WATER TREATING FILTRATION TANK USING PERFORATED HOLDER

PROBLEM TO BE SOLVED: To prevent the clogging of a perforated holder with an organism even when a highly contaminated raw water is introduced by providing a perforated holder formed by alternately joining a thin metallic sheet and a corrugated metallic sheet into a honeycomb on the inlet side, outlet side or both sides of a filtration chamber for passing the raw water through a filter medium to treat it. SOLUTION: A perforated holder 4 used in a water treating filtration tank is formed by alternately joining a thin metallic sheet and a corrugated metallic sheet into a honeycomb, hence the perforation ratio can be increased to 70-90% as the supporting structure of a filter medium, the shape of the perforation is uniform in the thickness direction, and clogging is hardly caused. The clogging is sufficiently prevented at 70% perforation ratio, and the strength as the holder is decreased at >90%. For example, a metal honeycomb as the holder 4 is furnished at the lower part of a filtration zone 3a in an upflow filtration tank using a filter medium 5 having >=1 sp.gr. A fluid is introduced from an inlet pipe 1, passed through the perforation of the holder 4 and then through the filtration medium 5 and continuously flows into an outlet pipe 2 from a water collector.