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: A process and an apparatus for an aerobic biological treatment of aqueous organic wastes, in which the aqueous organic waste is supplied to an aeration tank for an aerobic biological treatment in the presence of a biosludge composed essentially of aerobic microorganisms. The aerated aqueous suspension in the aeration tank is subjected to solid/liquid, separation, the so-separated liquid phase is removed as treated water, at least a portion of the separated sludge is recycled to the aeration tank, a part of the aqueous suspension in the aeration tank or of the separated sludge is treated with ozone at a pH of 5 or lower, and the ozonized suspension or sludge is recycled to the step of aerobic biological treatment. The biosludge is transformed into BOD components using a decreased amount of ozone to thereby decrease the amount of excess sludge and, in some cases, even reduce it to zero.

Abstract: An apparatus and method for the biological removal of phosphorus, in which raw water is introduced into the anaerobic tank 11, together with returned sludge from the sludge return pipe 14. Some of the water in the anaerobic tank 11 is sent to the solid/liquid separating device 16 and the rest is sent to the aerobic tank 12. Some of the water which contains the released phosphorus in the anaerobic tank 11 is sent via the pipe 15 to the second solid/liquid separating device 16, and subjected to a solid/liquid separation treatment. The separated water fraction is sent to the phosphorus-removing apparatus 17 and the phosphorus is removed. Some of the solid fraction is introduced into the anaerobic tank 11. The remainder is sent from the pipe 19 to the solubilizing tank 20 and subjected to a solubilizing treatment, and then it is returned to the anaerobic tank 11.

Abstract: An apparatus and method for the biological removal of phosphorus, in which raw water is introduced into the anaerobic tank 11, together with returned sludge from the sludge return pipe 14. Some of the water in the anaerobic tank 11 is sent to the solid/liquid separating device 16 and the rest is sent to the aerobic tank 12. Some of the water which contains the released phosphorus in the anaerobic tank 11 is sent via the pipe 15 to the second solid/liquid separating device 16, and subjected to a solid/liquid separation treatment. The separated water fraction is sent to the phosphorus-removing apparatus 17 and the phosphorus is removed. Some of the solid fraction is introduced into the anaerobic tank 11. The remainder is sent from the pipe 19 to the solubilizing tank 20 and subjected to a solubilizing treatment, and then it is returned to the anaerobic tank 11.

Abstract: An apparutus and a method for ozone-treating biosludges and reducing biosludges occurring upon a biological treatment of aqueous organic waste, wherein the apparatus is made up of a plurality of reactors for effecting the ozone treatment of the biosludge by contacting the biosludge with an ozone-containing gas, biosludge passages for flowing the biosludge to be ozone-treated through all the reactors in series, gas supply means for supplying the ozone-containing gas to each of the reactors, a pressurization means for maintaining each of the reactors under a pressurized condition and stirrers each disposed in each reactor for realizing a nearly equalized ozone absorption rate for all the reactors.

Abstract: A powder of magnetized material is added to an aeration chamber, and aeration is conducted. The mixture is then sent to a sedimentation chamber, and solid-liquid separation is conducted. A portion of the precipitated sludge is returned to the aeration chamber as return sludge and reused. Sedimented sludge is highly concentrated, due to the action of the magnetized material. By returning a portion to the aeration chamber as return sludge, the biomass concentration becomes high, and high load operation in the aeration chamber can be achieved.

Abstract: An apparatus and a method for ozone-treating biosludges and of reducing biosludges occurring upon a biological treatment of aqueous organic waste, wherein the apparatus is made up ofa plurality of reactors for effecting the ozone treatment of the biosludge by contacting the biosludge with an ozone-containing gas,biosludge passages for flowing the biosludge to be ozone-treated through all the reactors in series,gas supply means for supplying the ozone-containing gas to each of the reactors,a pressurization means for maintaining each of the reactors under a pressurized condition andstirrers each disposed in each reactor for realizing a nearly equalized ozone absorption rate for all the reactors.

Abstract: A process for reducing the amount of excess sludge by aerobically treating an aqueous organic waste in an aeration tank in the presence of a biosludge containing aerobic microorganisms, subjecting the resulting mixed liquor to a solid/liquid separation, the so-separated liquid phase being discharged as treated liquor, and supplying at least a part of the separated biosludge, after having been treated with ozone, to the aeration tank, wherein the ozone treatment is realized by passing a mixed flow of a biosludge-containing liquor to be treated or a liquor containing the ozonized biosludge and of an ozone-containing gas through a flow-down pipe in a downward flow and introducing the flow into an ozone-treating vessel in a state in which the ozone-containing gas is dispersed as finely disintegrated bubbles, whereby the clogging of a gas diffuser due to the adhesion of the biosludge is avoided and ozone treatment is attained at a high ozone yield.