Person: Klitzke, Sondra
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Veröffentlichung Transport and retention of differently coated CeO2 nanoparticles in saturated sediment columns under laboratory and near-natural conditions(2019) Degenkolb, Laura; Dippon-Deissler, Urs; Klitzke, Sondra; Pabst, SilkeWhere surface-functionalized engineered nanoparticles (NP) occur in drinking water catchments, understanding their transport within and between environmental compartments such as surface water and groundwater is crucial for risk assessment of drinking water resources. The transport of NP is mainly controlled by (i) their surface properties, (ii) water chemistry, and (iii) surface properties of the stationary phase. Therefore, functionalization of NP surfaces by organic coatings may change their fate in the environment. In laboratory columns, we compared the mobility of CeO2 NP coated by the synthetic polymer polyacrylic acid (PAA) with CeO2 NP coated by natural organic matter (NOM) and humic acid (HA), respectively. The effect of ionic strength on transport in sand columns was investigated using deionized (DI) water and natural surface water with 2.2 mM Ca2+ (soft) and 4.5 mM Ca2+ (hard), respectively. Furthermore, the relevance of these findings was validated in a near-natural bank filtration experiment using HA-CeO2 NP. PAA-CeO2 NP were mobile under all tested water conditions, showing a breakthrough of 60% irrespective of the Ca2+ concentration. In contrast, NOM-CeO2 NP showed a lower mobility with a breakthrough of 27% in DI and < 10% in soft surface water. In hard surface water, NOM-CeO2 NP were completely retained in the first 2 cm of the column. The transport of HA-CeO2 NP in laboratory columns in soft surface water was lower compared to NOM-CeO2 NP with a strong accumulation of CeO2 NP in the first few centimeters of the column. Natural coatings were generally less stabilizing and more susceptible to increasing Ca2+ concentrations than the synthetic coating. The outdoor column experiment confirmed the low mobility of HA-CeO2 NP under more complex environmental conditions. From our experiments, we conclude that the synthetic polymer is more efficient in facilitating NP transport than natural coatings and hence, CeO2 NP mobility may vary significantly depending on the surface coating. © The Author(s) 2019Veröffentlichung The fate of nitrification and urease inhibitors in simulated bank filtration(2023) Förster, Christina; Scheurer, Marco; Klitzke, Sondra; Ruhl, Aki Sebastian; Zeeshan, MuhammadThe application of nitrification and urease inhibitors (NUI) in conjunction with nitrogen (N) fertilizers improves the efficiency of N fertilizers. However, NUI are frequently found in surface waters through leaching or surface runoff. Bank filtration (BF) is considered as a low-cost water treatment system providing high quality water by efficiently removing large amounts of organic micropollutants from surface water. The fate of NUI in managed aquifer recharge systems such as BF is poorly known. The aim of this work was to investigate sorption and degradation of NUI in simulated BF under near-natural conditions. Besides, the effect of NUI on the microbial biomass of slowly growing microorganisms and the role of microbial biomass on NUI removal was investigated. Duplicate sand columns (length 1.7 m) fed with surface water were spiked with a pulse consisting of four nitrification (1,2,4-triazole, dicyanodiamide, 3,4-dimethylpyrazole and 3-methylpyrazole) and two urease inhibitors (n-butyl-thiophosphoric acid triamide and n-(2-nitrophenyl) phosphoric triamide). The average spiking concentration of each NUI was 5 ÎÌg/L. Experimental and modeled breakthrough curves of NUI indicated no retardation for any of the inhibitors. Therefore, biodegradation was identified as the main elimination pathway for all substances and was highest in zones of high microbial biomass. Removal of 1,2,4-triazole was 50% and n-butyl-thiophosphoric acid triamide proved to be highly degradable and was completely removed after a hydraulic retention time (HRT) of 24 h. 50% of the mass recovery for nitrification inhibitors except for 3,4-dimethylpyrazole was observed at the effluent (4 days HRT). In addition, a mild effect of NUI on microbial biomass was noted. This study highlights that the degradation of NUI in BF depends on HRT and microbial biomass. © 2023 Elsevier