PURPOSE: To improve filtering efficiency, a clad collecting amount and the volume reducibility of a used precoat material, by passing a suspension containing a fine particle comprising a metal oxide through a sintered filter material layer precoated with a predetermined amount of a granular metal oxide.
CONSTITUTION: A metal oxide with a particle size of 2W100μm such as AlO3, TiO2 or Fe2O3 is suspended in pure water and, thereafter, said suspension is recirculated while passed through a cylindrical multi-layered metal net sintered filter material element 17 having a pore size of below 10μm to form a granular metal oxide precoat layer with density of 0.01W0.06g/cm3 on the cylindrical outer surface of the filter material element 14 of a filter. Subsequently, water to be treated containing a fine particle comprising an oxide and a hydroxide of a metal such as iron or copper is passed through the aforementioned precoat layer 18 and the multi-layered metal net sintered filter material element 17 and, after clad in the water to be treated is removed, discharged out of the system as treated water from a treated water discharge pipe 6.
OKI SHINICHI
OOTA FUMIMA
SHIMIZU SATORU
TOYO ENGINEERING CORP