To make the air supply means for air cleaning the filter material in the filtration tower relatively small.SOLUTION: The water purification apparatus comprises a filtration tower 16, a water permeable support 22 horizontally provided inside the filtration tower and partitioning the interior of the filtration tower into an upper space and a lower space, a lower end provided in the upper space and fixed to a water permeable support A filter material 26 composed of a long fiber bundle 24 having an upper end as a free end, a raw water pump 14 which is an upper space and supplies raw water above the filter material, a filtered water pipe 28 which discharges filtered water from the lower space, , A backwash pump 36 for supplying backwash water to the lower space for backwashing the filtering material, an air supply means 52 for supplying air to the lower space for air cleaning the filtering material, a washing drainage washing filter medium A discharge pipe 40 which is an upper space and discharges from the upper side of the filter material, a raw water which is discharged from the vicinity of the lower end of the filter material in the upper space and discharged by discharging a part of the raw water supplied to the inside of the filtration tower for circulating and cleaning the filter material Circulates above the filter material in the upper space Having a water pump 14.BACKGROUND OF THE INVENTION【課題】ろ過塔内のろ材を空気洗浄するための空気供給手段を比較的小さなものにする。【解決手段】ろ過塔16と、ろ過塔内部に横設されろ過塔内部を上部空間と下部空間に区画する透水性の支持体22と、上部空間に設けられ下端を透水性の支持体に固定し上端を自由端とした長繊維束24から構成されるろ材26と、上部空間であってろ材の上方に原水を供給する原水ポンプ14と、下部空間からろ過水を排出するろ過水配管28と、ろ材を逆洗するために下部空間に逆洗水を供給する逆洗ポンプ36と、ろ材を空気洗浄するために下部空間に空気を供給する空気供給手段52と、ろ材を洗浄した洗浄排水を上部空間であってろ材の上方から排出する排出管40と、ろ材を原水循環洗浄するためにろ過塔内に供給した原水の一部を上部空間であってろ材下端の近傍から排出し排出した原水を上部空間のろ材の上方に循環する原水ポンプ14を有する。【選択図】図1
