WO2021015238A1

WO2021015238A1 - Wastewater treatment device

Info

Publication number: WO2021015238A1
Application number: PCT/JP2020/028441
Authority: WO
Inventors: 甲子男岡田
Original assignee: アリアケジャパン株式会社
Priority date: 2019-07-25
Filing date: 2020-07-22
Publication date: 2021-01-28
Also published as: JPWO2021015238A1

Abstract

[Problem] To provide a wastewater treatment device which suppresses a high increase in initial costs. [Solution] The present invention comprises: a plurality of raw water tanks to which raw water to be subjected to a wastewater treatment is supplied and which separate the raw water into a water component and an oil component and discharge the separated components; and an organic substance removing part which is supplied with the water component and removes an organic substance contained in the water component, wherein the plurality of raw water tanks have different timings at which the raw water is supplied thereto, and have different timings at which the raw water is separated into the water component and the oil component and the separated components are discharged.

Description

Wastewater treatment equipment

The present invention relates to a wastewater treatment device that treats wastewater containing organic substances and suspended substances.

In recent years, the regulation standards for final effluent have tended to become stricter year by year, especially in Europe, which is already stricter than in Japan. Under these circumstances, there is a demand for wastewater treatment equipment that can meet strict standards.

As a conventional wastewater treatment device, for example, the raw water of factory wastewater is treated, and the oil content is removed in the oil-water separation step including the oil-water separation tank, the raw water tank, and the pressurized flotation tank, and the oil-water separation step. It has an aeration step including a predetermined number of aeration tanks for removing organic substances from raw water, and a precipitation step for precipitating and removing particles in the raw water from which the organic substances have been removed, and the raw water from which the particles have been removed in the precipitation step is Some are discharged to the outside as discharged water.

In this wastewater treatment equipment, the amount of factory wastewater is increasing. Therefore, the raw water tank in the oil-water separation process has a large storage capacity. For example, in the raw water tank, the ground is dug to a depth of 2 to 3 m, the wall surface is hardened with concrete, and a large amount of raw water is stored.

JP-A-2010-162518 JP-A-2015-160172

However, according to the conventional wastewater treatment equipment, since a raw water tank for storing a large amount of raw water is required, it is necessary to acquire a land of a predetermined area and large-scale construction work requiring a large number of workers. There is a problem that the initial cost is soaring.

Therefore, the present invention is to provide a wastewater treatment apparatus capable of suppressing an increase in initial cost.

In the present invention, a plurality of raw water tanks to which raw water to be treated as wastewater is supplied and the raw water is separated into a water component and an oil component and discharged, and an organic substance contained in the water component is removed by supplying the water component. The plurality of raw water tanks are provided with an organic matter removing unit, and the timing at which the raw water is supplied is different from each other, and the timing at which the raw water is separated into the water component and the oil component and discharged is mutual. To provide different wastewater treatment equipment.

According to the wastewater treatment apparatus of the present invention, it is possible to suppress an increase in the initial cost.

It is a schematic flow chart which shows the wastewater treatment apparatus which concerns on embodiment of this invention. It is a schematic structural sectional view of the raw water tank 21 of the wastewater treatment apparatus which concerns on embodiment of this invention, and the periphery thereof. It is explanatory drawing of the treatment timing of the raw water tank 21, the raw water tank 22, and the raw water tank 23 of the wastewater treatment apparatus which concerns on embodiment of this invention. It is a schematic flow chart which shows the wastewater treatment apparatus which concerns on a comparative example.

[Embodiment]
FIG. 1 is a schematic flow chart showing a wastewater treatment apparatus according to an embodiment of the present invention. FIG. 2 is a schematic sectional view of the raw water tank 21 and its surroundings when the raw water of the wastewater treatment apparatus according to the embodiment of the present invention is accumulated and microbubbles are generated. FIG. 3 is an explanatory diagram of the treatment timing of the raw water tank 21, the raw water tank 22, and the raw water tank 23 of the wastewater treatment device according to the embodiment of the present invention.

As shown in FIG. 1, the wastewater treatment apparatus 1 according to the embodiment of the present invention includes a raw water tank 21, a raw water tank 22, a raw water tank 23 in an oil-water separation step, a dephosphorization tank 31 and a denitrification tank 32 in an anaerobic step, and aeration. The first aeration tank 33 and the second aeration tank 34 of the step, and the first settling tank 41 and the second settling tank 42 of the settling step are provided.

The wastewater treatment device 1 further includes the piping indicated by the arrow that guides the factory wastewater to the raw water tank 21, the raw water tank 22, and the raw water tank 23, and the raw water tank 21, the raw water tank 22, the raw water tank 23, the aeration tank 31, and the aeration tank 31. Tank 31 and denitrification tank 32, denitrification tank 32 and first aeration tank 33, first aeration tank 33 and second aeration tank 34, second aeration tank 34 and first settling tank 41, first settling tank 41 and second settling It is provided with a pipe indicated by an arrow to which each of the tanks 42 is connected, and a pipe indicated by an arrow for discharging water from the second settling tank 42 to the outside as discharged water 50. The raw water tank 21, the raw water tank 22, and the raw water tank 23 are piped in parallel, and the pipes indicated by arrows are connected to the factory and the dephosphorization tank 31, respectively.

Further, the pipes indicated by arrows are provided which are connected to the first settling tank 41 and the dephosphorization tank 31, the second settling tank 42 and the dephosphorization tank 31, and the second aeration tank 34 and the denitrification tank 32, respectively.

The pipe that guides the factory wastewater to the raw water tank 21, the raw water tank 22, and the raw water tank 23 is equipped with a valve for injecting the factory wastewater into a predetermined raw water tank at the end of one pipe from the factory. Further, the tip of the valve is provided with pipes connected to the raw water tank 21, the raw water tank 22, and the raw water tank 23, respectively. The raw water tank 21, the raw water tank 22, and the raw water tank 23 are connected to the oil storage tank 24 for storing the separated oil by a pipe indicated by an arrow.

FIG. 2 shows the raw water tank 21 as a representative from the raw water tank 21, the raw water tank 22, and the raw water tank 23. The raw water tank 21, the raw water tank 22, and the raw water tank 23 are made of stainless steel. Further, the raw water tank 21, the raw water tank 22, and the raw water tank 23 have a substantially cylindrical shape as a whole, and the bottom surface portion of the substantially cylindrical shape is provided with a conical inclination that descends toward the center.

The members of the raw water tank 21, the raw water tank 22, and the raw water tank 23 are not limited to those made of stainless steel as described above. It may be. Unlike the conventional large raw water tank, the concrete wall is formed by digging the ground, and the concrete wall is not held on the ground, but the wall of the raw water tank member can be made into an independent raw water tank that can be held by the member itself. All you need is.

Then, as shown in FIG. 2, on the upper side surface of the raw water tank 21, for example, there is an inlet 21a for the raw water 10 which is factory wastewater, and at the bottom of the raw water tank 21, there is an outlet 21b for the raw water 10. The piping of the extraction port 21b includes a detection unit 21c mainly composed of a sight glass and a transparency sensor, and a switching valve 21d. The switching valve 21d is connected to a pipe connecting the dephosphorization tank 31 and the oil storage tank 24.

Further, the micro-bubble generator 21f arranged at the center of the bottom of the raw water tank 21, the air compressor 21e arranged outside the raw water tank 21, the micro-bubble generator 21f and the air compressor 21e are connected. It is provided with a micro-bubble generator 21h composed of a pipe 21g to which compressed air is sent out. For example, when the "YJ nozzle" manufactured by Enviro Vision Co., Ltd. is used as the micro valve generator 21f, the structure is a straight pipe structure, so that micro / nano bubbles are used under conditions of low voltage loss, high efficiency, and no clogging. Can occur.

The raw water tank 22 and the raw water tank 23 are also the same as the raw water tank 21 in FIG. In addition, in the pipe connecting the raw water tank 21, the raw water tank 22, the raw water tank 23 and the dephosphorization tank 31, three pipes drawn from the three raw water tanks are merged into one in the middle and connected to the dephosphorization tank 31. It has been. Alternatively, three pipes may be connected to the dephosphorization tank 31 in parallel.

The dephosphorization tank 31 and the denitrification tank 32 are provided with a stirring device for stirring the treated water in the tank. Further, the first aeration tank 33 and the second aeration tank 34 are provided with an aeration device for blowing compressed air.

The operation of the wastewater treatment device 1 according to the present embodiment described above will be described below.

(Oil-water separation process) FIG. 3 shows the processing timing of the oil-water separation process. First, according to a predetermined treatment timing, the injection destination of the raw water 10 which is the factory wastewater is the raw water tank 21, and the raw water is poured only into the raw water tank 21. Raw water 10 is poured into the raw water tank 21, microbubbles are generated, and air bubbles of several microns to several hundreds of mikun size are passed through the accumulated raw water 10 to promote oil-water separation.

Air is supplied to the microbubble generator 21f through the pipe 21g, and the microbubbles are discharged from the microbubble generator 21f into the raw water 10 as fine bubbles.

The microbubble generator 21f is arranged at the center of the bottom of the raw water tank 21, but as the microbubbles are generated, the raw water 10 above the microbubble generator 21f of the raw water tank 21 rises together with the microbubbles. By doing so, the raw water 10 accumulated in the raw water tank 21 is convected, and the microbubbles are passed through the entire raw water 10 collected in the raw water tank 21. Microbubbles are likely to adhere to the oil, and oil with microbubbles is likely to float.

Then, when a predetermined amount of raw water 10 is accumulated in the raw water tank 21, the injection of the raw water 10 into the raw water tank 21 is stopped by setting the injection destination of the raw water 10 to the raw water tank 22 by controlling the valve. The generation of microbubbles is stopped shortly after the injection of raw water 10 is stopped.

The raw water tank 21 in which a predetermined amount of raw water 10 is accumulated, the injection of the raw water 10 is stopped, and the generation of microbubbles is stopped waits for the microbubbles in the raw water 10 to rise, and then the raw water 10 at the bottom of the raw water tank 21 The raw water 10 is extracted from the extraction port 21b.

At this time, the raw water 10 accumulated in the raw water tank 21 is separated into oil and water. First, the water layer formed by separating the oil content of the raw water 10 which is the lower layer is extracted from the raw water tank 21 and dephosphorized. Transferred to 31. The raw water 10 passing through the pipe of the extraction port 21b passes through the sight glass, and the water quality is detected by the detection unit 21c by the transparency sensor. Eventually, when the detection unit 21c detects that the quality of the raw water 10 passing through the extraction port pipe has become an oil layer, the switching valve 21d moves the transfer destination of the raw water 10 passing through the extraction port 21b pipe from the dephosphorization tank 31 to oil. Instead of the storage tank 24, the oil layer of the raw water 10 which is the upper layer is transferred to the oil storage tank 24.

In this way, all the raw water 10 accumulated in the raw water tank 21 is transferred, and the raw water tank 21 is emptied before the raw water 10 is injected. If there is a residue in the raw water tank 21 that cannot be transferred by natural drainage, it is cleaned as necessary.

On the other hand, when a predetermined amount of raw water 10 is accumulated in the raw water tank 21, the injection destination of the raw water 10 is the raw water tank 22. Similar to the raw water tank 21, microbubbles are generated in the raw water tank 22, and air microbubbles are passed through the accumulated raw water 10.

Then, when a predetermined amount of raw water 10 is accumulated in the raw water tank 22, the injection of the raw water into the raw water tank 22 is stopped by controlling the valve so that the raw water 10 is injected into the raw water tank 23, and microbubbles are generated after a while. Is stopped. After that, the raw water 10 collected in the raw water tank 22 is separately extracted from the raw water 10 outlet 21b at the bottom of the raw water tank 22 into an aqueous layer and an oil layer, and transferred to the dephosphorization tank 31 and the oil storage tank 24. Will be done.

Then, after a predetermined amount of raw water 10 is accumulated in the raw water tank 22, the raw water tank 23, which is the injection destination of the raw water 10, is also the same as the raw water tank 21 and the raw water tank 22. Then, the injection destination of the raw water 10 is again set to the raw water tank 21, and this is repeated.

FIG. 3 shows the treatment timing of each of the raw water tanks 21, the raw water tank 22, and the raw water tank 23 described so far, and the horizontal direction represents the time. Each raw water tank has "water injection", "oil-water separation", "extraction" of water layer and oil layer, and "empty state" waiting for the next water injection.

In each of the raw water tanks 21 to 23, the "injection" timing in which the raw water 10 is supplied is different from each other because the raw water tanks to be sequentially injected are changed. As a result, the timing of "oil-water separation" into the water layer and the oil layer and the timing of "extraction" of the raw water 10 and discharge are different between the raw water tanks 21 to 23. Further, when the raw water tanks 21 to 23 to which the raw water 10 is injected make a round, the raw water 10 is again injected into the raw water tanks 21 to 23 in the original order. Then, the treatments at different timings are repeated in each raw water tank, and the continuous raw water injection and the subsequent treatment are performed for the plurality of raw water tanks as a whole.

(Aerobic step) The aqueous layer of the raw water 10 from which the oil layer has been removed in the oil-water separation step is transferred to the dephosphorization tank 31 in the anaerobic step. Further, the sedimented sludge is returned from the first sedimentation tank 41 and the second sedimentation tank 42 to the dephosphorization tank 31. Then, phosphorus is removed by using a dephosphorization tank 31 containing activated sludge in an anaerobic state, which is only agitated but not aerated.

In an anaerobic state, polyphosphoric acid-accumulating bacteria contained in activated sludge release phosphoric acid as polyphosphoric acid in the process of taking in organic substances and accumulating substances stored in the body, and in an aerobic state, releasing more phosphoric acid than released. Take as polyphosphoric acid. Therefore, after being transferred from the anaerobic dephosphorization tank 31 or the like to the aerobic first aeration tank 33 and the second aeration tank 34, they settle in the first settling tank 41 and the second settling tank 42 in the settling step. Phosphorus in the wastewater is reduced by the cycle of returning the sludge to the dephosphorization tank 31. In addition, the phosphoric acid concentrated in the polyphosphate-accumulating bacteria is discharged to the outside of the system as excess sludge.

In addition to the biochemical method, which can use existing treatment facilities and is non-chemical injection, the coagulation sedimentation method, which has extremely high phosphorus removal ability and can be operated flexibly, the amount of sludge generated is small, and the dehydration rate is fast. A KHDS method with a pH of 8 to 9 or a bio-chemical simultaneous treatment method in which an existing treatment facility can be used and the phosphorus removing ability is stable can also be used as the dephosphorization step.

The treated water treated in the dephosphorization tank 31 is transferred to the denitrification tank 32. Further, a part of the treated water from the second aeration tank 34 is returned to the denitrification tank 32. Then, in the denitrification tank 32 containing the activated sludge in an anaerobic state in which aeration is performed only by stirring, nitrogen is decomposed by the denitrifying bacteria reducing nitrite and nitric acid with an organic carbon hydrogen serving such as methanol. To. Then, nitrogen is released to the atmosphere as nitrogen gas.

In addition to denitrifying bacteria, sulfur-oxidizing bacteria that take oxygen from nitrates to breathe, oxidize sulfur, and reduce nitrate nitrogen to nitrogen gas can also be used in the denitrification step.

(Aeration step) The treated water that has passed through the anaerobic step is transferred to the first aeration tank 33 in the aeration step. In the aeration tank 33, inflow water and activated sludge are mixed, air (oxygen) is blown into the aeration tank 33, and bacteria purify the organic matter by biodegradation and adsorption. It also removes nitrogen gas adhering to activated sludge. Then, the treated water in the first aeration tank 33 is transferred to the second aeration tank 34. In the second aeration tank 34, the same treatment as in the first aeration tank 33 is performed again, a part of the liquid in the second aeration tank 34 is returned to the denitrification tank 32, and the rest is transferred to the first settling tank 41. ..

(Settlement step) The treated water transferred from the second aeration tank 34 to the first settling tank 41 in the settling step is separated into activated sludge and treated water. Excess sludge is discarded from the separated activated sludge, and the rest is returned to the dephosphorization tank 31. On the other hand, the treated water from which the activated sludge has been separated is transferred to the ferric sedimentation tank 42 by adding polyiron (polyferric sulfate) as a coagulant. In the second settling tank 42, phosphorus is settled as iron phosphate due to the addition of polyiron. Then, the sediment is returned to the dephosphorization tank 31, and the rest is discharged to the outside as the final discharged water 50.

As the flocculant, in addition to polyiron (polyferric sulfate), aluminum salts such as ferric chloride and PAC (polyaluminum chloride), slaked lime, calcium chloride and the like may be used.

FIG. 4 is a schematic flow chart showing a wastewater treatment apparatus according to a comparative example. This comparative example has been described as a conventional wastewater treatment device, and belongs to the standard method among various activated sludge methods such as the standard method, the dispensing method, the complete mixing method, the reaeration method, and the oxide groove method, and wastewater is discharged. This will be described as the processing device 2. The wastewater treatment device 2 includes an oil-water separation tank 25, a raw water tank 26, a pressurized flotation tank 27 in the oil-water separation process, a first aeration tank 35, a second aeration tank 36, and a third aeration tank 37 in the aeration process, and settles. A settling tank 45 for the process is provided.

The wastewater treatment device 2 further includes a pipe indicated by an arrow for guiding the factory wastewater to the oil-water separation tank 25, an oil-water separation tank 25 and a raw water tank 26, a raw water tank 26 and a pressurized levitation tank 27, and a pressure levitation tank 27 and a second. (1) Aeration tank 35, 1st aeration tank 35 and 2nd aeration tank 36, 2nd aeration tank 36 and 3rd aeration tank 37, 3rd aeration tank 37 and settling tank 45 are connected by the pipes indicated by arrows, and A pipe indicated by an arrow is provided for discharging the discharged water 55 from the settling tank 45 to the outside.

In the wastewater treatment device 2, the oil-water separation tank 25 has a plurality of basins arranged in series, and has a connecting path for injecting raw water below each basin into a downstream basin. The oil-water separation tank 25 is a concrete-walled tank, which is manufactured by digging the ground. The raw water, which is the factory wastewater, is injected into the oil-water separation tank 25 and then discharged from the oil-water separation tank 25 via a plurality of basins of the oil-water separation tank 25. When the raw water of the upstream basin is transferred to the downstream basin by the connecting path, the raw water below the upstream basin is transferred, so that the oil having a small specific gravity is not transferred and stays in the upstream basin. Then, the treated water transferred from the plurality of boxes and discharged from the oil-water separation tank 25 is free of oil.

The raw water tank 26 is a water tank that adjusts the amount of water, digs the ground to a depth of 2 to 3 m, hardens the wall surface with concrete, and stores the raw water treated in the oil-water separation tank 25. The raw water tank 26 includes an air supply device that sends air from the bottom of the water tank to the treated water of the raw water. Then, air is sent from the bottom of the water tank to the treated water of the raw water to generate convection in the treated water of the raw water, thereby suppressing the sedimentation of sludge to the bottom of the water tank and the decay of sludge. For this purpose, a predetermined water level is required, and the raw water tank 26 is always in a state where treated water of raw water is accumulated.

In addition, the pressurized flotation tank 27 is a device having a function of applying pressure to dissolve air in water and releasing it to atmospheric pressure, and fine bubbles generated by this function are attached to a suspended substance and placed on the water surface. It is equipped with a schema device that discharges the suspended material that has surfaced. By these, the suspended substance is removed.

Further, as the first aeration tank 35, the second aeration tank 36, and the third aeration tank 37, substantially the same ones as the first aeration tank 33 and the second aeration tank 34 in FIG. 1 may be used. The explanation in is omitted.

Further, as the settling tank 45, substantially the same as the first settling tank 41 and the second settling tank 42 in FIG. 1 may be used, and thus the description thereof is omitted here.

Table 1 shows the emission standards for sewage and river discharges in Japan and river discharges in Belgium. BOD (Biochemical Oxygen Demand) is a biochemical oxygen demand, which is the amount of oxygen dissolved in water consumed when an organic substance is decomposed by a microorganism. COD (Chemical Oxygen Demand) is the amount of chemical oxygen demand, which is the amount of oxygen used to combine organic matter and oxygen with chemicals. For the measurement of COD, the manganese method using potassium permanganate as an oxidizing agent is used in Japan, and the chromium method using potassium dichromate as an oxidizing agent is used in Belgium. TN is the total amount of nitrogen and T-P is the total amount of phosphorus.

Table 2 shows the analysis results of the raw water tank, the pressurized flotation tank, and the discharged water according to the comparative example.

Table 3 shows the raw water tank I (without micro-bubble treatment), raw water tank II (with micro-bubble treatment), dephosphorization tank, denitrification tank, first aeration tank, second aeration tank, and discharged water according to the examples of the present invention. It is the analysis result of.

As can be seen from the comparison between the discharge standards in Table 1 and the analysis results of the discharged water in the comparative example in Table 2, the wastewater treatment method in the comparative example satisfies the sewage discharge standards in Japan, but the river discharge standards in Japan and It does not meet the Belgian river discharge standards.

On the other hand, as can be seen from the collation between the discharge standard of Table 1 and the analysis result of the discharged water of the example of the present invention in Table 3, the wastewater treatment apparatus of the example of the present invention has the Japanese sewage discharge standard. Moreover, it meets not only the river discharge standards but also the Belgian river discharge standards, which are strict worldwide.

(Effect of embodiment)
According to the above-described embodiment, the following effects can be obtained.

(1) In place of the conventional large raw water tank, the raw water tank divided into multiple parts can be used to cope with the increase in the amount of factory wastewater, and each raw water tank becomes smaller. For this reason, it is possible to reduce the restrictions on the land according to the shape and area of the large raw water tank, eliminate the need for large-scale construction that requires a large number of workers, and suppress the increase in initial cost.

Since the raw water tank is divided into multiple parts, each raw water tank can be arranged in any suitable manner. For example, by arranging a plurality of small tanks in a row, it can be accommodated in an elongated installation space. Further, it is not always necessary to arrange them collectively in one place. For example, it is possible to utilize a plurality of installation spaces as the raw water tanks are arranged for each process in which wastewater is generated in the factory. Furthermore, because of this degree of freedom, when the amount of drainage from the factory increases and it becomes necessary to increase the capacity of the raw water tank, instead of creating a new raw water tank with a large capacity, add a raw water tank. It can also be handled by adding it.

Since each raw water tank is small, the required strength of the raw water tank wall when raw water is accumulated is small. As a result, a commercially available or in-house resin or metal tank can be selected as the raw water tank. Then, the work of digging the ground and solidifying the wall surface with concrete can be eliminated. Further, the degree of freedom in selecting the raw water tank is increased, and a suitable shape can be selected from various commercially available or in-house manufactured tanks. For example, by selecting a tank with a high height, it is possible to accommodate the same capacity in a narrow installation space.

(2) Inject the raw water from the factory wastewater into the specified raw water tank, and after the specified amount of raw water has accumulated, remove all the accumulated raw water to make it empty or near empty, and then the raw water is poured. Since it is a method of waiting for the water to be drained, it is possible to suppress an increase in BOD and COD in the raw water tank. As a result, the processing load in the post-process of the oil-water separation step can be reduced, and the regulation standard for the final discharged water can be satisfied.

As a result of the research by the inventors, it was found that the factory wastewater having a BOD of about 1000 to 1500 ppm has a BOD of 3000 to 5000 ppm in the raw water tank of the factory septic tank. In the conventional oil-water separation tank and raw water tank such as the comparative example, since the water is supplied to the tank and discharged from the tank, the factory wastewater is accumulated in the tank for a long period of time. In such a state, factory wastewater containing a large amount of microbial nutrients such as fats and oils, proteins, and starch is considered to be decomposed in the oil-water separation tank and the raw water tank.

On the other hand, in the present invention, it is possible to suppress the progress of corrosion by treating all the factory wastewater in the tank within a predetermined time to make it empty or near empty without always storing raw water. it can. Therefore, as shown in the analysis result in the raw water tank according to the comparative example in Table 2 and the analysis result in the raw water tank I (without microbubble treatment) in the example of the present invention in Table 3, the treatment is performed in the subsequent step of the oil-water separation step. The initial values such as BOD and COD of raw water to be used can be significantly reduced.

As a result, the BOD and COD of the discharged water can be significantly reduced even if the step of passing the aeration tank three times in the post-process of the oil-water separation step in the comparative example is changed to the step of passing the aeration tank twice in the embodiment of the present invention. ing. That is, since the increase in BOD and COD in the oil-water separation step can be suppressed, the BOD and COD of the discharged water can be reduced even if the treatment equipment in the post-process of the oil-water separation step is omitted.

Since the divided raw water tank 21, raw water tank 22, and raw water tank 23 are piped in parallel, the raw water route in the oil-water separation step can be made shorter than that of the conventional large undivided water tank, and the raw water route can be shortened. It is possible to prevent dead water areas from occurring. In addition, since the raw water outlet is located at the bottom of the raw water tank, all the raw water can be extracted and emptied. Further, since the bottom of the raw water tank has a conical shape, the accuracy of extracting all the accumulated raw water can be improved as long as the bottom of the raw water tank has a flat shape.

Furthermore, raw water from factory wastewater is injected into a predetermined raw water tank, and after a predetermined amount of raw water has accumulated, all the accumulated raw water is extracted to make it empty or near empty, and then raw water is poured. Because it is a method of waiting for the water, the raw water that reaches the predetermined water level required for the convection of the treated water of the raw water becomes unnecessary. Therefore, it is possible to reduce the storage capacity required for the raw water tank and suppress the increase in the initial cost.

(3) Multiple raw water tanks are installed in parallel, and oil-water separation processing is also performed in parallel. As a result, the amount of oil-water separation treatment per hour increases, and the time for oil-water separation treatment becomes shorter. During that time, the amount of raw water discharged from the factory can be reduced, the minimum capacity required for storage can be reduced, and the capacity of the raw water tank can be reduced.

Furthermore, the raw water from the factory effluent is sequentially changed to the raw water tank at the injection destination, and the raw water from the factory effluent is injected into a predetermined raw water tank for processing. As a result, the oil-water separation treatment of the raw water from the factory wastewater is performed so that the timings are different from each other among the plurality of raw water tanks, and the oil-water separation treatment can be continuously performed for the entire multiple raw water tanks, making it a practical device. it can. In addition, since the raw water collected in the divided small raw water tanks is treated each time, the raw water from the factory wastewater can be treated in a short time.

(4) Separation of fats and oils can be promoted by passing air microbubbles through the raw water collected in the raw water tank. In the comparative example, the oil-water separation step provided with the oil-water separation tank, the raw water tank, and the pressurized flotation tank. In the embodiment of the present invention, only the raw water tank can be used. Therefore, the space of the process equipment can be saved.

In addition, a pressurized flotation tank is a facility that removes floating suspended matter by adhering fine bubbles generated by applying pressure to dissolve air in water and releasing it to atmospheric pressure. By omitting the above, it is possible to reduce the initial cost, the power cost for operating the device, and the running cost by eliminating the need for a chemical such as a coagulant used for pressurized flotation.

In addition, as shown in the analysis results of the raw water tank I (without microbubble treatment) and the raw water tank II (with microbubble treatment) of the examples of the present invention in Table 3, there is also an effect of preventing putrefaction by anaerobic bacteria, and oil water. It is possible to improve the quality of the treated water transferred to the subsequent step of the separation step.

Since the raw water tank is divided and small, the water level of the raw water injected into the raw water tank rises quickly, and the raw water injected into the raw water tank can be treated with microbubbles from an early timing. Further, since the raw water tank has a substantially cylindrical shape, the raw water in the raw water tank is easily convected, and microbubbles can be efficiently distributed throughout the raw water.

(5) Anoxic anaerobic steps for dephosphorization and denitrification are set before the aeration step in an aerobic state, and sedimented sludge containing phosphorus compounds in the final step of sedimentation is returned to the dephosphorization tank. However, by adopting a process flow in which a part of the aeration process is returned to the denitrification tank, TN and TP, which have been problems in the conventional method, can be reduced to low values. Then, the discharged water can be made to satisfy the Belgian river discharge standard.

Although the embodiments of the present invention have been described above, the embodiments described above do not limit the invention according to the claims. It should also be noted that not all combinations of features described in the embodiments are essential to the means for solving the problems of the invention.

Further, the present invention can be modified and implemented without departing from the spirit of the present invention. For example, in the above embodiment, it has been described that three raw water tanks having a substantially cylindrical shape are provided, but the raw water tank may be not limited to a substantially cylindrical shape but may have a substantially rectangular parallelepiped shape, and the number of raw water tanks may be two or more. .. As the capacity and quantity of raw water tanks according to the amount of wastewater from the factory, it is sufficient to install a suitable number of raw water tanks with specifications suitable for the installation location.

Further, in the above embodiment, the raw water is sequentially injected into a plurality of raw water tanks to make the raw water tanks empty or nearly empty in each cycle, but it is not necessarily empty or close to empty. It does not have to be in the state. Even if it is not empty or close to empty, there is time for separation processing without water injection, which reduces the retention of raw water in the tank for a long period of time and increases BOD and COD in the oil-water separation process. Can be suppressed.

Further, in the above embodiment, it has been described that the oil-water separation treatment is performed only in the raw water tank that generates microbubbles, but a tank other than the raw water tank may be provided, or a treatment other than the oil-water separation treatment may be added. Good. Further, it does not necessarily have to generate microbubbles.

Although the process using the activated sludge method has been described as a post-process of the oil-water separation step, the post-process of the oil-water separation step may be another biological treatment or another treatment such as a physicochemical treatment such as an ozone treatment method. .. Since it is possible to suppress an increase in BOD and COD in the tank in the oil-water separation process, the effect of lowering the BOD and COD of the discharged water and the post-process of the oil-water separation process can be combined with the post-process of various oil-water separation processes. Even if the equipment is lightened, the effect of satisfying the regulation standard for the final discharged water can be obtained.

1 Wastewater treatment device 10 Raw water 21 Raw water tank 21a Raw water inlet 21b Raw water outlet 21c Raw water tank 21 detector 21d Raw water tank 21 valve 21e Air compressor 21f Micro bubble generator 21g Piping 21h Micro bubble generator of raw water tank 21 22 Raw water tank 23 Raw water tank 24 Oil storage tank 31 Dephosphorization tank 32 Denitrification tank 33 First aeration tank 34 Second aeration tank 41 First settling tank 42 Second settling tank 2 Waste treatment Equipment 25 Oil-water separation tank 26 Raw water tank 27 Pressurized floating tank 35 1st aeration tank 36 2nd aeration tank 37 3rd aeration tank 45 Settlement tank 50 Discharge water 55 Discharge water

Claims

A plurality of raw water tanks to which raw water to be treated as wastewater is supplied and the raw water is separated into a water component and an oil component and discharged.
It is provided with an organic substance removing unit for supplying the water component and removing the organic substance contained in the water component.
In the plurality of raw water tanks, the timing at which the raw water is supplied is different from each other, and the timing at which the raw water is separated into the water component and the oil component and discharged is different from each other.
The wastewater treatment apparatus according to claim 1, wherein each of the plurality of raw water tanks has a micro-bubble generator that separates the raw water into the water component and the oil component.
The wastewater treatment device according to claim 2, wherein the microbubble generator has a straight pipe structure.
The wastewater treatment device according to claim 2 or 3, wherein the plurality of raw water tanks have a substantially cylindrical shape as a whole.
The wastewater treatment apparatus according to claim 1 or 2, wherein the plurality of raw water tanks are in an empty state or a state close to empty after the raw water is discharged.
The wastewater treatment device according to claim 5, wherein the plurality of raw water tanks have a raw water outlet at the bottom.
The wastewater treatment device according to claim 1, wherein the plurality of raw water tanks are made of synthetic resin or metal.
The wastewater treatment device according to claim 1, wherein the organic matter removing unit includes a dephosphorization tank, a denitrification tank, and an aeration tank.
The plurality of raw water tanks are connected to a discharge unit that discharges discharged water via a sedimentation tank that removes sludge from the treated water from which organic matter has been removed by the organic matter removing unit and the organic matter removing unit. Wastewater treatment equipment described in.