Das Projekt "Application of biofilm processes for advanced COD reduction in paper mill effluents" wird vom Umweltbundesamt gefördert und von Papiertechnische Stiftung durchgeführt. The aim of this project is to use biofilm processes as second stage process for the enhancement of biological treatment of pulp and paper mill waste water. This should be arranged by using biofilms which incorporate microorganisms with a high elimination potential for slowly degradable organic substances. Biofilms with increased COD reduction potential are to be identified and characterised. Samples of biofilms, which are growing in waste water treatment plants (wwtp) under substrate restricted conditions (e.g. at the end of a cascade or at the outflow of the secondary clarifier) will be investigated by static degradation tests to determine their potential for COD reduction. Samples with a high potential will be used for continuously test to cultivate biofilms. The conditions for optimum immobilisation and operation should be elaborated. Based on these results the operation conditions of an adapted biofilm process stage will be derived. A further decrease of COD by these processes may lower the costs for the reduction of the discharged organic load. The available processes of advanced treatment are mostly expensive and often need special installations. In addition separate steps for the disposal or treatment of generated wastes are oftentimes required. MBBR processes as second or final stage can be easily integrated in existing aerobic treatment stages of wwtp and are a cost effective alternative to advanced chemical and/or physical processes. Hence the treatment costs can be reduced, the economic competitiveness of the sme can be secured or the extension of production capacity is possible while still meeting the environmental limits.