TY - JOUR A1 - Vogel, Christian A1 - Stemann, Jan A1 - Holldack, K. A1 - Sekine, R. A1 - Lipiec, E. A1 - Adam, Christian T1 - Thermal treatment of chromium (III) oxide with carbonates analyzed by far-infrared spectroscopy PY - 2015 SN - 0003-7028 SN - 1943-3530 VL - 69 IS - 10 SP - 1210 EP - 1214 PB - Society for Applied Spectroscopy CY - Frederick, Md. AN - OPUS4-34635 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Vogel, Christian A1 - Radtke, Martin A1 - Reinholz, Uwe A1 - Schäfers, F. A1 - Adam, Christian T1 - Chemical state of chromium, sulfur, and iron in sewage sludge ash based phosphorus fertilizers N2 - As an essential element of all life forms, phosphorus (P) is vital to the fertilizer industry. With decreasing quantity and quality of phosphate rock resources, recycling P-fertilizers from wastewater is of increasing interest. The P-fertilizer products of a recently developed thermochemical process for P recovery from sewage sludge ash (SSA) were investigated by chromium, sulfur, and iron K-edge X-ray near-edge structure (XANES) spectroscopy. This paper focuses the formation and prevention of toxic chromium(VI) and toxic sulfides during the thermochemical processes. Reducing conditions prevent the oxidation of chromium(III) in the SSA to toxic chromium(VI). Sulfides formed under the reducing conditions are nontoxic iron sulfides. Hematite (Fe2O3) present in the SSA is reduced to magnetite (Fe3O4). A gentle post-treatment at 400 °C under oxidizing conditions converts the iron sulfides into plant-available iron sulfates. This oxidative post-treatment does not form undesired chromium(VI) compounds. KW - X-ray absorption near-edge structure (XANES) spectroscopy KW - Phosphorus recovery KW - Sewage sludge ash KW - Chromium KW - Sulfur KW - Iron PY - 2015 DO - https://doi.org/10.1021/acssuschemeng.5b00678 SN - 2168-0485 VL - 3 IS - 10 SP - 2376 EP - 2380 PB - ACS Publ. CY - Washington, DC AN - OPUS4-34166 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Adam, Christian A1 - Herzel, Hannes A1 - Krüger, Oliver ED - Schuhmann, R. T1 - Technische Prozesse zur Phosphorrückgewinnung aus Klärschlammaschen N2 - Klärschlammaschen weisen hohe Gehalte an Phosphor auf, dieser ist allerdings schlecht für Pflanzen verfügbar. Des Weiteren enthalten sie Schwermetalle die vor dem Einsatz als Düngemittel entfernt werden müssen. Vor diesem Hintergrund wurden in den letzten Jahren nasschemische und thermochemische Verfahren entwickelt und zum Teil bereits in Demonstrationsanlagen getestet. Ein thermochemischer Verfahrensansatz wird in diesem Beitrag näher vorgestellt. Klärschlammaschen werden mit Klärschlamm als Reduktionsmittel und Natriumsulfat als Aufschlussmittel im Drehrohrofen thermisch behandelt. Bei diesem Prozess wird pflanzenverfügbares NaCaPÜ4 gebildet, unerwünschte Elemente wie As, Cd, Hg und Pb werden zum Teil über die Gasphase separiert. Die Ergebnisse eines Demonstrationsversuchs werden vorgestellt. N2 - Sewage sludge ashes exhibit high phosphorus mass fractions. However, the availability of phosphorus to plants is poor. Furthermore, sewage sludge ashes contain eco-toxicologically relevant heavy metals that have to be removed prior to agricultural application. ln front of this background several wet-chemical and thermo-chemical processes were developed in the last years and some of them were already successfully demonstrated in large scale. A thermo-chemical approach is presented in this article. Sewage sludge ashes are mixed with dry sewage sludge as reductant and sodium sulfate. Düring thermal treatment in a rotary kiln at approx. 950°C plant available NaCaPCU is formed. Furthermore undesired elements such as As, Cd, Hg and Pb are separated via the gas phase. Results of demonstration trials are presented. T2 - 8. CMM-Tagung 2015 - Innovative Feuchtemessung in Forschung und Praxis - Material - Prozesse - Systeme CY - Karlsruhe, Germany DA - 07.10.2015 KW - Klärschlammasche KW - Phoshorrückgewinnung PY - 2015 N1 - Serientitel: Innovative Feuchtemessung in Forschung und Praxis – Series title: Innovative Feuchtemessung in Forschung und Praxis SP - 251 EP - 262 AN - OPUS4-34859 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -