This study focuses on the characterisation of sewage sludge ashes from 2 sites in Switzerland. The elemental composition and the acid neutralising capacity (ANC) were determined and mineral components identified. The leaching behaviour of major and minor inorganic components was assessed as a function of liquid:solid (L:S) ratio and leachate pH. The major elements are Ca, Al, Si, and P, all having concentrations around and above 5% w/w. In the SSA samples, the Fe concentrations are high (around 15%) and this is associated with the treatment of sewage sludge. Organic carbon concentrations are around 0.5% as HCHO. Carbonate concentrations lie between 0.1 and 0.7% for all samples. The heavy metal and metalloid components in the highest concentrations are Cu, Zn, Mn, Pb, Cr and Ni, which are all in the g kg−1 range. In the mg kg−1 range are V, Co, Sb, As, Mo, Cd, W and Se. The solubility of the heavy metal and metalloid ions is low due to the precipitation of solid phases and adsorption to Fe oxides.

  • Introduction

  • Sampling and Analytical Procedures

  • Results and Discussion

  • Conclusions

  • Acknowledgements

  • References

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