A rotary disc filtration device having a fluid filtration gap between a filtration surface and a disc is disclosed. The disc and/or filter has one or more spiral grooves in fluid communication with fluid in the gap. The disc and/or filter is rotated and one or both may be axially oscillated and/or vibrated...http://www.google.es/patents/US5143630?utm_source=gb-gplus-sharePatente US5143630 - Rotary disc filtration device
