TY - JOUR A1 - Stemann, Jan A1 - Peplinski, Burkhard A1 - Adam, Christian T1 - Thermochemical treatment of sewage sludge ash with sodium salt additives for phosphorus fertilizer production - Analysis of underlying chemical reactions JF - Waste management N2 - Stocks of high grade phosphate rock are becoming scarce, and there is growing concern about potentially harmful impurities in conventional phosphorus fertilizers. Sewage sludge ash is a promising secondary phosphorus source. However, to remove heavy metals and convert the phosphorus contained in sewage sludge ash into mineral phases available to plants, an after-treatment is required. Laboratory-scale calcination experiments of sewage sludge ash blended with sodium salts using dried sewage sludge as a reducing agent were carried out at 1000 °C. Thus, the Ca3(PO4)2 or whitlockite component of raw sewage sludge ash, which is not readily plant available, was converted to CaNaPO4 (buchwaldite). Consequently, nearly complete phosphorus solubility in ammonium citrate (a well-established indicator for plant availability) was achieved. Moreover, it was shown that Na2CO3 may be replaced by moderately priced Na2SO4. However, molar ratios of Na/P > 2 were required to achieve >80% phosphorus solubility. Such over-stoichiometric Na consumption is largely caused by side reactions with the SiO2 component of the sewage sludge ash – an explanation for which clear evidence is provided for the first time. KW - Phosphorus recovery KW - Plant availability KW - Solubility in ammonium citrate KW - Whitlockite-to-buchwaldite transformation PY - 2015 DO - https://doi.org/10.1016/j.wasman.2015.07.029 SN - 0956-053X VL - 45 SP - 385 EP - 390 PB - Pergamon Press CY - New York, NY AN - OPUS4-33876 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Peplinski, Burkhard A1 - Adam, Christian A1 - Adamczyk, Burkart A1 - Müller, Ralf A1 - Michaelis, Matthias A1 - Krahl, T. A1 - Emmerling, Franziska T1 - Nanocrystalline and stacking-disordered beta-cristobalite AlPO4: the now deciphered main constituent of a municipal sewage sludge ash from a full-scale incineration facility JF - Powder diffraction N2 - For the first time evidence is provided that a nanocrystalline and stacking-disordered, chemically stabilized β-cristobalite form of AlPO4 occurs in a sewage sludge ash (SSA). This proof is based on a combined X-ray powder diffraction and X-ray fluorescence investigation of an SSA produced at a large-scale fluidized bed incineration facility serving a catching area with a population of 2 million. The structural and chemical characterization was carried out on 'as received' SSA samples as well as on solid residues remaining after leaching this SSA in sodium hydroxide solution. Thus, it was ascertained that the observed nanocrystalline and stacking-disordered cristobalite-like component belongs to the aluminum phosphate component of this SSA, rather than to its silicon dioxide component. In addition, a direct proof is presented that the chemically stabilized β-cristobalite form of AlPO4 does crystallize from X-ray amorphous precursors under conditions that mimic the huge heating rate and short retention time (just seconds at T ≈ 850°C), typical for fluidized bed incinerators. KW - Aluminum phosphate KW - Chemical stabilization of high-temperature forms KW - Cristobalite form KW - Stacking disorder KW - Incinerator ash KW - Sewage sludge ash PY - 2015 DO - https://doi.org/10.1017/S0885715614001213 SN - 0885-7156 VL - 30 IS - Supplement S 1 SP - S31 EP - S35 PB - JCPDS CY - Swarthmore, Pa. AN - OPUS4-33435 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 JF - ACS sustainable chemistry & engineering 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 - JOUR A1 - Krüger, Oliver A1 - Adam, Christian T1 - Recovery potential of German sewage sludge ash JF - Waste management N2 - Incineration of sewage sludge is expected to increase in the future due to growing concerns about the direct use of sludge in agriculture. Sewage sludge is the pollutant sink of wastewater treatment and thus loaded with contaminants that might pose environmental hazards. Incineration degrades organic pollutants efficiently, but since the ash is currently mostly disposed of, all valuable component like phosphorus (P) and technologically relevant metals present in the sewage sludge ash (SSA) are removed from the economic cycle entirely. We conducted a complete survey of SSA from German mono-incineration facilities and determined the theoretical recovery potential of 57 elements. German SSA contains up to 19,000 t/a P which equals approximately 13% of phosphorus applied in the German agriculture in form of phosphate rock based mineral fertilizers. Thus, SSA is an important secondary resource of P. However, its P-solubility in ammonium citrate solution, an indicator for the bioavailability, is only about 26%. Treatment of SSA is recommended to enhance P bioavailability and remove heavy metals before it is applied as fertilizer. The recovery potential for technologically relevant metals is generally low, but some of these elements might be recovered efficiently in the course of P recovery exploiting synergies. KW - Sewage sludge ash KW - Recovery potential KW - Phosphorus KW - Critical raw materials KW - Bioavailability KW - Phosphorus recovery KW - Monitoring PY - 2015 DO - https://doi.org/10.1016/j.wasman.2015.01.025 SN - 0956-053X VL - 45 SP - 400 EP - 406 PB - Pergamon Press CY - New York, NY AN - OPUS4-34157 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - 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 JF - Applied 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 -