JP2008142603A - Sewage treatment device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce clogging on the surface of a solid-liquid separation membrane constituting a membrane module efficiently at a low operation cost. <P>SOLUTION: The sewage treatment device comprises: a reaction tank 1 where sewage made to flow is treated with activated sludge; a plurality of solid-liquid separation flat membrane 4 dipped into the reaction tank 1 so as to be vertically installed, and composing membrane modules separating a suspension and treatment water; floats 10 installed in the face of water between each solid-liquid separation flat membrane 4 and each solid-liquid separation flat membrane 4 in a plurality of the solid-liquid separation flat membranes; and brushes 11 fitted to a vertical direction from the upper part of the floats 10. In the sewage treatment device, a gate 13 is provided in an outflow port 6 in order to perform the water level control of the reaction tank 1. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a sewage treatment apparatus using a plurality of solid-liquid separation flat membranes constituting an immersion type membrane module.

  Conventionally, a sewage treatment apparatus using a plurality of solid-liquid separation flat membranes constituting an immersion type membrane module has been proposed. As a sewage treatment apparatus using a plurality of solid-liquid separation flat membranes constituting this immersion type membrane module, for example, a plurality of solid-liquid separations constituting a membrane module for separating suspension and treated water in a reaction tank A flat membrane whose surface is installed vertically (vertical) is used.

  In such a sewage treatment apparatus, air bubbles are diffused from an air diffuser installed below a plurality of solid-liquid separation flat membranes in a reaction tank. The purpose of this air bubble diffusion is to supply oxygen to the activated sludge in the reaction tank, and at the same time, clean the membrane surface of the solid-liquid separation flat membrane by the water flow generated as the air bubbles rise. It was to remove the deposits and suppress clogging.

  Such a sewage treatment apparatus can be operated with a high concentration of activated sludge because it is possible to prevent the turbidity component from flowing out. As a result, the apparatus can be reduced in size compared to a sewage treatment apparatus that does not use a membrane module, and the generated sludge can be reduced. However, since a large amount of air bubbles is required as compared with the conventional sewage treatment apparatus, a large amount of electric energy is consumed by the blower, resulting in high operating costs.

  Further, when the filtration operation of the solid-liquid separation flat membrane is continued, the clogging phenomenon of the membrane surface of the solid-liquid separation flat membrane gradually proceeds. In order to remove the clogging of the solid-liquid separation flat membrane, the liquid cleaning of the solid-liquid separation flat membrane is performed once every several months or years. When washing a solid-liquid separation flat membrane with a chemical solution, it is common to take out the immersed solid-liquid separation flat membrane from the reaction vessel, impregnate it into the chemical solution washing vessel, and wash it. In addition, there has been a problem that a solid-liquid separation flat membrane take-out device is required. For this reason, it is desirable to wash | clean this solid-liquid separation flat film in the state immersed in the reaction tank.

  In order to solve these problems, countermeasure techniques disclosed in Patent Documents 1, 2, and 3 have been proposed.

  In this Patent Document 1, a stirring means is provided between a solid-liquid separation flat membrane constituting a membrane module in a reaction tank and an air diffuser pipe for diffused air, and an upward stirring flow toward the membrane surface of the membrane module is enhanced. Thus, there has been disclosed a technique in which the cleaning action of the film surface is stabilized.

  Patent Document 2 proposes a membrane separation method for filtering water to be treated while ultrasonically washing a membrane element.

In addition, the one disclosed in Patent Document 3 uses a sliding brush to prevent clogging of the metal film.
JP 2003-251386 A JP 11-319517 A JP-A-11-267472

  However, in the thing disclosed in Patent Document 1, since the rising speed of the bubbles is increased because an ascending stirred flow is generated, the bubble residence time in the reaction tank is reduced, and the oxygen dissolution rate is reduced. As a result, the oxygen supply amount of the activated sludge becomes insufficient, and it is necessary to increase the amount of air diffused in order to ensure the treatment capacity of the activated sludge. In order to increase the amount of air diffused, electric power energy is required, which has the disadvantage of increasing the operating cost.

  Further, the ultrasonic characteristics of ultrasonic cleaning in Patent Document 2 have two points: attenuation is smaller in water and solid than gas, and the wavelength is short and the diffraction action is small. On the other hand, a reaction tank of a sewage treatment apparatus using a membrane module is provided with a plurality of solid-liquid separation flat membranes and aeration pipes and has a complicated structure, and bubbles and activated sludge exist together with liquid. As a result, the location where the ultrasonic wave is not sufficiently transmitted to the membrane surface of the solid-liquid separation membrane and the distance from the vibrator are so far that the energy is attenuated by the bubbles and activated sludge that exist between them, and the cleaning effect is reduced. There was an inconvenience that a part of the surface was generated.

  Moreover, in the thing disclosed by patent document 3, the solid-liquid separation flat membrane which comprises a membrane module has a structure integrated with the sliding brush, and it is in the reaction tank for the inspection and washing | cleaning of a sliding brush temporarily. When taking out from a solid-liquid separation flat membrane which comprises a membrane module, there also existed a problem which had to be taken out from a reaction tank.

  In view of such a point, an object of the present invention is to reduce clogging of the membrane surface of a solid-liquid separation flat membrane that constitutes a membrane module efficiently at low operating cost.

  The sewage treatment apparatus of the present invention includes a reaction tank that treats inflowing sewage with activated sludge, and a plurality of membrane modules that are vertically installed by being immersed in the reaction tank and that separate suspension and treated water. A solid-liquid separation flat membrane, a float installed on the water surface between the solid-liquid separation flat membrane and the solid-liquid separation flat membrane of the plurality of solid-liquid separation flat membranes, and attached vertically from the bottom of the float In a sewage treatment apparatus having a brush, a gate is provided at the outlet in order to control the water level of the reaction tank.

  According to the present invention, the water level of the reaction tank is moved up and down by controlling the gate provided at the outlet in order to control the water level of the reaction tank, and the brush moves up and down along with the floating according to this vertical movement. Thus, the deposits on the membrane surface of the plurality of solid-liquid separation flat membranes constituting the membrane module can be scraped off, and clogging of the membrane surface of the membrane module can be efficiently reduced at a low operating cost.

  Hereinafter, an example of the best mode for carrying out the sewage treatment apparatus of the present invention will be described with reference to FIGS. 1 and 2.

  FIG. 1 shows a perspective view of a sewage treatment apparatus according to this example, FIG. 2A shows a sectional view thereof, and FIG. 2B shows a top view thereof. 1 and 2, reference numeral 1 denotes a reaction tank for treating sewage (sewage) 3 flowing in from an inflow pipe 2 by an activated sludge method. The reaction tank 1 is immersed in the sewage 3 and membranes are arranged in series in the horizontal direction. A plurality of solid-liquid separation flat membranes 4 constituting the module are installed.

  A plurality of solid-liquid separation flat membranes 4 constituting this membrane module are fixed to a membrane for filtering solid components of sewage (sewage) 3 on the front side and the rear side of a rectangular support frame, for example. A separation space is formed from the sewage (sewage) 3 in the reaction tank 1 by the frame, the front side membrane and the rear side membrane, and all the upper part of the support frame communicates with the separation space of the solid-liquid separation flat membrane 4. A treated water take-out pipe 5 is provided, and treated water 5 a is sucked from the treated water take-out pipe 5.

  The plurality of solid-liquid separation flat membranes 4 are installed in the reaction tank 1 so as to be parallel to the flow direction of the sewage 3 to be treated. The solid-liquid separation flat membrane 4 has a function of separating the suspension in the reaction tank 1 and the treated water 5a, and obtains treated water 5a containing no turbidity by suction filtration. .

  From the outlet 6 of this reaction tank 1, the concentrated water 7 with which the density | concentration of the turbid component became high flows out. This concentrated water 7 may be processed by the next-stage sewage treatment apparatus, or may be circulated again into the reaction tank 1 from the inflow pipe 2.

  A diffuser tube 8 is provided below the plurality of solid-liquid separation flat membranes 4 in the reaction tank 1, and air bubbles are diffused from the diffuser tube 8. The purpose of this air bubble aeration is to clean the membrane surface of the solid-liquid separation flat membrane 4 by bubbles rising simultaneously with the supply of oxygen to the activated sludge in the reaction tank 1.

  In this example, a plurality of disk-like shapes are formed on the respective water surfaces between the solid-liquid separation flat membrane 4 and the solid-liquid separation flat membrane 4 of the plurality of solid-liquid separation flat membranes 4, 4,. And a brush 11 is arranged in a vertical (vertical) direction from the float 10 toward the water.

  For example, as shown in FIGS. 3A and 3B, the brush 11 has a predetermined length (solid-liquid separation flat membrane 4) having the same width as the diameter of the float 10 below the disk-like float 10. The substrate 11a is planted, and hairs 11b of a predetermined length made of a material that does not damage the solid-liquid separation flat film 4 such as silicon rubber are implanted on both surfaces of the substrate 11a. The outer shape of the brush 11 is rectangular when viewed from above.

  In this case, the brush 11 is in contact with the solid-liquid separation flat membrane 4 on both sides, and has a function of removing the suspended matter adhering to the membrane surface of the solid-liquid separation flat membrane 4, thereby further improving the cleaning effect by bubbles. Increase. Further, the brush 11 does not require power, and as shown in FIGS. 4A and 4B, the brush 11 also moves up and down along with the fluctuation of the water surface 12 due to the buoyancy of the float 10 provided on the upper portion of the brush 11, thereby solid-liquid separation. Membrane surface cleaning can be performed effectively by moving up and down between the flat membrane 4 and the solid-liquid separation flat membrane 4.

  In this example, in order to control the vertical movement of the brush 11, a water level control gate 13 is provided at the outlet 6 from which the concentrated water 7 flows out, and the gate 13 is moved up and down to move inside the reaction tank 1. Control the water level. This vertical movement of the gate 13 may be performed electrically or manually. The gate 13 may be moved up and down at a predetermined cycle.

  In this case, when the water level control gate 13 is raised, as shown in FIG. 5A, the water level in the reaction tank 1 rises as the treated sewage 3 flows from the inflow pipe 2. As the water level rises, the float 10 and the brush 11 attached to the float 10 rise due to buoyancy, and the membrane surface of the solid-liquid separation flat membrane 4 is cleaned. Conversely, when the water level control gate 13 is lowered, the concentrated water 7 accumulated in the reaction tank 1 flows out from the outlet 6. With the outflow of the concentrated water 7, the water level in the reaction tank 1 falls, the float 10 installed in the reaction tank 1 and the brush 11 attached to the float 10 descend, and the solid-liquid separation flat membrane 4 Perform film surface cleaning.

  As described above, according to this example, the water level in the reaction tank 1 moves up and down by controlling the gate 13 provided at the outlet 6 in order to control the water level in the reaction tank 1, and this vertical movement Accordingly, the brush 11 moves up and down together with the float 10 to scrape off deposits on the membrane surface of the plurality of solid-liquid separation flat membranes 4 constituting the membrane module, thereby reducing clogging of the membrane surface. Can do.

  Further, according to this example, the water level in the reaction tank 1 moves up and down by controlling the gate 13 provided at the outlet 6 in order to control the water level in the reaction tank 1, and the vertical movement is followed. Since the brush 11 moves up and down together with the float 10, power is not required for the vertical movement of the brush 11, and stable and stable film surface maintenance can be performed at low operating cost.

  Further, according to this example, the water level in the reaction tank 1 moves up and down by controlling the gate 13 provided at the outlet 6 in order to control the water level in the reaction tank 1, and the vertical movement is followed. The brush 11 moves up and down together with the float 10 to scrape off deposits on the membrane surface of the plurality of solid-liquid separation flat membranes 4 constituting the membrane module, thereby reducing clogging of the membrane surface. The amount of air diffused for the purpose of cleaning the membrane surface with only air bubbles can be reduced, and this reduction in air diffused amount directly reduces the amount of electricity consumed by the blower, thus reducing power costs. .

  In the above example, the gate 13 provided at the outlet 6 is moved up and down in order to control the water level in the reaction tank 1, but instead, as shown in FIG. 6 may be opened and closed.

  Moreover, the structure of the float 10 and the brush 11 is not restricted to the above-mentioned example, Various structures can be taken as needed.

  Further, the present invention is not limited to the above-described examples, and various other configurations can be adopted without departing from the gist of the present invention.

It is a perspective view which shows the example of the best form for implementing this invention sewage treatment equipment. A is a cross-sectional view of FIG. 1, and B is a top view of FIG. The example of a brush is shown, A is a side view and B is a front view. It is a diagram with which it uses for description of the vertical motion of a brush. It is sectional drawing of the example of the sewage treatment apparatus with which it uses for description of this invention. It is sectional drawing which shows the other example of the best form for implementing this invention sewage treatment equipment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Reaction tank, 2 ... Inflow pipe, 3 ... Sewage, 4 ... Solid-liquid separation flat membrane, 5 ... Treated water take-out pipe, 6 ... Outflow port, 7 ... Concentrated water, 8 ... Aeration pipe, 10 ... Floating, 11 ... Brush, 13 ... Gate

Claims (1)

A reaction tank that treats the inflowing sewage with activated sludge, a plurality of solid-liquid separation flat membranes that constitute a membrane module that is immersed vertically in the reaction tank and installed vertically and separates the suspension and the treated water; A sewage treatment apparatus having a float installed on the water surface between the solid-liquid separation flat membrane and the solid-liquid separation flat membrane of the plurality of solid-liquid separation flat membranes, and a brush attached in a vertical direction from the bottom of the float In
A sewage treatment apparatus comprising a gate at an outlet for performing water level control of the reaction vessel.

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