Since microscreening was introduced at the end of the 1940's, its application has continuously widened giving rise to the use of finer and finer screen meshes. These rotating drums covered with self-cleaning meshes, having very small aperture size, are used for screening of micro-plankton and/or finest suspended solids and flocks in water treatment plants as also in the tertiary treatment plants. In water treatment plants, microscreening is employed as primary clarification in order to reduce the load on the sand filter or flocculation plants whereby in waste water treatment plants, micro-screening is used for advanced waste water (tertiary) treatment. Bilfinger Water Technologies has gained considerable experience in the field of micro-screening.