Cylindrospermopsis raciborskii, a cyanobacterium of tropical origin, can produce the toxin cylindrospermopsin (CYN). This originally tropical cyanobacterium (blue-green alga) had spread to the waters of the Berlin area. Cylindrospermopsin had been detected in two lakes in the area, but none of the C. raciborskii strains isolated here so far were found to produce the toxin. The main objectives of the CYLIN project were therefore to analyze the distribution and regulation of C. raciborskii and cylindrospermopsin and to determine which cyanobacteria are producing this toxin in order to establish a basis to predict the further course of development of this species and the related health hazards for humans. The CYLIN project was implemented as a three-part program. A screening program was first conducted in 2004 to test regional water bodies for the presence of cylindrospermopsin and potential CYN-producing cyanobacteria in order to obtain an overview of their distribution in the study region. A total of 142 regional water bodies were sampled once each in this qualitative analysis of cylindrospermopsin and cyanobacteria. The screening program was followed by a monitoring program designed to generate quantitative data on the concentrations of dissolved CYN, particulate CYN, cyanobacteria and target environmental parameters at 20 selected lakes, which were sampled 3 times each. Furthermore, we investigated the seasonal dynamics of these parameters at two selected lakes in 2004 and 2005. Apart from this we isolated different cyanobacterial strains and conducted chemical and molecular biological analyses of CYN and CYN-coding genes, in order to identify CYN-producing cyanobacteria. The results show that C. raciborskii and CYN are much more widespread than was previously assumed for the region. C. raciborskii was detected in 22 % of the investigated water bodies, and cylindrospermopsin in 52 %. Additionally, two other toxic cyanobacteria of tropical origin were found for the first time in the Berlin-Brandenburg region, Anabaena bergii and Aphanizomenon aphanizomenoides. The mean and maximum CYN concentrations were 1 µg L-1 and 12 µg L-1, respectively. Since the particulate CYN fraction did not exceed 0.5 µg L-1, the dissolved CYN fraction was found to be responsible for the high CYN concentrations. The proposed guideline value for cylindrospermopsin in drinking water (1 µg L-1; Humpage and Falconer 2003) was exceeded 18 times at 8 different lakes. Although Aphanizomenon flos-aquae (Nostocales) has been unequivocally identified as a producer of cylindrospermopsin, the observed cylindrospermopsin concentrations cannot be attributed to this cyanobacterial species alone. Aphanizomenon gracile was also identified as a potential CYN-producing cyanobacterium. Based on the findings of the CYLIN project, we recommend that cylindrospermopsin be included as in hazard analyisis for drinking and bathing water quality assessments. To identify risk conditions associated with this cyanotoxin, further investigations are needed to identify all cyanobacteria that produce cylindrospermopsin and to elucidate the mechanisms regulating the occurrence of CYN-producing cyanobacteria, CYN synthesis by these organisms, and CYN decomposition in aquatic ecosystems. Our analysis of C. raciborskii population dynamics showed that its germination is temperature-dependent and its population growth light-dependent. Population size was determined by the time of germination, that is, the earlier the time of germination, the bigger the population. Based on these findings, it appears highly likely that the climate-related early rise in water temperatures over the course of the years has promoted the spread of this species to temperate regions. Our hypothesis for the future course of cyanobacterial and cyanotoxin development in German waters is as follows: The combination of trophic decline and global warming works to the general benefit of cyanobacteria of the order Nostocales and leads to a shift in cyanobacterial species and toxin composition. This may ultimately lead to an increase in the incidence of neurotoxins as well as cylindrospermopsin.

Treated municipal wastewater may contain pathogenous micro-organisms and persistent trace organics leading to problems when being discharged into the surface waters. The investigations of the research project PILOTOX aimed at their elimination from treated municipal wastewater through subsequent oxidation by ozone. For this purpose, the TU Berlin (department of Water Quality Control) in cooperation with the Berliner Wasserbetriebe at the WWTP Berlin-Ruhleben, carried out several tests with a pilot plant by the company WEDECO aiming at the ozonation of the effluent. The results show that ozonation is a suitable procedure to remove and transform respectively, substantial quantities of the pharmaceutical residues detected in the effluent of the Ruhleben WWTP and, at the same time, to achieve a germ reduction complying with the threshold values stipulated in the European directive on bathing water. It was found that many trace organics such as the anti-epilepticum carbamazepin or the hormone estron can be removed at a very low ozone dosage to below their analytic detection limit. The X-ray contrast media however, turned out to be more resistant: even at a high ozone dosage, their concentrations could be reduced only partially. In this context, the tests detected that through the combination of H2O2 and ozone, an elevated elimination rate for the substances iopamidol and iohexol can be achieved. The elimination of the analysed trace organics correlated with the decrease of the water’s UV activity. Thus, it is advisable to use the rapidly and simply traceable parameter SAK254 as process control parameter to determine the necessary ozone dosage. In addition, it could be proven that ozonation increases the biological degradability of water components. Laboratory test looking at recontamination levels however, indicate that the threshold values stipulated in the EU directive on bathing water will not be exceeded if the ozone-treated effluent is mixed with water originating from the River Spree. A study regarding the water’s acute and chronic toxicity, to its gene toxicity and endocrine impacts, revealed that – compared to the untreated effluent - no eco-toxicological risk potential can be detected in the ozone-treated water samples.The specific treatment cost covering the large-scale application of ozone treatment at the WWTP Ruhleben range between 1,0 cent/m3 and 2,2 cent/m3, of which the investment costs account for a percentage of 20-30 %.

Zentrale, konventionelle Wasserver- und Abwasserentsorgungskonzepte, in industrialisierten Ländern seit Jahrzehnten entwickelt und angewandt, sind aufgrund hoher Kosten, hohen Wasserverbrauches und geringer Wiederverwendung von Nährstoffen nicht hinreichend nachhaltig, insbesondere nicht für den Einsatz in Entwicklungsländer. Zielvorstellungen der nachhaltigen Konzepte sind eine weitgehende Wiederverwendung des gereinigten Abwassers, sowie der Nährstoffe, verbunden mit einem geringeren Energiebedarf bzw. einer Produktion von Energie. Alternative Konzepte und Techniken stehen bereits seit einiger Zeit zur Verfügung und werden auch angewendet, dennoch sind weitere Entwicklungen und Plausibilitätsprüfungen erforderlich. Aus diesem Grund hat das Kompetenzzentrum Wasser Berlin (KWB) zusammen mit den Berliner Wasserbetrieben (BWB) und Veolia Water ein entsprechendes EUDemonstrationsprojekt (Sanitation Concepts for Separate Treatment (SCST)) durchgeführt. Hierbei wurden zwei unterschiedliche Sanitärkonzepte in Gebäuden der BWB auf dem Gelände des Klärwerks Stahnsdorf erprobt. Ziel dieses Projektes war es zu erproben, ob diese neuen Sanitärkonzepte sowohl in ökologischer als auch in ökonomischer Hinsicht signifikante Vorteile gegenüber den konventionellen Sanitärsystemen mit Schwemmkanalistation und Kläranlage (end-ofpipe- system) bieten.

Within the EU-funded demonstration project 'Sanitation Concepts for the Separate Treatment of Urine, Faeces and Greyweater' (SCST), initiated, financed, and coordinated by Berlin Centre of Competence for Water (Kompetenzzentrum Wasser Berlin), Berliner Wasserbetriebe and Veolia Water the Institute of Wastewater Management and Water Protection of Hamburg University of Technology (TUHH) investigated processes for resource recovery and elimination of pharmaceutical residues from separate collected human urine. The main processes for resource recovery were steam stripping for nitrogen extraction and vacuum evaporation for volume reduction and obtaining highly concentrated nutrient solutions. The processes precipitation, crystallization, and adsorption, were used for nutrient recovery as follow-up techniques. The effect of steam stripping and evaporation on the reduction of PhaR was investigated, as well as the effect of the additional processes UVCradiation, ozonation.

The discussion of sanitation concept differing from the conventional one, i.e. systems with one sewer system and a central wastewater treatment station, is an ongoing increasing process. These new sanitation concepts have the target of saving and reuse the water as well as the nutrients. The approach of being a more appropriate technology can be demonstrated by life cycle analysis (Peter-Fröhlich et al, 2007). Due to the lack of implementation and long time experiences detailed cost comparison are not available yet. First estimations have been done and have shown a tendency, but detailed investigations have been missing. The results of the SCST-project, which represents an experience of four years implementation and operation of a new sanitation concept, will be used for a cost comparison of different sanitation systems. It is obvious that the prerequisite for a successful implementation beside the technical applicability is the demonstration of the systems benefits. These new sanitation systems will receive only acceptance, when economical benefits or other significant benefits will support their introduction. Therefore studies of cost comparisons are necessary and an important issue.

Access to microbiologically and chemically safe water is limited not only in developing countries, but also in transition countries and even in remote areas of developed countries. For these cases, decentralized water supply concepts such as point-of-use (POU), point-of-entry (POE) or small-scale system (SSS) technologies can be promising alternatives to centralized treatment concepts. Membrane-based treatment systems have gained importance for drinking water treatment in the developed countries. In principle, application of membrane technology is attractive also for the transition and developing countries, because it provides absolute barriers for control of hygienic hazards (Ultrafiltration (UF)) and because the modular construction enables implementation on each possible scale size. However membrane technology is still not affordable for the poorest part of the world population. The sustainable application of POU membrane system presumes that system should be operated without or with limited addition of chemicals, with limited possibility of regular backflushing and with low pressure, presumably hydrostatic. On the other hand, while the water needs for drinking and cooking for a family of four people constitute approx. 20 l/day, operation of POU UF system under low flux conditions is possible. One of the most important limitations for application of ultrafiltration in simple household devices, is membrane fouling. In order to overcome the reasons of the limited application of UF in POU systems, the better understanding of the UF process in these specific conditions and specially membrane fouling is needed. Recent studies have shown that dissolved or colloidal polysaccharides and proteins and their interactions with the membrane and between macromolecules might have more severe impact. During long term dead-end filtration, accumulation of the macromolecules on the membrane surface and increase of their concentration is severe. The interactions between those macromolecules in the conditions of high concentrations in the boundary layer affect the structure of the layer and its permeability. However, in most of the studies, only the foulant-membrane interactions are considered like relevant for reversibility of fouling. The foulant-foulant interactions in the boundary layer have been studied only superficially. Therefore, we systematically investigated the impact of polysaccharide and solution properties on UF membrane fouling in conditions of low flux and limited backflushing, under constant TMP conditions (hydrostatic pressure of 120 mbar - 150 mbar. Our experimental results lead us to the following conclusions: Regarding the initial stage of flux decline (0-80 ml permeate/cm2) the polysaccharide structure, and particularly availability of carboxyl groups, has a major impact on the membrane fouling, while the molecular weights of polysaccharides does not play a significant role (in the studied range of Mw 5-250 kDa). Such solution conditions as presence of metal ions and ionic strength are also detrimental for the fouling, while both metal ions and ionic strength have impact on the gel structure and properties, generally stabilizing it, and increasing the possibility of water trapping by hydrogen bonding, which leads to the higher permeability. However, independently of the initial solution conditions, after approx. 80 ml has been filtered through 1 cm2 of the membrane, flux becomes stable on the level of approx. 10 L/(hm2) over the whole period of operation (several weeks in some cases). We suppose that the gel layer formed by polysaccharides play a role of a “second” membrane on the surface of the PES UF membrane, keeping remaining permeability on the certain level, determined by the water retention properties of the gel structure. Regarding practical application, the obtained results open a new direction for the ultrafiltration in specific conditions of household systems. The long term ultrafiltration should be studied on natural waters to prove the flux stabilization phenomenon. This phenomenon may give a possibility to produce up to 10 L/h of water from 1 m2 of the membrane applying only 120 mbar of hydrostatic pressure (1.2 m water level difference) without backflushing or crossflow, which may simplify the design and maintenance of the system and significantly reduce its costs. Next activities in Techneau project will include the further evaluation of the long term ultrafiltration on natural waters; characterization of the impact of biofouling on the flux decline; and evaluation of the operational parameters of the Point-of-use system, based on the proposed above concept to treat at least 20 L/day.

Urban water courses are considerably degraded in terms of their hydrology, riparian and channel morphology, substrate heterogeneity and habitat features as well as water and sediment quality. In addition, the combined sewer overflows and the ecotoxicological impacts of its components lead to a change of the physical-chemical and microbial mass balance affecting the biocenoses of higher trophic levels. Combined sewer overflows are therefore an additional stress to the ecological status of the urban course of the River Spree and of its channels, which is damaged already by both preload and background load of the aquatic environment. With regard to the assessment of the ecological water status, the European Water Framework Directives gives priority to the aquatic biocenoses in their capacity as ecological quality parameters. Against this background, an immission-oriented approach for the assessment of combined sewer overflows has to describe also their impacts on the biocenoses of the macrozoobenthos, the fish fauna, the macrophytes and the phytoplancton. Initially, the most important factors, mechanisms and processes determining the mass balance of a water course are described. Particular attention is given to the mass balance of eutrophic lowland streams and rivers and of river-lake–systems. In this context, the abiotic mass balance is discussed together with the biotic use of resources. After introducing the basic processes of the mass balance, the impacts of the anthropogenic use on these processes are subsequently described with regard to Berlin’s specific water resources environment. The result is a compilation of the hydraulic, physical-chemical and ecological parameters relevant to Berlin’s water resources serving for water quality assessment purposes. Starting from the ecological processes disturbed by the anthropogenic use, the potential effects of the combined sewer overflow are examined. The parameters selection is concentrated on the essential processes connected to combined sewer overflow issues. Based on the large number of stress factors and their interactive impact system, those influences of the combined sewer discharge are worked out which have to be categorised as particularly jeopardising and which are important target values for the future water quality simulation. Due to the high background load, the highest priority has to be given to the acute load caused by nutrients and carbon load peaks resulting from combined sewer discharges, since they overcharge the self-cleaning potential of the urban course of the River Spree and its channels. Even if the organic substances and the chemical contaminants discharged lead to chronic loads, the main objective is to avoid to the greatest possible extent the temporary but extremely hypoxic conditions, since combined sewer overflows cause fish die-offs when the water resources situation is already critical. Primarily, the water quality modelling has to be concentrated on the realistic mapping of the highly dissolved concentration charts of the target parameters oxygen and ammonia, since the degree of the biocenoses’ damage is rather determined through discharge duration, discharge intensity and frequency than through the medium rates of pollutant loads.