The use of groundwater for public water supply and irrigation has many benefits for water suppliers as well as for consumers. Over the last decades availability and consumption of this valuable resource has increased worldwide along with technical progress, but it has often been ignored that any abstraction of groundwater is an intervention in the balance of the natural water cycle. Managed aquifer recharge (MAR) present the double interest : 1. to be a possible technical answer to over-exploitation of groundwater reservoirs and can contribute to water resource preservation and possibly reuse 2. to provide a natural cleaning step to pre-treat surface water for drinking water supply, and therefore could contribute to reduce the need for highly sophisticated treatment methods which are cost intensive in installation and also in maintenance. In many parts of the world, such as low income countries, MAR offers the possibility to profit from the storage and purification capacity of natural soil/rock and to guarantee a sustainable management of groundwater. River bank filtration is an ancient and widely used method that currently provides water to a large number of population in EU (45% of Hungarian water supply, 16% of German water supply, 5% of The Netherland water supply). River bank filtration relies on natural conditions to operate efficiently and allow to produce a quality of water which, in some cases, doesn't required further treatment before distribution (such as in Berlin). There are now many evidences that global environmental conditions are progressively changing and may impact existing water supply scheme by bank filtration. The extensive study of bank filtration systems in different environmental settings (such as in India with higher temperature, different surface water quality, systems subject to monsoons and flooding …) will allow apprehending the limitation that current bank filtration systems may face, and highlight the possible need for adaptive strategies. The aim of this report is to document work performed within the first 6 months since the start of WP 5.2 of TECHNEAU integrated project and to give an overview of the results and future planning. This includes detailed regional investigations, field studies and laboratory work performed in collaboration between the KompetenzZentrum Wasser Berlin gGmbH (KWB), the Indian Institute of Technology in Delhi (IIT) and the Freie Universität Berlin (FUB). Preliminary studies at potential sites in different parts of the world were performed prior to the TECHNEAU Project with the aim to investigate their suitability for RBF and thus to allow for deeper investigation within TECHNEAU. These preliminary studies were carried out in the cities Kaliningrad (Russia), Recife (Brazil) and New Dehli (India), and were funded by Veolia Water. In Recife (Brazil), the investigation performed by the FUB showed that both hydrogelogical data and model results indicate that the area is not suitable for the production of drinking water by RBF in sufficient amounts due an unfavorable hydrogeological conditions (too low transmissivity of the target aquifer because of the low content of sand in the samples and the scarce distribution of sandy sediments). At this point further investigations were stopped since no alternative field site area was found. In Kalingrad, water quality data that was gained in the preliminary study from the field site and will be compared with the data gained from investigations in Delhi and Berlin. In Delhi, India, the appropriate conditions, as well as the establishment of a valuable collaboration with the IIT, has lead to the implementation of three different field sites (in three different conditions). The activity performed within the techneau framework and included (i) the integration of existing information and literature on local climate, geology and water supply system, (ii) the detailed investigation about the local hydrogeology and ground and surface water quality and (iii) the development of a GIS (Geo Information System). In agreement with local authorities, three different field sites were selected in the territory of Delhi, representing distinctly different environmental conditions within the district. According to local conditions, a net of 17 groundwater observation points (piezometers) has been designed and installed on each of the field sites. A description of local geology, including stratigraphical charts has been elaborated, based on the evaluation of information obtained during the drilling and from analysis of sediment samples. A strategy for monitoring of water level and water sampling analysis has been developed, and monthly field campaigns have been carried out. Water samples have been analyzed, considering a broad variety of parameters including major chemical contents, trace substances and pathogens. Hydraulic tests have been conducted to obtain aquifer properties in order to estimate travel velocities during underground passage.

Investigations on the behavior of bulk organics and trace organic compounds in a temperated soil column system are reported. Objective of the research was to assess the importance of temperature for the degradation of bulk and trace organics. The analysis of the bulk organic behavior showed a fast mineralization of easy degradable organic carbon in the first few centimeters of the columns, which does not seem to be temperature-dependent. Along the further infiltration path an influence of the different temperatures on the bioactivity was clearly visible. However, a significant increase of mineralization potential of bulk organic compounds with increasing temperature was shown. The monitoring of the single organic pollutants Iopromide, Sulfamethoxazole and naphthalenedisulfonic acids showed that temperature has an influence on the degradation behavior of the monitored compounds. In most cases higher temperatures increased the mineralization potential.

Cyanobacterial toxins are toxic substances produced by cyanobacteria or blue-green-algae. The can occur in surface waters wordwide and have to be removed sufficiently when using infested surface waters as drinking water source. Bank filtration has been used since 150 years for drinking water (pre-)treatment and utilizes natural elimination processes like sorption and degardation in the sub-surface. During several research projects the German Federal Environmental Agency (Umweltbundesamt, UBA) carried out field investigations and experiments in different scales in order to assess under which conditions secure elimination of microcystins (the most common group of cyanobacterial toxins) takes place. Filtration of cells on the sediment surface is the most prominent process for eliminating the primarily cell-bound toxins. Middle to coarsly grained sands eliminated more than 99.9 % of intracellular toxins within the first 10 centimeters. Elimination of extracellular microcystin during underground passage is mainly due to biodegradation. Reversible adsorption processes do not reduce the total load but lead to longer contact times for extended biodegradation. Laboratory experiments showed that high clay and silt content is crucial for maximum adsorption. However, redox conditions play an important role for degradation rates: under aerobic conditions half lives of less than one day occured frequently whereas anoxic conditions resulted in lag phases of one day and more as well as in half lives of up to 25 days. Field experiments could show that temperature is crucial for degradation velocity under natural conditions.

In Berlin – wie auch in anderen Regionen Deutschlands – wird ein Großteil des Trinkwassers durch Uferfiltration gewonnen. Durch eine Untergrundpassage mit einer Dauer von meist mehreren Wochen erhält es eine Aufreinigung, die den Aufwand der konventionellen Trinkwasseraufbereitung verringert und eine zusätzliche Barriere gegenüber Schadstoffen darstellt (Kühn 2001). Das Ziel eines interdisziplinären Forschungsvorhabens mit dem Titel NASRI (Natural and Artificial Systems for Recharge and Infiltration) war, die Reinigungsprozesse für verschiedenste Substanzen zu ermitteln und Empfehlungen für das zukünftige Wassermanagement in Berlin abzuleiten (Fritz 2003). Aufgabe der Arbeitsgruppe des Umweltbundesamtes war dabei zu klären, wie wirksam Microcystinen (MCYST) als wichtigste Gruppe der Cyanobakterientoxine durch die Bodenpassage eliminiert werden. Im Folgenden werden einige Schlüsselergebnisse berichtet. Für eine ausführliche Ergebnisdarstellung siehe Grützmacher et al. (2006). MCYST sind in der Regel überwiegend (> 90 %) zellgebunden, so dass die physikalische Filtration der Zellen an der Sedimentoberfläche als Eliminationsprozess im Vordergrund steht (Grützmacher et al. 2003). Das extrazelluläre MCYST wird dagegen überwiegend biologisch abgebaut (Lahti et al. 1998, Grützmacher et al. 2005a). Um unter naturnahen Bedingungen Extremfälle für den biologischen Abbau zu simulieren, wurden i) Freilandversuche unter variierenden Redoxbedingungen und ii) Laborsäulenversuche bei unterschiedlichen Temperaturen durchgeführt. Ferner wurde die Freisetzung von MCYST aus sedimentierten Zellen untersucht.

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).

Eine Forschungsgruppe derTechnischen Universität Berlin beschäftigt sich mit dem Verhalten von gelöstem organischen Kohlenstoff, DOC und organischen Einzelstoffen beider Uferfiltration. Die Ergebnisse zeigten, dass sowohl oxische als auch anoxisch/anaerobe Infiltrationsbedingungen zu einem ähnlich niedrigen DOC führen können. Unter oxischen Verhältnissen ist zur Mineralisierung des bioverfügbaren DOC (BDOC) nur eine einmonatige Bodenpassage notwendig, während es unter anoxisch/anaeroben Verhältnissen aufgrund der langsameren Abbauklnetik bis zu sechs Monate dauern kann. Bezüglich der Spurenstoffe konnte gezeigt werden, dass das Röntgenkontrastmittel lopromid in allen Felduntersuchr./ngen schnell entfernt wurde. Das Antibiotikum Sulfamethoxazol wurde unter anoxisch/anaeroben Verhältnissen effektiver entfernt (bis zu 80%), während unter oxischen Bedingungen maximal 50% der Ausgangskonzentration abgebaut wurden. Zusammenfassend kann die Uferfiltration als eine durchaus sehr.wirksame Stufe zur Entfernung von Organika bewertet werden.

The behaviour of residues of phenazone-type pharmaceuticals during bank filtration was investigated at a field site in Berlin, Germany, where bankfiltered water is used for drinking water production. The concentrations of the pharmaceutical residues in the shallow, young bank filtrate (travel times < 1 month) were correlated to the prevailing hydrochemical conditions at the field site. In addition, their behaviour in an undisturbed sediment core from the lake base at the site (clogging layer) was evaluated in the laboratory. Phenazone, 4-acetylaminoantipyrin (AAA), 4formylaminoantipyrin (FAA) and 1,5-dimethyl-1,2- dehydro-3pyrazolone (DP) were eliminated more efficiently under oxic conditions, while 1-acetyl-1-methyl-2-dimethyloxamoyl-2phenylhydrazide (AMDOPH) was not eliminated at all. The redox conditions and the elimination of the respective pharmaceutical residues displayed strong seasonal variations. Oxic conditions were only encountered close to the shore in winter, when temperatures were low. The column study showed that the elimination is restricted to the uppermost decimetres of the lake base, where oxygen is present. While phenazone elimination is almost complete during aerobic rapid sand filtration in the waterworks, the compounds were found to be more persistent under anoxic field conditions.