Abstract: To provide a cleaning apparatus suitable for removing clogging substances trapped in a surface layer of a sand filtration layer. A cleaning apparatus equipped with drive wheels serving as a driving device configured to move across a surface of a sand filtration layer. A pump and a jet nozzle are provided as an agitation device configured to agitate a surface layer portion of the sand filtration layer only at a desired depth, and which blows the clogging substances upward into the seawater in a turbid water intake pit together with a filtration sand. A perforated pipe for suctioning turbid water, a pump, an ejector, and a discharge pipe for dilute turbid water are provided as a suction and discharge device configured to suction turbid water blown upward into seawater in the water intake pit by the agitation device, and discharge it to outside of the turbid water intake pit.

Abstract: A water treatment apparatus including one or more mixed raw water stream jet nozzles, a filtering tank housing a filter layer disposed below the mixed raw water stream jet nozzle or nozzles, the filter layer having an upper layer and a lower layer, the upper layer containing a filter material with a smaller specific gravity and a larger particle diameter than a filter material of the lower layer, a water collecting and distributing pipe for removing water filtered through the filter layer and supplying reverse stream cleaning water to the filter layer during reverse cleaning, filter material vibrating means for vibrating a filter material of the upper layer including a vibrating element connected to a power source and vibration expanding element buried in the upper layer for transmitting vibration of the vibrating element, and an overflow outlet provided in the filtering tank above the filter layer.

Abstract: To provide a cleaning apparatus suitable for removing clogging substances trapped in a surface layer of a sand filtration layer. A cleaning apparatus equipped with drive wheels serving as a driving device configured to move across a surface of a sand filtration layer. A pump and a jet nozzle are provided as an agitation device configured to agitate a surface layer portion of the sand filtration layer only at a desired depth, and which blows the clogging substances upward into the seawater in a turbid water intake pit together with a filtration sand. A perforated pipe for suctioning turbid water, a pump, an ejector, and a discharge pipe for dilute turbid water are provided as a suction and discharge device configured to suction turbid water blown upward into seawater in the water intake pit by the agitation device, and discharge it to outside of the turbid water intake pit.

Abstract: To clean sediments and the like trapped not only in a top layer of a sand filtration layer, but also in intermediate layers. A seawater infiltration method which uses a water infiltration intake unit which is formed in advance and provided with a water intake pipe embedded in a gravel layer which forms a deep layer of the sand filtration layer, and a backwashing pipe embedded in a sand layer which forms an intermediate layer and a surface layer of the sand filtration layer, and a water suction pipe which is disposed above the sand layer. A desired number of water infiltration intake units are combined to form a sand filtration layer at an installation site on an ocean floor, and they intake seawater from the sea which has undergone natural infiltration in the sand filtration layer and this is introduced into the water intake pipe. The seawater infiltration rate is set at less than 400 m/day.

Abstract: A mixed stream nozzle which can prevent accumulation and solidifying of oxides on an inner wall of a raw-water-air mixed stream nozzle of a water treatment apparatus with a simple device is provided. In a mixed stream nozzle having, at one end thereof, a water supply tube connecting portion (2), an air inlet (3) formed on the downstream side of the water supply tube connecting portion, and a mixed stream outlet (4) provided at the other end of the mixed stream nozzle from which mixed stream of water and air is jetted out, nozzle inner wall cleaning means is provided which is made of a twisted-ring chain (11) which is fixed to an inner wall of the nozzle on the downstream side of the air inlet (3) and extends to the vicinity of the mixed stream outlet (4) for colliding with the mixed stream and moving continuously in the nozzle in a manner to swivel by force received from the mixed stream and thereby contacting the inner wall of the nozzle.

Abstract: A water treatment apparatus including one or a plurality of mixed raw water stream jet nozzles (7), a filtering tank (5) housing a filter layer (4) disposed below the mixed raw water stream jet nozzle or nozzles, the filter layer consisting of an upper layer (2) and a lower layer (3) and the upper layer containing a filter material which has a smaller specific gravity and a larger particle diameter than a filter material of the lower layer, a water collecting and distributing pipe (13) for taking out water filtered through the filter layer and supplying reverse stream cleaning water to the filter layer during reverse cleaning, filter material vibrating means for vibrating a filter material of the upper layer which includes a vibrating element (9) connected to a power source and vibration expanding element (10) which is buried in the upper layer for transmitting vibration of the vibrating element, and an overflow outlet (12) provided in the filtering tank above the filter layer.

Abstract: A water treatment apparatus includes a raw water supply tube, mixed raw water stream jet nozzles each communicating at one end thereof with the raw water supply tube and having at the other end thereof a raw water outlet from which mixed stream of raw water and air is jetted out, a filtering tank housing a filter layer disposed below the mixed raw water stream jet nozzles with a predetermined distance between the surface of the filter layer and the raw water outlet of the mixed raw water stream jet nozzles, a filtered water takeout tube provided in the filtering tank for taking out water filtered through the filter layer, a reverse stream cleaning water supply tube provided in the filtering tank for supplying reverse stream cleaning water to the filter layer, filter layer cleaning jet nozzles each communicating at one end thereof with a filter layer cleaning water supply tube and having at the other end thereof a cleaning water outlet from which cleaning water is jetted out, and an overflow outlet provided in

Abstract: A water treatment apparatus includes a raw water supply tube, mixed raw water stream jet nozzles each communicating at one end thereof with the raw water supply tube and having at the other end thereof a raw water outlet from which mixed stream of raw water and air is jetted out, a filtering tank housing a filter layer disposed below the mixed raw water stream jet nozzles with a predetermined distance between the surface of the filter layer and the raw water outlet of the mixed raw water stream jet nozzles, a filtered water takeout tube provided in the filtering tank for taking out water filtered through the filter layer, a reverse stream cleaning water supply tube provided in the filtering tank for supplying reverse stream cleaning water to the filter layer, filter layer cleaning jet nozzles each communicating at one end thereof with a filter layer cleaning water supply tube and having at the other end thereof a cleaning water outlet from which cleaning water is jetted out, and an overflow outlet provided in