Das Projekt "Natuerliche Biofilme als High-Tech-Aufbereitungsmittel fuer Trinkwasser" wird vom Umweltbundesamt gefördert und von Forschungszentrum Karlsruhe GmbH in der Helmholtz-Gemeinschaft, Institut für Technische Chemie, Bereich Wasser- und Geotechnologie, Abteilung für Umwelt-Mikrobiologie durchgeführt. Objective: Problems to be solved: Drinking water companies in Europe have installed sophisticated treatment facilities to prepare drinking water from moderate quality surface water. However, the quality of the 'raw' water remains important, because increasing urbanisation enhances the load of pathogens and substances with suspected hormonal, mutagenic or other health risks. Shortage of water, especially in the Mediterranean countries, implies that surface water of any quality is to be exploited. In view of these problems it is imperative for the drinking water sector to improve environmental technologies increasing water quality prior to treatment. Biofilms are sites of biological activity, that abound in all natural rivers and lakes, as well as in all stages of the drinking water system. The aim of the research planned is to develop the knowledge needed to exploit biofilms upstream of the water plant and to optimise their capacity to regulate organic matter content in water, to retain noxious compounds and to trap potential pathogens. Scientific objectives and approach. Analysing the practical problems of the drinking water companies and considering the basic functioning of biofilms, the following research activities will be undertaken. - Construction of a dynamic model for the exchange of solutes and particles between autotrophic/heterotrophic biofilms and water. The model facilitates the application of ecological, ecotoxicological and chemical information to water technology. - The basic architecture of biofilms, composed of micro-algae, bacteria and their mucus envelope, and the sites of major biological activity are described and localised. Confocal microscopy is one of the tools used. - Analysis of biofilm development and quantification of its capacity to trap particles from the water. These particles are detritus flocs, invading natural micro-organisms, but also bacteria of hygienic interests. Fluorescently labelled particles and genetic probes for pathogens are used. - To quantify the budget of carbon production in biofilms by micro-algae and the carbon consumption by bacteria. The resulting net production or consumption is specified for dissolved compounds, exchangeable with overlying water, and particulate carbon increasing or decreasing total density of the organic mass. Pulse-amplitude modulated fluorometry (PAM) is used for micro-algae production and thymidine or leucine based production estimates for bacteria are combined with chemical determinations of organic carbon. Total DOC and TOC will be measured as well as main classes of protein, carbohydrates (in mucus), and fatty acids. Prime Contractor: Universiteit van Amsterdam, Amsterdam Research Institute for Substances in Ecosystems, Department of Aquatic Ecology and Ecotoxicology; Amsterdam.