10 research outputs found
Contaminant transport in a highly dynamic riverbank filtration system
Wie die vielen Maßnahmen von Organisationen wie die Europäische Union und die World Health Organisation zeigen, wird die Notwendigkeit für sicheres Trinkwasser immer deutlicher. Seit der Abnahme der Qualität der Trinkwasserresourcen werden alte und neue Methoden verwendet um die Qualität zu verbessern. Eine dieser alten Methoden ist Uferfiltration. Uferfiltrations-Systeme (UFS) sind relativ preisgünstig und können einfacher Wasser von einer stabilen Qualität herstellen. Prozesse wie Adsorption, biologischer Abbau und physisch-chemische Filtration sind verantwortlich für die Zuhname der Wasserqualität während Uferpassage. Nicht nur diese Prozesse, sondern auch die Qualität von infiltrierenden Oberflächengewässern sind wichtig für die endgültige Qualität des Grundwassers. Der Schwerpunkt dieser Doktorarbeit war deswegen der Einfluss von Oberflächengewässern auf die chemische und mikrobiologische Qualität vom Grundwasserleiter. Weil die weltweite chemische und mikrobiologische Verunreinigungen von Oberflächengewässern zunehmen, ist die Kombination dieser Parameter sehr kritisch. Viele UFS liegen neben Flüssen mit einer hohen Dynamik in Wasserstand und chemischer und mikrobiologischer Qualität. Es ist sehr wichtig um diese Dynamik zu verstehen, weil Flussund Transportprozesse im Grundwasserleiter davon beeinflusst werden können. UFS entlang großen Flüssen wie die Donau liefern Trinkwasser an Millionen von Menschen. Die Dynamik bei UFS an größen Flüssen kann viel höher sein als bei UFS an z.B. Seeen. Zusammen mit zunehmenden antropogenen Aktivitäten in vielen Einzugsgebieten, nimmt der Stress auf Grundwasser zu. Organische Spurenstoffe und mikrobiologische Verunreinigungen werden in die Umwelt introduziert durch z.B. Kläranlagen und können große Gesundheitsschäden verursachen. Deren Verhalten während Uferfiltration ist unterschiedlich, sowie auch deren Analytik. Das Ziel dieser Doktorarbeit ist deswegen, den Einfluss von infiltrierenden Oberflächengewässern auf das Grundwasser zu erforschen, einerseits auf die natürliche mikrobielle Gemeinschaft im Grundwasser und andererseits auf das Verhalten von organischen Spurenstoffen bei Uferfiltration. Die höchste biologische Aktivität und deswegen der schnellste Abbau der Verunreinigungen wird in den ersten paar Metern des Grundwasserleiters gefunden. Es ist darum äußerst wichtig, Proben zu nehmen, die repräsentativ sind für den umliegenden Grundwasserleiter, vor allem in der Nähe von einem Fluss. Entlang einem hoch dynamischen Fluss wie der Donau kann das eine Herausforderung sein, weil die Stabilisation der Parameter vielleicht nicht so schnell ist wie die Veränderungen im Wasserspiegel. Kapittel 2 diskuttiert deswegen den Effekt von Pumpvolumen auf die Konzentration von u.a. organischen Spurenstoffen und mikrobiologischen Verunreinigungen im hoch dynamischen UFS an der Donau. Die Proben wurden nach unterschiedlichen Pumpvolumen entnommen, sowohl in direkter Nähe vom Fluss als auch weiter im Grundwasserleiter. Die Schwankungen des Grundwasserspiegels und der Konzentrationen von Verunreinigungen haben keinen Effekt gehabt auf die Stabilität der chemischen Parameter. Mikrobielle Parameter wie Leucin-Inkorporation (ein Maß für die biologische Aktivität der mikrobiellen Gemeinschaft) zeigten jedoch einen signifikanten Zusammenhang zwischen Stabilität und Pumpvolumen. Mit diesen Informationen behandelt Kapittel 3 den Einfluß von Oberflächengewässern auf die mikrobielle Charakteristika des Grundwasserleiters. Die Reaktion der mikrobiellen Gemeinschaft auf saisonbedingte Dynamik, Nährstoffe und hydrologische Schwankungen wurde während einer Periode von 20 Monaten erforscht, wobei 2 Hochwässer öfter beprobt wurden. Die Ergebnisse zeigten, dass bakterieller Reichtum, Biomasse und Bakterienproduktion vom Fluss in Richtung Trinkwasserquelle signifikant abgenommen haben. Das wurde nicht beeinflusst durch die Anwesentheit von Nährstoffen oder die saisonbedingte Dynamik, sondern hauptsächlich durch Schwankungen in der Strömungsgeschwindigkeit des Grundwassers. Während der Hochwässer war diese Korrelation noch deutlicher, und man hat sehen können, dass die Donau mehr Einfluss auf den Grundwasserleiter hatte als unter normalen Umständen. Das wurde deutlich durch einen höheren Anteil großer Zellen im Grundwasser während Hochwässern. In Kapittel 4 ist das Verhalten von organischen Spurenstoffen während der Uferfiltration erforscht worden. Die Proben wurden während einer längeren Periode entnommen als die Proben die in Kapittel 3 beschrieben wurden und enthielten auch die beiden Hochwässer. Die organischen Spurenstoffe haben auch einen verlängerten Einfluß vom Fluss gezeigt während der 2 Hochwässer. Die einfach abbaubaren Spurenstoffe sind nicht im Grundwasser gefunden, während die Konzentrationen der Abwassermarker Benzotriazole (BTri), Carbamazepine (CBZ) und Sulfamethoxazole (SMZ) höher waren als unter normalen Bedingungen. In diesem oxyschen Grundwasserleiter war BTri fast völlig verschwunden. CBZ und SMZ, die normalerweise ein eher konservatives Verhalten haben während Uferfiltration, haben zu einem gewissen Punkt abgenommen. Vermischung mit Grundwasser einer höheren Qualität war nicht ausreichend um den Konzentrationsabbau zu erklären. Diese Dissertation hat gezeigt, dass die Probenentnahme für eine Kombination von chemischen und mikrobiologischen Parametern nicht einfach war. Grundwassersonden in der Nähe vom Fluss in oxyschen Grundwasserleitern mit hoher hydraulischer Leitfähigkeit können schnell reagieren auf Veränderungen der hydrologischen Bedingungen. Einer der wichtigsten Parameter für den Ausmaß der Interaktion von Oberflächengewässer auf Grundwasser war der Potentialunterschied zwischen Wasserspiegel vom Fluss und vom Grundwasser. Nicht nur das Vorhandensein von organischen Spurenstoffen kann beeinflusst werden durch den infiltrierenden Fluss, auch die mikrobielle Gemeinschaft kann dadurch verändert werden. Weil mikrobielle Eigenschaften des Grundwassers und der Potentialunterschied fast Realtime gemessen werden können, könnte das eine effektive Möglichkeit für Trinkwasserbetriebe sein um ihre Wasserentnahme zu steuern während Perioden mit höheren Durchflüssen und schnellen Veränderungen in den hydrologischen Bedingungen.As can be seen by the amount of actions taken by several international organizations, the need for safe drinking water is becoming more and more evident. Since the quality of drinking water sources is decreasing, old and new methodologies are being used to improve the quality of the source water. One of these old methods is riverbank filtration (RBF). RBF systems are relatively inexpensive and are able to produce water which is relatively consistent in quality and usually easier treatable. Processes like adsorption, biodegradation and physicochemical filtration are responsible for the increase in water quality during aquifer passage. Not only these processes, but also the quality of the infiltrating surface water is of importance for the eventual quality of the groundwater. Therefore, the focus of this doctoral thesis was on the influence of surface water on both the chemical and microbial quality of the aquifer. The combination of chemical and microbial parameters is crucial due to the increasing global contamination of surface waters with these contaminants. Many RBF systems are situated along rivers with a high dynamics in water levels and in chemical and microbial water quality. It is of paramount importance to get an insight in this dynamics, since processes taking place in the aquifer can be influenced by it. RBF systems along large rivers like the Danube provide drinking water for millions of people. The dynamics in RBF systems along large rivers can be much higher than in RBF systems connected to for example lakes. Together with the increasing anthropogenic activities in many of the (sub-)catchments, the stress on the groundwater is increasing. Organic micropollutants (OMPs) and microbial contaminants are introduced to the environment through for example wastewater treatment plant (WWTP) effluents and can have serious health effects. Their behaviour during aquifer passage is different, just as their analysis. The aim of this doctoral thesis is therefore to elucidate the influences of surface water infiltrating into the aquifer, on one hand on the microbial community naturally found in the groundwater and on the other hand on the behavior of OMPs during aquifer passage. The highest biological activity, and therefore the fastest removal of contaminants, can be found in the first few meters of the aquifer. It is therefore crucial to obtain samples representative for the surrounding aquifer, especially close to the river. Along a highly dynamic river like the Danube, this can be a challenge since stabilization of parameters might not be as quick as the changes in water levels. Therefore, chapter 2 discusses the effect of pumping volume on the concentration of OMPs and microbial contaminants amongst others in a highly dynamic RBF system along the river Danube. Samples were taken after different pumping volumes, both close to the river as well as further into the aquifer. It was found that both the fluctuations in groundwater table and the fluctuations in contaminant concentrations did not affect the stability of the obtained chemical samples. Microbial parameters such as leucine incorporation (which is a measure for the biological activity of the microbial community) however did show a significant relation between stabilization and pumping volume. With this information at hand, chapter 3 discusses the influence of surface water on the microbial characteristics of the aquifer. The response of the microbial community on seasonal dynamics, nutrient stimuli and hydrological fluctuations was studied during a 20 months period including 2 flood events which were sampled more extensively. The results showed that bacterial abundance, biomass and carbon production decreased significantly from the river towards the drinking water abstraction well. This was not influenced by the availability of nutrients or by seasonal dynamics, but mainly by fluctuations in groundwater flow velocity. During the flood events, this correlation was even more apparent and it could be seen that the rivers influence extended further into the aquifer, as was shown by a much higher proportion of larger cells in the groundwater during flood events than under normal conditions. In chapter 4, the behavior of OMPs during RBF was studied. The samples were drawn over a slightly longer period than described in chapter 3 and also included the 2 flood events. The OMPs showed a likewise extended influence of the river during the two flood events. Some highly degradable OMPs were not found in the groundwater, whereas concentrations of common wastewater markers benzotriazole (BTri), carbamazepine (CBZ) and sulfamethoxazole (SMZ) were higher than under normal conditions. It was shown that in this oxic aquifer, BTri was almost fully removed under normal conditions. CBZ and SMZ, which were assumed to have a rather conservative behavior during aquifer passage, were attenuated to a certain extent. Mixing with groundwater of a better quality could not solely explain this decrease in concentration. This thesis showed that obtaining samples for a combination of chemical and microbial parameters was not an easy task. Furthermore, wells especially close to the river and situated in oxic aquifers with high hydraulic conductivities can react quickly on changing hydrological conditions. One of the most important parameters for the extent of the surface water groundwater interaction was shown to be the potential difference between the river water and groundwater level. Not only the presence of OMPs can be influenced, also the microbial community can be altered by the infiltrating river. Since microbiological characteristics and the potential difference can be measured (near) real-time, this could be a very effective way for drinking water utilities to manage their abstraction strategies during periods of high discharge and rapidly changing hydrological conditions.11
Meer inzicht in toxische druk in het water
Er komt een groeiend aantal chemische stoffen in ons milieu terecht, ook in het oppervlaktewater. Het wordt daarmee voor waterbeheerders steeds lasti ger om inzicht te krijgen in de effecten van al die stoffen, en die kennis vervol gens te relateren aan bronnen, zodat de juiste beheersmaatregelen genomen kunnen worden. Hoe maken we toxiciteit van individuele stoffen, stofgroepen en stofmengsels inzichtelijk en hanteerbaar
The effective design of sampling campaigns for emerging chemical and microbial contaminants in drinking water and its resources based on literature mining.
As well as known contaminants, surface waters also contain an unknown variety of chemical and microbial contaminants which can pose a risk to humans if surface water is used for the production of drinking water. To protect human health proactively, and in a cost-efficient way, water authorities and drinking water companies need early warning systems. This study aimed to (1) assess the effectiveness of screening the scientific literature to direct sampling campaigns for early warning purposes, and (2) detect new aquatic contaminants of concern to public health in the Netherlands. By screening the scientific literature, six example contaminants (3 chemical and 3 microbial) were selected as potential aquatic contaminants of concern to the quality of Dutch drinking water. Stakeholders from the Dutch water sector and various information sources were consulted to identify the potential sources of these contaminants. Based on these potential contamination sources, two sampling sequences were set up from contamination sources (municipal and industrial wastewater treatment plants), via surface water used for the production of drinking water to treated drinking water. The chemical contaminants, mycophenolic acid, tetrabutylphosphonium compounds and Hexafluoropropylene Oxide Trimer Acid, were detected in low concentrations and were thus not expected to pose a risk to Dutch drinking water. Colistin resistant Escherichia coli was detected for the first time in Dutch wastewater not influenced by hospital wastewater, indicating circulation of bacteria resistant to this last-resort antibiotic in the open Dutch population. Four out of six contaminants were thus detected in surface or wastewater samples, which showed that screening the scientific literature to direct sampling campaigns for both microbial and chemical contaminants is effective for early warning purposes.</p
Assessing biological stability in a porous groundwater aquifer of a riverbank filtration system: combining traditional cultivation-based and emerging cultivation-independent in situ and predictive methods
Riverbank filtration systems are important drinking water resources. Aquifers of riverbank filtration systems are subjected to considerable dynamics concerning the quantity and quality of the infiltrating water. The microbiological quality is mainly jeopardized by faecal contamination of the main river. Besides, water quality can be impacted by growth of natural water-borne bacteria due to the input of nutrients resulting in the proliferation of opportunistic pathogens, impairment of odour and taste or bio-corrosion. The occurrence of such phenomena indicates a biological instability. For highly dynamic riverbank filtration systems, it is thus of high relevance to assess the biological stability of the groundwater resource.
In the present study, we applied a holistic, two-tiered concept of in situ and predictive methods to assess the biostability of the aquifer in a bank filtration system of the Danube River. We applied traditional cultivation-based and selected cultivation-independent methods—including cultivation on yeast extract and R2A agar, determination of total cell counts via fluorescence microscopy and flow cytometry, leucine incorporation and 16S rRNA gene amplicon sequencing—at critical control points along the infiltration path from the river to the abstraction well.
The concentration of organic nutrients and the hydrological variability were the main controlling factors driving the biological stability of the groundwater body. Wells situated at greater distance displayed significantly lower dissolved organic carbon concentrations and a dampened hydrological influence in comparison to the well situated next to the river. Apparent discrepancies between the methods used indicated a different indicator function of the cultivation-based and cultivation-independent approaches. For complex systems, we thus recommend this new holistic concept for assessing biostability by combining in situ as well as predictive parameters and using cultivation-based and cultivation-independent methods.Flussuferfiltrationssysteme sind wichtige Trinkwasserressourcen. Die Aquifere von Uferfiltrationssystemen sind einer erheblichen Dynamik in Bezug auf die Menge und Qualität des infiltrierenden Wassers unterworfen. Die mikrobiologische Qualität wird hauptsächlich durch die fäkale Verunreinigung des Hauptflusses gefährdet. Darüber hinaus kann die Wasserqualität durch das Wachstum natürlicher wasserbürtiger Bakterien aufgrund von Nährstoffeinträgen beeinträchtigt werden, was zur Vermehrung opportunistischer Krankheitserreger, zur Beeinträchtigung von Geruch und Geschmack oder zur Biokorrosion führen kann. Das Auftreten solcher Phänomene deutet auf eine biologische Instabilität hin. Für hochdynamische Uferfiltrationssysteme ist es daher von großer Bedeutung, die biologische Stabilität der Grundwasserressource zu bewerten.
In der vorliegenden Studie wurde ein ganzheitliches, zweistufiges Konzept aus In-situ- und Vorhersage-Methoden angewandt, um die biologische Stabilität des Aquifers in einem Uferfiltrationssystem der Donau zu bewerten. Wir wendeten traditionelle kultivierungsbasierte und ausgewählte kultivierungsunabhängige Methoden – einschließlich Kultivierung auf Hefeextrakt und R2A-Agar, Bestimmung der Gesamtzellzahl mittels Fluoreszenzmikroskopie und Durchflusszytometrie, Leucin-Inkorporation und 16S rRNA-Genamplikon-Sequenzierung – an kritischen Kontrollpunkten entlang des Infiltrationspfads vom Fluss zum Entnahmebrunnen an.
Die Konzentration der organischen Nährstoffe und die hydrologische Variabilität waren die wichtigsten Einflussfaktoren für die biologische Stabilität des Grundwasserkörpers. Brunnen in größerer Entfernung wiesen deutlich niedrigere Konzentrationen an gelöstem organischem Kohlenstoff und einen gedämpften hydrologischen Einfluss im Vergleich zum Brunnen in Flussnähe auf. Offensichtliche Diskrepanzen zwischen den verwendeten Methoden deuten auf eine unterschiedliche Indikatorfunktion der kultivierungsbasierten und kultivierungsunabhängigen Ansätze hin. Für komplexe Systeme empfehlen wir daher dieses neue ganzheitliche Konzept zur Bewertung der Biostabilität durch die Kombination von In-situ- und Vorhersage-Parametern und die Verwendung kultivierungsbasierter und kultivierungsunabhängiger Methoden.49050011FTI—Forschungs‑, Technologie- und Innovationsprogramm NiederösterreichWiener Wasser (MA 31
Science of The Total Environment / Spatiotemporal analysis of bacterial biomass and activity to understand surface and groundwater interactions in a highly dynamic riverbank filtration system
Characterization of surface water groundwater interaction in riverbank filtration (RBF) systems is of decisive importance to drinking water utilities due to the increasing microbial and chemical contamination of surface waters. These interactions are commonly assessed by monitoring changes in chemical water quality, but this might not be indicative for microbial contamination. The hydrological dynamics of the infiltrating river can influence these interactions, but seasonal temperature fluctuations and the supply of oxygen and nutrients from the surface water can also play a role. In order to understand the interaction between surface water and groundwater in a highly dynamic RBF system of a large river, bacterial abundance, biomass and carbon production as well as standard chemical parameters were analyzed during a 20 month period under different hydrological conditions. In the investigated RBF system, groundwater table changes exhibited striking dynamics even though flow velocities were rather low under regular discharge conditions. Bacterial abundance, biomass, and bacterial carbon production decreased significantly from the river towards the drinking water abstraction well. The cell size distribution changed from a higher proportion of large cells in the river, towards a higher proportion of small cells in the groundwater. Although biomass and bacterial abundance were correlated to water temperatures and several other chemical parameters in the river, such correlations were not present in the groundwater. In contrast, the dynamics of the bacterial groundwater community was predominantly governed by the hydrogeological dynamics. Especially during flood events, large riverine bacteria infiltrated further into the aquifer compared to average discharge conditions. With such information at hand, drinking water utilities are able to improve their water abstraction strategies and react quicker to changing hydrological conditions in the RBF system.(VLID)469955
Spatiotemporal resolved sampling for the interpretation of micropollutant removal during riverbank filtration
Riverbank filtration (RBF) systems along rivers are widely used as public water supplies. In these systems, many organic micropollutants (OMPs) are attenuated, but some compounds have shown to be rather persistent. Their fate and transport has been studied in RBF sites along lakes and small rivers, but not extensively along large and dynamic rivers. Therefore, the influence of flood events on OMP behavior in these large and dynamic RBF sites was investigated. Monthly samples were taken from surface- and groundwater up to a distance of 900 m from the riverbank of the Danube from March 2014 till May 2016. Two flood events were sampled more extensively nearby the river. Results showed that changes in flow conditions in the river not only caused changes in OMP concentrations, but also in their load. It was seen that the load of benzotriazole, carbamazepine and sulfamethoxazole in the river increased with increasing river discharges. After a relatively long, oxic groundwater passage, several OMPs were reduced. In contrast to previous work, we found that benzotriazole was almost fully removed under oxic conditions. When entering the aquifer, benzotriazole concentrations were significantly reduced and at a distance of 550 m from the river, >97% was degraded. Carbamazepine and sulfamethoxazole showed relatively persistent behavior in the aquifer. The concentrations measured during flood events were in the same range as seasonal sampling. Furthermore concentrations in the groundwater were higher during these events than in the Danube and can reach further into the aquifer. During flood events some highly degradable compounds (i.e. diclofenac) were found up to a distance of 24 m from the river. These results implied that drinking water utilities with RBF wells in oxic, alluvial aquifers located close to highly dynamic rivers need to consider a potential reduction in groundwater quality during and directly after flood events.Austrian Science Fund (FWF)Austrian Science Fund (FWF)Danube-Lower Lobau Network Projec
The effective design of sampling campaigns for emerging chemical and microbial contaminants in drinking water and its resources based on literature mining
As well as known contaminants, surface waters also contain an unknown variety of chemical and microbial contaminants which can pose a risk to humans if surface water is used for the production of drinking water. To protect human health proactively, and in a cost-efficient way, water authorities and drinking water companies need early warning systems. This study aimed to (1) assess the effectiveness of screening the scientific literature to direct sampling campaigns for early warning purposes, and (2) detect new aquatic contaminants of concern to public health in the Netherlands. By screening the scientific literature, six example contaminants (3 chemical and 3 microbial) were selected as potential aquatic contaminants of concern to the quality of Dutch drinking water. Stakeholders from the Dutch water sector and various information sources were consulted to identify the potential sources of these contaminants. Based on these potential contamination sources, two sampling sequences were set up from contamination sources (municipal and industrial wastewater treatment plants), via surface water used for the production of drinking water to treated drinking water. The chemical contaminants, mycophenolic acid, tetrabutylphosphonium compounds and Hexafluoropropylene Oxide Trimer Acid, were detected in low concentrations and were thus not expected to pose a risk to Dutch drinking water. Colistin resistant Escherichia coli was detected for the first time in Dutch wastewater not influenced by hospital wastewater, indicating circulation of bacteria resistant to this last-resort antibiotic in the open Dutch population. Four out of six contaminants were thus detected in surface or wastewater samples, which showed that screening the scientific literature to direct sampling campaigns for both microbial and chemical contaminants is effective for early warning purposes.Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Sanitary Engineerin
QMRAcatch : Human-Associated Fecal Pollution and Infection Risk Modeling for a River/Floodplain Environment
Protection of drinking water resources requires addressing all relevant fecal pollution sources in the considered catchment. A freely available simulation tool, QMRAcatch, was recently developed to simulate concentrations of fecal indicators, a genetic microbial source tracking (MST) marker, and intestinal pathogens in water resources and to conduct a quantitative microbial risk assessment (QMRA). At the same time, QMRAcatch was successfully applied to a region of the Danube River in Austria, focusing on municipal wastewater emissions. Herein, we describe extension of its application to a Danube River floodplain, keeping the focus on fecal sources of human origin. QMRAcatch was calibrated to match measured human-associated MST marker concentrations for a dry year and a wet year. Appropriate performance characteristics of the human-associated MST assay were proven by simulating correct and false-positive marker concentrations, as determined in human and animal feces. With the calibrated tool, simulated and measured enterovirus concentrations in the rivers were compared. Finally, the calibrated tool allowed demonstrating that 4.5 log enterovirus and 6.6 log norovirus reductions must be achieved to convert current surface water to safe drinking water that complies with a health-based target of 10 infections person yr. Simulations of the low- and high-pollution scenarios showed that the required viral reductions ranged from 0 to 8 log. This study has implications for water managers with interests in assessing robust catchment protection measures and water treatment criteria by considering the fate of fecal pollution from its sources to the point of abstraction