TY - JOUR A1 - Vogel, Christian A1 - Adam, Christian A1 - Kappen, P. A1 - Schiller, T. A1 - Lipiec, E. A1 - McNaughton, D. T1 - Chemical state of chromium in sewage sludge ash based phosphorus-fertilisers T2 - Chemosphere N2 - Sewage sludge ash (SSA) based P-fertilisers were produced by thermochemical treatment of SSA with Cl-donors at approximately 1000 °C. During this thermochemical process heavy metals are separated as heavy metal chlorides via the gas phase. Chromium cannot be separated under normal conditions. The risk of the development of toxic Cr(VI) during the thermochemical process was investigated. X-ray Absorption Spectroscopy measurements showed that SSA and thermochemically treated SSA with CaCl2, MgCl2 and NaCl contain Cr(III) compounds only. In contrast, treating SSA with elevated quantities of Na2CO3, to enhance the plant-availability of the phosphate phases of the fertiliser, developed approximately 10–15% Cr(VI). Furthermore, Raman microspectroscopy showed that using Mg-carbonate reduces the risk of a Cr(VI) development during thermochemical treatment. Additionally, leaching tests showed that only a Cr–water solubility >10% is an indicator for Cr(VI) in SSA based P-fertilisers. PB - Elsevier Science CY - Kidlington, Oxford KW - Chromium KW - Fertiliser KW - Sewage sludge ash KW - Raman microspectroscopy KW - X-ray absorption spectroscopy PY - 2014 UR - https://opus4.kobv.de/opus4-bam/frontdoor/index/index/docId/30062 AN - OPUS4-30062 SN - 0045-6535 SN - 0366-7111 VL - 103 SP - 250 EP - 255 AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany