4 Material und Umwelt
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- 4.4 Thermochemische Reststoffbehandlung und Wertstoffrückgewinnung (91) (entfernen)
During the last decades the material composition of buildings has become increasingly diverse. However, largely sorted material flows are needed for generating high quality secondary building materials. The use of secondary building materials can meet the requirements of sustainability in several ways: the extended time availability of primary raw materials and, thereby, the preservation of natural resources as well as the conservation of landfill sites.
Recycling of gypsum (calcium sulfate) can be a good example for the environmental benefits of closed-loop recycling. The content of sulfates in other secondary building materials, in particular in recycled concrete aggregates, should be minimized for quality reasons. In contrast, separated gypsum can also be used in gypsum production if the high quality requirements for the recycled gypsum are met. Since almost all processing steps in the recycling process are associated with environmental impacts, an environmental evaluation of the use of recycled gypsum as a substitute in gypsum production has to be carefully conducted.
This paper focusses on the techniques for generating recycled gypsum from gypsum plasterboards, the related quality requirements and a comprehensive environmental evaluation of the complete process.
The aim of this study was to investigate the passive sampler method Diffusive Gradients in Thin-films (DGT) for ammonium and nitrate in amended soils. Therefore, we used soils from a pot experiment with maize where nitrogen (N) was supplied as ammonium sulfate nitrate (ASN), without and with a nitrification inhibitor (NI). The additional use of a NI can delay the nitrification in the soil and making the ammonium available for a longer period in the soil solution after its application. Homogenized soil samples were collected directly from each pot after one week of incubation before sowing and after harvesting the maize. Nitrate and ammonium in these soil samples were extracted using DGT devices equipped with a Putolite A520E (for nitrate) and Microlite PrCH (for ammonium) binding layer. Ammonium DGT which determined the mobile and labile ammonium forms based on diffusion and the resupplies from the solid soil phase, only showed a significantly higher amount of extractable ammonium with NI compared to that without NI for some samples. However, significantly lower values were found for nitrate of treatments with NI compared to without NI after harvest. Thus, the lower nitrate amounts for treatments with NI compared to the treatments without NI after harvest indicated the delay of the nitrification process by the NI. Furthermore, we compared also the ammonium and nitrate
DGT results to chemical extraction with KCl solutions. The results demonstrated that the trends of DGT results and chemical extraction were complimentary through all the treatments.
Analyseverfahren und Messhäufigkeit zur Bestimmung des Phosphorgehalts im Klärschlamm nach AbfKlärV
(2022)
Auf dem Betreiberforum der DWA-Plattform P-Rück wurden die Empfehlungen für den Vollzug der Phosphorrückgewinnungspflicht aus Klärschlamm vorgestellt. Diese Empfehlungen behandeln die Häufigkeit der Phosphoruntersuchungen im Klärschlamm, wo ein Jahresgang empfohlen wird und eine Empfehlung der Phosphorbestimmung über Aufschluss der Probe in der Mikrowelle und Messung mit ICP-OES. Untermauert wurden die Empfehlungen mit den Ergebnissen von Klärschlamm-Monitoring, Ringversuch und Analytikvergleich aus dem Vorhaben extraWERT.
The challenge of the project ASHES is focused on the recycling of nutrients from residues of thermochemical processing of by-products of sugar cane industry (bagasse/straw) in Brazil to increase the energy efficiency of thermal conversion and to enable the recycling of process ashes as fertilisers. Dry lignocellulosic biomass (straw, bagasse) are combusted, gasified and subsequently combined with post-thermochemical treatment in the AshDec process to increase the plant availability of phosphorus. Different fertilizer formulations are granulated/pelletized and tested regarding their storage/handling characteristics.
Die landwirtschaftliche Klärschlammverwertung ist in der Bundesrepublik Deutschland seit Jahren rückläufig. Neben den Risiken durch Schadstoffeinträge gibt es in Deutschland Regionen mit einem stark erhöhten Nährstoffüberschuss. Um die Grundwasserbelastung zu verhindern wurde u.a. das Düngerecht verschärft, was die Flächenkonkurrenz zwischen Klärschlamm und Wirtschaftsdünger vergrößern wird.
Es ist davon auszugehen, dass sich die neuen Regelungen im Düngerecht und der Klärschlammverordnung massiv auf die landwirtschaftliche Verwertung von Klärschlamm und damit auf die Kreislaufwirtschaft verschiedener Nährstoffe auswirken werden. In diesem Beitrag werden erste Ergebnisse des Projekts extraWERT vorgestellt.
In Deutschland ist ab 2029 eine Phosphorrückgewinnung aus Klärschlamm verpflichtend. Ausgenommen sind Klärschlämme mit weniger als 20 g P/kg TM. Für die Phosphorbestimmung sind verschiedene Methoden nach Klärschlammverordnung als gleichwertig zugelassen: Der Königswasseraufschluss in der Mikrowelle und am Rückfluss sowie die Messung an ICP-OES, ICP-MS und die photometrische Bestimmung mittels Ammoniummolybdaten. An der BAM wurden die unterschiedlichen Methodenkombinationen aus Aufschluss- und Messmethode an 15 Klärschlämmen überprüft und in einem Ringversuch mit einem Klärschlamm getestet. Die Ergebnisse werden in diesem Vortrag zusammengefasst. Als Folge der Untersuchungen wird für die Phosphorbestimmung in Klärschlamm die ICP-OES-Messung nach Königswasseraufschluss in der Mikrowelle empfohlen.
Phosphorus (P) fertilizers from secondary resources became increasingly important in the last years. However, these novel P-fertilizers can also contain toxic pollutants. Chromium in its hexavalent state (Cr(VI)) is regulated with low limit values for agricultural products due to its high toxicity, but the determination of Cr(VI) in these novel fertilizer matrices can be hampered by redox processes that lead to false results. Thus, we applied the passive sampler technique Diffusive Gradients in Thin-films (DGT) for the determination of Cr(VI) in fertilizers and compared the results with the standard wet chemical extraction method (German norm DIN EN 15192) and Cr K-edge X-ray absorption near-edge structure (XANES) spectroscopy. We determined an overall good correlation between the wet chemical extraction and the DGT method. DGT was very sensitive and in most cases selective for the analysis of Cr(VI) in P-fertilizers. However, hardly soluble Cr(VI) compounds cannot be detected with the DGT method since only mobile Cr(VI) is analyzed. Furthermore, Cr K-edge XANES spectroscopy showed that the DGT binding layer also adsorbs small amounts of mobile Cr(III) compounds which leads to overestimated Cr(VI) values. The results of certain types of P-fertilizers containing mobile Cr(III) or partly immobile Cr(VI), showed that optimization of the DGT method is required to avoid over- or underestimation of Cr(VI).
Lightweighting as a cross-cutting technology contributes significantly to achieve the European Green Deal goals. Based on, but not limited to, advanced materials and production technologies, the demand for natural resources and CO2 emmissions are reduced by lightweighting during production, as well as use phase. Therefore, lightweighting is a crucial transformation technology assisting in decoupling economic growth from resource consumption. In this manner, lightweighting contributes significantly as a key technology of relevance for many industrial sectors such as energy, mobility, and infrastructure, towards resource efficiency, climate action and economic strength, as well as a resilient Europe. To strengthen international partnerships, addressing global issues of today at the edge of science with high performance lightweight material based on carbon fibers, an overview about the BAM expertise in carbon fiber reinforced materials is given.