In early 2002, Linde-KCA-Dresden GmbH received an order from RWE Industrie-Losungen GmbH for the construction of a water treatment plant for the Stendal Pulp Mill at Ameburg near Stendal (Germany). Within the scope of the project one of the largest water treatment plants based on the reverse osmosis process in Europe was built and commissioned in the years 2003 and 2004. The water treatment plant operating since January 2004 has been capable of meeting the process water requirements of the Stendal pulp mill from the time of its commission. Differences in the quality of the water taken from the Elbe river which are due to season and weather conditions are compensated for by a pre-treatment system. The water supplied to the reverse osmosis system meets the required good quality standards. During the first year of operation, the output of the reverse osmosis membranes was found to decrease. It was possible by cleaning the membranes to achieve a complete or at least partial restoration of the original flow.