JP7177727B2 - biological treatment equipment - Google Patents

Description

TECHNICAL FIELD The present invention relates to a technology of a biological treatment apparatus for anaerobically biologically treating water to be treated.

For the treatment of waste water containing organic substances and nitrogen (organic nitrogen, ammonium nitrogen, nitrate nitrogen and/or nitrite nitrogen), aerobic microorganisms and facultative anaerobic Biological treatment using sexual microorganisms is applied. In addition to the standard activated sludge method, biological treatment includes a carrier method (fixed bed or fluidized bed) that retains organisms at a high concentration using a microorganism-retaining carrier. The carrier method can be operated under a higher load than the activated sludge method, and since it is not necessary to return the sludge that has been solid-liquid separated in the sedimentation tank, it is easy to maintain. In particular, the method using a fluidized carrier does not require backwashing, so stable operation is possible, but a screen is required to separate the carrier from the treated water.

The screen includes, for example, a cylindrical screen as disclosed in Patent Document 1, a planar screen as disclosed in Patent Document 2, and the like.

JP 2010-75837 A JP-A-7-47390

By the way, if SS or the like contained in the water to be treated adheres to the screen, the screen may become dirty and clogged. Therefore, it is necessary to jet a gas such as air from below the screen to clean the screen. However, in a biological treatment tank that anaerobicly biologically treats water to be treated, it is necessary to maintain an anaerobic atmosphere inside the tank, so the amount of gas (amount of air) used to clean the screen installed in the tank is limited. , it was difficult to sufficiently clean the screen.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a biological treatment apparatus that is highly effective in cleaning a screen with a gas.

A biological treatment apparatus according to an embodiment of the present invention includes a biological treatment tank that accommodates a carrier holding microorganisms and performs anaerobically biological treatment of water to be treated, a stirring means that agitates the carrier, and the biological treatment tank. a planar screen provided at an angle inside and separating the treated water subjected to the biological treatment and the carrier; an air diffusion means for ejecting gas from below the screen to the screen; spaced apart baffles , said air diffuser means comprising a first air diffuser means and a second air diffuser means, said first air diffuser means and said second air diffuser means being horizontal and a flow path is formed between the screen and the baffle through which the gas ejected from the first air diffuser and the second air diffuser passes. It is characterized by

In the biological treatment apparatus, the second air diffuser has a longer horizontal distance from the lower end of the screen than the first air diffuser, and is vertically displaced from the first air diffuser. It is preferably arranged.

ADVANTAGE OF THE INVENTION According to this invention, the biological treatment apparatus with the high cleaning effect of a screen by gas can be provided.

BRIEF DESCRIPTION OF THE DRAWINGS It is a schematic diagram which shows an example of a structure of the biological treatment apparatus of this embodiment. FIG. 4 is a schematic diagram for explaining the cleaning effect of the screen by the air diffuser in the present embodiment. FIG. 5 is a schematic diagram for explaining the cleaning effect of the screen by the air diffusion pipe when the baffle is installed in the present embodiment. FIG. 4 is a schematic diagram for explaining the installation state of the screen, the first air diffuser, and the second air diffuser.

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below. In addition, this embodiment is an example which implements this invention, Comprising: This invention is not limited to this embodiment.

FIG. 1 is a schematic diagram showing an example of the configuration of the biological treatment apparatus of this embodiment. A biological treatment apparatus 1 shown in FIG. 1 includes a biological treatment tank 10 . A waste water inflow line 14 is installed at the inlet 10 a of the biological treatment tank 10 , and a treated water discharge line 16 is installed at the outlet 10 b of the biological treatment tank 10 .

A biological treatment tank 10 shown in FIG. 1 contains carriers 12 holding microorganisms, and the water to be treated is anaerobically biologically treated while the carriers 12 are made to flow within the tank. The carrier 12 is a carrier or the like to which microorganisms such as anaerobic microorganisms adhere as, for example, a biofilm. A biofilm is, for example, a membranous structure in which microorganisms and products such as exopolysaccharides produced by microorganisms aggregate.

The biological treatment apparatus 1 shown in FIG. 1 includes an agitating device 20 for agitating the carrier 12 in the biological treatment tank 10 . The stirring device 20 shown in FIG. 1 is equipped with a stirring blade connected to a motor, and driven by the motor, the stirring blade rotates to stir the carrier 12 . Note that the stirring device 20 used in the present embodiment is not limited to the above configuration as long as it has a device configuration capable of stirring the carrier 12 in the biological treatment tank 10 .

The biological treatment apparatus 1 shown in FIG. 1 includes a screen 22 that separates the treated water that has undergone biological treatment from the carrier 12 . The screen 22 is planar and is provided at an angle inside the biological treatment tank 10 . The screen 22 is preferably provided near the outlet 10b of the biological treatment tank 10 to which the treated water discharge line 16 is connected, for example.

The biological treatment apparatus 1 shown in FIG. 1 includes a first air diffuser 24 and a second air diffuser 26 provided below the screen 22 . The first air diffuser 24 and the second air diffuser 26 may be arranged with their positions shifted from each other in the horizontal direction, but they are preferably arranged with their positions shifted from each other in the vertical direction as well. Note that the vertical direction in FIG. 1 is the vertical direction, and the horizontal direction is the horizontal direction. The same applies to other drawings.

Also, the first air diffusion pipe 24 and the second air diffusion pipe 26 extend, for example, along the width direction (the depth direction in FIG. 1) of the screen 22, and each is provided with a plurality of ejection ports. A gas supply device (for example, a blower, etc.) (not shown) is connected to the first air diffusion pipe 24 and the second air diffusion pipe 26, and gas is supplied from the gas supply device to each air diffusion pipe.

The biological treatment apparatus 1 shown in FIG. 1 preferably has a hydrogen donor supply pipe 28 .

An example of the operation of the biological treatment apparatus 1 shown in FIG. 1 will be described.

The water to be treated, which is the object of treatment in this embodiment, is, for example, waste water discharged from food manufacturing factories, electronics industry factories, pulp manufacturing factories, chemical factories, and the like.

Water to be treated is introduced into the biological treatment tank 10 from the waste water inflow line 14 . In the biological treatment tank 10 , the carrier 12 and the water to be treated are agitated by the stirring device 20 , and the microorganisms retained on the carrier 12 anaerobically perform the biological treatment of the water to be treated. In addition, in the biological treatment tank 10, for example, when performing denitrification treatment for reducing nitrate nitrogen and nitrite nitrogen contained in the water to be treated to nitrogen gas, a hydrogen donor supply pipe 28 A hydrogen donor such as alcohol is supplied to the biological treatment tank 10 from the . The treated water biologically treated in the biological treatment tank 10 is separated from the carrier 12 by the screen 22 and discharged out of the system through the treated water discharge line 16 .

If such treatment is continued, SS or the like will adhere to the surface of the screen 22, causing clogging. It jets out and cleans the screen 22 . The gas ejection from the first air diffuser 24 and the second air diffuser 26 may be performed continuously or intermittently.

FIG. 2 is a schematic diagram for explaining the cleaning effect of the screen by the diffuser tube in this embodiment. Broken line arrows shown in FIG. As shown in FIG. 2, the gas ejected from the ejection port of the first diffuser pipe 24 installed below the screen 22 contacts the inclined screen 22 and rises along the surface of the screen 22. passes through the screen 22. Therefore, it is difficult to bring a sufficient amount of gas into contact with the entire surface of the screen 22 only with the first diffuser pipe 24, so the entire surface of the screen 22 cannot be effectively cleaned. However, in this embodiment, as shown in FIG. Since the gas can be jetted toward the region of , it is possible to clean the region that is difficult to clean with the first diffuser pipe 24 . Therefore, the cleaning effect of the screen 22 by the first air diffuser 24 and the second air diffuser 26 which are horizontally displaced from each other is higher than the cleaning effect of the screen 22 by the first air diffuser 24 alone.

The screen 22 may be a planar screen, and examples thereof include a planar wedge wire screen, a planar wire mesh, and punching metal on a flat surface. A planar wedge wire screen is particularly preferred because it is strong and is less likely to clog.

The slit width, opening ratio, etc. of the screen 22 are not particularly limited, and may be appropriately set according to the size of the carrier 12 to be used, the water flow rate, the strength of the material constituting the screen 22, and the like.

FIG. 4 is a schematic diagram for explaining the installation state of the screen, the first air diffuser, and the second air diffuser. The tilt angle of the screen 22 (θ1 shown in FIG. 4) may be more than 0° and less than 90° with respect to the vertical direction, preferably 5° to 15° with respect to the vertical direction. . The inclination angle of the screen 22 is the angle θ1 between the primary side surface 22a of the screen 22 and the vertical direction H1, as shown in FIG. The greater the tilt angle of the screen 22, the greater the amount of gas that passes through the screen 22 and the higher the cleaning effect. Become. Therefore, considering the balance between the cleaning effect and the amount of gas for cleaning, the tilt angle of the screen 22 is more preferably in the range of 5 to 7 degrees with respect to the vertical direction.

In this embodiment, the first air diffusion pipe 24 and the second air diffusion pipe 26 are separate pipes, but the first air diffusion pipe 24 and the second air diffusion pipe 26 may be connected to form a single pipe. The spouts provided in the first diffuser pipe 24 and the second diffuser pipe 26 may be installed at any position of each diffuser pipe. , is preferably arranged in the lower part of the air diffusion pipe, and in terms of increasing the contact efficiency between the gas and the screen 22, it is preferably arranged in the upper part of the air diffusion pipe.

FIG. 3 is a schematic diagram for explaining the cleaning effect of the screen by the diffuser when the baffle is installed in this embodiment. As shown in FIG. 3, the biological treatment apparatus 1 of this embodiment includes a screen 22 and a baffle 30 arranged at a predetermined interval, and between the screen 22 and the baffle 30, a first air diffuser 24 and a It is preferable to form a channel 30a through which the gas ejected from the second diffuser pipes 26 which are displaced from each other in the vertical direction and the horizontal direction passes through the first diffuser pipe 24 . As a result, the gas ejected from the first air diffuser 24 and the second air diffuser 26 easily rises along the surface of the screen 22, and the cleaning effect of the screen 22 is further enhanced.

The first air diffuser 24 and the second air diffuser 26 may be positioned below the bottom edge of the screen 22, as shown in FIGS. 1 and 2, or even a horizontal distance from the bottom edge of the screen 22 (FIG. 4). ) may be positioned above and below the first diffuser 24, or as shown in FIG. , the first air diffuser 24 is located at a position lower than the lower end of the screen 22 so that the gas can be ejected to the lower end of the screen 22, and the horizontal distance from the lower end of the screen 22 is greater than the first air diffuser 24 The second diffuser pipe 26 at a far position may be arranged at a position higher than the lower end of the screen 22 and below a position where the gas ejected from the first diffuser pipe 24 does not contact the screen 22 . In addition to the first air diffuser 24 and the second air diffuser 26, a third air diffuser vertically and horizontally displaced from at least one of these air diffusers may be provided. Further, more air diffusers may be provided.

In the present embodiment, the diffuser pipes (the first diffuser pipe 24 and the second diffuser pipe 26) have been described as an example of the diffusion means for ejecting gas onto the screen 22, but the invention is not limited to this. A diffuser or the like may be used. However, the air diffusion means is preferably an air diffusion pipe having a low oxygen dissolution efficiency in the water to be treated, because the inside of the biological treatment tank 10 can be easily maintained in an anaerobic atmosphere.

Although not shown in the drawings, the biological treatment apparatus 1 of the present embodiment is installed vertically (or substantially vertically) in the biological treatment tank 10, and includes a draft tube that is open at the top and bottom. It is preferable to install a stirring blade of the device. By rotating the stirring blade within the draft tube, for example, a downward flow is formed inside the draft tube, an upward flow is formed outside the draft tube, and the fluidity of the carrier 12 is enhanced.

The carrier 12 is not particularly limited, and examples thereof include plastic carriers, sponge-like carriers, gel-like carriers, and the like. A gel-like carrier suppresses floating due to nitrogen gas in the denitrification treatment and has high fluidity due to agitation, so it is preferable in that high-load treatment is possible compared to plastic carriers and sponge-like carriers. . The gel-like carrier is not particularly limited, but includes water-absorbing polymer gel-like carriers containing polyvinyl alcohol, polyethylene glycol, polyurethane, and the like.

The shape of the carrier 12 is not particularly limited, but preferably spherical, cubic, rectangular, or cylindrical with a diameter of about 1 mm to 10 mm. A spherical or cylindrical gel carrier having a diameter of about 3 to 8 mm is particularly preferred.

The specific gravity of the carrier 12 is preferably greater than 1.0 in terms of facilitating the formation of a fluid state in the biological treatment tank. is preferred.

The amount of carrier 12 introduced into biological treatment tank 10 is preferably in the range of 10 to 70% of the volume of biological treatment tank 10 . If the input amount of the carrier 12 is less than 10% with respect to the volume of the biological treatment tank 10, the reaction rate of the biological treatment may decrease. Raw water may be short-passed due to clogging with sludge, etc., and the quality of treated water may deteriorate.

Agitation of the carrier 12 in the biological treatment tank 10 is not limited to that by the agitator 20. For example, the water to be treated in the biological treatment tank 10 is drawn out of the tank and returned from the bottom of the tank in an upward flow. A circulation device or the like may be used. The carrier 12 in the biological treatment tank 10 is agitated by the water to be treated returned in an upward flow by the circulation device. In general, a system in which the carrier is stirred by a stirring device is called a complete mixing system, and a system in which the water to be treated is returned in an upward flow by a circulation device is called an upward flow system.

In this embodiment, the pH of the water to be treated is preferably in the range of 6.0 to 8.0, more preferably in the range of 7.0 to 8.0, from the viewpoint of the reaction rate of biological treatment. The pH adjustment of the water to be treated is performed, for example, by supplying a pH adjusting agent from a pH adjusting agent supply line (not shown) to a raw water tank (not shown) in which the water to be treated is stored.

The pH adjuster is not particularly limited and may be an acid agent such as hydrochloric acid, an alkali agent such as sodium hydroxide, or the like. Also, the pH adjuster may be, for example, sodium bicarbonate, phosphate buffer, or the like, which has a buffering action.

In the present embodiment, when the water to be treated is biologically treated, it is preferable to add a nutrient to the untreated water, for example, from the viewpoint of maintaining good decomposition activity of the anaerobic microorganisms. Nutrients are not particularly limited, but include, for example, carbon sources, nitrogen sources, and other inorganic salts (Ni, Co, Fe, etc.).

In this embodiment, it is preferable to adjust the temperature of the water in the biological treatment tank 10 to 20° C. or higher. Generally, when the temperature is lower than 20°C, the reaction rate of biological treatment tends to decrease. The method of adjusting the temperature of the water in the biological treatment tank 10 is not particularly limited, but for example, a heating device such as a heater is installed in the biological treatment tank 10, and the temperature in the biological treatment tank 10 is adjusted by the heat of the heater. A method of adjusting the water temperature and the like can be mentioned.

1 biological treatment apparatus 10 biological treatment tank 10a inlet 10b outlet 12 carrier 14 wastewater inflow line 16 treated water discharge line 20 stirring device 22 screen 22a primary side surface 24 first diffuser pipe 26 second 2 air diffuser, 28 hydrogen donor supply pipe, 30 baffle, 30a channel.

Claims (2)

a biological treatment tank containing a carrier holding microorganisms and performing anaerobically biological treatment of the water to be treated;
a stirring means for stirring the carrier;
a planar screen provided at an angle in the biological treatment tank for separating the treated water subjected to the biological treatment from the carrier;
a diffuser for ejecting gas from below the screen to the screen;
a baffle spaced apart from the screen ,
The air diffuser includes a first air diffuser and a second air diffuser, wherein the first air diffuser and the second air diffuser are arranged with their positions shifted from each other in the horizontal direction ,
A biological treatment apparatus according to claim 1, wherein a flow path is formed between the screen and the baffle for passage of gas ejected from the first air diffuser and the second air diffuser . The second air diffuser is located horizontally farther from the lower end of the screen than the first air diffuser, and is vertically displaced from the first air diffuser. The biological treatment apparatus according to claim 1, characterized by:

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