JP5666187B2 - Waste water treatment apparatus and waste water treatment method - Google Patents

Description

  The present invention relates to a wastewater treatment apparatus and a wastewater treatment method applied to biological treatment of wastewater.

  There are two types of biological treatment methods for wastewater: an aerobic treatment method using an aerobic bacterium represented by an activated sludge method and an anaerobic treatment method using an anaerobic bacterium. In particular, in the case of the anaerobic treatment method, organic substances are converted into methane gas and carbon dioxide gas by several types of bacteria, energy recovery is possible, and there are advantages such as less excess sludge. In recent years, the UASB method and the EGSB method are representative of anaerobic treatment, and these can increase the concentration of useful bacteria in the tank, so that the apparatus can be downsized. However, since methane-fermenting bacteria generally achieve high concentration of cells by self-granulation (granule) action, it takes time to acclimate (grow) the granule. There are problems such as embracing and outflow, and solid and gas separation techniques have become issues. Normally, the CODcr volumetric load is 7 to 15 kg / m3 · day in the UASB method, and the EGSB method is operated in the range of 15 to 30 kg / m3 · day.

  As a stirring technique for mixing and dispersing with low shear for such solid and gas separation, there is a stirring device having a stationary blade extending radially at the bottom of the stirring tank and a rotating blade near the liquid surface in the tank. It is known (see Patent Document 1). Further, in the water treatment plant, the carrier is prevented from being damaged by low shear and low power, and the stirring blade is disposed in the upper layer part of the treatment tank for the purpose of uniform dispersion in the tank and disperses the carrier holding the anaerobic bacteria, There is known an agitation apparatus including a guide vane that guides drainage that is disposed at the bottom and mainly descends outside from the center upward, and a baffle plate disposed above the agitation blade (Patent Document 2). reference).

  In addition, there is provided a reaction tank having a baffle with a baffle extending radially at the bottom of the tank and a baffle with a baffle provided near the liquid level in the tank, and a settling tank communicating with the reaction tank at the bottom. In addition, in a device that treats fluorine or phosphoric acid by adding a granular carrier, the granular carrier is uniformly dispersed in the reaction tank, and the shaking of the water in the settling tank is reduced to maintain the granular carrier in the reaction tank. There is known a waste water treatment apparatus that enhances the granular carrier to prevent the granular carrier from coming off (see Patent Document 3).

  Furthermore, an upward flow rectifying plate and a flow velocity accelerating plate are provided in the tank, and these plates make the flow velocity section on the downstream side of the outflow side smaller than the flow velocity section on the upstream side to maintain the circulation of the carrier of the small-diameter spherical object and remove the carrier. There is known a sewage treatment apparatus that prevents water (see Patent Document 4).

  In addition, a diving weir is disposed in the nitrification tank to form a treatment zone and a carrier separation zone, and an inclined guide plate is provided in the treatment zone, and the carrier is returned to the treatment zone again by the rising water flow generated by the inclined guide plate. There is known a wastewater treatment apparatus that floats and prevents the carrier from coming off (see Patent Document 5).

Japanese Patent No. 3578882 JP 2004-188413 A JP 2000-246269 A JP-A-8-103781 JP-A-9-122684

  With any of these conventional devices, it is difficult to sufficiently prevent the carrier from coming off during continuous operation. Therefore, measures such as finally providing a net in the extraction opening are taken, but the carrier is jammed in the net. As a result, there are problems in operation such as regular maintenance is required.

  Further, in the apparatus for preventing the carrier from coming off by the upward flow rectifying plate, the inclined guide plate, etc. in the continuous treatment without using the stirring blade, such as the sewage treatment apparatus of Patent Document 4 and the waste water treatment apparatus of Patent Document 5, In terms of mixing and uniform dispersion of the carrier to the inside, it is not perfect and it is difficult to greatly improve the processing capacity, and there is a method of increasing the input energy of the inflow pump, but there is a problem in terms of energy saving.

  The present invention is a wastewater treatment apparatus which can be operated with low shear and low power without damaging the carrier, prevents the removal of the carrier during operation, solves the above problems, and enables continuous operation. An object is to provide a wastewater treatment method.

The present invention is to achieve the above object, in a treatment tank having a rotary blade in the vicinity of the liquid surface below the stationary blade and the vessel radially extending the tank bottom, the opening to the tank side wall of a lower position than the rotary blade the provided Rutotomoni provided carrier separation unit communicating with the opening to the outside of the cistern wall, the edge of the opening so as to protrude into the cistern, a cover member for covering the opening, the The cover body was formed with openings on the front side and the lower side in the rotational direction of the rotor blades .

  According to the present invention, the carrier can be mixed and uniformly dispersed in the tank with low power, and the carrier does not flow out of the wastewater treatment system without requiring a current plate or the like in the tank. It has the effect of enabling continuous operation.

It is a longitudinal cross-sectional view of Example 1 of the waste water treatment apparatus of this invention. FIG. 2 is a cross-sectional view taken along line II of FIG. 1. FIG. 3 is an enlarged cross-sectional view taken along the line II-II in FIG. 2. It is an expanded sectional view of a carrier separation part. It is explanatory drawing which shows the flow of the treated water in a processing tank, and a support | carrier. It is explanatory drawing which shows the flow of the treated water in a support | carrier separation part, and a support | carrier.

  The example of the form for carrying out the present invention is shown below.

  Embodiment 1 of a processing apparatus of the present invention will be described with reference to the drawings.

  1 is a longitudinal sectional view of a processing apparatus 1 according to a first embodiment of the present invention, FIG. 2 is a sectional view taken along line II of FIG. 1, FIG. 3 is an enlarged sectional view taken along line II-II of FIG. FIG. 5 is an explanatory view showing the flow of treated water and carrier in the treatment tank, and FIG. 6 is an explanatory view showing the flow of treated water and carrier in the carrier separating unit.

  Reference numeral 2 denotes a processing tank of the processing apparatus 1, 3 denotes a stationary blade, and the stationary blade 3 is formed of a linear strip plate, and is fixed radially to the bottom of the processing bath 2 and at the intersection of the strip plates. The corresponding centers of the bottoms have a gap between them.

  Reference numeral 4 denotes a rotating blade. The rotating blade 4 is composed of a blade plate radially fixed to the lower end of the rotating shaft 4a. The rotating shaft 4a is driven by a motor 4b fixed to the top surface of the processing tank 2. It was made to rotate in the vicinity of the liquid level in this processing tank 2.

  Reference numeral 5 denotes a carrier separating portion. The carrier separating portion 5 has an interval between the side plates 6a parallel to each other, the back plate 6b fixed to the peripheral surface of the processing tank 2, and the back plate 6b. A front plate 6c that is steeply inclined so as to become larger, and is formed in a box 6 of a bottom plate 6d and a top plate 6e that are gently inclined and connected to the front plate 6c. The opening 7 is formed on the peripheral surface of the processing tank 2 below the rotor blade 4, and the opening 8 covers the opening 7 so that the cover 8 protrudes into the processing tank 2. The cover body 8 is provided with openings 8 a and 8 b on the front side and the lower side in the rotation direction of the rotary blade 4.

  2 and 3, A indicates the flow direction of the treated water and the carrier in the treatment tank 2.

  The carrier separating portion 5 is connected to a discharge pipe 9 in the vicinity of the top surface plate 6e of the box 6 and is inclined to the front plate 6c near the top in the box 6 toward the back plate 6b. A separating plate 10a that is inclined downward is provided, and a second return plate 10c that is inclined obliquely downward from the back plate 6b toward the front plate 6c is also provided below the separating plate 10a in the box 6. Below the two return plates 10c, there are provided first return plates 10b that are inclined obliquely downward from the front plate 6c toward the back plate 6b.

  Reference numeral 12 denotes an inflow conduit connected to the bottom of the treatment tank 2.

  Next, a processing method performed by the processing apparatus 1 according to the first embodiment will be described.

  From the inflow pipe 12, treated water having a carrier flows into the treatment tank 2.

  The carrier is not particularly limited in terms of material, shape, and structure as long as organisms can adhere and flow. For example, organic carriers such as gel, sponge, plastic, and fiber, inorganic powders such as powdered activated carbon and ceramics. A carrier is used.

  The treated water having a carrier in the treatment tank 2 generates a swirling flow downward as shown in FIG. 5 by the rotating rotor blade 3 and an upward flow at the center by the stationary blade 4 at the bottom.

  As described above, during the flow of the treated water having the carrier, the anaerobic bacteria grow and live on the surface and inside with the carrier as the nucleus, and the organic matter is converted into a gas such as methane gas by the anaerobic bacteria that live on the carrier. Is removed from the carrier by the rotating blade 4 rotating in the vicinity of the liquid surface.

  The carrier from which the gas has been removed descends along with the treated water, and flows into the box 6 of the carrier separation unit 5 through the openings 8a and 7.

  Here, it is preferable to provide the opening 7 at a position below the rotary blade 4 and in the periphery of the treatment tank 2 where the carrier generates a high-speed swirling flow and a downward flow. Don't get out of it.

  In the box 6, the flow rate of the treated water is reduced almost without being affected by the flow of the rotor blades 3 in the treatment tank 2, and the carrier having a higher specific gravity than the treated water is lowered. Separate from treated water.

  The space between the box 6 and the back plate 6b increases as the front plate 6c is inclined and positioned upward, so that the flow rate of the treated water decreases as the treatment water moves upward and the carrier is separated. Further, as shown in the flow in FIG. 6, the treated water is detoured by the first and second return plates 10b and 10c and rises around the return plates 10b and 10c, and finally the front end of the separation plate 10a. Further, the flow rate of the treated water is further reduced, and the descending separation of the carrier is further promoted, so that the carrier is completely separated above the separation plate 10a, and only the treated water is discharged from the discharge pipe 9. And the carrier is not discharged out of the processing system.

  Further, since the lower side is formed in the opening 8b by the cover body 8 covering the opening 7, the carrier that has sunk in the box 6 can be easily discharged and removed into the processing tank 2 from the opening 8b.

  In addition, although the said box 6 showed the example in which the front board 6c inclined in the said Example, this front board 6c may be a vertical surface.

  Further, in the carrier separation unit 5, when the first and second return plates 10b and 10c are not provided, the first and second return plates 10b and 10c may be omitted if the single separation is sufficiently possible. . Also, the separation plate 10a may be detachable in consideration of maintenance.

  Next, the inventor manufactured a methane treatment tank having a tank volume of 100 L, and 20 L of a polyvinyl alcohol gel carrier (4 mm) was charged into the tank. A stirring blade for flowing the carrier was installed below the water surface. The treatment flow was acid generation + methane fermentation, and an anaerobic wastewater treatment test was conducted. The drainage load was started at CODcr = 3000 mg / L, 100 L / day, and then the load was increased by increasing the raw water concentration in stages, and increased to the maximum CODcr = 50000 mg / L. The biotreatability by this flow was very good with the CODcr removal rate of approximately 90%. When anaerobic treatment is performed, the organic matter in raw water is decomposed into methane gas and carbon dioxide gas. Also in this test, the gas generation in the tank progressed so as to be visually discernable from the point where the raw water CODcr = 15000 mg / L (CODcr volumetric load = 15 kg / m 3 · day) was exceeded. After that, the concentration was increased stepwise, but even in CODcr volumetric load = 50 kg / m3 · day, the gas generated from the gel inside and surface of the methane fermentation tank and the gas floating in the tank were separated at the top of the tank, The carrier was separated in the slope type carrier separation area and could be operated without being discharged out of the system.

  The comparison results between the method according to Example 1 and the conventional UASB method and EGSB method are as follows.

  According to the present invention, it is possible to stably process the carrier without flowing out of the system, and even in Example 1, the CODcr volumetric load of the reaction tank is 40 kg / m 3 · day or more and the conventional processing method (UASB, EGSB). ) Could be processed with a higher load than This is presumably because the contact efficiency of the substrate and the like was increased because the stirring efficiency was improved in addition to the carrier not flowing out.

  The wastewater treatment apparatus or wastewater treatment method of the present invention can be used in anaerobic treatment, denitrification / nitrification treatment, etc. in addition to anaerobic treatment, and uses are also in the electronics industry, food, livestock, agriculture, office, sewage, etc. It can be used for industrial wastewater and domestic wastewater.

DESCRIPTION OF SYMBOLS 1 Waste water treatment apparatus 2 Processing tank 3 Stator blade 4 Rotor blade 5 Carrier separation part 6 Box body 6b Back plate 6c Front plate 10a Separation plate

Claims (3)

In a processing tank comprising a stationary blade extending radially at the bottom of the tank and a rotating blade near the lower liquid level in the tank ,
An opening is provided on the tank side wall surface at a position below the rotor blade ,
Cistern wall surface of the outside provided a carrier separation unit communicating with the opening Rutotomoni,
A cover body that covers the opening is provided at the edge of the opening so as to protrude into the tank, and the cover body is a drainage having openings formed on the front side and the lower side in the rotational direction of the rotor blades. Processing equipment. The carrier separating unit is a box body that is inclined so that the back plate comes into contact with the peripheral surface of the processing tank and the front plate becomes larger as the gap between the back plate and the back plate increases .
In the box, the treated water flowing from the opening and moving upward is diverted at the tip to reduce the flow velocity, and the treated water is detoured at the tip to further reduce the flow velocity. The wastewater treatment apparatus according to claim 1, further comprising a separation plate for separating the carrier . The carrier separating unit is a box body that is inclined so that the back plate comes into contact with the peripheral surface of the processing tank and the front plate becomes larger as the gap between the back plate and the back plate increases.
The opening is formed in the lower part of the back plate, and a discharge pipe is formed on the front plate side of the top plate of the box,
In the box, a separation plate is provided on the front plate that is deviated obliquely downward toward the rear plate, bypassing the front end portion to reduce the flow rate of the treated water. The second return plate is provided with a second return plate that is inclined downwardly from the back plate toward the front plate, and further reduces the flow rate of the treated water by detouring at the tip. The waste water treatment apparatus of Claim 1 which provided the 1st return plate which inclines in the diagonally downward toward the backplate from the front plate below .

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