METHOD AND SYSTEM FOR FILTRATION AND FILTRATION CAKE LAYER FORMATION

摘要

The present invention relates to a method of filtering a feed and waste water treatment system using the filtration method. The method utilizes a filtration cake for the filtration, which filtration cake is formed by elements contained in a liquid having a different composition than the feed to the filtered. The invention relates in particular to a method for filtering a liquid containing solid particles of different sizes which utilizes a filtration cake formed at least partly and preferably only from particles contained in said liquid containing solid particles of different sizes. The particles of the filtration cake are deposited on a filtration cake support and the method involves separation of the liquid containing solid particles of different sizes into two fractions: one fraction containing solid particles above a certain size and one containing smaller particles, and filtering the fraction containing smaller particles through the filtration cake. According to preferred aspects of the invention, the feed to be filtered is activated sludge supernatant and the filtration cake is formed from floes of an activated sludge mixed liquor.