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 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 U6 - 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 - Petzet, S. A1 - Peplinski, Burkhard A1 - Cornel, P. T1 - On wet chemical phosphorus recovery from sewage sludge ash by acidic or alkaline leaching and an optimized combination of both N2 - The advantages and drawbacks of existing wet chemical phosphorus (P) recovery technologies, their applicability to different types of sewage sludge ash (SSA) and the role of the decay products of detergent zeolites as a source of reactive Al in SSA are analyzed. Since neither a purely acidic nor a purely alkaline treatment are able to provide satisfactory technical solutions a wet chemical phosphorus (P) recovery process for sewage sludge ashes (SSAs) is investigated in detail that is based on a sequential treatment of SSA with an acid and a base. As a result of an acidic pre-treatment, the P fraction of the raw SSA that was bound as – alkaline-insoluble – calcium phosphate (Ca–P) is converted into aluminum phosphate (Al–P). This newly formed Al–P can be easily dissolved via alkaline treatment and then easily separated from the alkaline leachate via precipitation of Ca–P. The Al-component can be reused as precipitant for P-removal in waste water treatment plants (WWTPs). The investigated process requires fewer chemicals than the direct acidic dissolution of all P-compounds contained in the SSA. This is due to the described rearrangement of the P component from Ca–P to Al–P. That such a rearrangement of P occurs indeed was confirmed through a combination of XRD, ICP and XRF analyses together with mass balance calculations. The present investigation proves that the process works for very different types of SSAs: For Al-rich SSAs that come from WWTPs where Al-salt is used for chemical P-removal the described sequential treatment process works best and yields P-recovery rates as high as 70–77%. But even for SSAs from WWTPs where only iron salt is used for chemical P-removal, a considerable amount of the reactive Al necessary for the described P-rearrangement is supplied by decay products of detergent zeolites, a hidden Al-source present in most SSAs produced in Europe. KW - Phosphorus recovery KW - Sewage sludge ash KW - Alkaline and acidic leaching KW - Calcium phosphate KW - Aluminum phosphate KW - Detergent zeolites KW - XRD analysis PY - 2012 U6 - https://doi.org/10.1016/j.watres.2012.03.068 SN - 0043-1354 VL - 46 IS - 12 SP - 3769 EP - 3780 PB - Elsevier CY - Amsterdam AN - OPUS4-26005 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -