TY - JOUR
A1 - Krüger, Oliver
A1 - Adam, Christian
T1 - Phosphorus in recycling fertilizers - analytical challenges
N2 - The importance of secondary raw materials for phosphorus (P) fertilizer production is expected to increase in the future due to resource depletion, supply risks, and heavy metal contamination of fossil phosphate resources. Municipal wastewater is a promising source for P recovery. In Germany for instance, it contains almost 50% of the total amount of P that is currently applied as mineral fertilizer. Several procedures have been developed to recover and re-use P resulting in a growing number of recycling fertilizers that are currently not regulated in terms of fertilizer efficiency. We tested various materials and matrices for their total P content, solubility of P in neutral ammonium citrate (Pnac) and water, and performed robustness tests to check if existing analytical methods are suitable for those new materials. Digestion with inverse aqua regia was best suited to determine the total P content. Pnac sample preparation and analyses were feasible for all matrices. However, we found significant time and temperature dependencies, especially for materials containing organic matter. Furthermore, several materials didn’t reach equilibrium during the extractions. Thus, strict compliance of the test conditions is strongly recommended to achieve comparable results.
KW - Recycling fertilizer
PY - 2017
DO - https://doi.org/10.1016/j.envres.2017.02.034
SN - 0013-9351
SN - 1096-0953
VL - 155
SP - 353
EP - 358
PB - Elsevier
CY - Rotterdam
AN - OPUS4-39430
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Auer, G.
A1 - Spanka, M.
A1 - Hamann, Christopher
A1 - Adam, Christian
T1 - Thermal zinc extraction from steel mill dust
N2 - Treatment and reusing of hazardous wastes have become significant issues of modern societies. Blast furnace sludge (BFS) and electric arc furnace dust (EAFD) are such typical wastes, because they usually contain high amounts of undesirable elements such as zinc (Zn) and lead (Pb).
These elements can cause operational problems in reusing of BFS and EAFD. In this study, the Ferro Duo GmbH and the Federal Institute for Materials Research and Testing have investigated a novel approach for eliminating and/or recovering Zn and Pb from both wastes. Applied was a selective chlorination and volatilization of Zn and Pb as chlorides at temperatures between 500 °C and 1100 °C. Both product obtained, Zn and Pb in the form of ZnCl2 and PbCl2 and the purified solid mineral compound are attractive materials for further use. Hydrochloric acid and iron(II) chloride were used as chlorination agents. Exceptionally high Zn and Pb removal efficiencies of >99.5 % could be achieved with both chlorination agents, whereby iron(II) chloride exhibited better performance.
KW - Blast furnace sludge
KW - Chlorination
KW - Electric arc furnace dust
KW - Lead
KW - Zinc
KW - Thermochemical treatment
PY - 2019
SN - 1613-2394
VL - 72
IS - 1
SP - 27
EP - 31
PB - GDMB Verlag GmbH
CY - Clausthal-Zellerfeld
AN - OPUS4-47288
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Jovičević-Klug, Matic
A1 - Souza Filho, Isnaldi R.
A1 - Springer, Hauke
A1 - Adam, Christian
A1 - Raabe, Dierk
T1 - Green steel from red mud through climate-neutral hydrogen plasma reduction
N2 - AbstractRed mud is the waste of bauxite refinement into alumina, the feedstock for aluminium production1. With about 180 million tonnes produced per year1, red mud has amassed to one of the largest environmentally hazardous waste products, with the staggering amount of 4 billion tonnes accumulated on a global scale1. Here we present how this red mud can be turned into valuable and sustainable feedstock for ironmaking using fossil-free hydrogen-plasma-based reduction, thus mitigating a part of the steel-related carbon dioxide emissions by making it available for the production of several hundred million tonnes of green steel. The process proceeds through rapid liquid-state reduction, chemical partitioning, as well as density-driven and viscosity-driven separation between metal and oxides. We show the underlying chemical reactions, pH-neutralization processes and phase transformations during this surprisingly simple and fast reduction method. The approach establishes a sustainable toxic-waste treatment from aluminium production through using red mud as feedstock to mitigate greenhouse gas emissions from steelmaking.
KW - Multidisciplinary
PY - 2024
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-594424
DO - https://doi.org/10.1038/s41586-023-06901-z
SN - 0028-0836
VL - 625
IS - 7996
SP - 703
EP - 709
PB - Springer Science and Business Media LLC
AN - OPUS4-59442
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Schraut, Katharina
A1 - Adamczyk, Burkart
A1 - Adam, Christian
A1 - Stephan, Dietmar
A1 - Meng, Birgit
A1 - Simon, Sebastian
A1 - von Werder, Julia
A1 - Hirsch, Tamino
A1 - Manninger, Tanja
T1 - Effect of gypsum on the hydration of fused cement clinker from basic oxygen furnace slag
N2 - Fused cement clinker can be produced from molten basic oxygen furnace slag (BOFS) by way of a reductive thermochemical treatment. During the thermochemical treatment, oxidic iron is reduced to metallic iron and separated. The resulting low-iron slag has a chemical and mineralogical composition similar to ordinary Portland cement (OPC) clinker. In this study, the hydraulic reactivity of the fused clinker from BOFS with and without gypsum was investigated using isothermal calorimetry, differential scanning calorimetry, in situ X-ray diffraction and powder X-ray diffraction. Furthermore, a synthetic fused clinker without foreign ions and fused clinker produced by a mixture of both materials was studied. The hydraulic reaction of the fused clinker from BOFS was considerably slower than that of OPC. However, the reaction can be accelerated by adding gypsum as a sulfate carrier. Furthermore, the results showed an increased reaction rate with decreasing content of foreign ions such as Fe, P or Mn.
KW - General Materials Science
KW - Building and Construction
PY - 2024
DO - https://doi.org/10.1680/jadcr.23.00070
SN - 0951-7197
SP - 1
EP - 19
PB - Telford
AN - OPUS4-59391
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Hamann, Christopher
A1 - Piehl, Patrick
A1 - Weingart, Eric
A1 - Stolle, Dirk
A1 - Al-Sabbagh, Dominik
A1 - Ostermann, Markus
A1 - Auer, Gerhard
A1 - Adam, Christian
T1 - Selective removal of zinc and lead from electric arc furnace dust by chlorination–evaporation reactions
N2 - Re-melting of scrap in an electric arc furnace (EAF) results in the accumulation of filter dust from off-gas treatment that predominantly consists of iron and zinc oxides. Filter dust is classified as hazardous waste due to its high contents of potentially toxic or ecotoxic elements such as Pb, Cr, Cd, and As. A promising processing route for this waste is selective chlorination, in which the non-ferrous metal oxides are chlorinated and selectively evaporated in form of their respective chlorides from the remaining solids via the process gas flow. Here, we investigate stepwise thermochemical treatment of EAF dust with either waste iron(II) chloride solution or hydrochloric acid at 650, 800, and 1100 ◦C. The Zn and Pb contents of the thermochemically processed EAF dust could be lowered from 29.9% and 1.63% to 0.09% and 0.004%, respectively. Stepwise heating allowed high separation between zinc chloride at the 650 ◦C step and sodium-, potassium-, and lead-containing chlorides at higher temperatures. Furthermore, the lab-scale results were transferred to the use of an experimental rotary kiln highlighting the possibilities of upscaling the presented process. Selective chlorination of EAF dust with liquid chlorine donors is, therefore, suggested as a potential recycling method for Zn-enriched steelworks dusts.
KW - Electric arc furnace dust
KW - Zinc
KW - Selective Chlorination
KW - Hazardous waste
KW - Resource Recovery
PY - 2024
DO - https://doi.org/10.1016/j.jhazmat.2023.133421
SN - 0304-3894
VL - 465
SP - 1
EP - 13
PB - Elsevier
AN - OPUS4-59345
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Sichler, Theresa Constanze
A1 - Adam, Christian
A1 - Becker, Roland
A1 - Sauer, Andreas
A1 - Ostermann, Markus
A1 - Barjenbruch, M.
T1 - Phosphorus determination in sewage sludge: comparison of different aqua regia digestion methods and ICP-OES, ICP-MS and photometric determination
N2 - Phosphorus recycling from sewage sludge will be obligatory in Germany from 2029. Phosphorus content determination in sewage sludge is crucial to assess the prescribed recycling rates. Currently, German law regards sample preparation using aqua regia digestion in a microwave or under reflux conditions as well as instrumental phosphorus determination by ICP-OES, ICP-MS, or photometric determination with ammonium molybdate as equivalent. However, it is questionable whether these methods are indeed equivalent regarding phosphorus quantification in sludges near the limit of 20 g/kg for mandatory recycling. To answer this question, 15 sewage sludges of 11 different wastewater treatment plants were investigated with all permitted method (digestion and measurement) combinations. Moreover, one sewage sludge was also examined in an interlaboratory comparison (ILC) with 28 participants. This study shows that the above-mentioned methods differ in some cases significantly but across all method combinations and sludges, phosphorus recovery was between 80 and 121% after normalization to the grand mean (average of 15 sludges between 85 and 111%). The ILC and the examination of 15 sludges produced largely similar results. There is a tendency to higher phosphorus recovery after microwave digestion compared to reflux digestion and ICP-OES measurements determine higher phosphorus contents than ICP-MS and photometric phosphorus determination. As a result, the authors recommend ICP-OES determination of phosphorus in sewage sludge after microwave digestion.
KW - Sewage sludge
KW - ICP-OES
KW - Phosphous recovery
KW - ICP-MS
KW - Photometric P determination
KW - Interlaboratory comparison
PY - 2022
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-558869
DO - https://doi.org/10.1186/s12302-022-00677-1
VL - 34
IS - 99
SP - 1
EP - 14
PB - Springer
AN - OPUS4-55886
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Adam, Christian
A1 - Kley, Gerd
A1 - Simon, Franz-Georg
T1 - Thermal treatment of municipal sewage sludge aiming at marketable P-fertilisers
N2 - Municipal sewage sludge is a carrier of nutrients most important phosphorus (P) but also contains organic pollutants and heavy metals. A two steps thermal treatment is suggested based on 1. mono-incineration of sewage sludge under destruction of organic pollutants and 2. thermochemical treatment of the resulting ashes to remove heavy metals and increase P-bioavailability. The targeted products are marketable P-fertilisers. The thermochemical treatment was investigated in a gas tight lab-scale rotary furnace. Seven sewage sludge ashes of different origin and composition and one residue from gasification of sewage sludge were mixed with a chlorine donor (e.g. MgCl2) and thermochemically treated under systematic variation of operational parameters. The distributions of the heavy metals between solid and gas phase were determined. The heavy metals concentrations of the treated ashes met the legislative limits in most cases. The products from thermochemical treatment are suited raw materials for P-fertiliser production. Relevant process parameters such as temperature, type and concentration of Cl-donor and retention time were optimised for the thermochemical treatment step.
KW - Sewage sludge
KW - Mono-incineration
KW - Ash treatment
KW - Thermochemical treatment
KW - Phosphorus-fertiliser
PY - 2007
SN - 1345-9678
SN - 1347-5320
VL - 48
IS - 12
SP - 3056
EP - 3061
PB - Japan Institute of Metals
CY - Sendai
AN - OPUS4-16647
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Adam, Christian
A1 - Kley, Gerd
A1 - Simon, Franz-Georg
A1 - Lehmann, Annekatrin
T1 - Recovery of nutrients from sewage sludge - Results of the European research-project SUSAN
N2 - Municipal sewage sludge is a carrier of nutrients most important phosphorus (P) but also contains organic pollutants and heavy metals. A two steps thermal treatment based on 1. mono-incineration of sewage sludge under destruction of organic pollutants and 2. thermochemical treatment of the resulting ashes to remove heavy metals and increase P-bioavailability is suggested by the authors. The process aims at P-fertilisers production from sewage sludge. Seven sewage sludge ashes of different origin and composition and one residue from gasification of sewage sludge were thermochemically treated. The raw ashes were mixed with a chlorine donor (e.g. MgCl2) and thermally treated in a gas tight lab-scale rotary furnace. The distributions of the heavy metals between solid and gas phase were determined. The heavy metals concentrations of the treated ashes matched the legislative limits in most cases. The products from thermochemical treatment are suited raw materials for P-fertiliser production. Relevant process parameters such as temperature, type and concentration of Cl-donor and retention time were optimised for the thermochemical treatment step.
KW - Phosphorus recovery
KW - Sewage sludge ash
KW - Thermochemical treatment
KW - Fetiliser
PY - 2008
DO - https://doi.org/10.2166/wpt.2008.001
SN - 1751-231X
VL - 3
IS - 1
SP - 1
EP - 8
PB - IWA Publishing
AN - OPUS4-17700
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Adam, Christian
A1 - Peplinski, Burkhard
A1 - Michaelis, Matthias
A1 - Kley, Gerd
A1 - Simon, Franz-Georg
T1 - Thermochemical treatment of sewage sludge ashes for phosphorus recovery
N2 - Phosphorus (P) is an essential element for all living organisms and cannot be replaced. Municipal sewage sludge is a carrier of phosphorus, but also contains organic pollutants and heavy metals. A two-step thermal treatment is suggested, including mono-incineration of sewage sludge and subsequent thermochemical treatment of the ashes. Organic pollutants are completely destroyed by mono-incineration. The resulting sewage sludge ashes contain P, but also heavy metals. P in the ashes exhibits low bioavailability, a disadvantage in farming. Therefore, in a second thermochemical step, P is transferred into mineral phases available for plants, and heavy metals are removed as well. The thermochemical treatment was investigated in a laboratory-scale rotary furnace by treating seven different sewage sludge ashes under systematic variation of operational parameters. Heavy metal removal and the increase of the P-bioavailability were the focus of the investigation. The present experimental study shows that these objectives have been achieved with the proposed process. The P-bioavailability was significantly increased due to the formation of new mineral phases such as chlorapatite, farringtonite and stanfieldite during thermochemical treatment.
KW - P-recovery
KW - Sewage sludge ash
KW - Thermochemical treatment
KW - Mineral phases
KW - X-ray diffraction
PY - 2009
DO - https://doi.org/10.1016/j.wasman.2008.09.011
SN - 0956-053X
VL - 29
IS - 3
SP - 1122
EP - 1128
PB - Pergamon Press
CY - New York, NY
AN - OPUS4-18605
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Peplinski, Burkhard
A1 - Adam, Christian
A1 - Michaelis, Matthias
A1 - Kley, Gerd
A1 - Emmerling, Franziska
A1 - Simon, Franz-Georg
T1 - Reaction sequences in the thermochemical treatment of sewage sludge ashes revealed by X-ray powder diffraction - A contribution to the European project SUSAN
N2 - The sequence of reactions accompanying the thermochemical treatment of an iron- and aluminium-bearing sewage sludge ash was ascertained by investigating two systematic series of samples. The ash was thermochemically treated in a lab-scale rotary furnace after mixing it with a chlorine-donor, either CaCl2 or MgCl2. Within each of these two sample series only a single process parameter, the reaction temperature, was varied, namely between 350 and 1050°C. It was found, that among the numerous crystalline phases present in the raw ash only quartz and hematite continue to exist after thermochemical treatments carried out at 1050°C, whereas all other components undergo at least one decomposition-recrystallization cycle. Some of the components re-crystallize even several times. It was proved that the restructuring of the calcium- and phosphorus-bearing mineral phases proceeds via the formation of chlorspodioside, Ca2PO4Cl. The influence of the type of chlorine-donor on the final product was elucidated in detail and - to the best of our knowledge - for the first time crystalline AlPO4 was found in a sewage sludge ash and its decomposition was investigated, too.
KW - XRD
KW - Phosphorus recovery
KW - Sewage sludge ash
KW - Urban mining
KW - Fertilizers
PY - 2009
DO - https://doi.org/10.1524/zksu.2009.0068
SN - 0930-486X
VL - 30 EPDIC 2008
SP - 459
EP - 464
PB - Oldenbourg
CY - München
AN - OPUS4-20562
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Herzel, Hannes
A1 - Grevel, K.-D.
A1 - Emmerling, Franziska
A1 - Dachs, E.
A1 - Benisek, A.
A1 - Adam, Christian
A1 - Majzlan, J.
T1 - Thermodynamic properties of calcium alkali phosphates Ca(Na,K)PO4
N2 - Calcium alkali phosphates Ca(Na,K)PO4 are main constituents of bioceramics and thermochemically produced phosphorus fertilizers because of their bioavailability. Sparse thermodynamic data are available for the endmembers CaNaPO4 and CaKPO4. In this work, the missing data were determined for the low-temperature phase modifications of the endmembers CaNaPO4 and CaKPO4 and three intermediate Ca(Na,K)PO4 compositions. Standard enthalpy of formation ranges from - 2018.3 ± 2.2 kJ mol-1 to - 2030.5 ± 2.1 kJ mol-1 and standard entropy from 137.2 ± 1.0 J mol-1 K-1 to 148.6 ± 1.0 J mol-1 K-1 from sodium endmember b-CaNaPO4 to potassium endmember b0-CaKPO4.
Thermodynamic functions are calculated up to 1400 K for endmembers and the sodium-rich intermediate phase b-Ca(Na0.93K0.07)PO4. Functions above 640 K are extrapolated because of the phase transition from low- to high-temperature phase. Impurities in the synthesized intermediate phases c-Ca(Na0.4K0.6)PO4 and c-Ca Na0.35K0.65)PO4 and one additional phase transition around 500 K impeded the determination of high-temperature thermodynamic functions. In general, data for phase transition temperatures agree with the previously reported phase diagrams.
KW - Formation enthalpy
KW - Heat capacity
KW - Phase transformation
KW - Bioceramics
KW - Phosphorus fertilizer
KW - Entropy
PY - 2020
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-507640
DO - https://doi.org/10.1007/s10853-020-04615-5
VL - 55
SP - 8477
EP - 8490
PB - Springer
AN - OPUS4-50764
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Dombinov, V.
A1 - Herzel, Hannes
A1 - Meiller, M.
A1 - Müller, F.
A1 - Willbold, S.
A1 - Zang, J. W.
A1 - da Fonseca-Zang, W. A.
A1 - Adam, Christian
A1 - Klose, H.
A1 - Poorter, H.
A1 - Jablonowski, N. D.
A1 - Schrey, S. D.
T1 - Sugarcane bagasse ash as fertilizer for soybeans: Effects of added residues on ash composition, mineralogy, phosphorus extractability and plant availability
N2 - Sugarcane bagasse is commonly combusted to generate energy. Unfortunately, recycling strategies rarely consider the resulting ash as a potential fertilizer. To evaluate this recycling strategy for a sustainable circular economy, we characterized bagasse ash as a fertilizer and measured the effects of co-gasification and co-combustion of bagasse with either chicken manure or sewage sludge: on the phosphorus (P) mass fraction, P-extractability, and mineral P phases. Furthermore, we investigated the ashes as fertilizer for soybeans under greenhouse conditions. All methods in combination are reliable indicators helping to assess and predict P availability from ashes to soybeans. The fertilizer efficiency of pure bagasse ash increased with the ash amount supplied to the substrate. Nevertheless, it was not as effective as fertilization with triple-superphosphate and K2SO4, which we attributed to lower P availability. Co-gasification and co-combustion increased the P mass fraction in all bagasse-based ashes, but its extractability and availability to soybeans increased only when co-processed with chicken manure, because it enabled the formation of readily available Ca-alkali phosphates. Therefore, we recommend co-combusting biomass with alkali-rich residues to increase the availability of P from the ash to plants.
KW - Combustion and gasification
KW - Phosphate extractability and availability
KW - X-ray diffraction (XRD)
PY - 2022
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-567632
DO - https://doi.org/10.3389/fpls.2022.1041924
SN - 1664-462X
VL - 13
SP - 1
EP - 13
PB - Frontiers Media
CY - Lausanne
AN - OPUS4-56763
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Huber, F.
A1 - Herzel, Hannes
A1 - Adam, Christian
A1 - Mallow, O.
A1 - Blasenbauer, D.
A1 - Fellner, J.
T1 - Combined disc pelletisation and thermal treatment of MSWI fly ash
N2 - An environmentally friendly and cost efficient way for the management of municipal solid waste incineration (MSWI) fly ash represents its thermal co-treatment together with combustible waste. However, the safe introduction and storage of MSWI fly ash in the waste bunker is challenging and associated with severe problems (e.g. dust emissions, generation of undefined lumps and heat in case of moistened MSWI fly ash). Therefore, the aim of this study is to investigate the suitability of pelletisation as a pretreatment of MSWI fly ash. In particular, MSWI fly ash was characterised after sampling, pelletisation and thermal treatment and the transfer of constituents to secondary fly ash and flue gas was investigated. For this purpose, MSWI fly ash pellets with a water content of about 0.15 kg/kg and a diameter of about 8 mm have been produced by disc pelletiser and treated in an electrically heated pilot-scale rotary kiln at different temperatures, ranging from 450°C to 1050°C. The total contents of selected elements in the MSWI fly ash before and after thermal treatment and in the generated secondary fly ash have been analysed in order to understand the fate of each element. Furthermore, leachable contents of selected elements and total content of persistent organic pollutants of the thermally treated MSWI fly ash were determined. Due to the low total content of Hg (0.7 mg/kg) and the low leachate content of Pb (<0.36 mg/kg), even at the lowest treatment temperature of 450°C, thermally treated MSWI fly ash pellets can be classified as nonhazardous waste. However, temperatures of at least 650°C are necessary to decrease the toxic equivalency of PCDD/F and DL-PCB. The removal of toxic heavy metals like Cd and Pb is significantly improved at temperatures of 850°C, 950°C or even 1050°C. The observed metal removal led to relatively high contents of e.g. Cu (up to 11,000 mg/kg), Pb (up to 91,000 mg/kg) and Zn (up to 21,000 mg/kg) in the secondary fly ash. This metal enriched secondary fly ash might represent a potential raw material for metal recovery (e.g. via acidic leaching). Due to the high content of total dissolved solids observed in the leachate of thermally treated MSWI fly ash pellets, a wet extraction procedure is suggested to enable its safe disposal at non-hazardous waste landfills.
KW - MSWI fly ash
KW - Thermal treatment
PY - 2018
DO - https://doi.org/10.1016/j.wasman.2017.12.020
SN - 0956-053X
VL - 73
SP - 381
EP - 391
PB - Elsevier Ltd.
CY - Rotterdam
AN - OPUS4-44481
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Herzel, Hannes
A1 - Stemann, J.
A1 - Simon, Sebastian
A1 - Adam, Christian
T1 - Comparison of thermochemical treatment of sewage sludge ash with sodium sulphate in laboratory-scale and pilot-scale experiments
N2 - There is an ongoing debate on European scale concerning the criticality of phosphorus. In Switzerland and Germany, phosphorus recovery from phosphorus-rich waste streams will become obligatory. Sewage sludge ash is rich in phosphorus and may become an important secondary feedstock. Thermochemical treatment of sewage sludge ash with sodium sulphate under reducing conditions was shown to remove heavy metals from the solid product and produce the fully plant available crystalline phase CaNaPO4. Pilot-scale experiments in a rotary kiln were carried out at temperatures between 750 and 1000 °C and were compared to laboratory-scale experiments with crucibles. Process upscaling was successfully demonstrated but a series of differences were noticed: In comparison to laboratory-scale, solubility of phosphorus in samples from pilot-scale experiments was lower at all chosen treatment temperatures because of shorter retention time and incomplete decomposition of sodium sulphate. X-ray diffraction analysis revealed remaining phase fractions of whitlockite (Ca3-x(Mg,Fe)x(PO4)2) and sodium sulphate from the starting materials in products and thus indicated incomplete reaction. In contrast to the results of laboratory-scale experiments, the crystalline phase CaNaPO4 was clearly absent in the products from the rotary kiln but instead a Mg-bearing phase (Ca,Mg)NaPO4 was formed. Laboratory-scale experiments confirmed (Ca,Mg)NaPO4 is an intermediate phase between whitlockite and CaNaPO4. However, both crystalline phases are characterized by high plant availability. It was shown that heavy metal removal increased at higher temperatures whereas solubility and thus plant availability of phosphorus already reached its maxima at temperatures of 950 °C in pilot-scale and 875 °C in laboratory-scale experiments.
KW - Crystalline phase identification
KW - Heavy metal removal
KW - Phosphorus availability
KW - Process upscaling
KW - Recovery
KW - Rhenanite
PY - 2021
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-524084
DO - https://doi.org/10.1007/s13762-021-03252-y
VL - 19
IS - 3
SP - 1997
EP - 2006
PB - Springer
AN - OPUS4-52408
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Herzel, Hannes
A1 - Krüger, Oliver
A1 - Hermann, L.
A1 - Adam, Christian
T1 - Sewage sludge ash - A promising secondary phosphorus source for fertilizer production
N2 - Sewage sludge incineration is extensively practiced in some European countries such as the Netherlands, Switzerland, Austria and Germany. A survey of German sewage sludge ash showed that the recovery potential is high, approx. 19,000 t of phosphorus per year. However, the survey also discovered that the bioavailability of phosphorus in the sewage sludge ash is poor and that more than half of the ashes cannot be used as fertilizers due to high heavy metal content. A new thermochemical process for sewage sludge ash treatment was developed that transforms the ash into marketable fertilizer products. Sewage sludge ash was thermochemically treated with sodium and potassium additives under reducing conditions, whereby the phosphate-bearing mineral phases were transformed into plant available phosphates. High P-bioavailability was achieved with a molar Na/P ratio > 1.75 in the starting materials. Sodium sulfate, carbonate and hydroxide performed comparably as additives for this calcination process. Potassium carbonate and -hydroxide have to be added in a molar K/P ratio > 2.5 to achieve comparable P-solubility. The findings of the laboratory scale investigations were confirmed by an industrial demonstration trial for an ash treatment with sodium sulfate. Simultaneously, the volatile transition metal arsenic (61% removal) as well as volatile heavy metals such as cadmium (80%), mercury (68%), lead (39%) and zinc (9%) were removed via the off-gas treatment system. The product of the demonstration trial is characterized by high bioavailability and a toxic trace element mass fraction below the limit values of the German fertilizer ordinance, thus fulfilling the quality parameters for a P-fertilizer.
KW - Sewage sludge ash
KW - Phosphorus recovery
KW - Thermochemical treatment
KW - Reducing conditions
KW - Heavy metal evaporation
KW - Bioavailability
KW - Sodium sulfate
PY - 2016
DO - https://doi.org/10.1016/j.scitotenv.2015.08.059
SN - 0048-9697
SN - 1879-1026
IS - 542
SP - 1136
EP - 1143
PB - Elsevier
CY - Amsterdam
AN - OPUS4-34165
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Maresca, A.
A1 - Krüger, O.
A1 - Herzel, Hannes
A1 - Adam, Christian
A1 - Kalbe, Ute
A1 - Astrup, T. F.
T1 - Influence of wood ash pre-treatment on leaching behaviour, liming and fertilising potential
N2 - In Denmark, increasing amounts of woody biomass are being used for the production of renewable energy, resulting in more wood ashes being generated. While these materials have been mainly landfilled, wood ashes may also be utilised for fertilizing and liming purposes on top of soils. Pre-treatments involving hardening or granulation may be carried out prior to soil application. In this study, two Danish wood ash samples were hardened and/or granulated. Lab-hardening induced rapid changes in the shape of the acid neutralisation capacity curve of the ashes. Up-flow column tests, assuming local equilibrium conditions, were employed to investigate the leaching from pre-treated ashes. Granules and loose ashes demonstrated similar leaching behaviours, indicating that similar geochemical processes were governing their leaching. In comparison with untreated fresh ashes, the hardened ashes demonstrated reduced leaching of Ca, Ba, Pb and Zn with concentration levels generally below or close to the analytical limits of quantification; to the contrary, the leaching of As, P, Sb, Si, V and Mg was enhanced in the hardened ashes. The release of alkalinity was reduced by hardening. In general, all granules were barely breakable by finger-pinching and they could withstand one month of continuous leaching, preserving their overall shape. The solubility of phosphorous in neutral ammonium citrate indicated that about 30–51% of the total P content in the ash samples was released, suggesting that the ashes could be potentially valuable as P-fertiliser if applied onto soil.
KW - Wood ash
KW - Phoshpor availability
KW - Leaching
KW - Forest soils
PY - 2019
DO - https://doi.org/10.1016/j.wasman.2018.11.003
SN - 0956-053X
VL - 83
SP - 113
EP - 122
PB - Elsevier
AN - OPUS4-46583
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -