The microbial degradation of pharmaceuticals found in surface water used for artificial recharge is strongly dependent on redox conditions of the subsurface. Furthermore the durability of production wells may decrease considerably with the presence of oxygen and ferrous iron due to the precipitation of trivalent iron oxides and subsequent clogging. Field measurements are presented for oxygen at a bank filtration site in Berlin, Germany, along with simplified calculations of different oxygen pathways into the groundwater. For a twodimensional vertical cross-section, oxygen input has been calculated for six scenarios related to different water management strategies. Calculations were carried out in order to assess the amount of oxygen input due to (1) the infiltration of oxic lake water, (2) air entrapment as a result of water table oscillations, (3) diffusive oxygen flux from soil air and (4) infiltrating rainwater. The results show that air entrapment and infiltrating lake water during winter constitute by far the most important mechanism of oxygen input. Oxygen input by percolating rainwater and by diffusive delivery of oxygen in the gas phase is negligible. The results exemplify the importance of well management as a determining factor for water oscillations and redox conditions during artificial recharge.

Large-scale dispersion was studied in an unconsolidated, sandy, glaciofluvial, river-recharged, and confined aquifer in Germany. Groundwater observation wells from a 3.5-km-long transect located in flow direction from the river Oder into a large lowland area (Oderbruch polder) were sampled for noble gases in order to date the groundwater with the tritium and helium (3H-3He) technique. The apparent 3H-3He ages of the groundwater increased from only a few months to >40 years along the flow path. Highest values for initial 3H (sum of 3H and its decay product tritiogenic helium, 3Hetri) were encountered in 2.6-km river distance. Concentrations of 4He in the water increased to 1.1 × 10-7 cm3 STP/g with distance from the river. The initial 3H data enabled an estimation of the longitudinal dispersivity with a simplified one-dimensional transport model. The best fit of modeled and measured initial H data was obtained using a dispersivity of 120 m. Deviations of modeled hydraulic ages and measured apparent 3H- 3He ages for older samples can be explained by dispersive mixing.

The intention of the work package 5.2 is to analyze the function and relevance of managed aquifer recharge (MAR) techniques with a main focus on Riverbank Filtration (RBF) to enable sustainable water resources management, especially in developing or newly industrialized countries. For this aim three RBF sites in Delhi were equipped with groundwater observation wells and sampled monthly for determination of surface and groundwater quality. This report includes information of more than 150 samples from surface- and groundwater, which were analyzed for a broad series of chemical and physicochemical parameters. For each sample, physicochemical parameters were determined in situ (pH, T, ORP, EC, DO) along with alkalinity, nitrite, ammonia and hydrogensulphide content by the Freie Universität Berlin (FUB) and the Indian Institute of Technology, Delhi (IITD). Additionally, water samples were collected and prepared under appropriate conditions for analysis of inorganic substances (major ions, heavy metals and other inorganic substances) and stable isotopes at FUB laboratories and microbiological parameters and organic contaminants at IIT laboratories. At FUB, in general all parameters were determined monthly except for some heavy metals for which the analysis is very time consuming and costly. For these metals, three sampling campaigns (monsoon, pre- and postmonsoon) were selected for analysis to get an overview of possible contaminations. Investigations on RBF are being performed at three different field sites within the National Capital Territory of Delhi (NCT), two of them on the banks of River Yamuna (Palla and Nizamuddin) and one of them at it’s major tributary in the Delhi stretch, called Najafgarh Drain (Najafgarh). At each of the field sites, at least five piezometers were constructed with varying depths and distances from the surface water. For each field site, groups of piezometers were built, to differentiate surface water and piezometers tapping shallow, medium and deep groundwater. For each parameter distribution and range of the values are shown with boxplots and compared to the German and the Indian drinking water standards. At the Palla field site positive effects during bankfiltration can be observed for several heavy metals like Pb, Al and Cu, while no significant changes or an increase in the concentration can be observed for Fe and Mn, respectively. Other substances like As, NO2- and Ammonia decrease during underground passage while no significant changes or an increase in the concentration can be observed for B and F, respectively. Only Fluoride exceeds the threshold for drinking water standard (Indian standard 1.5 mg/l) and must be considered as critical. At the Nizamuddin field site positive effects during bankfiltration can be observed only for one heavy metal (Al), while no significant changes can be observed for Pb and Cu and an increase in the concentration can be observed for Fe and Mn. Other substances like As, F and Ammonia increase during the underground passage while no significant changes or an decrease in the concentration can be observed for B and NO2-, respectively. At this field site elevated concentrations of several substances like As, Fe, Mn, F and NH4 will make a post-treatment necessary. At the Najafgarh field site the main constraints is the high salinity of the groundwater and the seasonal disavailability of fresh surface water. Due to the high mineralization of the groundwater a possible RBF site must be situated very close to the drain with shallow filter screens in order to obtain a high share of bank filtrate. The design and the potential capabilities of RBF facilities are currently subject to ongoing work and cannot evaluated finally. The sampling campaigns carried out so far are very useful to evaluate i) the seasonal changes in the surface water and ii) the depth dependent changes of the ambient groundwater. It needs to be taken into account that nitrogen species will promote the occurrence of problematic substances like ammonia, nitrite or nitrate due to a load with untreated sewage. Fluoride is expected to be no problematic substance.

Riverbank Filtration (RBF) is a valuable method for the (pre-)treatment of surface water for drinking water production. It has successfully been used in different parts of Europe for more than one century. The main intention of work package 5.2 of the TECHNEAU integrated project is to analyze the function and relevance of Riverbank Filtration (RBF) to enable sustainable water resources management, especially in developing and newly industrialized countries. A review on the attenuation capacity of RBF with a main focus on the significance for developing and newly industrialized countries is given in the D 5.2.3. This report (D 5.2.6) provides an overview on pathogen and organic trace compound content in water samples from the three TECHNEAU riverbank filtration (RBF) sites in Delhi, India. It is a follow up of the D 5.2.1 report that gives an introduction to the studies in Delhi, including regional information to water stressed mega city, environmental conditions at the three field sites and a summary of the hydrogeological investigations. Further information on hydrogeochemistry including inorganic ions (major ions, heavy metals and inorganic trace substabnces) and physicochemical parameters was submitted in D 5.2.2. The data published in this report represents water samples that have been collected during several field campaigns between May 2007 and March 2008 and analysed in different laboratories in India and Europe. Microbiological analysis includes faecal bacteria and indicator bacteria, bacteriophages and enteric viruses. For the analysis of organic contaminants, a non target GC-MS screening was performed as well as a quantitative analysis of pesticides and other trace pollutants.

Das Berliner Trinkwasser wird überwiegend durch induzierte Uferfiltration entlang der Oberflächengewässer gewonnen. Durch die geringen Durchlässigkeiten der Seesedimente findet eine Infiltration nur an den besser durchlässigen Uferzonen statt, und es kommt zu einer Unterströmung der Seen. Durch die Kombination verschiedener Umwelttracer konnte eine starke vertikale Altersdifferenzierung des Uferfiltrats nachgewiesen werden. Die Fließzeiten betragen in den flacheren Grundwasserleiterbereichen einige Monate, in den tieferen Bereichen sogar mehrere Jahre. Das den Abbau redox-sensitiver Substanzen beeinflussende, vorherrschende Redoxmilieu weist ebenfalls eine starke vertikale Differenzierung auf, die Infiltration erfolgt überwiegend anoxisch, und das Uferfiltrat wird mit der Tiefe reduzierender. Da das Oberflächenwasser einen variablen Anteil geklärten Abwassers enthält, konnten einige abwasserbürtige Substanzen (z.B. pharmazeutische Rückstände) in Oberflächenwasser- und im Uferfiltrat nachgewiesen werden. Obwohl der überwiegende Teil pharmazeutischer Rückstände effizient während der Untergrundpassage entfernt wird, erwiesen sich einige Substanzen als äußerst persistent (AMDOPH, Primidon und Carbamazepin).

Redox processes during bank filtration were evaluated in Berlin, where bank filtered water is abstracted for drinking water production. The investigations included the mapping of the infiltration zone, a column study and hydrochemical analyses of the groundwater sampled between lake and production well. The organic carbon content increased and the permeability of the lake sediments decreased with distance from the shoreline. The most important changes with regard to the redox state of the infiltrate occurred within the first metre of flow. Infiltration was mostly anoxic, as oxygen was rapidly consumed within the organic rich sediments. The infiltration zone revealed a vertical redox stratification with hydrochemical conditions becoming more reducing with depth rather than with distance from the lake. The redox zones were found to be very narrow below the lake and wider towards the production wells, suggesting that other than differing flow paths, reaeration after infiltration may also occur and possible mechanisms are presented. Redox conditions were influenced by strong annual temperature variations of the surface water affecting the microbial activity. Aerobic infiltration only took place close to the shore in winter.

Berlin relies on induced bank filtration from a broad-scale, lake-type surface water system. because the hydraulic conductivity of the lake sediments is low, infiltration only occurs close to the more permeable shore zones. Using multiple environmental tracer methods, a strong vertical age stratification of the bank filtrate could be shown. travel times are generally long and vary throughout the upper aquifers from a few months near the ground surface to several decades in greater depth. infiltration is mostly anoxic and redox zones were found to be vertically stratified too, becoming more reducing with depth. because berlin’s watercourses contain a proportion of treated municipal sewage a number of wastewater residues, e. g. pharmaceutical residues, were detected in surface water and groundwater. While the majority of the pharmaceutical residues studied were efficiently removed during underground passage, some substances (aMDOPh, primidone and carbamazepine) were found to be very persistent.

Berlin relies on induced bank filtration from a broad-scale, lake-type surface water system. Because the surface water contains treated sewage, wastewater residues are present in surface water and groundwater. Multiple environmental tracers, including tritium and helium isotopes (3H, 3He, 4He), stable isotopes (d18O and d2H) and a number of persistent sewage indicators, such as chloride, boron and a selection of pharmaceutical residues (phenazone-type analgesics and their metabolites, carbamazepine and anthropogenic gadolinium, Gdexcess), were used to estimate travel times from the surface water to individual production and observation wells at two sites. The study revealed a strong vertical age stratification throughout the upper aquifer, with travel times varying from a few months to several decades in greater depth. Whereas the shallow bank filtrate is characterized by the reflection of the time-variant tracer input concentrations and young 3H/3He ages, the deeper, older bank filtrate displays no tracer seasonality, 3H/3He ages of a few years to decades and strongly deviating concentrations of several pharmaceutical residues, reflecting concentrations of the source surface water over time. The phenazone-type pharmaceuticals persist in the aquatic environments for decades. Bank filtration in Berlin is only possible at the sandy lakeshores. In greater water depth, impermeable lacustrine sapropels inhibit infiltration. The young bank filtrate originates from the nearest shore, whereas the older bank filtrate infiltrates at more distant shores. This paper illustrates the importance of using multiple tracer methods, capable of resolving a broad range of residence times, to gain a comprehensive understanding of time-scales and infiltration characteristics in a bank filtration system.