Eine optimierte Abwasserbehandlung führte seit den 1990er Jahren zu stark abnehmenden, kontinuierlich aus Punktquellen in die Vorfluter eingeleiteten Nährstofffrachten (HEINZMANN, 1998, SENSTADT, 2001), wodurch sich die Wasserqualität der aufnehmenden Gewässer Berlins merklich verbesserte. Episodische Belastungen durch Mischwasserentlastungen stellen jedoch weiterhin eine bedeutende Ursache einer herabgesetzten Wasser- und Sedimentqualität und eine der wichtigsten Managementaufgaben für die Berliner Stadtspree und der Kanäle dar (vgl. LESZINSKI ET AL., 2006, RIECHEL 2009). Hinsichtlich des von der EU-WRRL geforderten guten ökologischen und chemischen Zustandes der Binnengewässer bzw. des guten ökologischen Potenzials für stark veränderte und künstliche Gewässer, stellt die Lebensraumfunktion für die aquatischen Lebensgemeinschaften der Berliner Gewässer das wesentliche gewässerinterne Schutzziel dar. Neben dem erheblichem ökologischen Gefährdungspotenzial, das insbesondere von extremen Ereignissen der Mischwasserentlastung ausgeht, reduzieren vorrangig hydromorphologische Defizite (Stauhaltung, Uferbefestigung, Sohleintiefung, etc.) die Lebensraumqualität für die aquatischen Lebensgemeinschaften. Aufgrund der Schifffahrtsnutzung der Berliner Spree und der Kanäle stellen Wellenschlag und Sunk- und Schwalleffekte während Schiffspassagen eine zusätzliche, bedeutende Belastung dar (vgl. LESZINSKI ET AL., 2006). Wie in der Studie „Immissionsorientierte Bewertung von Mischwasserentlastungen in Tieflandflüssen“ (LESZINSKI ET AL., 2007) dargelegt, liegen die in Laboruntersuchungen ermittelten Ansprüche bzw. Toleranzen hinsichtlich der Wasserqualität für die Fischarten und Arten wirbelloser Bodenorganismen der Berliner Spree und der Kanäle in einem vergleichbaren Bereich (JACOB ET AL., 1984, LAMMERSEN, 1997). Die Herleitung von Gütestandards hinsichtlich der Wasserqualität für die Fischfauna schließt somit den Schutz der Lebensgemeinschaft der wirbellosen Bodenorganismen mit ein. Ebenso besteht bei beiden Organismengruppen ein grundsätzlicher, vergleichbarer funktioneller Zusammenhang zwischen der Ausprägung der Lebensgemeinschaft und der hydromorphologischen und strukturellen Lebensraumausstattung des Gewässers (z.B. SHELDON, 1968, KARR & SCHLOSSER, 1978, MINSHALL, 1984; MINSHALL & ROBINSON, 1998, TANIGUCHI & TOKESHI, 2004). So korrelieren Artenzahl und Diversität beider Organismengruppen höchst signifikant negativ mit dem Ausbaugrad der Ufer. Als Resultat der verschiedenen Belastungen findet sich in der Berliner Stadtspree eine extreme Dominanz von wenigen sehr anspruchslosen, toleranten Arten. Folglich sind Verbesserungen des ökologischen Zustandes und des Besiedlungspotenzials für wirbellose Bodenorganismen und Fische neben der Reduzierung der negativen Auswirkungen der Mischwasserentlastung, vorrangig durch Aufwertung der Uferstrukturen zu erreichen. Strukturelle Aufwertungen der Ufer müssen zusätzlich die hydrodynamische Belastung durch den schiffsinduzierten Wellenschlag berücksichtigen, um einerseits das Besiedlungspotenzial zu erhöhen, andererseits die Ufer vor Erosion zu schützen. Die vorliegende Studie gibt Hinweise auf die Möglichkeiten und Grenzen einer Revitalisierung der Berliner Stadtspree und der Kanäle am Beispiel der Fischfauna, indem sie die wesentlichen Belastungen und deren Auswirkungen skizziert. Potenzielle Maßnahmen zur Aufwertung der Uferstruktur sollten aufgrund der oben angesprochenen sehr ähnlichen Wirkmechanismen zwischenUmweltausprägungen und Zusammensetzung der Lebensgemeinschaften beiden, wirbellosen Bodenorganismen und Fischen, zu Gute kommen. Zur Beurteilung möglicher struktureller Maßnahmen wird zunächst davon ausgegangen, dass die negativen Auswirkungen der Mischwasserentlastung derart minimiert werden können, dass sie keine akute Beeinträchtigung der Wasserqualität und der aquatischen Lebensgemeinschaften mehr verursacht. Des Weiteren soll beurteilt werden, ob durch solche Maßnahmen ein Lebensraum für Fischarten geschaffen werden kann, die höhere Ansprüche an die Sauerstoffbedingungen im Gewässer haben als die aktuelle Lebensgemeinschaft.

An international review of the market, current practices and R&D projects on the topic of rainwater harvesting management was performed. The review highlighted leading countries in different regions of the world, but also the variety of practices and acceptance. Current R&D issues and further research needs are identified and discussed. The application of RWHM techniques at household level seems to be mature, but sanitary risks exist when rainwater is used inside homes and also reserve on economical an environmental aspects can be drawn when drinking water supply is available. Promising concepts are being developed and demonstrated at larger scale such as industrial or commercial buildings or even urban catchments where the use of rainwater and the operation of the systems are under full control. For schemes of this scale, the integration and optimization of several beneficial aspects such as –traditionally- additional water supply and stormwater management, but also urban planning with water and green spaces, energy compensation in buildings and in the cities or ecological enhancement seems to be promising. Specific expertise will be required to best plan these schemes according to the local conditions and targets and to operate, maintain and upgrade them over their entire life time.

Well biofouling is a complex and not yet sufficiently understood process. Water wells represent a unique habitat, since they create a link between the anaerobic ground water containing Fe(II) and the aerobic surface. This groundwater is rich in soluble Fe(II) and the presence of trace amounts of free oxygen in the well screens presents ideal conditions for the growth of iron bacteria. The ochreous deposits produced block not only the filter area, but also the adjacent gravel pack or even parts of the aquifer, and result in a steady decrease of well performance. In this project, the bacterial communities of several Berlin wells have been compared using standard microscopic techniques and molecular techniques like DGGE. The aim of this study is to identify the responsible bacteria and associated processes that lead to well clogging. The sampling system allows easy and effective collection of undisturbed biofilm samples with minimal impact on normal well operation. Fingerprinting analysis indicates the presence of bacterial populations that are ubiquitous in the wells and certain indicator bacteria which can be found in only few wells. Free water and biofilm populations show distinct similarities. Some well populations can be grouped in clusters, depending on the location of the well. Further comparison with chemical data of the wells is planned to asses the impact of chemical conditions of the respective groundwater on the bacteria responsible for clogging. A sampling device was designed and built for exposure of carrier materials into different Berlin drinking water abstraction wells. In addition, samples from well components (pumps and pipes) and water samples were collected. The DNA was extracted using the FastDNA SPIN Kit for Soil (MP). 16S rDNA polymerase chain reaction (PCR) of the V3 region and denaturing gradient gel electrophoresis (DGGE) analyses were performed on the DNA samples (Muyzer et al., 1993).

The overall objective of MIA-CSO is to develop a model-based planning instrument for impact based CSO control. The objective of this study was to examine the potential and the drawbacks of different model coupling techniques that may be taken into account within the MIA-CSO project.

The sewer system of the city shows predominantly low gradients and partly high inline sewer capacities. A historically founded system of 63 pump stations is used for the delivery and distribution of combined water and wastewater from the collection systems via long force mains to six wwtps. Simultaneously, in case of rainfall events the pumps act as variable throttles on the outflow of the combined sewerage and activate the inline sewer capacities. High demands are formulated by the water authority to the emissions out of the waste water system into the sensible water bodies. Five of six wwtps of the city are situated in the surrounding area of Berlin. Due to the long distances between the pump stations in the inner city and the wwtps, the time until the dilution effect of the stormwater will be noticed at the inlet of the wwtp may last several hours. Due to the increased delivery rate at the pump stations of the combined sewer system during stormwater runoff (twice the dry weather peak flow), the pollution load at the wwtp increases immediately in the same amount. Due to the enlargement of storage within the combined sewer systems until the year 2020 to meet higher demands of the water authority, the total duration of a raised inflow to the wwtp during and after rain events will increase. To furthermore keep the processes at the wwtp stable (especially the nitrogen removal) the construction of a storage tank at the inlet of the wwtp (=outlet of the pressure main) as an option shall be taken under research. The volume of the storage tank is not only determined by the quantity but also by the quality of the inflow To provide evidence, that the new version of InfoWorks 9.5 CS® is able to calculate the flow and pollution processes in the pressure main network, a diploma thesis is carried out at the Berlin Centre of Competence for Water with the participation of the Berliner Wasserbetriebe

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.

The use of bank filtration for drinking water treatment in Europe dates back to the days of beginning industrialization in the 19th century. With regard to improved source water quality in Europe, the millennium development goals and global climate change, aquifer recharge (AR) and bank filtration (BF) need to be reassessed in terms of sustainability and their role within an integrated water resource management. Based on the IC-NASRI study comprising 194 drinking water facilities worldwide integrating aquifer recharge techniques in their treatment system, an average AR/BF site would be located in Central Europe alongside a river and is characterized by: a sandy gravel aquifer with a hydraulic conductivity of 2x10-3 m/s, a maximum aquifer thickness of 30 m, 175 m travel distance from bank to well, a travel time of 70 days and by vertical well operation with a daily capacity of 55.000 m³. A literature survey conducted within the TECHNEAU project demonstrated that for substances highly relevant to newly-industrialized or developing countries (e.g. pathogens) the removal efficiency is good. Hydro-chemical analyses from three study sites in Delhi support these results. However, it was also shown that poor surface water quality, saline groundwater or subsurface conditions leading to mobilization of trace metals like iron, manganese or arsenic may limit the applicability of AR / BF without further post-treatment. Climate change might affect the performance of AR / BF worldwide, impairing source water quality and influencing removal efficiency. However, other factors like changes in demography or land-use can impact the systems by far more severely.