TECHNOLOGY FOCUS - INSTRUMENTATION AND TESTING - The filter unit is a filter belt attached to the pore roller. The suspension is arranged in the separation chamber or in pore roller and medium is transported into the pores of pore roller during separation or into the separation chamber during separation. A filter belt covers at least a part of the surface of the pore roller, such as a filter belt surrounding the surface of the pore roller. The suspension is provided as a continuous stream or as non-continuous stream. The suspension has a dry matter content prior to the separation of at least 5%. The pore size of the filter belt is smaller or larger than the pore size of the pore roller. The filter belt is endless, disposable, coated. The coating comprises gel particles. The coating comprises binding members for at least one dry matter particles in suspension. The filter belt comprises a catalyst, charged, magnetic, grooved. The filter belt is passing over at least one guide roller. The at least one filter belt is made from Juncus or grass or metal or textile or artificial textile or plastic. The filter belt is made from a flexible material, sterile. The roller from the at least one set of rollers is made from a material selected from metal, steel, stainless steel, rubber, plastic including nylon, glass, and/or ceramics. At least one roller from the at least one set of rollers is inflatable. The pore roller is made from a ceramic material and/or a glass material, material selected from rubber, plastic, metal, ceramics, and glass. The filter cake is removed from the at least one filter belt by means of compressed air, and/or by the means of vibration, and/or by the means of scraping. The at least one filter belt is cleaned by enzymes, and/or cleaned by the means of high-pressure washing, and/or cleaned by chemicals. The chemical is a detergent. The pressure difference across the filter belt is established by applying vacuum to the channel in the pore roller. The pressure difference across the filter belt is established by applying an overpressure to the channel in the pore roller. The medium is a liquid. The medium is air or a gas. The filter cake is removed from filter belt by compressed air, vibration, and/or scraping. The filter belt is cleaned by enzymes, high-pressure washing, and/or chemicals. The apparatus for applying a pressure difference across the filter belt by applying vacuum or overpressure to the channel in the pore roller.