JP2013220387A - Method and apparatus for treating wastewater - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method and apparatus for treating waste water which give a high throughput to address wastewater containing volatile organic compounds and organic matter at high concentrations.SOLUTION: Since ozone treatment and activated sludge treatment are applied again to treated water subjected once to ozone treatment and activated sludge treatment, throughput can be increased by using expensive ozone efficiently, so that wastewater containing dispersed solid components including a coating material at high concentration can be treated at a low cost.

Description

  The present invention relates to a method and apparatus for treating wastewater containing volatile organic compounds and organic substances.

  As is well known, industrial wastewater (waste liquid) discharged from automobile painting equipment contains various pigments, organic resins, cross-linking agents, volatile substances, surfactants, etc., solid components, readily decomposable components, hardly degradable Consists of components, volatile components, water and the like. An apparatus and a method for treating such waste water are disclosed in Patent Document 1, for example.

JP 2007-29825 A

  In the invention described in Patent Document 1, when the raw water has a high concentration, that is, when the raw water contains a large amount of organic matter, it becomes difficult to obtain the primary treated water having the required water quality due to the lack of the coagulation treatment ability. Further, in the electrolytic treatment, since the wastewater is electrolyzed by energizing between the electrodes arranged in the water tank, there is a possibility that clogging occurs between the electrodes when the wastewater contains a large amount of resin component. Furthermore, when the raw water contains volatile organic compounds (hereinafter referred to as VOC), the volatilized VOC may contaminate the environment.

  Then, this invention is made | formed in view of the said situation, and it is made as a subject to provide the wastewater treatment method and apparatus provided with the high processing capacity corresponding to the waste_water | drain containing a volatile organic compound and organic substance with high concentration. It is a thing.

  In order to solve the above-mentioned problems, a wastewater treatment method of the present invention is a method for treating wastewater containing a volatile organic compound and an organic substance, and a first step of removing separated solid components while ozone treatment of raw water is performed. A second step of treating the primary treated water obtained by the first step by a coagulation sedimentation method, a third step of treating the secondary treated water obtained by the second step by an activated sludge method, A wastewater treatment method comprising: a fourth step of treating the tertiary treated water obtained in the third step with ozone; and a fifth step of treating the fourth treated water obtained in the fourth step by an activated sludge method. And collecting the volatile organic compound contained in the exhaust gas discharged from each step and reprocessing in the first step or the third step.

  In order to solve the above-described problems, a wastewater treatment apparatus of the present invention is a device for treating wastewater containing a volatile organic compound and an organic substance, and includes a first ozone reaction tank to which raw water is supplied, A first ozone treatment device for adding ozone to raw water in an ozone reaction tank, a sludge separation device for removing separated solid components contained in primary treated water treated by the first ozone treatment device, and the primary treatment A treated water circulation device for circulating water between the first ozone reaction tank and the sludge separation device; and a coagulation sedimentation tank to which primary treated water treated by the first ozone treatment device and the sludge separation device is supplied. A coagulation sedimentation apparatus that coagulates and precipitates the primary treated water in the coagulation sedimentation tank, and a first biological treatment tank that is supplied with the secondary treated water treated by the coagulation sedimentation apparatus. Living A first biological treatment device for treating the secondary treated water in the treatment tank with activated sludge; and a second ozone reaction tank to which the tertiary treated water treated by the first biological treatment device is supplied. A second ozone treatment device for adding ozone to the tertiary treatment water in the reaction tank; and a second biological treatment tank to which the quaternary treatment water treated by the second ozone treatment device is supplied. A wastewater treatment apparatus including a second biological treatment apparatus that treats quaternary treated water in a treatment tank with activated sludge, and collects volatile organic compounds contained in exhaust discharged in the process of treating the wastewater. Including a collecting device.

  ADVANTAGE OF THE INVENTION According to this invention, the waste water treatment method and apparatus provided with the high processing capability for respond | corresponding to the waste_water | drain containing a volatile organic compound and organic substance with high concentration can be provided.

It is a schematic diagram for demonstrating the structure of this embodiment. It is a figure for demonstrating the effect | action of this embodiment.

  An embodiment of the present invention will be described with reference to the accompanying drawings. In this embodiment, for example, it is discharged from a painting facility and contains various pigments, organic resins, cross-linking agents, volatile substances, surfactants, etc., and includes solid components, easily decomposable components, hardly decomposable components, volatilization. A method and apparatus 1 for treating waste water (raw water) composed of components, water and the like will be described.

  FIG. 1 schematically shows the configuration of a wastewater treatment apparatus 1 of the present embodiment. As shown in this figure, the waste water treatment device 1 includes a first ozone treatment device 2, a sludge separation device 3, a coagulation sedimentation device 4, a first biological treatment device 5, a second ozone treatment device 6, and a second biological treatment. Including device 7

  The first ozone treatment device 2 has a first ozone reaction tank 8 to which raw water is supplied. The raw water in the first ozone reaction tank 8 is subjected to ozone treatment by adding ozone (ozone gas) supplied from the ozone generator 9. The primary treated water that has been subjected to ozone treatment by the first ozone treatment device 2 can have a property that promotes treatment by the activated sludge method, that is, treatment in the first biological treatment device 5. Specifically, by adding ozone, surfactants, crosslinking agents, etc. in raw water are destroyed and sludge (solid components) such as pigments, dyes, organic resins, etc. floats or settles and is separated. . The ozone generator 9 may be a known device that generates ozone gas using, for example, a photochemical reaction, an electrolytic reaction, a discharge reaction, a radiation reaction, or the like.

  The primary treated water treated by the first ozone treatment device 2 is sent to the sludge separation device 3 by the pump 10. The sludge separation device 3 removes the separated sludge contained in the primary treated water treated by the first ozone treatment device 2. In the present embodiment, the sludge separation device 3 can be applied as it is, for example, an existing facility of floating separation type. Further, the sludge collected by the sludge separator 3 is dehydrated by the dehydrator 11 and then carried out by, for example, a conveyor. In the present embodiment, the sludge separation device 3 and the first ozone reaction tank 8 are communicated with each other by the treated water circulation path 12 (treated water circulation apparatus), and the sludge separation apparatus 3 and the first ozone reaction tank are communicated with the treated water circulation path 12. The primary treated water can be circulated between the two and treated (process by the first step). In addition, this embodiment can arrange | position the valve | bulb for switching the supply destination of the primary treated water which passed the sludge separation apparatus 3 to the 1st ozone reaction tank 8 and the coagulation sedimentation tank 13.

  The coagulation sedimentation device 4 has a coagulation sedimentation tank 13 to which the primary treated water treated by the sludge separation device 3 is supplied. A flocculant is added to the primary treated water in the coagulation sedimentation tank 13. Thereby, the organic substance with high aggregation separability contained in the primary treated water in the aggregation sedimentation tank 13 can be precipitated and removed (treatment by the second step). In this embodiment, the existing equipment can be applied to the coagulation sedimentation apparatus 4 as it is. In addition, the sludge collected by the coagulation sedimentation device 4 is dehydrated by the dehydration device 14 and then carried out by, for example, a conveyor.

  The first biological treatment device 5 has a first biological treatment tank 15 to which secondary treated water treated by the coagulation sedimentation device 4 is supplied. The secondary treated water in the first biological treatment tank 15 is activated sludge treatment, that is, easily decomposable components are decomposed by activated sludge (treatment in the third step). The first biological treatment apparatus 5 has a blower 17 for supplying air to the first biological treatment tank 15 via the supply path 16. The air supplied by the blower 17 is released as bubbles from the bottom of the first biological treatment tank 15 into the secondary treatment water in the first biological treatment tank 15. Thereby, the living thing in activated sludge is activated and processing capacity can be improved. An oxygen generator may be provided instead of the blower 17 so that oxygen is supplied to the organisms in the activated sludge in the first biological treatment tank 15.

  The tertiary treated water treated by the first biological treatment apparatus 5 is freed from solid matter (activated sludge) by a submerged film disposed in the first biological treatment tank 15, and the second ozone reaction tank 19 by the pump 18. Water is sent to The tertiary treated water in the second ozone reaction tank 19 is subjected to ozone treatment (re-ozone treatment) by adding ozone (ozone gas) supplied from the ozone generator 9 (treatment by the fourth step). The quaternary treated water that has been subjected to ozone treatment by the second ozone treatment device 6 can obtain a property that promotes treatment by the activated sludge method, that is, treatment in the second biological treatment device 7. The solid matter removed by the submerged film in the first biological treatment tank 15 is dehydrated by the dehydrator 25 and then carried out by, for example, a conveyor. The second ozone reaction tank 19 can be the same type as the first ozone reaction tank 8.

  The quaternary treated water treated by the second ozone treatment device 6 is sent to the water storage tank 21 by the pump 20, and further the quaternary treated water in the water storage tank 21 is sent to the second biological treatment tank 23. The quaternary treated water in the second biological treatment tank 23 is activated sludge treatment (reactivated sludge treatment), that is, easily decomposable components are decomposed by activated sludge (treatment in the fifth step). Air is supplied from the blower 17 through the supply path 24 to the quaternary treated water in the second biological treatment tank 23. The air supplied by the blower 17 is released as bubbles from the bottom of the second biological treatment tank 23 to the quaternary treated water in the second biological treatment tank 23. As described above, an oxygen generator may be provided in place of the blower 17 so that oxygen is supplied to the organisms in the activated sludge in the second biological treatment tank 23.

  The treated water treated by the second biological treatment device 7 is subjected to removal of solid matter (activated sludge) by the submerged membrane disposed in the second biological treatment tank 23, and then the purified water by the pump 22 such as a river. It can be discharged into the environment or used in other equipment. The solid matter removed by the submerged membrane in the second biological treatment tank 23 is dehydrated by the dehydrator 25 and then carried out by, for example, a conveyor.

  As shown in FIG. 1, the wastewater treatment apparatus 1 includes a VOC collection device 26 that collects VOC (volatile organic compound) generated through the above-described treatment in water. In the present embodiment, VOCs discharged from the sludge separation device 3, the coagulation sedimentation tank 13, the first biological treatment tank 15, the water storage tank 21, and the second biological treatment tank 23 are collected by the VOC collection device 26. The treated water containing VOC collected by the VOC collecting device 26 is sent to the first ozone reaction tank 8 or the first biological treatment tank 15 to decompose the organic components. Moreover, a part of the treated water (purified water) treated by the second biological treatment device 7 is used as the water for recovering the volatile organic compounds in the VOC collection device 26, and this treated water (purified water) is Then, the water is fed to the VOC collection device 26 via the supply path 27.

  The raw water whose water pollution index is shown in FIG. 2 is sequentially processed by the above-described waste water treatment apparatus 1, that is, the first process, the second process, the third process, the fourth process, and the fifth process, and the first process. Biochemistry of each treated water in primary treated water after treatment, tertiary treated water after treatment in the third step, quaternary treated water after treatment in the fourth step, and treated water (purified water) after treatment in the fifth step The chemical oxygen demand (BOD), chemical oxygen demand (COD) (chemical oxygen demand), and suspended substance (SS) are measured.

Here, the biochemical oxygen demand BOD was measured based on the JIS K 0102-21. JIS K 0102-32.3: 1998 diaphragm electrode method. The chemical oxygen demand COD was measured based on JIS K 0102-17.:1998 titration method. Furthermore, the suspended solid SS was measured based on JIS K 0102-14.1: 1998 filtration weight method. In addition, referring to FIG. 2, the water pollution index of raw water is as shown below.
(Raw water)
BOD: 50,000 to 90,000 [mg / L]
COD: 37,000-60,000 [mg / L]
SS: 4,850 to 37,500 [mg / L]

Referring to FIG. 2, the water pollution index of the primary treated water that has been subjected to the ozone treatment in the first step is as shown below.
(Primary treated water)
BOD: 19,000-35,000 [mg / L]
COD: 14,000-21,000 [mg / L]
SS: ~ 42,000 [mg / L]

In addition, referring to FIG. 2, the water pollution index of the tertiary treated water that has been subjected to the activated sludge treatment in the third step through the first and second steps is as shown below.
(Tertially treated water)
BOD: 1.2 to 6.0 [mg / L]
COD: 140 to 190 [mg / L]
SS: ≒ 0

Referring to FIG. 2, the water pollution index of the quaternary treated water that has been subjected to the ozone treatment (re-ozone treatment) in the fourth step through the first to third steps is as follows.
(Fourth treated water)
BOD: 4.8-24 [mg / L]
COD: 4.3-30 [mg / L]
SS: ≒ 0

Further, referring to FIG. 2, the water pollution index of treated water (purified water) subjected to activated sludge treatment (reactivated sludge treatment) in the fifth step through the first to fourth steps is as shown below.
(Purified water)
BOD: 0.6 to 3.6 [mg / L]
COD: 25 to 33 [mg / L]
SS: ≒ 0

  As can be seen from the above measurement results, the removal rate of biochemical oxygen demand BOD, chemical oxygen demand COD, and suspended solid SS could be 99% or more. In addition, the chemical oxygen demand COD of tertiary treated water treated by activated sludge in the third step is 140 to 190 [mg / L], whereas ozone treated (re-ozone treatment) in the fourth step is four. As can be seen from the chemical oxygen demand COD of the secondary treated water being 4.3 to 30 [mg / L], the hardly decomposable components that could not be decomposed by the activated sludge treatment in the third step were It could be decomposed by ozone treatment (re-ozone treatment) in four steps.

This embodiment has the following effects.
According to this embodiment, since ozone treatment and activated sludge treatment are performed again on treated water that has been subjected to ozone treatment and activated sludge treatment, the treatment capacity is increased by efficiently using expensive ozone. High concentration drainage (waste liquid) containing solid components such as paint in a dispersed state can be treated at low cost.

  Moreover, since the primary treated water treated by the first ozone treatment device 2 was circulated between the sludge separation device 3 and the first ozone reaction tank 8 by the treated water circulation path 12 (treated water circulation device), from the coating facility Contains various pigments, dyes, organic resins, crosslinking agents, organic solvents, surfactants, oils and fats, and other inorganic and organic components such as discharged wastewater, solid components, easily decomposable components, hardly decomposable components Alternatively, high-concentration raw water containing a hydrophobic organic substance, a hydrophilic organic substance or the like can be efficiently separated into a solid component and a liquid. Further, the coagulation and precipitation treatment is facilitated by the decomposition of the surfactant and the like by the ozone treatment. In addition, it contains dyes, organic resins, cross-linking agents, organic solvents, surfactants, oils and fats, and other inorganic and organic components, solid components, easily decomposable components, hardly decomposable components, or hydrophobic organic substances, hydrophilic organic substances Since these components are destroyed by the strong oxidizing action of ozone to lower the molecular weight, the activated sludge treatment in the first biological treatment apparatus 5 can be promoted.

  Furthermore, the VOC (volatile organic compound) generated by each treatment is collected in water by the VOC collection device 26, and the treated water containing VOC collected by the VOC collection device 26 is the first ozone treatment device 2. Or since an organic component is decomposed | disassembled by the 1st biological treatment apparatus 5, it can prevent that VOC is discharge | released in the environment (atmosphere). Moreover, since the water used with the VOC collection device 26 uses the water processed with the 2nd biological treatment apparatus 7, it does not require a fresh water newly.

In addition, embodiment is not limited above, For example, it can comprise as follows.
In the first step, when it is determined that a large amount of suspended matter SS that could not be removed by the sludge separation device 3 is present in the primary treated water, the wastewater treatment device 1 is set so that the primary treated water is coagulated and settled. Can be configured.
As for VOC (volatile organic compound), when it is determined that there are a large amount of components having low solubility in water, the VOC collection device 26 can be changed to a VOC removal device.
Further, since the VOC is forcibly removed, the sludge separation device 3 can be aerated.

DESCRIPTION OF SYMBOLS 1 Waste water treatment apparatus, 2 1st ozone treatment apparatus, 3 Sludge separation apparatus, 4 Coagulation sedimentation apparatus, 5 1st biological treatment apparatus, 6 2nd ozone treatment apparatus, 7 2nd biological treatment apparatus, 8 1st ozone reaction tank, 12 treated water circulation path (treated water circulating device), 15 first biological treatment tank, 19 second ozone reaction tank, 23 second biological treatment tank, 26 VOC collection device

Claims (3)

In a method for treating wastewater containing volatile organic compounds and organic matter,
A first step of removing the separated solid components while treating raw water with ozone;
A second step of treating the primary treated water obtained in the first step by a coagulation sedimentation method;
A third step of treating the secondary treated water obtained in the second step by an activated sludge method;
A fourth step of ozone treatment of the tertiary treated water obtained in the third step;
A fifth step of treating the quaternary treated water obtained in the fourth step by an activated sludge method;
A wastewater treatment method comprising:
A wastewater treatment method comprising a step of collecting a volatile organic compound contained in exhaust gas discharged from each step and reprocessing in the first step or the third step. In an apparatus for treating wastewater containing volatile organic compounds and organic matter,
A first ozone treatment device having a first ozone reaction tank to which raw water is supplied, and adding ozone to the raw water in the first ozone reaction tank;
A sludge separation device for removing the separated solid component contained in the primary treated water treated by the first ozone treatment device;
A treated water circulation device for circulating the primary treated water between the first ozone reaction tank and the sludge separation device;
A coagulation sedimentation apparatus having a coagulation sedimentation tank to which primary treated water treated by the first ozone treatment apparatus and the sludge separation apparatus is supplied, and coagulating sedimentation treatment of the primary treatment water in the coagulation sedimentation tank;
A first biological treatment apparatus having a first biological treatment tank to which secondary treated water treated by the coagulation sedimentation apparatus is supplied, and treating the secondary treated water in the first biological treatment tank with activated sludge;
A second ozone treatment tank having a second ozone reaction tank to which the tertiary treatment water treated by the first biological treatment apparatus is supplied, and adding ozone to the tertiary treatment water in the second ozone reaction tank;
A second biological treatment apparatus having a second biological treatment tank to which the quaternary treatment water treated by the second ozone treatment apparatus is supplied, and for treating the quaternary treatment water in the second biological treatment tank with activated sludge; ,
Wastewater treatment equipment including
A wastewater treatment apparatus comprising a collection device for collecting a volatile organic compound contained in exhaust gas discharged in the process of treating the wastewater. The wastewater treatment apparatus according to claim 2, further comprising a supply path for supplying the volatile organic compound collected by the collection apparatus to the first ozone treatment apparatus or the first biological treatment apparatus.

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