JPH0720599B2 - Intermittent aeration type activated sludge treatment method - Google Patents

Description

TECHNICAL FIELD The present invention relates to an intermittent aeration type activated sludge treatment method for treating wastewater using a membrane module.

Conventional technology Conventionally, in a wastewater treatment facility, an anaerobic tank and an aerobic tank are separately provided to treat the liquid to be treated with activated sludge, or an anaerobic and aerobic environment is alternately formed in a single tank. To remove the microbiological nitrogen.

However, according to the above-described conventional configuration, when the anaerobic tank and the aerobic tank are separately provided, the construction cost increases and a large space is required for installing the equipment. There is a problem that is required, and there is a problem that continuous processing cannot be performed when the batchwise processing is performed in a single tank.

The present invention is to solve the above problems, and an object of the present invention is to provide an intermittent aeration type activated sludge treatment method for removing not only BOD in wastewater but also nitrogen content by performing anaerobic decomposition and aerobic decomposition in a single tank. To do.

Means for Solving the Problems In order to solve the above problems, the present invention continuously supplies the liquid to be treated to the activated sludge retained in the reaction tank, aerates the air from the air diffuser to perform stirring and oxygen supply. While aerobically decomposing the mixed liquid of the liquid to be treated and the activated sludge in the reaction tank, solid-liquid separation is performed by the membrane module immersed in the reaction tank, and the membrane permeated liquid is taken out from the reaction tank for solid-liquid separation. When the liquid level in the reaction tank, which falls with it, reaches a low level, the air supply by the air diffuser and the solid-liquid classification by the membrane module are stopped, and the liquid level in the reaction tank is increased while the liquid to be treated is supplied. When the liquid level in the reaction tank reaches a high level, the air supply by the air diffuser and the solid-liquid separation by the membrane module are restarted at the time when the liquid level in the reaction vessel reaches a high level, and the liquid to be treated is continuously supplied and is aerobic. With a configuration that performs decomposition and anaerobic decomposition Is.

With the above-mentioned configuration, aerobic decomposition of the mixed liquid proceeds in a state where air is supplied from the air diffuser, and the separated liquid is taken out of the reaction tank by solid-liquid separation by the membrane module, and mainly the microorganisms Since the solid content remains in the reaction tank, the liquid level drops while the liquid to be treated flows in. Then, in a state where air is not supplied from the air diffuser, anaerobic decomposition and aerobic decomposition proceed and solid-liquid separation is stopped, so that the liquid level rises with the inflow of the liquid to be treated.

Therefore, the liquid to be treated can be continuously supplied to the reaction tank regardless of whether the aerobic decomposition or the anaerobic decomposition is performed in the reaction tank. By alternately performing aerobic decomposition, the liquid to be treated can be continuously treated with microorganisms.

Embodiment An embodiment of the present invention will be described below with reference to the drawings. First
In the figure, a mud supply pipe 2 is provided at an upper portion of a reaction tank 1, and the mud supply pipe 2 communicates with a raw water source via a mud supply pump 3. In addition, the membrane module 4 is immersed in the reaction tank 1, and the membrane module 4 is connected to the suction pump 5 to communicate with the membrane module 4.
Is provided. Furthermore, an air diffuser 6 is provided below the module 4 in the membrane, and a blower 7 is provided in communication with the air diffuser 6. Further, the reaction tank 1 is provided with a stirrer 8, a sludge drawing pipe 9 is opened at the bottom of the reaction tank 1, and a drawing pump 10 is provided in the middle of the sludge drawing pipe 9.

The operation of the above configuration will be described below. The sludge supply pump 3 is driven to supply the liquid to be treated to the reaction tank 1 through the sludge supply pipe 2, and the liquid to be treated is continuously stirred and mixed with the stirrer 8 in the activated sludge accumulated in the reaction tank 1. Supply.

Then, the blower 7 is driven to aerate the air from the air diffusing pipe 6, the mixed liquid of the activated sludge and the liquid to be treated is stirred by the rising stirring flow of the aerated air, and oxygen is supplied to the mixed liquid. In this state, aerobic decomposition of the mixed solution in the reaction tank 1 proceeds. Further, in the aerobic state, the suction pump 5 is driven to perform solid-liquid separation of the mixed liquid by the membrane module 4 immersed in the reaction tank 1 to take out the separated liquid to the outside of the reaction tank 1 and aerate from the air diffuser 6. The cake adhering to the membrane surface of the membrane module 4 is washed away by the rising stirring flow of air. During this period, the liquid to be treated flows in, but the liquid level in the reaction tank 1 drops due to the solid-liquid separation due to the removal of the separated liquid.

Then, when the liquid level in the reaction tank 1 reaches a predetermined low level, the blower 7 is stopped to stop the air supply from the air diffuser 6 and the suction pump 5 is stopped to stop the membrane module 4
Stop solid-liquid separation by. In this state, the anaerobic decomposition of the mixed liquid proceeds, and the liquid level rises as the liquid to be treated is supplied. Then, when the liquid level in the reaction tank 1 reaches a predetermined high level, the blower 7 is driven to supply air from the air diffuser 6 and the suction pump 5 is driven to restart the fixed separation by the membrane module 4. . After that, the above operation is repeated to perform aerobic decomposition and anaerobic decomposition while continuously supplying the liquid to be treated.

Excess sludge accumulated in the reaction tank 1 is appropriately discharged through the sludge drawing pipe 9 by driving the drawing pump 10.

Therefore, the liquid to be treated is continuously supplied to the reaction tank 1 regardless of whether the aerobic decomposition or the anaerobic decomposition is performed in the reaction tank 1, and the reaction tank 1 performs the anaerobic decomposition and the aerobic decomposition. By alternately performing decomposition, the liquid to be treated can be microbiologically subjected to BOD removal and nitrogen removal.

Effect of the Invention As described above, according to the present invention, the liquid to be treated is continuously supplied to the reaction tank regardless of whether aerobic decomposition or anaerobic decomposition is performed in the reaction tank. The liquid to be treated can be continuously treated by microorganisms by alternately performing anaerobic decomposition and aerobic decomposition in the reaction tank.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram of a reaction tank showing an embodiment of the present invention. 1 ... Reactor, 4 ... Membrane module, 5 ... Suction pump, 6 ... Air diffuser, 7 ... Blower.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical indication C02F 9/00 502 E 7446-4D 503 C 7446-4D 504 A 7446-4D C 7446-4D (72 Inventor Masatsugu Yamagata 1-24-2 Shikitsuhigashi, Naniwa-ku, Osaka-shi, Osaka Kubota Co., Ltd. (56) Reference JP-A-62-155991 (JP, A)

Claims (1)

[Claims] 1. A liquid to be treated is continuously supplied to the activated sludge accumulated in the reaction tank, and air is aerated from an air diffusing pipe to perform stirring and oxygen supply, while the liquid to be treated and the activated sludge in the reaction tank are aerated. Aerobic decomposition of the mixed liquid and solid-liquid separation by the membrane module immersed in the reaction tank, and the membrane permeate is taken out from the reaction tank, and the liquid level in the reaction tank that drops with solid-liquid separation becomes low. When it reaches, the air supply by the air diffuser and the solid-liquid separation by the membrane module are stopped, and the liquid mixture in the reaction tank is anaerobically decomposed while raising the liquid level with the supply of the liquid to be treated,
When the liquid level in the reaction tank reaches a high level, air supply by the air diffuser and solid-liquid separation by the membrane module are restarted, and aerobic decomposition and anaerobic decomposition are performed while continuously supplying the liquid to be treated. An intermittent aeration type activated sludge treatment method characterized by the following.