Investigations into the fate of engineered transition metal nano particles during sewage sludge incineration

Medientyp: Dissertation; Elektronische Hochschulschrift; E-Book

Titel: Investigations into the fate of engineered transition metal nano particles during sewage sludge incineration

Beteiligte: Wielinski, Jonas [Verfasser:in]; id_orcid0 000-0002-7017-3164 [Verfasser:in]

Erschienen: ETH Zurich, 2020

Sprache: Englisch

DOI: https://doi.org/20.500.11850/473625; https://doi.org/10.3929/ethz-b-000473625

Schlagwörter: Nanoparticle ; Civil engineering ; Transformation ; X-ray absorption spectroscopy ; Environment ; Landfill effluxes ; Incineration

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Beschreibung: Engineered nanoparticles (ENP) are applied in consumer products and industrial processes to increase profitability and sustainability through reduced resource consumption, e.g., TiO2-NP in sun screens, ZnO-NP in cosmetics and paints or Ag-NP and CuO-NP as anti-microbial agents. However, critical discussions about unintended, adverse effects of ENP on humans, soil- and aquatic organisms have always accompanied their usage. Therefore, investigations into the fate of ENP after their use phase are necessary to enable a reliable assessment of the risks associated with the use of such novel materials. Previous research efforts showed that after usage, large shares of ENP applied in consumer products are discharged to wastewater and transported to wastewater treatment plants (WWTPs). WWTPs retain > 95% of ENP leading to their accumulation in sewage sludge. In Switzerland, sewage sludge is incinerated preferably in mono-combustion fluidized bed reactors (FBRs) and the resulting ashes are landfilled for resource recovery in the future. To contribute to a better understanding of the fate and behavior of ENP in the urban environment, the following research questions were addressed: (i) how can the kinetics of sewage sludge devolatilization be quantified, (ii) what chemical and physical transformations of ENP occur during the sewage sludge combustion, (iii) what are the possibilities of synchrotron hard X-ray chemical imaging to study transformation products of ENP, and lastly (iv) to what extent are ENP released from sewage sludge ash landfill sites? The devolatilization kinetics of digested sludge were studied using thermogravimetric analysis. Results revealed that 10 individual first-order reactions with Arrhenius rate constants are sufficient to describe the devolatilization kinetics. The detailed analyses of the kinetic parameters was used to estimate the speciation of the major compounds of the combustibles which were cellulose (36%), lignin (20%), calcite (11%), alginate (8%) and hemicellulose (6%). Generalized, ...

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