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Mattenberger H.,Bioenergy 2020+ GmbH | Mattenberger H.,ASH DEC Umwelt AG | Fraissler G.,Bioenergy 2020+ GmbH | Joller M.,Bioenergy 2020+ GmbH | And 7 more authors.
Waste Management | Year: 2010

Ashes from monoincineration of sewage sludge suggest themselves as an ideal base for inorganic fertiliser production due to their relatively high phosphorus (P)-content. However, previously they need to be detoxified by reducing their heavy metal content. The core process considered in this paper consists of three steps: mixing of the ashes with suitable chlorine-containing additives, granulation of the mixture and thermochemical treatment in a rotary kiln. Here relevant heavy metal compounds are first transformed into volatile species with the help of the additives and then evaporated from the granules. In this study two chemically different ashes and their mixture were agglomerated to two different granulate types, briquettes and rolled pellets. The resulting six different materials were subjected to thermal treatment at different temperatures. The heavy metals examined were Cu and Zn due to their strong dependence on treatment conditions and their relevance concerning thermal treatment of sewage sludge ashes. Besides, the behaviour of Cl and K was monitored and evaluated. The experiments showed that ash type and temperature are more influential on Cl and heavy metal chemistry than granulate type. Temperature is a primary variable for controlling removal in both cases. Cu removal was less dependent on both ash and granulate type than Zn. The Cl utilization was more effective for Cu than for Zn. Depending on the treatment conditions some K could be retained, whereas always all P remained in the treated material. This satisfies the requirement for complete P recycling. © 2010 Elsevier Ltd. Source


Ante A.,Bamag GmbH Wetzlarer | Trumpler A.,Bamag GmbH Wetzlarer | Niermann S.,Bamag GmbH Wetzlarer | Decker R.,Bamag GmbH Wetzlarer | And 2 more authors.
GWF, Wasser - Abwasser | Year: 2010

The data from the pilot plant in Leoben, especially of long-term operation, will be of essential benefit for the realisation of the demonstration plant. Resistance of materials and performance of the flue gas cleaning and Cl-recovery, respectively, can be optimised with this information. In addition cooperation with universities should be used to investigate these aspects of the phosphorus recovery in more detail. Chlorine recovery from the wash water at the existing pilot plant could be researched in master or diploma theses before implementing the technology at a productive demonstration plant. Fertiliser production should be engineered as an integral part of the thermal treatment of sewage sludge to utilise synergies of the both processes such as e.g. energy and infrastructure. The financial investigations showed big potentials for production cost optimisation but also showed that the condition regarding useful equipment (e.g. with or without Cl-recycling, dry or wet FGT system), minimum plant size etc. is highly depending on the location and it surrounding conditions. Source


Nowak B.,Vienna University of Technology | Perutka L.,Vienna University of Technology | Aschenbrenner P.,Vienna University of Technology | Kraus P.,ASH DEC Umwelt AG | And 2 more authors.
Waste Management | Year: 2011

Phosphate recycling from sewage sludge can be achieved by heavy metal removal from sewage sludge ash (SSA) producing a fertilizer product: mixing SSA with chloride and treating this mixture (eventually after granulation) in a rotary kiln at 1000±100°C leads to the formation of volatile heavy metal compounds that evaporate and to P-phases with high bio-availability. Due to economical and ecological reasons, it is necessary to reduce the energy consumption of this technology. Generally, fluidized bed reactors are characterized by high heat and mass transfer and thus promise the saving of energy. Therefore, a rotary reactor and a fluidized bed reactor (both laboratory-scale and operated in batch mode) are used for the treatment of granulates containing SSA and CaCl 2. Treatment temperature, residence time and - in case of the fluidized bed reactor - superficial velocity are varied between 800 and 900°C, 10 and 30min and 3.4 and 4.6ms -1. Cd and Pb can be removed well (>95 %) in all experiments. Cu removal ranges from 25% to 84%, for Zn 75-90% are realized. The amount of heavy metals removed increases with increasing temperature and residence time which is most pronounced for Cu. In the pellet, three major reactions occur: formation of HCl and Cl 2 from CaCl 2; diffusion and reaction of these gases with heavy metal compounds; side reactions from heavy metal compounds with matrix material. Although, heat and mass transfer are higher in the fluidized bed reactor, Pb and Zn removal is slightly better in the rotary reactor. This is due the accelerated migration of formed HCl and Cl 2 out of the pellets into the reactor atmosphere. Cu is apparently limited by the diffusion of its chloride thus the removal is higher in the fluidized bed unit. © 2011 Elsevier Ltd. Source


Nowak B.,Vienna University of Technology | Pessl A.,Vienna University of Technology | Aschenbrenner P.,Vienna University of Technology | Szentannai P.,Vienna University of Technology | And 4 more authors.
Journal of Hazardous Materials | Year: 2010

Municipal solid waste (MSW) fly ash is classified as a hazardous material because it contains high amounts of heavy metals. For decontamination, MSW fly ash is first mixed with alkali or alkaline earth metal chlorides (e.g. calcium chloride) and water, and then the mixture is pelletized and treated in a rotary reactor at about 1000°C. Volatile heavy metal compounds are formed and evaporate. In this paper, the effect of calcium chloride addition, gas velocity, temperature and residence time on the separation of heavy metals are studied. The fly ash was sampled at the waste-to-energy plant Fernwärme Wien/Spittelau (Vienna, Austria). The results were obtained from batch tests performed in an indirectly heated laboratory-scale rotary reactor. More than 90% of Cd and Pb and about 60% of Cu and 80% of Zn could be removed in the experiments. © 2010 Elsevier B.V. Source

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