A porous multilayered hollow fiber for outer side pressed filtration is made of a multilayer comprising a supporting layer constituted of the thickness of an expanded porous polytetrafluoroethylene tube, and a filtration layer provided on the outer surface of the supporting layer, wherein pores surrounded by fibrous frameworks in the filtration layer are smaller than those of the supporting layer, and the mean of the maximum fibril length (L) of the fibrous frameworks surrounding each pore in the outer surface of the filtration layer is designed to be small such that (X) and (Y) fall within the range on the XY plane, where (X) is a particle diameter of particles captured when the particle trapping ratio is equal to or more than 90% in the case where the filtration is done under an elevated pressure of 0.1 MPa, and (Y) is a value designated as RFL obtained by dividing (L) by (X). Thus, the degradation of flow rate due to the elapse of time can be prevented, since solid particles to be separated do not enter into pores, and clogging and blockade of the pores do not occur even in the case of filtering a solution of high turbidity. As a result, it is possible to recover filtration property easily by performing back-wash reverse filtration and to maintain excellent filtration property for a long time.

 
Web www.patentalert.com

< Method and apparatus for generating standardized carbon emission reduction credits

< Substrate processing method and apparatus

> Water control valve

> In situ thermal processing of an oil shale formation containing carbonate minerals

~ 00613