The behaviour of residues of phenazone-type pharmaceuticals during bank filtration was investigated at a field site in Berlin, Germany, where bank-filtered water is used for drinking water production. The concentrations of the pharmaceutical residues in the shallow, young bank filtrate (travel times < one month) were correlated to the prevailing hydrochemical conditions at the field site. In addition, their behaviour during passage through an undisturbed sediment core from the lake base at the site (clogging layer) was evaluated in the laboratory. Phenazone, 4-acetylaminoantipyrine (AAA), 4-formylaminoantipyrin (FAA) and 1,5-dimethyl-1,2-dehydro-3-pyrazolone (DP) were eliminated more efficiently under oxic conditions, while 1-acetyl-1-methyl-2-dimethyloxamoyl-2-phenylhydrazide (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.

Im Oktober 2006 wurde das NASRI (Natural and Artificial Systems for Recharge and Infiltration) Projekt, ein Vorhaben der Kompetenzzentrum Wasser Berlin gGmbH, endgültig mit einer öffentlichen Präsentation der wichtigsten Ergebnisse abgeschlossen. In fast vier Jahren interdisziplinäre Forschungstätigkeit untersuchten mehr als 40 Wissenschaftler aus mehreren Berliner Universitäten und dem Umweltbundesland, gemeinsam mit den Berliner Wasserbetrieben die Prozesse während der Uferfiltration und künstlichen Grundwasseranreicherung. Es war ein Hauptziel des Projektes ein umfassendes Prozessverständnis zu entwickeln, um so die nachhaltige Nutzung der Uferfiltration und künstlichen Grundwasseranreicherung unter Berücksichtigung zukünftiger Anforderungen und Bedrohungen langfristig sicherzustellen.

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.

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.

The aim of the study was to evaluate the influence of variable redox conditions on a number of pharmaceutically active compounds, namely carbamazepine, phenazone and AMDOPH (1-acetyl-1-methyl-2-dimethyl-oxymoyl2-phenylhydrazide) below an artificial recharge pond in Berlin. The redox conditions change seasonally, mainly as a result of temperature changes of 0 to 24°C in the infiltrate. Aerobic conditions prevail in winter, while manganese reducing conditions are reached below the pond in summer. Phenazone is redox sensitive and was generally fully degraded before reaching the first groundwater well as long as oxygen was present. When conditions turned anaerobic, phenazone was not fully eliminated. AMDOPH (1-acetyl-1-methyl-2-dimethyl-oxymoyl2-phenylhydrazide) and carbamazepine are very persistant drug residues. However, results suggest that AMDOPH may be degradable under certain favourable conditions (i.e. aerobic conditions; relatively high temperatures, low recharge rates), but further studies will need to verify this statement.

The aim of the study was to calculate mixing proportions of treated wastewater in the surface water and production wells during bank filtration as well as the travel times to observation and abstraction wells. For this purpose, a variety of tracers such as the stable isotopes deuterium (D) and 18O and several wastewater indicators like chloride, EDTA (ethylenediaminetetraacetic acid), boron and the rare earth element (REE) gadolinium (Gd) are used and compared to each other. Time series measurements in the surface water could be traced back in bank filtrates and raw water. Gd-DTPA was found to be a useful sewage indicator, even though it is biodegradable at favourable conditions at very slow rates. The travel times of the bank filtrates were obtained by the analysis of the peak shift in time-series of the tracer. Most tracers were found to be applicable but best results were obtained with the stable isotopes.

Hydrochemical conditions were evaluated at both bank filtration and artificial recharge sites in Berlin. All bank filtration sites show a strong vertical age stratification. Rather than showing a typical redox zoning with more reducing conditions in greater distance from the surface water, the redox zones are horizontally layered, with more reducing conditions in greater depth. This is believed to be an effect of the strongly alternating groundwaterlevels and by the age stratification. The redox conditions are generally more reducing at the bank filtration sites, mainly as a result of the longer travel times and operational differences. Redox conditions at all sites vary seasonally in particular at the artificial recharge site, which is mainly caused by temperature changes.