Filter for river water treatment

Flusswasseraufbereitung/Riverwater filtrationFlusswasseraufbereitung/Riverwater filtration

A large chemical company selected different filter techniques in a long test. The filter technology of GEFA Processtechnik stood out from a multitude of competitors. The patented back-flushing process and an excellent separating filter medium convinced the user. In the future this customer will use GEFA filter technology for the treatment of river water.



The protection of pump bearings in river water pumps is a general problem. Sand and other abrasive particles from the incoming water settle on the rubber bearings and thus cause damage to bearings and pump shafts. The replacement of shafts and bearings causes considerable costs. The rubber bearing manufacturers therefore recommend using water with a maximum permissible particle size of 30 µm. The customer's aim during a 1-year trial phase was to test various filter systems with regard to these minimum requirements. Gap-type filters from the competition and GEFA back-flushing filters with fabric screen were used.



For technical reasons, the slotted filters used in the test could only be supplied with a maximum possible filtration fineness of 20 µm. Although this fulfilled the minimum requirements, the remaining abrasive and also softer particles will continue to impair the bearings and pump shafts in the future. In the course of the test, additional malfunctions of these filters proved to be extremely disadvantageous, especially in the case of relatively high dirt loads caused by flooding. The reason for this is the considerably smaller net filter area of the gap-type filter compared to the GEFA back-flushing filter. The free open screen area, especially in the case of gap-type filters below 50 µm, is very small (approx. 5%). This results in a poorer filter cake build-up which, due to the small surface area, is faster, not as thick and less fine filtering.
During the tests carried out, the GEFA-Filtomat type M104XLP with fabric screen clearly showed its design advantages over the gap filters used. Fabric screens have a much higher separation efficiency of solids and suspended matter, which are smaller than the mesh size. The technical meshes used in the GEFA-Filtomat achieve a net filter area of approx. 48% compared to the already mentioned slotted filters with only approx. 5%. The filter cake structure is therefore considerably thicker, denser and finer. With a filter insert of 15 µm and a resulting nominal filter fineness of 12 µm, the test filter GEFA-Filtomat type M104XLP best fulfilled the requirements regarding pump protection. In combination with the punctual cleaning of the fine screen and the high backwash speeds, trouble-free operation is guaranteed even under the most difficult operating conditions. Especially the tests carried out after completion of the test also amazed the customer: even after 1 year of operation, neither damage nor wear worth mentioning could be detected on the GEFA-Filtomat.


 Comparison of slotted and woven screen:


The gap height (w) indicates the filtration fineness of the tissue sieve (e.g. 50 mic.). The gap length (>>w) is many times larger.
Compared to fabric filters with the same ball passage of the free openings, slotted screens have a poorer separation efficiency of solids, since they rarely have the spherical shape and elongated particles are retained in a mesh rather than in a slot. The separation efficiency of slotted sieves of solids that are smaller than the slot is very low.


You can find more product information here!

Type FW Type M1XX
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