The UBA’s experimental field on the outskirts of Berlin offers a unique possibility of simulating bank filtration, artificial recharge and slow sand filtration on a technical scale. The site consists of a storage reservoir (pond) with an adjacent artificial aquifer consisting of sand and gravel. Additionally the surface water can be conducted into 4 infiltration basins (two slow sand filters and two aquifer infiltration ponds). Three enclosures as well as large scale columns can be used for shorter and longer term simulation of groundwater transport. The whole site is separated from the surrounding aquifer by a layer of clay. A variety of physico-chemical parameters can be measured continuously and observed online. The travel times for the bank filtration passage determined by tracer experiments range from a few days to a maximum of 3 weeks. In the enclosures, infiltration ponds and large scale columns contact time can be varied between a few hours up to 3 months.

More than two years of monitoring data from a bank filtration site in Berlin, Germany, and a long retention soil column system (30 m) were analyzed to study the influence of redox conditions on the degradation of bulk organics. Dissolved organic carbon (DOC), UV-absorption at 254 nm (UVA254) and liquid chromatography with online carbon detection (LC-OCD) was employed to receive qualitative and quantitative information about the fate of different fractions of DOC. It was found that the kinetics of DOC-degradation depend significantly on the dominant redox conditions during infiltration. A faster mineralization of biodegradable DOC was observed during oxic soil passage (~1 month). Anoxic infiltration led to a comparable residual DOC-concentration, but 3-6 months were required for complete removal of biodegradable DOC (BDOC). LC-OCD measurements revealed that the fraction of polysaccharides (PS) is removed very fast during infiltration in the field. Under strictly anoxic conditions the PS were more stable. The fractions of humic substances, building blocks and low molecular weight acids were degraded partially, independently from the redox potential, while the change in aromaticity of the residual DOC was influenced by the dominant redox conditions.

Investigations on the behaviour of different trace organic compounds at a bank filtration site at Lake Wannsee in the city of Berlin, Germany are reported. More than two years of monitoring for the bulk parameter differentiated adsorbable organic halogens (AOX) revealed a more efficient degradation of adsorbable organic iodine (AOI) and adsorbable organic bromine (AOBr) under anoxic/anaerobic conditions. 64% of AOI were removed under reducing condition, whereas under oxic conditions only ~35% were dehalogenated. One year of monitoring of the single organic pollutants Iopromide (X-ray contrast agent), Sulfamethoxazole (bacteriostatica) and naphthalenesulfonic acid (industrial chemical) showed that the redox conditions have a strong influence on the degradation behaviour of some of the monitored compounds. Iopromide was efficiently removed under oxic conditions, but no evidence for a dehalogenation under oxic conditions was found. Sulfamethoxazole showed a better removal under anoxic/anaerobic conditions (97% in 0.5 month retention time). Oxic infiltration only led to a removal of 62%, even with longer retention times of 2.8 months. The very stable 1.5-naphthalenesulfonic acid was not removed under either redox conditions.

Several physical, chemical and biological mechanisms play a role in the clogging of sediment interstices regularly observed in sand filter and infiltration basin systems. Whereas the hyporheic zone has been the focus of many investigations, little is known about the lenitic limnic zone, which is typical in lowland areas with lakes and low flow rivers. One must assume that clogging is regulated by both the build-up and the input of particulate organic matter (POM). In the present study, we collected samples from the littoral zone of Lake Tegel, Berlin, Germany, to analyze relevant carbon turnover processes. High concentrations of POM were detected in the upper sediment layer, with 3.4% ds down to 20 centimeters depth. A very high biomass of interstitial algae was found in the first 5 cm of sediment (25 µg Chl a per cm–3); this was 1000 times higher than in the lake water. The pore system of the sediment was filled to about 50% with POM, and the algae volume comprised about 25 % of POM. Only low amounts of POM were transported from the lake water downwards into the interstices, and the transport of FPOM (a few centimeters per day) was much lower than the water flow (32–260 cm d–1). The DOC concentrations in lake water (~8 mg L–1) and interstitial water (~6 mg L–1) were determined by the in situ bioactivity of interstitial organisms in addition to DOC input from lake water.

Dieser Leitfaden wurde im Rahmen des Forschungs- und Entwicklungsprojektes „Getrennte Erfassung von jodorganischen Röntgenkontrastmitteln in Krankenhäusern“ der Kompetenzzentrum Wasser Berlin gGmbH erstellt. Er soll dazu dienen Ihnen einen kurzen Überblick zu geben, wie und warum die getrennte Sammlung von Urin der Patienten, die mit jodorganischen Röntgenkontrastmitteln untersucht werden, in Krankenhäusern durchgeführt werden könnte. Das Projekt wurde in zwei Phasen in Zusammenarbeit mit zwei Berliner Krankenhäusern, einem Universitäts-Klinikum und einem Krankenhaus der Grundversorgung, realisiert, die beispielhaft für das Krankenhauswesen in Deutschland stehen. Die 1. Phase, eine Machbarkeitsstudie, dauerte von April 2004 bis April 2005 und bildete die Grundlage für die 2. praktische Projektphase, die bis zum Dezember 2005 durchgeführt wurde. In der 2. Projektphase wurde das dezentrale Erfassungskonzept mit mobilen Urinbehältern (siehe Bild 1), entsprechend der Machbarkeitsstudie, im Zeitraum von 20 Wochen auf jeweils einer Krankenhausstation getestet, um die Röntgenkontrastmittel an der Quelle zurückzuhalten und nicht ins Abwasser gelangen zu lassen (Pineau et al., 2005; Pineau und Heinzmann, 2005; Schuster et al., 2006).

At Lake Tegel in Berlin, Germany, drinking water is produced by induced bank filtration. Under such increased infiltration conditions, it is very important to understand the natural purification processes in the upper littoral zone (sediment depth of about 0–30 cm) in order to maintain a high drinking water quality. We therefore analyzed the pore water and measured the redox potential at Lake Tegel regularly to detect fluctuations in the concentrations of physicochemical parameters due to seasonal variations in the redox potential. The redox potential is not only influenced by the biological activity of the interstitial biocoenosis, but also by hydraulic conditions that occasionally produce unsaturated zones leading to an intrusion of gaseous oxygen. The result is an increase in the redox potential, which declines during the summer due to intensive dissimilatory reduction and microbial activity, thus leading to distinctly anaerobic conditions. When this is the case, the oxygen supplied by primary production and bioturbation cannot meet the oxygen demand needed for the mineralization of organic material. Negative redox values (minimal –200 mV) are accompanied by increases in nitrite (max. conc. 150 µg/L) and ammonium levels (max. conc. 0.45 mg/L), while the nitrate concentrations decreased (min. conc. 0.2 mg/L). This indicates that processes such as denitrification and ammonification occur, and that, after depletion of free oxygen reserves, other electron acceptors, such as nitrate and also heavy metal ions (Fe3+), are used.

A modelling concept is presented that enables a quantitative evaluation of transport and natural attenuation processes during bank filtration. The aim is to identify ranges of degradation rates for which bank filtration is effective or ineffective. Such modelling should accompany experimental work, as otherwise the meaning of determined degradation rates for a field situation remains uncertain. The presented concept is a combination of analytical and numerical methods, solving differential equations directly for the steady state. It is implemented using FEMLABs code and demonstrates a typical idealized situation with a single well near a straight bank boundary. The method can be applied to confined, to unconfined and to partially confined/unconfined aquifers and may be extended for applications in more complex situations, including a clogging layer, galleries of pumping and recharge wells, etc.

In several slow-sand-filter experiments the behaviour of phages during the subsurface passage was measured and modelled. Here the focus is on the effect of the velocity. The observed data show a strong effect of decreasing filter efficiency with increasing velocity. Using a modelling approach, which is based on the transport differential equation, the theoretical influence of velocity on filter efficiency is examined. Finally an extrapolation of the results to large scale filtration units or bank filtration processes is attempted.

In several slow-sand-filter experiments the behaviour of phages during the subsurface passage was measured and modelled. Here the focus is on the effect of the velocity. The observed data show a strong effect of decreasing filter efficiency with increasing velocity. Using a modelling approach, which is based on the transport differential equation, the theoretical influence of velocity on filter efficiency is examined. Finally an extrapolation of the results to large scale filtration units or bank filtration processes is attempted.