TY - JOUR A1 - Vogel, Christian A1 - Adam, Christian T1 - Heavy metal removal from sewage sludge ash by thermochemical treatment with gaseous hydrochlorid acid JF - Environmental science & technology N2 - Sewage sludge ash (SSA) is a suitable raw material for fertilizers due to its high phosphorus (P) content. However, heavy metals must be removed before agricultural application and P should be transferred into a bioavailable form. The utilization of gaseous hydrochloric acid for thermochemical heavy metal removal from SSA at approximately 1000 °C was investigated and compared to the utilization of alkaline earth metal chlorides. The heavy metal removal efficiency increased as expected with higher gas concentration, longer retention time and higher temperature. Equivalent heavy metal removal efficiency were achieved with these different Cl-donors under comparable conditions (150 g Cl/kg SSA, 1000 °C). In contrast, the bioavailability of the P-bearing compounds present in the SSA after thermal treatment with gaseous HCl was not as good as the bioavailability of the P-bearing compounds formed by the utilization of magnesium chloride. This disadvantage was overcome by mixing MgCO3 as an Mg-donor to the SSA before thermochemical treatment with the gaseous Cl-donor. A test series under systematic variation of the operational parameters showed that copper removal is more depending on the retention time than the removal of zinc. Zn-removal was declined by a decreasing ratio of the partial pressures of ZnCl2 and water. KW - Phosphorus recycling KW - Sewage sludge ash KW - Heavy metal elimination KW - Urban mining PY - 2011 DO - https://doi.org/10.1021/es2007319 SN - 0013-936X SN - 1520-5851 VL - 45 IS - 17 SP - 7445 EP - 7450 PB - ACS Publ. CY - Washington, DC AN - OPUS4-24170 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -