JP2012075988A - Waste water pretreatment method and waste water pretreatment apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a waste water pretreatment method and apparatus remarkably improving dissolved oxygen (DO) by pretreating waste water introduced into an aeration tank, and to make aeration treatment efficient to reduce a running cost required for the aeration treatment.SOLUTION: Waste water treatment includes jetting waste water to cause cavitation and pretreating waste water with the erosion action, and then carrying out decomposition treatment with aerobic microorganisms in an aeration tank 3. In the waste water treatment, the waste water pretreatment method includes allowing waste water in pretreatment to pass through a water activating device 11 formed by winding a conductive wire 112 around a water passing pipe and then jetting activated waste water to cause cavitation and mixing concentrated oxygen at the same time. The waste water pretreatment apparatus is used for the method.

Description

The present invention relates to a wastewater pretreatment method for pretreating wastewater when performing wastewater treatment with aerobic microorganisms, and a wastewater pretreatment apparatus used in the method.

When discharging factory wastewater, aeration processing using aerobic microorganisms is performed. This treatment method is called activated sludge method. In order to sufficiently propagate aerobic microorganisms and decompose organic substances, it is necessary to operate the aeration facility for a long time, and the running cost is high.

Patent Document 1 describes that factory wastewater (raw water) is passed through a magnetic field or an electric field to increase the amount of dissolved oxygen in the factory wastewater and increase the microorganism concentration in the aeration tank.

On the other hand, in Patent Document 2, a device that is an ultrafine device is used to cause cavitation to make the contained organic matter and sludge ultrafine, and then aerated by mixing the refined waste water and fermenting bacteria. A treatment method for performing aeration treatment in a tank is described.

Patent Document 3 describes an oxygen-aeration type denitrification apparatus, and describes an oxygen mixing apparatus 4 that mixes an oxygen-rich gas and a denitrification liquid. Paragraph 0021 describes the use of concentrated oxygen or pure oxygen as the oxygen-rich gas.

Further, Patent Literature 4 discloses a liquid alteration bubble box including a box, a jet nozzle that ejects liquid toward the box, and a fluid induction hole for drawing the fluid. However, there is no description relating to the active water device or the use of this box for the aeration process.

Patent Documents 1 to 4 attempt to improve the efficiency of wastewater treatment, but there is room for further efficiency.

JP2003-10880 (page 3, column 3 and column 4) JP 2006-212483 (FIG. 1, paragraph 0015, paragraph 0022, etc.) JP-A-9-85279 (FIG. 1, FIG. 2, paragraph 0021, etc.) Japanese Patent Publication No. 3373444 (FIG. 1, FIG. 2, etc.)

An object of the present invention is to provide a wastewater pretreatment method for pretreating wastewater introduced into an aeration tank and dramatically increasing the amount of dissolved oxygen (DO), and a wastewater pretreatment device used in the method. It is another object of the present invention to improve the efficiency of the aeration process and reduce the running cost required for the aeration process.

In the wastewater treatment method in which wastewater is ejected to cause cavitation and the wastewater is pretreated by its erosion action, and then decomposed by aerobic microorganisms in an aeration tank, the wastewater in the pretreatment is a pipe through which water can pass. The above-mentioned problem is solved by a wastewater pretreatment method characterized by mixing concentrated oxygen while causing cavitation by ejecting activated wastewater after passing through an active water device in which a conductive wire is wound around.

The method of the present invention includes an active water device in which a conductive wire is wound around a pipe through which waste water is passed, an oxygen concentrator for supplying concentrated oxygen, activated waste water supplied from the active water device, This can be realized by using a wastewater pretreatment device comprising a mixing device for mixing concentrated oxygen supplied from an oxygen concentrator while causing cavitation, and a pump for supplying wastewater to the active water device.

Cavitation is well-known as a phenomenon such as a screw propeller that causes bubbles to form on the surface of the screw propeller when the pressure drops for a very short time in the flow of liquid. . The surface of the screw propeller may even be perforated by erosion (erosion) due to jet flow.

It is described in Patent Document 1 that organic matter in wastewater is refined by this erosion. The present inventors have found that the amount of dissolved oxygen increases dramatically when the wastewater is activated by passing it through a pipe wrapped with an energized conductive wire and mixed with concentrated oxygen while causing cavitation. It came to complete.

Examples of wastewater to which the present invention is applied include factory wastewater such as food factories and wastewater containing a large amount of organic matter such as manure, but are not particularly limited as long as they can be treated by aerobic microorganisms.

In order to generate cavitation, a known cavitation generating nozzle may be used. For example, a liquid is ejected to cause a pressure change in the vicinity, thereby causing cavitation. Concentrated oxygen supply ports may be provided around the nozzle so that the concentrated oxygen is attracted by a jet or may be injected using a pump or the like. In the present invention, a supply port for concentrated oxygen is provided in a nozzle for generating cavitation and used as a mixing device. It is more preferable that the cavitation generating nozzle is installed toward the mixing chamber and a vortex is formed in the mixing chamber because the efficiency of dissolving oxygen is increased. The shape of the mixing chamber is preferably a flat shape in which water is attracted to the wall surface of the mixing chamber by the Coanda effect, so that eddy currents are easily formed.

A well-known thing is used for the oxygen concentrator used by this invention. It is not particularly limited as long as it can supply a high concentration of oxygen, such as a PSA (Pressure Swing Adsorption) type and an oxygen-enriched film type.

The active water device used in the present invention is configured by winding a conductive wire around a pipe through which waste water can flow. A pipe made of a synthetic resin such as polyvinyl chloride may be used. When a large amount of water is activated using a large-diameter pipe, the waste water flowing through the center of the pipe is less likely to be activated. In addition, the magnetic field generated outside the coil cannot be used effectively. Therefore, the pipe may have a multiple structure, and the small diameter pipe around which the conductive wire is wound may be covered with the large diameter pipe. That is, an active water device in which a conductive wire is wound around a small-diameter pipe through which wastewater is passed, and a small-diameter pipe and a conductive wire are housed in a large-diameter pipe having a diameter larger than that of the pipe, and are configured in multiple. Waste water is passed inside the pipe and between the small diameter pipe and the large diameter pipe. By passing waste water inside the small diameter pipe and between the small diameter pipe and the large diameter pipe and energizing the conductive wire, waste water in the small diameter pipe and between the small diameter pipe and the large diameter pipe can be activated simultaneously.

The active water device comprising the above-mentioned multi-structure pipe can be used for purposes other than water purification. For example, water (hereinafter referred to as treated water) treated with an active water device composed of multiple-structured pipes acts as a scale remover in the piping. Moreover, if treated water is used as cleaning water for window glass or the like, dirt is peeled off from the surface of the window glass, and an excellent cleaning effect is exhibited.

The buffer tank is installed in front of the aeration tank. The buffer tank functions as a sedimentation tank and prevents solids from being brought into the aeration tank by precipitating solids in the wastewater. It also prevents the amount of water in the aeration tank from changing significantly due to increase or decrease in the amount of wastewater discharged. The buffer tank may be omitted when the amount of solid matter is small or when the amount of discharged wastewater is constant.

According to the wastewater pretreatment method and the wastewater pretreatment apparatus of the present invention, the amount of dissolved oxygen in wastewater can be dramatically increased, and the decomposition efficiency of organic substances by aerobic microorganisms can be enhanced. Since it is not necessary to perform the aeration process for a long time as in the prior art, it is possible to reduce running costs such as electricity costs required for the aeration process. In addition, it is possible to reduce the generation of excess sludge, which has been a problem in the conventional aeration process. Furthermore, it is possible to reduce bad odor that has been a problem in conventional treatment systems and to quickly purify wastewater.

The wastewater pretreatment device of the present invention does not require repair work for the aeration tank. Therefore, the wastewater pretreatment apparatus of the present invention can be applied using existing facilities. Moreover, the wastewater pretreatment device of the present invention is installed outside the aeration tank. Therefore, it is excellent in maintainability of the apparatus, and replacement of consumable parts is extremely easy.

By making the active water device into a multiple structure, the amount of waste water subjected to active water treatment can be increased, and the waste water pretreatment of the present invention can be made more efficient. For example, if the volume between the small-diameter pipe and the large-diameter pipe is the same as that inside the small-diameter pipe, it is possible to activate twice the amount of waste water with the same power as in the conventional case.

It is a block diagram which shows the wastewater pretreatment apparatus and wastewater pretreatment method of this invention. It is a perspective view of the active water apparatus in this invention. The flow of wastewater is schematically shown by arrows. It is a partially broken perspective view which shows another example of the active water apparatus in this invention. In order to show the internal structure, the large-diameter pipe is cut out and illustrated. The flow of wastewater is schematically shown by arrows. It is a partially broken perspective view which shows another example of the active water apparatus in this invention. In order to show the internal structure, the large-diameter pipe and the partition pipe are cut out and illustrated. The flow of wastewater is schematically shown by arrows. It is a perspective view of the mixing apparatus in this invention. It is AA sectional drawing of the mixing apparatus shown in FIG. It is a block diagram which shows another example of the wastewater pretreatment apparatus and wastewater pretreatment method of this invention.

Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings.

FIG. 1 is an example in which a buffer tank 2 for flow rate adjustment is provided in front of an aeration tank 3, the wastewater pretreatment device 1 of the present invention is installed in the buffer tank 2, and the wastewater pretreatment method is circulated. . Waste water that has been decomposed by aerobic microorganisms in the aeration tank 3 is transferred to the precipitation tank 4 where it is separated into solids (P) and moisture (W), and the moisture (W) is discharged out of the system.

As shown in FIG. 1, the wastewater pretreatment device 1 of the present invention includes an active water device 11 in which a conductive wire is wound around a pipe through which wastewater is passed, an oxygen concentration device 12 that supplies concentrated oxygen, From the mixing device 13 for mixing the activated wastewater supplied from the active water device 11 and the concentrated oxygen supplied from the oxygen concentrating device 12 while causing cavitation, and the pump 14 for supplying wastewater to the active water device Become.

In this example, a pump 14 for water supply is installed in the buffer tank 2, and waste water is sent to the active water device 11 via the water inlet side pipe 111. As shown in FIG. 2, the active water device 11 is a device in which a conductive wire 112 coated with a resin is wound around a polyvinyl chloride pipe (conductive coil). The conductive wire 112 is connected to the power supply unit 114 and energized. Waste water activated by the active water device 11 is discharged from the water discharge side pipe 113 and introduced into the injection nozzle 131 of the mixing device 13.

As the water activation apparatus 11, another example of the water activation apparatus 11 shown in FIG. 3 may be used. That is, a conductive wire 112 is wound around a small-diameter pipe 115 (first pipe) through which waste water is passed, and a small-diameter pipe is disposed in a large-diameter pipe 117 (second pipe) having a diameter larger than that of the pipe 115. 115 and the conductive wire 112 are configured to be double, and waste water is passed between the inside of the small diameter pipe 115 and between the small diameter pipe 115 and the large diameter pipe 117.

Also, as shown in FIG. 4, a partition pipe 116 (third pipe) is inserted between the small-diameter pipe 115 (first pipe) and the large-diameter pipe 117 (second pipe) so that the conductive wire 112 does not get wet. It may be triple. As schematically shown by the arrows in FIG. 4, the waste water flows inside the small diameter pipe 115 and between the partition pipe 116 and the large diameter pipe 117. The conductive wire 112 is resin-coated as described above. The conductive wire 112 is provided with a through-hole having a diameter through which the conductive wire 112 passes through the partition pipe 116 and the large-diameter pipe 117, and is taken out of the through hole and connected to the power supply unit 114 similar to that in FIG. What is necessary is just to prevent a liquid leak by attaching packing to a through-hole. If no through-hole is provided, the waste water flow path formed between the partition pipe 116 and the large-diameter pipe 117 at the right or left end of the pipe is sealed with a rubber plug or a wall surface, and then the pipe is sealed. It is good also as a structure which takes out a conductive wire from the right or left end. In this case, in order to introduce waste water between the partition pipe 116 and the large-diameter pipe 117, a water inlet and a drain outlet may be provided on the outer peripheral surface near the left end or the right end of the large-diameter pipe 117, respectively.

For example, the mixing device 13 shown in FIGS. 5 and 6 is used. That is, an injection nozzle 131 that has a flow path 131a inside and injects waste water discharged from the active water device 11, a mixing chamber 132 that forms a vortex with the waste water discharged from the injection nozzle 131, and discharges the mixed waste water. The mixing device 13 includes a discharge port 133 that performs the above operation. The injection nozzle 131 is provided with a supply port 134 for concentrated oxygen, and has a structure in which concentrated oxygen is dissolved in activated wastewater by vortex flow and cavitation generated in the mixing chamber 132. The mixing chamber 132 is formed as a flat space with a small height. Waste water sprayed from the spray nozzle 131 is drawn to the right or left side wall surface of the mixing chamber 132 by the Coanda effect to form a vortex. The rotation direction of the vortex can be adjusted by adjusting whether the injection direction of the injection nozzle 131 is directed to the right side wall or the left side wall. The amount of dissolved oxygen can be further increased by attaching the injection nozzle 131 to the mixing device 13 so that the injection direction can be adjusted and operating to repeat the clockwise and counterclockwise vortex alternately. The waste water in which the concentrated oxygen is dissolved in the mixing chamber 132 is discharged from the discharge port 133 and flows into the pipe 135. The end of the pipe 135 opens into the buffer funk 2 (FIG. 1), and the waste water treated by the waste water pretreatment device 1 of the present invention is returned to the buffer tank 2. The wastewater pretreatment device of this example is a circulation type, and the amount of dissolved oxygen can be increased while circulating the wastewater.

The oxygen concentrating device 12, the active water device 11, and the mixing device 13 of this example are all provided on the ground, and the water inlet side pipe 111 and the pipe 135 only enter the buffer tank 2. Therefore, it is excellent in maintainability and it is easy to apply the wastewater pretreatment apparatus 1 of the present invention to an existing facility.

In this example, a dissolved oxygen measuring device 6 (DO measuring device) and a control panel 5 are installed. That is, the amount of dissolved oxygen in the aeration tank is measured by the probe 61 of the dissolved oxygen measuring device 6, and the oxygen concentration device 12, the active water device 11, the mixer 13, and the buffer tank 2 are measured by the control panel 5 based on the measured value. The pump 14 and the pump of the aeration tank 3 are feedback-controlled. The control panel 5 and the dissolved oxygen measuring device 6 are not essential and may be omitted.

Further, as shown in FIG. 7, the buffer tank 2 of this example may be removed and the waste water may be directly introduced into the aeration tank 3. In this other example, the active water device 11 is formed by winding the conductive wire 112 around the pipe 136 of the factory waste water. Since the device configuration of the water activation device 11 is the same as that shown in FIG. The waste water activated by the active water device 11 is mixed with the concentrated oxygen supplied from the oxygen concentrating device 12 by the mixing device 13 by vortex while causing cavitation. As the mixing apparatus, the mixing apparatus 13 shown in FIGS. 5 and 6 is used. In another example, the control panel 5 and the dissolved oxygen measuring device 6 are provided as in the present example, but these are not essential.

[Example 1]
Using the wastewater pretreatment device 1 (FIG. 1) shown in the above example, wastewater purification treatment was performed. That is, the waste water discharged from the food factory is stored in the buffer tank 2 and activated by the active water device 11, and then the activated waste water and the concentrated oxygen supplied from the oxygen concentrating device 12 are mixed by the mixing device 13. Then, the method returns to the buffer tank 2. The control panel 5 and the dissolved oxygen measuring device 6 were removed, and wastewater pretreatment was performed.

As the active water device 11, a conductive wire in which a copper wire with a diameter of 2 mm is coated on a vinyl chloride pipe with an inner diameter of 65 mm is wound 12 times, and a further space is provided, and further 12 times are wound, for a total of 24 times. It was used. As operating conditions, a voltage of 100 V was constantly applied, and wastewater was supplied to the active water device 11 by the pump 14 at a flow rate of 400 L / min.

As the mixing device 13, an injection nozzle 131 provided with a flow path 131a having an inner diameter of 16 mm was used (FIG. 6). The mixing chamber 132 has a flat shape with a depth of 65 mm, a width of 420 mm, and a height of 670 mm, and has a shape in which a vortex is likely to occur due to the Coanda effect. Further, the injection nozzle 131 is provided so that the injection direction can be adjusted to the left and right, so that right-handed and left-handed vortex flows are alternately formed. From the supply port 134, 90% or more of concentrated oxygen was supplied at a flow rate of 10 ml / min.

With the above apparatus configuration, waste water in the buffer tank 2 was circulated to the waste water pretreatment apparatus 1 in FIG. 1 for 5 minutes. After 5 minutes, the waste water discharged from the mixing device 13 was fully stored in a bucket, and the dissolved oxygen amount (DO) was measured by the electrode method. The measurement results are shown in Table 1. The temperature of the waste water stored in the bucket was 37.8 ° C.

After that, the waste water after the pretreatment was sequentially transferred to the aeration tank 3, and air was continuously supplied to the aeration tank 3 through the air filter 32 and the pump 31 at a flow rate of 6.5 m ³ / min. Next, the wastewater after the aeration treatment was transferred to the precipitation tank 4 and separated into solid content (P) and moisture (W). The separated water (W) was discharged out of the system.

[Example 2]
Instead of the live water device 11 of Example 1, the live water device 11 of another example shown in FIG. That is, the activation of the waste water by the active water device 11 is performed by passing the waste water simultaneously inside the small diameter pipe 115 and between the small diameter pipe 115 and the large diameter pipe 117 and energizing the conductive wire 112 wound around the small diameter pipe 115. The waste water between the inside of the small diameter pipe 115 and between the small diameter pipe 115 and the large diameter pipe 117 is activated at the same time. The operating conditions of the wastewater pretreatment device 1 were the same as in Example 1.

About Example 2, the amount of dissolved oxygen (DO) was measured by the same electrode method as Example 1. The results are shown in Table 1. The temperature of the waste water stored in the bucket was 35.6 ° C.

[Comparative Example 1]
The active water apparatus 11 of Example 1 was excluded and it was set as the comparative example 1. That is, it is the structure which mixes the concentrated oxygen and waste water from the oxygen concentration apparatus 12 by the mixing means 13 of FIG.5 and FIG.6. Other configurations and operating conditions of the apparatus were the same as in Example 1.

For Comparative Example 1, the dissolved oxygen amount (DO) was measured by the same electrode method as in Example 1. The results are shown in Table 1. The temperature of the wastewater stored in the bucket was 35.3 ° C.

[Comparative Example 2]
The active water device 11, the mixing device 13, and the oxygen concentrating device 12 of Example 1 were excluded and used as Comparative Example 2. That is, the air is supplied only in the aeration tank 3. Other configurations and operating conditions of the apparatus were the same as in Example 1.

For Comparative Example 1, the dissolved oxygen amount (DO) was measured by the same electrode method as in Example 1. The results are shown in Table 1. The temperature of the waste water stored in the bucket was 35.0 ° C.

As is clear from Table 1, in Example 1, DO reached 8.5 mg / L in only 5 minutes after the start of circulation. In Example 2, DO exceeded 11.1 and DO reached 11.1 mg / L in only 5 minutes after the start of circulation. On the other hand, it was 7.2 mg / L in Comparative Example 1 and 2.3 mg / L in Comparative Example 2. Since the saturated dissolved oxygen amount of distilled water at 35 ° C. under 1 atm is 7.04 mg / L, according to the present invention, it becomes possible to dissolve high concentration oxygen into waste water in a very short time. I understand that.

In addition, in the aeration treatment and the solid precipitation treatment after the wastewater pretreatment methods of Examples 1 and 2, anaerobic odors (such as hydrogen sulfide) derived from the growth of anaerobic bacteria can be completely eliminated. It was. On the other hand, in the methods of Comparative Examples 1 and 2, the pretreatment for 5 minutes was insufficient and an anaerobic odor became a problem. Moreover, when the activated sludge sedimentation rate (SV30) was measured and calculated, Comparative Example 1 was about 78% and Comparative Example 2 was about 98%, but the wastewater pretreatment methods of Examples 1 and 2 were applied. However, it was able to improve to about 50 to 60%. Thereby, it became possible to reduce the amount of excess sludge withdrawn, and the cost could be reduced by about 20 to 30% compared to the conventional case (Comparative Example 2). The amount of reduction in Comparative Example 1 was about 20%. Furthermore, according to the wastewater pretreatment of Examples 1 and 2, it was possible to achieve a BOD that is lower than the reference value in a very short aeration treatment. As a result, the electricity cost required for the conventional aeration process (Comparative Example 2) could be reduced by about 45 to 50%. The electricity cost reduction of Comparative Example 1 was about 30%.

DESCRIPTION OF SYMBOLS 1 Waste water pretreatment apparatus 11 Active water apparatus 111 Inlet side pipe 112 Conductive wire 113 Water discharge side pipe 114 Power supply unit 115 Small diameter pipe 116 Partition pipe 117 Large diameter pipe 12 Oxygen concentrator 13 Mixing apparatus 131 Injection nozzle 132 Mixing chamber 133 Discharge port 134 Supply port 14 Pump 31 Pump 32 Air filter 4 Sedimentation tank 5 Control panel 6 Dissolved oxygen measuring instrument 61 Probe

Claims (4)

In a wastewater treatment method in which wastewater is ejected to cause cavitation and pretreat the wastewater by its erosion action, and then decompose by aerobic microorganisms in an aeration tank.
The waste water in the pretreatment is characterized by mixing concentrated oxygen while causing cavitation by ejecting the activated waste water after passing through an active water device in which a conductive wire is wound around a pipe capable of passing water. Wastewater pretreatment method. The active water device is formed by winding a conductive wire around a small-diameter pipe that allows waste water to pass through, and is configured in a multiple manner with a small-diameter pipe and a conductive wire inside a large-diameter pipe larger in diameter than the pipe, The waste water in the small-diameter pipe and between the small-diameter pipe and the large-diameter pipe are simultaneously activated by passing waste water through the small-diameter pipe and between the small-diameter pipe and the large-diameter pipe and energizing the conductive wire. Wastewater pretreatment method. An active water device in which a conductive wire is wound around a pipe through which waste water is passed, an oxygen concentrator for supplying concentrated oxygen, activated waste water supplied from the active water device, and an oxygen concentrator supplied from the oxygen concentrator A wastewater pretreatment device comprising a mixing device that mixes the concentrated oxygen while causing cavitation, and a transfer pump that transfers the wastewater to the active water device. The active water device is formed by winding a conductive wire around a small-diameter pipe that allows waste water to pass through, and is configured in a multiple manner with a small-diameter pipe and a conductive wire inside a large-diameter pipe larger in diameter than the pipe, The waste water pretreatment device according to claim 3, wherein waste water is passed through the inside of the small diameter pipe and between the small diameter pipe and the large diameter pipe.

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