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Artificial sweeteners: Studies of their environmental fate, drinking water relevance, use as anthropogenic markers, and ozonation products

  • The world wide population growth and the increasing water scarcity endanger more and more the human society. Water saving measures alone will not be sufficient to solve all associated problems. Therefore, people in arid countries might come back to any kind of water available. In this context the way people regard wastewater must change in terms that it has to be recognized as a water resource. The reuse of wastewater, treated and untreated, for irrigation purposes in agriculture is already established in some semi-arid and arid countries. Countries with absolute water scarcity like Israel might not only be forced to reduce their water consumption, but even to transfer reused water to other sectors. Concerns of authorities and the general public about potential health risks are completely understandable. The health risks of wastewater are mainly originating from pathogens which are negatively correlated with its treatment. Therefore, the quality of a wastewater effluent derived from mechanical-biological treatment can be further improved by additional treatment steps like soil aquifer treatment (SAT). This process is adopted at the Israeli Shafdan facility in the south of Tel Aviv. Conventionally treated wastewater is applied on surface basins from where it percolates into the coastal plain aquifer which supplies approximately one quarter of Israel ́s drinking water. After a certain residence time in the subsurface the water is recovered by wells surrounding the recharge area. Although the pumping regime creates a hydraulic barrier to the pristine groundwater, concerns exist that a contamination of the surrounding drinking water wells could occur. So far, little is known about the removal of organic trace pollutants during the SAT process in general and for the Shafdan site in particular. Consequently, the need arose to study the purification power of the SAT process in terms of the removal of organic trace pollutants. For this purpose reliable wastewater tracers are essential to be able to differentiate between degradation and sorption processes on the one hand and dilution with pristine groundwater on the other hand. Based on their chemical properties, their worldwide usage in a variety of foodstuffs and beverages, and first data about the fate and occurrence of sucralose, artificial sweeteners came into the focus as promising tracer candidates. Thus, in the present work an analytical method for the simultaneous determination of seven commonly used artificial sweeteners in different water matrices, like surface water and wastewater, was developed (see chapter 2). The method is based on the solid phase extraction (SPE) of the analytes by a styrene-divinylbenzene (SDB) copolymer material, and the analysis by liquid chromatography-electrospray ionization tandem mass-spectrometry (LC-ESI- MS/MS). The sensitivity in negative ionization mode was considerably enhanced by postcolumn addition of the alkaline modifier tris(hydroxymethyl) aminomethane. In potable water, except for aspartame and neohesperidine dihydrochalchone, absolute recoveries >75 % were obtained for all analytes under investigation, but were considerably reduced due to matrix effects in treated wastewater. The widespread distribution of the artificial sweeteners acesulfame, saccharin, cyclamate, and sucralose in the aquatic environment was proven. Concentrations in two German wastewater treatment plant (WWTP) influents ranged up to 190 μg/L for cyclamate, several tens of μg/L for acesulfame and saccharin, and about 1 μg/L for sucralose. For saccharin and cyclamate removal rates >90 % during wastewater treatment were observed, whereas acesulfame and sucralose turned out to be very persistent. As a result of high influent concentrations and low removal rates in WWTPs, acesulfame was the dominant sweetener in German surface waters with concentrations up to 2.7 μg/L. The detection of acesulfame and sucralose in recovery wells in the Shafdan SAT site in Israel in the μg/L range was a promising sign for their possible use as anthropogenic markers. As acesulfame and sucralose showed a pronounced stability in WWTPs and were detected in recovery wells of the SAT site in Israel it became worthwhile to assess their tracer suitability compared to other organic trace pollutants suggested as anthropogenic markers in the past (see chapter 3). Therefore, the prediction power of the two sweeteners was evaluated in comparison with the antiepileptic drug carbamazepine (CBZ), the X-ray contrast medium diatrizoic acid (DTA) and two benzotriazoles (1H-benzotriazole (BTZ) and its 4-methyl analogue (4TTri)). The concentrations of these compounds and their ratios were tracked from WWTPs with different treatment technologies, to recipient waters and further to river bank filtration (RBF) wells. Additionally, acesulfame and sucralose were compared with CBZ during advanced wastewater treatment by SAT in Israel. Only the persistent compounds acesulfame, sucralose, and CBZ showed stable ratios when comparing influent and effluent concentrations of four German WWTPs with conventional wastewater treatment. However, by the additional application of powdered activated carbon in a fifth WWTP CBZ, BTZ, and 4-TTri were selectively removed resulting in a pronounced shift of the concentration ratios towards the nearly unaffected sweeteners. Results of a seven months monitoring program along the rivers Rhine and Main showed an excellent correlation between CBZ and acesulfame concentrations (r2 = 0.94), and still good values when correlating the concentrations with both benzotriazoles (r2 = 0.66 - 0.82). In RBF wells acesulfame and CBZ were again the compounds with the best concentration correlation (r2 = 0.85).
  • Das weltweite Bevölkerungswachstum und die damit verbundene Wasserknappheit gefährden zunehmend die menschliche Gesellschaft. Lediglich den Wasserverbrauch zu reduzieren wird nicht ausreichen, um alle damit verbundenen Probleme zu lösen. Deshalb wird die Bevölkerung in ariden Ländern möglicherweise in Zukunft auf alle verfügbaren Wasserressourcen zurückgreifen müssen. In diesem Zusammenhang muss sich die Betrachtungsweise von Abwasser dahingehend ändern, dass die Bevölkerung solcher Länder dieses als Ressource erkennt. Die Wiederverwendung von unbehandeltem oder behandeltem Abwasser ist für Bewässerungszwecke bereits in einigen semi-ariden und ariden Ländern etabliert. Allerdings könnten Länder mit extremer Wasserknappheit, wie beispielsweise Israel, in Zukunft nicht nur dazu gezwungen sein ihren Wasserverbrauch zu reduzieren, sondern auch wiedergewonnenes Wasser in anderen Bereichen als der Landwirtschaft zu nutzen. Bedenken von Behörden und Öffentlichkeit bezüglich einer potentiellen Gesundheitsgefährdung sind dabei nur allzu verständlich. Die gesundheitlichen Risiken von Abwasser sind vor allem durch darin enthaltene Pathogene begründet, deren Anwesenheit negativ mit einer zunehmenden Abwasserbehandlung korreliert. Aus diesem Grund kann die Qualität eines Abwassers, das eine biologische Abwasserbehandlung durchlaufen hat, durch weitere Aufbereitungsschritte, wie das Versickern über eine Bodenpassage (engl. soil aquifer treatment, SAT), weiter verbessert werden. Im israelischen Shafdan-Gebiet südlich von Tel Aviv wird zu diesem Zwecke gereinigtes Abwasser auf Becken ausgebracht, von wo es in den Küstenaquifer versickert, der rund ein Viertel des israelischen Trinkwassers liefert. Nach einer gewissen Aufenthaltszeit im Untergrund wird das Wasser durch Förderbrunnen in der Peripherie des Versickerungsfeldes wiedergewonnen. Obwohl durch das Pumpregime eine hydraulische Barriere zum unbeeinflussten Grundwasser geschaffen werden soll, bestehen Bedenken, dass umliegende Trinkwasserbrunnen kontaminiert werden könnten. Insbesondere über die Entfernung von organischen Spurenstoffen während des SAT-Prozesses im Allgemeinen und für das Shafdan-Gebiet im Besonderen ist bislang wenig bekannt. Für die Beurteilung der Reinigungsleistung des SAT-Prozesses hinsichtlich der Elimination organischer Spurenstoffe war es notwendig, zuverlässige Abwassermarkierungsstoffe (Tracer) zu identifizieren. Nur so war es möglich, zwischen einer Verdünnung mit landseitigem Grundwasser einerseits sowie biologischem Abbau und Sorption andererseits zu unterscheiden. ...

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Metadaten
Author:Marco ScheurerGND
URN:urn:nbn:de:gbv:luen4-opus-142150
URL: https://pub-data.leuphana.de/frontdoor/index/index/docId/603
Title Additional (German):Künstliche Süßstoffe: Untersuchungen zu ihrem Umweltverhalten, Trinkwasserrelevanz, Einsatz als anthropogene Markierungsstoffe und Ozonungsprodukten
Referee:Wolfgang K. L. Ruck (Prof. Dr. - Ing.)GND, Brauch, Heinz-Jürgen (Prof. Dr.)
Document Type:Doctoral Thesis
Language:English
Year of Completion:2012
Date of Publication (online):2012/05/30
Publishing Institution:Leuphana Universität Lüneburg, Universitätsbibliothek der Leuphana Universität Lüneburg
Granting Institution:Leuphana Universität Lüneburg
Date of final exam:2012/03/21
Release Date:2012/05/30
Tag:Abwassermarkierungsstoffe; Ozonungsprodukte
ozonation products; wastewater tracers
GND Keyword:Süßstoff; Abwasseranalyse; Trinkwasser; Ozonisierung
Pagenumber:150
Note:
Das Rahmenpapier der kumulativen Dissertation enthält 4 Beiträge
Institutes:Fakultät Nachhaltigkeit
Dewey Decimal Classification:5 Naturwissenschaften und Mathematik / 54 Chemie / 540 Chemie und zugeordnete Wissenschaften
Licence (German):License LogoDeutsches Urheberrecht