Indicator bacteria and coliphages along the transects of Lake Tegel, Lake Wannsee and the artificial recharge pond Tegel The indicator microorganisms, Escherichia coli, intestinal enterococci, and coliphages were analysed in water samples from both transects for bank filtration at the Lakes Tegel and Wannsee as well as from the artificial recharge pond of Tegel. Surface water samples of both lakes were examined from May 2002 to December 2004. In addition, samples were analysed from four shallow observation wells and three pumping sites for drinking water supply along the transect Wannsee, as well as four deep and seven shallow observation wells and 2-3 pumping sites along the transect of Lake Tegel. Sampling at the artificial recharge pond of Tegel was carried out during four field surveys (August 2002-December 2002) in two shallow, three deep wells and one pumping well for drinking water supply. In addition, the microbial flora was studied in the sand filter of the recharge pond in Tegel.

The ENREM project aims at demonstrating a novel wastewater treatment process based on the technology of membrane bioreactor (MBR), set up in a configuration to enable enhanced biological elimination of nutrients. A new plant, and the related sewer system, was built in a unsewered periurban area of Berlin. The plant is to be operated over more than one year, and the process to be optimised. Performances and costs of the treatment system will be then assessed for the size 250 – 10,000pe, corresponding to semi-central schemes. The plant was started on 28 February 2006 with 8 month delay on the program identified in the LIFE proposal. As a consequence, a project extension request of 8 months will be lodged, in order to match the initial duration of 18 months for the optimisation, evaluation and dissemination phase. This delay incidentally caused also a 6 month delay for the preparation of this Interim Report. Despite these aspects, the management of the project has been achieved according to the organisation identified in the LIFE proposal. Annex 7.1 presents and discusses the key deliverables and milestones depending on the LIFE proposal and the current status. In relation to the technical content, Task 2 “Site and process definition” and Task 4 “Detailed design” were completed early 2005. Task 3 “Preliminary testing on representative site” was completed in September 2005 and enabled to validate the design, operation and start-up criteria of the MBR demonstration plant. The public tenders for the construction of the sewer network and the MBR container unit occurred during the first semester of 2005, and the construction of the scheme was completed by end 2006. In parallel, the required legal permits were acquired (for plant construction & operation, water discharge), as well as the parcel hosting the treatment unit. A relationship with the inhabitants of Margaretenhöhe was maintained in order to ensure a smooth construction phase, and a quick connection to the new sewer system. The dissemination activities covered several communication vectors (Tri-lingual website www.kompetenz-wasser.de, press-release and articles and bi-lingual KWB Newsletter, local press, scientific press, plant visits and inauguration, communication material etc). The project results will be widely communicated in the national and international medien, and a final project workshop will be organised in June 2007. The main task in 2006 will be the operation, optimisation and technical / economical evaluation of the low sewer system and the MBR demonstration plant. So far, the budget is generally in line with the expectations, or slightly below. The project finances allow the project extension of 8 months, required to achieve all announced technical outcomes of the project. After the 8 month extension the final project budget is expected to remain about 20% below the planned proposal, i.e. approx. € 600,000 savings on the total budget should be recorded, corresponding to a subvention reduction of approx. € 100,000 (also close to 20% reduction).

To evaluate the potential hazard of a harmful substance on its pathway from a source to a sensitive site, it is important to know if degradation or reversible sorption is the dominant process. While, in case of degradation, mass is removed from the system, in the case of reversible sorption the transport is only retarded. A mathematical analytical concept is outlined, which can be applied to evaluate data from field experiments, from technical and semitechnical facilities and from the laboratory. The concept is exemplified on a series of enclosure experiments performed with phages within a project investigating processes during bank filtration. Results show that parameters are not constant in the experiments and indicate a significant influence of redox conditions on both retardation and deactivation rates. On the other hand, an influence of the clogging layer could not be detected.

Four international projects subsidised by the European Commission should push forward the development and application of membrane bioreactor processes in the municipal wastewater sector.

Extracellular polymeric substances (EPS) are considered as the major cause of membrane fouling in membranebioreactors. Recent studies have revealed a linear relationship between fouling rate (increase of filtration resistanceover time) and polysaccharide (PS) concentration [1]. Several factors like the type of wastewater, sludge loading rate, sludge age, MLSS concentration, and mechanical stress are known to influence the concentration of dissolved EPS. Also, unsteady states like intermittent feeding or shifts in the oxygen supply have been identified as additionalfactors leading to an increase in EPS formation or to a change in its fouling propensity. However, no systematicinvestigation to quantify such influences has been undertaken so far. This study is aimed at determining the influenceof discontinuous excess sludge withdrawal often applied in small decentralised plants and resulting unsteady loadingrates on EPS formation and filtration resistance. The general trend of increased fouling rate at higher PS concentrationsis confirmed but data show a larger scatter which could be due to a change in the PS structure and hence their fouling potential. The levels of dissolved oxygen and nitrate which also fluctuate more strongly in MBRs withirregular sludge wastage appear to have a profound impact on EPS uptake rate and thereby on EPS concentration.