JPH0635000B2 - Sewage treatment equipment - Google Patents

Description

TECHNICAL FIELD The present invention relates to an apparatus for treating wastewater, and more particularly to an apparatus for treating wastewater in which a fluidized bed reactor and a membrane separator are combined.

[Prior Art] There is a biological treatment method as a treatment method of organic wastewater such as various industrial wastewater and domestic wastewater.

The biological treatment method is a method mainly used for removing organic matter in water by utilizing microorganisms. As a device for performing this biological treatment, there is a fluidized bed type.

A fluidized bed type wastewater treatment device forms a fluidized bed by adding a carrier supporting cells to a container-shaped reaction tank, and supplies raw water into the reaction tank to bring the tank into a fluidized state. The processing is carried out while keeping it. The fluidized bed type sewage treatment apparatus has a high treatment efficiency because it can retain the microorganisms on the surface of the carrier particles at a high concentration, which is a preferable treatment method.

Further, in recent years, there are many cases in which advanced treatment for improving the quality of treated water is required. Therefore, for example, a higher-order treatment for applying a higher-order treatment to the secondary treatment (biological treatment) liquid may be adopted. There is a membrane separation device as one of the devices for performing this higher-order treatment.

By the way, in a fluidized bed reaction tank, a part of the treatment liquid taken out from the fluidized bed reaction tank is generally stored in the fluidized bed reaction tank in order to develop a carrier (zeolite, sand, etc.) in the fluidized bed at a predetermined expansion rate. It is arranged to circulate on the inlet side, and a circulation pump for circulating this treatment liquid is installed.

Further, in a membrane separation device having a permeable membrane such as a microfiltration membrane or an ultrafiltration membrane, it is necessary to supply the liquid to be treated at a predetermined pressure to the liquid receiving side of the membrane separation device. A pump for liquid supply is installed on the upstream side of the separator.

Thus, in the conventional sewage treatment apparatus in which the fluidized bed type reaction tank and the membrane separator are combined, at least two pumps, that is, the treatment of the reaction tank in order to maintain the expansion rate of the fluidized bed reaction tank. A circulation pump for circulating the liquid and a supply pump for supplying the liquid to the membrane separation device had to be installed.

[Problems to be Solved by the Invention] In a conventional sewage treatment apparatus that combines a fluidized bed reactor and a membrane separator, the number of pumps installed is large, and the cost (both initial cost and running cost) increases. Was.

Further, the concentrated liquid of the membrane separation device is heated by the heat generated from the supply pump, the ball cleaning device, the membrane module, etc., but the heat applied to this concentrated liquid has not been effectively utilized. It was (When the fluidized bed reaction tank is an anaerobic fluidized bed reaction tank, increasing the liquid temperature in the treatment tank activates the anaerobic decomposition reaction. Therefore, the heat applied to the concentrated liquid of the membrane separation device is applied to the fluidized bed reaction tank. If it is used as a heat source for heating to raise the temperature of the liquid in the reaction tank, it should be possible to increase the treatment efficiency without adding heat energy from the outside. The heat generated in such a membrane separation device has not been effectively used.) Therefore, there is a waste of energy consumption in the entire system of the wastewater treatment device.

[Means for Solving the Problems] The present invention comprises a fluidized bed reaction tank containing flowable carrier particles carrying microorganisms, and a treatment liquid taken out from an outlet at the upper part of the reaction tank, In a sewage treatment device that circulates to an inlet at the bottom of a reaction tank through a circulation pump and treats sewage with microorganisms held on the carrier particles, the circulated reaction tank treatment that is connected to the discharge side of the circulation pump A membrane separation device having a built-in permeable membrane for receiving the liquid and performing a membrane separation process is installed, and a membrane separation device and a fluidized bed reaction tank are provided so that the concentrated liquid of the membrane separation device is circulated to the inlet at the bottom of the reaction tank. Characterized in that the membrane permeation treatment in the membrane separation device and the carrier particle flow in the fluidized bed reaction tank are performed by the discharge pressure and discharge flow of the circulation pump. Is.

[Operation] In the present invention, a liquid which is taken out from the outlet of the upper portion of the fluidized bed reaction tank and circulated to the inlet of the lower portion of the fluidized bed reaction tank in order to make the expansion rate of the carrier particles in the fluidized bed reaction tank a predetermined value. As the liquid, a concentrated liquid of the membrane separation device (concentration side outlet liquid) is used.

Therefore, the number of installed pumps can be reduced,
The cost (both initial cost and running cost) can be reduced.

Further, the heat retained by the concentrated liquid of the membrane separation device can be used as heat energy for increasing the liquid temperature in the fluidized bed reaction tank.

The amount of liquid supplied to the membrane separator (for example, about several tens of times larger than the amount of water taken out from the membrane separator as treated water) keeps the expansion rate of the fluidized bed reaction tank at a predetermined expansion rate or more. Greater than the minimum level required for
Concentrated liquid taken out from the membrane separator is usually 1 kg / m
Since the pressure of ² or more is maintained, the concentrated liquid of the membrane separation device can be sufficiently used as a circulating liquid for developing the carrier in the fluidized bed reaction tank.

Embodiments Embodiments will be described below with reference to the drawings.

FIG. 1 is a system diagram showing a configuration of a wastewater treatment apparatus according to an embodiment of the present invention. In FIG. 1, reference numeral 2 denotes a fluidized bed reaction tank having an appropriate fluid carrier such as zeolite or sand, and raw water is introduced from a raw water supply pipe 1 connected to the bottom of the fluidized bed reaction tank. A take-out pipe 3 for taking out the liquid treated in the fluidized-bed reaction tank 2 is connected to the upper part of the fluidized-bed reaction tank 2, and a pump 4 is installed in the middle of the taken-out pipe 3. .

The liquid pressurized by the pump 4 is a membrane separation device (for example, microfiltration device, ultrafiltration device, reverse osmosis device, etc.) 5
Will be introduced to. The liquid that has permeated the permeable membrane 6 of the membrane separation device 5 is taken out from the pipe 7 as a treatment liquid and sent to the discharge process or the reuse process. The concentrated liquid of the membrane separation device 5 is circulated from the pipe 8 to the liquid introduction side of the fluidized bed reaction tank 2.

In the present embodiment, a bypass pipe 9 that bypasses the membrane separation device 5 is installed, and the liquid pressurized by the pump 4 is directly introduced into the fluidized bed reaction tank 2 through the bypass pipe 9. It is possible to circulate to the side.

In the figure, 10, 11 and 12 are valves provided in the pipes 3, 8 and 9, respectively.

In the sewage treatment apparatus according to the example configured as described above, the liquid supplied from the introduction pipe 1 to the bottom of the fluidized bed reaction tank 2 is anaerobic or favorable due to the fluidized bed formed inside the reaction tank. Receive a tempered treatment. In the fluidized bed reaction tank 2, the fluidized carrier is developed by the liquid circulated through the pipes 3 and 8 so that the fluidized carrier has a predetermined development rate.

The circulated liquid is heated by heat such as Joule heat generated in the membrane separation device 5 and the pump 4 (for example, the temperature is raised to about 10 to 20 ° C. depending on operating conditions), and the fluidized bed reaction tank 2 is used. The liquid temperature inside is also raised. Therefore, extremely efficient biological treatment is performed in the fluidized bed reaction tank 2.

The liquid subjected to the biological treatment is introduced into the membrane separation device 5 through the pipe 3 and the pump 4 and undergoes the membrane separation treatment, whereby treated water having extremely excellent water quality is obtained.

The bypass line 9 is a system used when the membrane separation device 5 is stopped in order to repair the membrane separation device 5 or clean the membrane, and the valves 10 and 11 are closed and the valve 10 is closed. By opening 12, the liquid taken out from the take-out pipe 3 in the upper part of the fluidized bed reaction tank 2 is fed from the pump 4 to the pipe 9
And is circulated to the liquid introduction side at the bottom of the fluidized bed reaction tank 2.
Therefore, in this embodiment, the operation of the fluidized bed reaction tank 2 can be continuously continued even when the membrane separation device 5 is stopped.

In the present invention, the fluidized bed reaction tank 2 may be either an anaerobic fluidized bed reaction tank or an aerobic fluidized bed reaction tank.

[Effect] As described in detail above, in the wastewater treatment apparatus of the present invention, in order to make the expansion rate of the carrier particles in the fluidized bed reaction tank a predetermined expansion rate, it is taken out from the outlet of the upper part of the reaction tank and the bottom of the reaction tank. As the circulating liquid to be circulated to the inlet of the reactor, the concentrated liquid obtained by subjecting the treated liquid taken out from the outlet on the upper part of the reaction tank to the membrane separation treatment with a membrane separator is used. Sufficient, both initial cost and running cost are reduced.

The heat generated in the membrane separation device or the pump can be used as a heat source for increasing the liquid temperature in the fluidized bed reaction tank, which enables efficient biological treatment.

Since the liquid temperature in the fluidized bed reactor is increased, the amount of permeated water of the membrane separation device can be increased. (In general, in a membrane separator, the higher the temperature of the liquid to be treated, the larger the amount of permeated water. In the present invention, when the fluidized bed reaction tank is an anaerobic fluidized bed reaction tank, the temperature of the treated liquid is increased. However, the amount of permeated water through the membrane is much higher than that of the aerobic fluidized reactor, because the amount of heat generated by the biological reaction is even greater.) Therefore, the water quality is extremely excellent.

And so on.

[Brief description of drawings]

FIG. 1 is a system diagram showing a configuration of a wastewater treatment apparatus according to an embodiment of the present invention. 2 ... Fluidized bed reaction layer, 4 ... Pump, 5 ... Membrane separation device.

Front page continuation (72) Miwako Hattori Inventor Miwako 1723, Bulguko-cho, Hodogaya-ku, Yokohama, Kanagawa Prefecture Kurita Water Industries Co., Ltd. Research Institute (56) (2) Gentle Life Science Encyclopedia, The New Future and Industry Opened by Biotechnology ”, p. 146, May 31, 1981, published by The Nihon Kogyo Shimbun.

Claims (2)

[Claims] 1. A fluidized bed reaction tank containing flowable carrier particles carrying microorganisms is provided, and a treatment liquid taken out from an outlet at the upper part of the reaction tank is supplied to a bottom of the reaction tank via a circulation pump. In a sewage treatment device that circulates to the inlet and treats sewage with microorganisms retained on the carrier particles, it is connected to the discharge side of a circulation pump and receives the circulated reaction tank treatment liquid to perform membrane separation treatment. A membrane separation device having a built-in membrane is installed, and the membrane separation device and the fluidized bed reaction tank are connected to each other so that the concentrated liquid of the membrane separation device is circulated to the inlet at the bottom of the reaction tank. The sewage treatment apparatus characterized in that the membrane permeation treatment in the membrane separation apparatus and the carrier particle flow in the fluidized bed reaction tank are performed by the discharge pressure and the discharge flow. 2. A bypass system is provided, which bypasses the membrane separation device and connects the discharge side of the circulation pump to the fluidized bed reaction tank, and is provided with a bypass system through which liquid is passed when the operation of the membrane separation device is stopped. The sewage treatment apparatus according to claim 1.