Abstract: A method includes: stopping the supply of the oxygen to the membrane support; pushing a chemical solution that cleans the plurality of holes from a lower end of the membrane support to inside of the membrane support; pushing water or first air that pushes out the chemical solution inside the plurality of holes to a side of the reaction tank from the lower end to the inside of the membrane support; performing closing control of a valve that controls an amount of air to be discharged from an upper end of the membrane support; and pushing second air to dry the inside of the plurality of holes by pushing out the water or the first air inside the plurality of holes to the side of the reaction tank from the lower end to the inside of the membrane support.

Abstract: A biological treatment method for biologically treating nitrogen components contained in organic wastewater, the method includes: performing, in a first reaction tank, partial nitrification treatment on ammonium nitrogen contained in the organic wastewater with use of ammonia-oxidizing bacteria contained in activated sludge; supplying the activated sludge from the first reaction tank to an inactivation tank; inactivating, in the inactivation tank, nitrite-oxidizing bacteria contained in the activated sludge supplied from the first reaction tank with use of nitrite nitrogen while keeping pH at an approximately neutral level or lower; and supplying an inactivated sludge to the first reaction tank.

Abstract: An organic wastewater treatment method that includes a raw sludge removal step, a raw sludge concentration step, a biological treatment step, an excess sludge separation step, an excess sludge concentration step, a sludge mixing step, and a methane fermentation treatment step. The treatment method further includes a sterilization step for heating and sterilizing the concentrated excess sludge upstream of the sludge mixing step. At least one among: (1) the temperature to which the concentrated excess sludge is heated during sterilization, (2) the concentration of concentrated raw sludge and/or the concentration of the concentrated excess sludge, and (3) the mixture ratio between the concentrated raw sludge and the concentrated excess sludge is adjusted according to the fluctuation in the amount of raw sludge generated and the amount of the excess sludge generated, and the temperature of the mixed sludge is controlled to a temperature suited for methane fermentation.

Abstract: An organic wastewater treatment method that includes a raw sludge removal step, a raw sludge concentration step, a biological treatment step, an excess sludge separation step, an excess sludge concentration step, a sludge mixing step, and a methane fermentation treatment step. The treatment method further includes a sterilization step for heating and sterilizing the concentrated excess sludge upstream of the sludge mixing step. At least one among: (1) the temperature to which the concentrated excess sludge is heated during sterilization, (2) the concentration of concentrated raw sludge and/or the concentration of the concentrated excess sludge, and (3) the mixture ratio between the concentrated raw sludge and the concentrated excess sludge is adjusted according to the fluctuation in the amount of raw sludge generated and the amount of the excess sludge generated, and the temperature of the mixed sludge is controlled to a temperature suited for methane fermentation.

Abstract: In a settling tank of the invention, treated water has good quality and whose operation is stable over a long period. A settling tank includes a tank body having a circular-cylindrical shape whose axial direction corresponds to the vertical direction, a distributor provided in a lower part (near the bottom) of the tank body, an outlet provided in a middle part or a part slightly above the middle part of a side face of the tank body, a receiving tank communicating with the tank body via the outlet, a stirring device provided in the tank body, a trough for extracting treated water provided in an upper part of the tank body, a sludge discharge port through which concentrated sludge is extracted from a lower part of the receiving tank, and so forth. A stirring member is provided below the distributor.

Abstract: In a water treatment method and an apparatus therefor, after an anionic polymer flocculant is added to water to be treated, granulation is performed by stirring, and solid-liquid separation is then performed to obtain treated water, and flocs which are not disintegrated by a shearing force during stirring and have a preferable settling property can be formed, so that the quality of treated water is also improved. Particularly, a water treatment method includes a flocculating step of adding an anionic polymer flocculant to water to be treated to form flocculated flocs, a subsequent granulating step of stirring the water to be treated to granulate the flocculated flocs, and a solid-liquid separation step of performing solid-liquid separation of generated granulated substances, wherein a cationic polymer flocculant having a cationic group rate of 10 to 50 mole % is added to the water to be treated before the anionic polymer flocculant is added.

Abstract: Provided is a desalting device which includes a tower body and a bulge portion bulging downward therefrom, and which prevents uneven flow and causes no dead space within the tower body. The desalting device includes a tower body having a bulge portion 1b bulging downward at a bottom portion thereof, an ion-exchange resin packed in the tower body, and a plurality of strainers 3 for collecting water being arranged within the bulge portion 1b. The strainers are arranged only in a central region of an inside of the bulge portion excluding an outer peripheral portion of the bulge portion.

Abstract: In a settling tank of the invention, treated water has good quality and whose operation is stable over a long period. A settling tank includes a tank body having a circular-cylindrical shape whose axial direction corresponds to the vertical direction, a distributor provided in a lower part (near the bottom) of the tank body, an outlet provided in a middle part or a part slightly above the middle part of a side face of the tank body, a receiving tank communicating with the tank body via the outlet, a stirring device provided in the tank body, a trough for extracting treated water provided in an upper part of the tank body, a sludge discharge port through which concentrated sludge is extracted from a lower part of the receiving tank, and so forth. A stirring member is provided below the distributor.

Abstract: Provided are a distributor capable of feeding a liquid in a state of evenly flowing out from an entire opening while avoiding the opening from being blocked by sludge and keeping a pressure loss small, a settling tank that employs the distributor, and a method for operating the settling tank. A distributor 10 being in the form of a rectangular frame and having straight tubular sides 11 to 14 is disposed in a lower space within a settling tank 1. A liquid outlet opening 16 extending in a lengthwise direction of the distributor 10 is formed in a bottom surface of the distributor 10. An open angle ? of the opening 16 with respect to a tube axis is 60 to 180°, and preferably 90 to 150°.

Abstract: In a water treatment method and an apparatus therefor, after an anionic polymer flocculant is added to water to be treated, granulation is performed by stirring, and solid-liquid separation is then performed to obtain treated water, and flocs which are not disintegrated by a shearing force during stirring and have a preferable settling property can be formed, so that the quality of treated water is also improved. Particularly, a water treatment method includes a flocculating step of adding an anionic polymer flocculant to water to be treated to form flocculated flocs, a subsequent granulating step of stirring the water to be treated to granulate the flocculated flocs, and a solid-liquid separation step of performing solid-liquid separation of generated granulated substances, wherein a cationic polymer flocculant having a cationic group rate of 10 to 50 mole % is added to the water to be treated before the anionic polymer flocculant is added.

Abstract: Provided is a desalting device which includes a tower body and a bulge portion bulging downward therefrom, and which prevents uneven flow and causes no dead space within the tower body. The desalting device includes a tower body having a bulge portion 1b bulging downward at a bottom portion thereof, an ion-exchange resin packed in the tower body, and a plurality of strainers 3 for collecting water being arranged within the bulge portion 1b. The strainers are arranged only in a central region of an inside of the bulge portion excluding an outer peripheral portion of the bulge portion.

Abstract: There is provided an apparatus and method for fluid mixing, which enable mixing efficiency to be enhanced and enable a lodging impurity to be easily removed. A liquid, powder, or the like is added from a pipe 2 to a liquid flowing in a pipe 1, and the resultant liquid then passes a plurality of half-open ball valves 3A to 3C, thereby being mixed. The ball valves 3A to 3C each have angular difference ? in the position around the axis thereof. Sufficient mixing can be performed without preparing a static mixer having a complicated structure. In addition, in the case where clogging due to an impurity occurs, the valve is opened with the result that the impurity can be released.