Die Berliner Wasserbetriebe haben zusammen mit Veolia Water im Rahmen des Kompetenzzentrums Wasser Berlin ein Pilotprojekt zu neuen Sanitärkonzepten begonnen. Zur Ermittlung der zu erprobenden neuen, nachhaltigen Sanitärkonzepte wurde eine Vorstudie durchgeführt. Diese Studie beinhaltet u.a. einen Kostenvergleich zwischen zwei neuen Sanitärkonzepten mit Schwerkraft- und Vakuumseparationstoiletten und dem konventionellen System. Es konnte gezeigt werden, dass die neuen Sanitärkonzepte, abhängig von den Rahmenbedingungen, Kostenvorteile haben. Dies war eine weitere Motivation, ein Pilotprojekt zur Erprobung der neuen Sanitärkonzepte unter realistischen Bedingungen in Berlin/Brandenburg durchzuführen. Der Betrieb des Sanitärkonzepts mit Schwerkrafttrenntoiletten hat im Sommer 2003 begonnen.

Die Grundidee des Projektes berlinbeach ist im Rahmen einer Diplomarbeit (Berger, Steeg, 2001) im Studiengang Landschaftsarchitektur und Umweltplanung an der Technischen Fachhochschule Berlin entwickelt worden. Unter anderem aufbauend auf der Geschichte des Badens in Flüssen ist die Vision entstanden, die zukünftige Nutzung der innerstädtischen Spree als Badegewässer trotz der vorhandenen Ge-wässerverschmutzung zu realisieren. Das Baden in Flüssen war bis zum Beginn des letzten Jahrhunderts in Berlin eine Selbstverständlichkeit. Zahlreiche öffentliche Flussbäder befanden sich im Bereich der innerstädtischen Spree. Erst durch die mit der beginnenden Industrialisierung und der wachsenden Bevölkerung zunehmende Verschlechterung der Wasserquali-tät mussten die städtischen Bäder geschlossen werden und wurden durch die auch heute noch weitgehend genutzten Strandbäder im Stadtrandgebiet ersetzt. Die derzeitige stoffliche Belastung der Spree im Projektgebiet erfolgt durch die Ein-träge aus den Brandenburger Zuflüssen, dem Klarwasserablauf des Klärwerkes Mün-chehofe, den Einleitungen aus dem Berliner Trennsystem sowie den Mischwasser-entlastungen des Berliner Mischsystems. Es ist davon auszugehen, dass die Überläufe aus dem Mischsystem der Berliner Ka-nalisation eine wesentliche Verschmutzungsquelle der Spree darstellen. Vorrangiges Ziel des Projektes berlinbeach ist es daher, die Mischwasserentlastungen durch in der Spree angeordnete Speicher (Fangbecken) weitgehend zu vermeiden und da-durch die Badegewässerqualität in der innerstädtischen Spree nach Möglichkeit zu gewährleisten. Darüber hinaus ist vorgesehen, die Speicher mit entsprechenden Aufbauten zu versehen und diese zur Refinanzierung der Maßnahme zu nutzen.

With the application of advanced treated wastewater to the ancient wastewater irrigation field Karolinenhöhe, the Berlin Water Company (Berliner Wasserbetriebe) started in 1990 an ecological passable and water economical reasonable cultivation of an old wastewater irrigation field. After a period of 10 years of operation the functional capability and the efficiency is assed. In the first aquifer a hydrodynamic impact by the trickled water could be proved in the measuring facilities and certified by modelling. Altogether the application of the advanced treated wastewater stabilized the water balance and therefore the basis flow of the river Havel. Especially admissions during the low water periods (summer and autumn) counteract the low water level in the surface water by a raised basis discharge. Since 1990 the ecological status of the first aquifer of the wastewater irrigation field is clearly improved. The concentration of the relevant parameters of eutrophication NO3, NH4 und PO4 regressed significantly. In the second aquifer the parameter boron and phosphate improved from 1990 to April 2002. For the other parameters a diffuse basis load remained. The admission of the advanced treated water has a positive effect to the quality of the groundwater compared to the initial situation. The concentration of most of the parameters regressed. Just the concentration of potassium (in the first and second aquifer) and of AOX (in the first aquifer) stayed almost constant because of the input. There are no risks by continuing applications. There is a degradation of the nitrogen compounds due of the soil passage of the water and a dilution by the natural groundwater recharge. Therefore the receiving water bodies are less polluted compared to a direct discharge (exception potassium). A clear improvement is reached for the river Havel. The retention time of the water in the underground passage is very long because of the great depth of the groundwater level. Therefore a degradation of germs is assured. More detailed studies and analyses must follow this primal estimation.

At the Ruhleben wastewater treatment plant (WWTP) two membrane bioreactor (MBR) pilot plants have been operated since September 2001 by Veolia Water and Berliner Wasserbetriebe. The primary aim of the piloting is the investigation of biological phosphorus removal in conjunction with nitrification/denitrification in MBRs for later use in remote areas and small scale applications (WWTP serving a few thousand inhabitants) [Gnirss et al 2003a]. Both plants are fed with the same raw wastewater as it is treated in the conventional wastewater treatment plant. Instead of the mechanical treatment of the conventional plant, the raw wastewater passes a 1 mm punch hole screen prior to the biological treatment in the two MBR pilot plants. The two pilot plants are operated under parallel operating conditions (same raw wastewater, same sludge age and sludge concentration , etc.), but there are two different biological process configurations: pre-denitrification and postdenitrification without addition of a carbon source. Over the first year of operation, it has been observed that the unit with post-denitrification exhibited more rapid membrane fouling than the one with pre-denitrification. Preliminary LC-OCD (liquid chromatography-organic carbon detection) measurements carried out with the permeate compared to paper filtered sludge showed differences between the two units regarding the concentration of colloids and large macromolecules (as measured in the polysaccharide peak). Hence, an assessment and investigation of the fouling behaviour of the two MBR pilot plants was commenced. The results are presented in this report.

Two configurations of membrane bioreactors were identified to achieve enhanced biological phosphorus and nitrogen removal, and assessed over more than two years with two parallel pilot plants of 2 m3 each. Both configurations included an anaerobic zone ahead of the biological reactor, and differed by the position of the anoxic zone: standard pre-denitrification, or postdenitrification without dosing of carbon source. Both configurations achieved improved phosphorus removal. The goal of 50µgP/L in the effluent could be consistently achieved with two types of municipal wastewater, the second site requiring in addition a low dose of ferric salt ferric salt < 3mgFe/L. The full potential of biological phosphorus removal could be demonstrated during phosphate spiking trials, where up to 1mg of phosphorus was biologically eliminated for 10mg BOD5 in the influent. The post-denitrification configuration enabled a very good elimination of nitrogen. Daily nitrate concentration as low as 1 mgN/L could be monitored in the effluent in some periods. The denitrification rates, greater than those expected for endogenous denitrification, could be accounted for by the use of the glycogene pool, internally stored by the denitrifying microorganisms in the anaerobic zone.

Induced by well abstraction, surface water infiltrates into Berlin aquifers and is used for drinking water production. A major advantage of bank filtration is the capability of the subsurface to remove contaminants and save natural groundwater resources. Since a large proportion of the surface water in Berlin originates from treated effluents released by wastewater treatment plants, certain wastewater residues can be traced into the groundwater. A powerful tool to characterise bank filtration systems is the use of wastewater indicators and additional environmental tracers to estimate flow velocities and proportions of bank filtrate in the abstraction wells prior to reactive transport evaluations. Examples for tracer applications at the Berlin system are introduced in this paper. In addition, an overview on results of various studies conducted on contaminant transport and removal during underground passage of the bank filtrate in Berlin is given.

Cyanobacteria proliferation and the potential health risk related with the release of the associated toxins have lead the local association EDEN to initiate a comprehensive study on cyanobacteria in the river Erdre. Within the consortium in charge of the project, the Berlin Centre of Competence for Water (KWB) realised lab-scale research in cooperation with the German Federal Environmental Agency (UBA), on the species Planktothrix agardhii which predominates in the river Erdre, and the associated toxin microcystin. The objective was to determine the influence of key factors such as nutrients (nitrogen, phosphorus), light, flow velocity and sediments on cyanobacteria growth and competition as well as microcystin release from the Planktothrix population in the river Erdre. Results from the lab-scale cultures proved that nutrient-limited conditions lead to a decrease of cyanobacteria biomass and may favour some genotypes with reduced needs among the Planktothrix population. Given the current state of scientific knowledge, no differences in competition between toxic and non-toxic Planktothrix strains can be established. Nutrient limitation favours microcystin release from cells, however the global decrease of cyanobacteria biomass induces a decrease of the total quantity of released toxin. These results can be applied in a water body where nutrients concentrations are very low (below 50 µg/L for total phosphorus). In the river Erdre, as long as external nutrients inputs remain considerable, light is the limiting factor. Internal nutrient recycling from the sediments is globally negligible in comparison with external inputs. Culture experiments in a flow simulation flume proved that flow velocity had substantial impact neither on Planktothrix growth nor on microcystin release. Only a short transition phase with negative effects was observed. Overwintering of Planktothrix in Erdre-sediments could be proved by the detection of a substantial population using fluorescence analysis. This inoculum should be large enough for initiation of Planktothrix development in the next vegetation period. However, the high adsorption capacities of the analysed sediments from the river Erdre allow to put aside a potential risk of microcystin release from sludge. While providing innovative results on the species Planktothrix agardhii, this project contributes to the comprehensive study initiated by the EDEN association in order to preserve the values associated with environment, health and tourism in the river Erdre.

River bank or slow sand filtration is a major procedure for processing surface water to drinking water in central europe. In order to model the performance of river bank and slow sand filtration plants, we are studying the different mechanisms by which the elimination of pathogens is realized. An important question concerning the mode of action of slow sand filters and river bank filtration units is the role of the colmation layer or “schmutzdecke” on the elimination of human pathogens. The schmutzdecke is an organic layer which develops at the surface of the sand filter short after the onset of operation. We have inoculated a pilot plant for slow sand filtration with coliphages and determined their rate of breakthrough and their final elimination. In the first experiment, with a colmation layer still missing, the breakthrough of the coliphages in the 80 cm mighty sandy bed amounted to ca. 40 %. In contrast, less than 1 % of coliphages escaped from the filter as the same experiment was repeated two months later, when a substantial colmation layer had developed. Our preliminary conclusions are that the colmation layer is extremely efficient in eliminating of viruses.