摘要：In the present study, physical properties , chemical composition and leaching properties of a special waste type; fuel oil combustion residue of thermal a power plant, have been studied. Toxicity Characteristic Leaching Procedure (TCLP), sequential chemical extraction (SCE), alkalinity solubility and release as a function of pH` leach tests and X-ray Diffraction (XRD) analysis have been employed to achieve a more comprehensive understanding of waste characteristics. Elemental V, Ni, Fe, Cr, Pb and Cd concentrations have been traced in leachates from different tests. Results have shown special characteristics such as; extremely low pH level about 2.7, high Sulphur content; 21.50 weight percent and elemental V complex formation in untreated material. Results of TCLP test have shown excessively high concentration of V, Ni, Fe, Cr, Pb and Cd in leachates as 537.75, 472.5, 518.5, 38.54, 19.3 and 5.55 mg L-1, respectively. Results of SCE test show Ni, Fe and Cr, are most likely to be present in residue fraction, Pb in exchangeable fraction, Cd in bound to iron and manganese oxides and V is most likely to be present in bound to organic matter and sulfides but also a considerable fraction of it resulted to be in bound to iron and manganese oxides. Results of alkalinity, solubility and release as a function of pH test show relatively same release change pattern for Ni and Fe in pH range 2 to 5, but release reduction in pH 6 for Fe has steeper pattern than Ni. For other constituents, release changes do not show such abrupt pattern with pH variation. According to TCLP test results, the studied waste should be classified as hazardous and should certainly be stabilized and then disposed of according to hazardous waste disposal considerations. Sequential chemical extraction and release as a function of pH tests have made useful insights of waste intrinsic characteristics that can help for a better decision on best remedial technology that matches the waste characteristics.
