H3 - Abiotic transformation of halogenated organic compounds during bank filtration
student: Marcel Yuki Sorgler 
Supervisors: Dr. Anke Putschew  (TUB), Prof. Lorenz Adrian  (UFZ+TUB), Prof. Martin Jekel  (TUB), PD Dr. Jörg Lewandowski  (IGB)
Iodinated X-ray contrast media (ICM) are found at much higher concentration than any other pharmaceutical compound in waste water, surface water and bank filtrate (Fabbri et al., 2016; Pérez and Barceló, 2007; Putschew et al., 2000; Putschew et al., 2001; Sacher et al., 2005; Seitz et al., 2006). Several studies have shown that ICM are persistent to deiodination in aerobic environments, but side chain transformations lead to diverse metabolites (Kalsch, 1999; Redeker et al., 2014, 2018; Schulz et al., 2008). During anoxic/anaerobic bank filtration a partial deiodination could be detected by an AOI reduction of around 63% (Grünheid et al., 2005; Schittko et al., 2004; Wiese et al., 2011). As shown for the ICM diatrizoate (Redeker et al., 2014) and iopromide (Redeker et al., 2018) the deiodination plays a major role in the degradation pathway of the ICM. However, the deiodination of iodinated organic compounds and the behaviour of the subsequent partly deiodinated transformation products (TP) during the bank filtration process is scarcely investigated so far. In the first cohort of UWI El-Athman et al. (2019a; 2019c) have shown, to our best knowledge for the first time, that an abiotic deiodination catalysed by corrinoids can be responsible for the deiodination (Figure 1).
- Figure 1: Reaction scheme of the electron-shuttled deiodination (El-Athman et al., 2019b)
- © El-Athman
To follow up the work of the first cohort the relevance of the abiotic deiodination of iodinated organic compounds catalysed by electron shuttles under natural conditions will be investigated using naturally occurring reacting agents (reducing agent and electron-shuttle). The overall aim is to improve the prediction of the contaminant fate of iodinated compounds during bank filtration to finally apply this obtained knowledge for (managed) artificial groundwater recharge. For this reason, it is very important to determine the deiodination/dehalogenation mechanism and the kinetics under natural conditions to obtain a comprehensive understanding of the reductive deiodination/dehalogenation. Besides, the behaviour of the completely deiodinated as well as partly deiodinated TP must be studied concerning adsorptive uptake and biodegradability during the drinking water treatment processes.
The reductive deiodination/dehalogenation tests are conducted under oxygen-free conditions in a glove box (Figure 2) using naturally occurring reducing agents like iron, manganese or sulphur species as well as other electron shuttles such as quinones or porphyrins in addition to the already investigated corrinoids. Quinones are model compounds of natural organic matter and have already shown catalytic effects on dechlorination of polychlorinated compounds. Porphyrins have a similar structure to corrinoids and build different metal-complexes, which can be found in nature such as heme or chlorophyll. In a preliminary test, it was already observed that quinones can act as electron shuttles for deiodination of ICM.
The examination of the behaviour of the partly and completely deiodinated TP during bank filtration and subsequent drinking water treatment focusses on i) the sorption by soil (batch-tests according to OECD 106), ii) the general aerobic biodegradability (batch-tests according to OECD 302B) and iii) sorption by activated carbon (batch-tests with powdered active carbon).The applied partly and completely deiodinated TP are produced by an abiotic deiodination using the electron donor titanium-III-citrate and the electron shuttle vitamin B12 (El-Athman et al., 2019a) controlling the extent of the deiodination by adding a certain amount of the electron donor. Catalytic hydrogenation with platinum-IV-oxide was applied for the production of the deiodinated compounds for analytical purpose.
This doctoral project mainly focuses on lab work, but is also going transfer obtained knowledge from the lab results to field work data. In the last working package, samples from a monitoring campaign at the urban River Erpe (Figure 3) which is highly anthropogenically influenced will be investigated for ICM and their iodinated TP.
- Figure 3: Urban river Erpe
- © Sorgler
- Figure 2: Oxygen free glove box
- © Sorgler
First results of the batch tests investigating the influence of the deiodination on the sorption to soil and the general aerobic biodegradability suggest that the deiodination influences the removal and transformation processes during the bank filtration and the subsequent drinking water treatment. A closer look into the biodegradability tests indicates that depending on the degree of deiodination different biological transformation pathways are preferred. The sorption tests indicate an impact of the deiodination on the sorption to the soil but also reveal a strong dependence of the soil composition which can predominate the impact of the deiodination.
UWI projects: H1 , H4 , F1 
External cooperation: Jonas Schaper  (former UWI doctoral student - 1st cohort)
Common topic: Interface urban hyporheic zones 
El-Athman, F., Adrian, L., Jekel, M., Putschew, A., 2019a. Abiotic reductive deiodination of iodinated organic com-pounds and X-ray contrast media catalyzed by free corrinoids. Chemosphere 221, 212–218.
El-Athman, F., Adrian, L., Jekel, M., Putschew, A., 2019b. Deiodination in the presence of Dehalococcoides mccartyi strain CBDB1: comparison of the native enzyme and co-factor vitamin B12. Environmental science and pollu-tion research international 26 (31), 32636–32644.
El-Athman, F., Jekel, M., Putschew, A., 2019c. Reaction kinetics of corrinoid-mediated deiodination of iodinated X-ray contrast media and other iodinated organic compounds. Chemosphere 234, 971–977.
Fabbri, D., Calza, P., Dalmasso, D., Chiarelli, P., Santoro, V., Medana, C., 2016. Iodinated X-ray contrast agents: Photoinduced transformation and monitoring in surface water. The Science of the total environment 572, 340–351.
Grünheid, S., Amy, G., Jekel, M., 2005. Removal of bulk dissolved organic carbon (DOC) and trace organic com-pounds by bank filtration and artificial recharge. Water research 39 (14), 3219–3228.
Kalsch, W., 1999. Biodegradation of the iodinated X-ray contrast media diatrizoate and iopromide. Science of The Total Environment 225 (1-2), 143–153.
Pérez, S., Barceló, D., 2007. Fate and occurrence of X-ray contrast media in the environment. Analytical and bioan-alytical chemistry 387 (4), 1235–1246.
Putschew, A., Schittko, S., Jekel, M., 2001. Quantification of triiodinated benzene derivatives and X-ray contrast media in water samples by liquid chromatography–electrospray tandem mass spectrometry. Journal of Chro-matography A 930 (1-2), 127–134.
Putschew, A., Wischnack, S., Jekel, M., 2000. Occurrence of triiodinated X-ray contrast agents in the aquatic envi-ronment. Science of The Total Environment 255 (1-3), 129–134.
Redeker, M., Wick, A., Meermann, B., Ternes, T.A., 2014. Removal of the iodinated X-ray contrast medium diatri-zoate by anaerobic transformation. Environmental science & technology 48 (17), 10145–10154.
Redeker, M., Wick, A., Meermann, B., Ternes, T.A., 2018. Anaerobic Transformation of the Iodinated X-ray Contrast Medium Iopromide, Its Aerobic Transformation Products, and Transfer to Further Iodinated X-ray Contrast Me-dia. Environmental science & technology 52 (15), 8309–8320.
Sacher, F., Raue, B., Brauch, H.-J., 2005. Analysis of iodinated X-ray contrast agents in water samples by ion chro-matography and inductively-coupled plasma mass spectrometry. Journal of Chromatography A 1085 (1), 117–123.
Schittko, S., Putschew, A., Jekel, M., 2004. Bank filtration: a suitable process for the removal of iodinated X-ray con-trast media? Water science and technology : a journal of the International Association on Water Pollution Re-search 50 (5), 261–268.
Schulz, M., Löffler, D., Wagner, M., Ternes, T.A., 2008. Transformation of the X-ray Contrast Medium Iopromide In Soil and Biological Wastewater Treatment. Environ. Sci. Technol. 42 (19), 7207–7217.
Seitz, W., Weber, W.H., Jiang, J.-Q., Lloyd, B.J., Maier, M., Maier, D., Schulz, W., 2006. Monitoring of iodinated X-ray contrast media in surface water. Chemosphere 64 (8), 1318–1324.
Wiese, B., Massmann, G., Jekel, M., Heberer, T., Dünnbier, U., Orlikowski, D., Grützmacher, G., 2011. Removal ki-netics of organic compounds and sum parameters under field conditions for managed aquifer recharge. Water research 45 (16), 4939–4950.