization of solid residues from the incineration of expired and unused medicines

Abstract

Expired or unused medicines are potentially toxic substances that should be managed effectively and correctly to avoid their presence and accumulation in the environment. The objective of this study is to determine bottom ash and fly ash chemical composition resulting from expired and unused drugs and maximum leaching of heavy metals (copper, iron, zinc). This paper reports a detailed and complete characterization of two samples of different type of combustion ashes as bottom and fly ashes collected from incineratorslocated in Si Mustapha – Boumerdes. The study focused on physicochemical, mineralogical and environmental characterization. For this purpose, several techniques such as: DRX, XRF, ICP-MS, SEM, UV-visible, titrimetric andgravimetric methods were used.  The physical results indicated that the unburnt rate in these residues is less than 5% which indicates a good incineration; the particle size population varies between 0.5μm to 50 μm for bottom ash and between 0.5μm to 8 μm for fly ash (more homogeneous particle size distribution). With regard to leaching behavior, leachates pH of the two solid residues is basic and oscillates between 8 and 11. Theconcentration of sulfate ions obtained is much less than 10.000 mg / Kg andthe same is true for chlorides where the concentration is less than 800 mg / Kg. XRF analysis showed that the sum of the following maj elements expressed as oxides: Al2O3, SiO2 and Fe2O3 is 83.51% for fly ash and 60.68% for bottom ash. The results of the analysis of heavy metals show that the concentration of elements leached by these residues does not exceed the so-called «inert and recoverable category», namely : pb < 0.5 ppm, Cd < 0.04 ppm and Cr < 0.5 ppm, Hg< 0.2 ppm and As< 0.5 ppm; which makes it possible to classify these residues in the category of inert and recoverable waste. Results of physicochemical analyzes and leaching tests suggest that fly ash from solid waste incineration fly ash should be classified as hazardous waste and should be properly managed.