Characterization of trace elements in chicken and duck litter ash

For safe and Sustainable management Of Poultry litter, it is important to evaluate and understand the chemical forms and concentrations of their Constituent trace elements during treatment for disposal. This experiment was carried out to compare changes in metal (Cu, Mn, Zn, Pb and Ni) fractions in chicken and duck litter after incineration at temperatures ranging from 200 to 900 degrees C. The metals were stepwise fractionated into exchangeable, adsorbed, organically bound, carbonate precipitated and residual forms by extracting with 0.5 M KNO3, de-ionized water, 0.5 M NaOH, 0.05 M Na-2 EDTA and 4 M HNO3, respectively. The content of total metal and other elements (i.e.. Ca, Mg and K) were was also determined. Results showed an increasing trend in the total concentrations of metals with increasing temperature with higher amounts in chicken litter ash (CLA) than duck litter ash (DLA). Higher temperatures significantly reduced the levels of H2O-soluble Mn, Zn and Ni and enhanced those of Cu and Pb. The metal fractions extracted by EDTA and HNO3 increased directly with increasing temperature while the fraction extracted with KNO3 and NaOH decreased with ashing. For Cu, Mn, Pb and Ni, the amount extracted varied in the order EDTA > HNO3 > NaOH > KNO3 > H2O, but the absolute amounts differed between CLA and DLA. Peak concentrations of the total metals were achieved at the highest burning temperature. The amount of H2O Soluble Ca and Mg decreased and K increased in both CLA and DLA with temperature. Total and exchangeable forms of cations increased with increasing temperature. Total Ca was highest in DLA, whereas total Mg and K were higher in CLA. This study indicated that incinerating Poultry litter before soil application may have mixed effects on the vulnerable metal fractions by increasing or decreasing some fractions, depending on poultry type. (C) 2008 Elsevier Ltd. All rights reserved.