SAND FILTER APPARATUS AND FILTERING METHOD

摘要

PROBLEM TO BE SOLVED: To provide a sand filter apparatus which can efficiently filter raw water surely and cope satisfactorily with the advanced treatment of sewage or the like and to provide a filtering method. SOLUTION: Raw water is made to flow in the lower part of a filtration tank 1 holding filter sand S. A water collecting means for collecting the filtrate P obtained by filtering the raw water and a washing means for washing the sand S used for filtering the raw water are arranged in the upper part of the tank 1. The washing means is provided with a sand pumping-up means 7 for pumping up the sand S and a vertical washing pipe 6 having a labyrinth 11 on the inside. The sand S can be washed by dispersing the sand S pumped-up by the means 7 in the pipe 6 by the labyrinth 11 and making the dispersed sand S fall down and making a part of the filtrate P rise in the pipe 6. COPYRIGHT: (C)2003,JPO