JP2002079280A - Wastewater treatment apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a wastewater treatment apparatus capable of shortening a treatment time to suppress running cost low in the treatment of wastewater containing a hardly decomposable substance such as dioxins or the like and capable of being minimized in its volume. SOLUTION: In the wastewater treatment apparatus 1 for oxidizing and decomposing a hardly decomposable substance such as endocrine disruptive substance or the like represented by dioxins, co-PCB and bisphenol A contained in wastewater by using two or more oxidizing agents among ultraviolet rays, ozone, hydrogen peroxide or the like, treatment regions 1A, 1B, 1C and 1D equipped with ultraviolet irradiation means 3 or/and oxidizing agent supply means 4 are provided almost in series over a plurality of stages and waste water 5 can be successively moved from the upstream region to the downstream gions so that the concentration of the hardly decomposable substance is stepwise reduced along the flow direction of the waste water 5 and the treatment regions are partitioned up and down by perforated plates 2a or rectifying plates 2b.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to dioxins contained in leachate of waste incineration ash landfills, smoke incineration effluent of waste incinerators, and environmental hormones represented by co-PCB and bisphenol A. In particular, the present invention relates to a wastewater treatment apparatus that oxidizes and decomposes a hardly decomposable substance by oxidizing and decomposing the hardly decomposable substance using ultraviolet rays and an oxidizing agent such as ozone or hydrogen peroxide.

[0002]

2. Description of the Related Art Hitherto, dioxins represented by 2,3,7,8-TCDD or environmental hormones represented by co-PCB and bisphenol A, which are extremely harmful to humans and organisms in general. Various methods are employed for treating hardly decomposable substances. Most of the harmful substances discharged mainly from waste incinerators are contained in fly ash, but also large amounts are contained in wastewater discharged from the waste incineration facilities. One of these wastewater treatment methods is an ozone / ultraviolet ray combined decomposition method. This dissolves ozone in the wastewater containing the hardly decomposable substance, and irradiates it with ultraviolet light to decompose the dissolved ozone, thereby generating extremely high oxidative hydroxyl radicals. This is a method for decomposing decomposable substances with high efficiency. The hydroxyl radical is extremely reactive and reacts with any oxidizable substances in the wastewater.

[0003] Accordingly, Japanese Patent Application Laid-Open No. 11-335 discloses an ozone / ultraviolet ray combined decomposition method utilizing the above-mentioned hydroxyl radical.
In No. 69, as shown in FIG. 9, sewage containing an organic chlorine compound is introduced from a first treatment step of treating with an ozone-containing gas or an ozone-containing gas and hydrogen peroxide, and then (A) ultraviolet light, ( B) UV and ozone containing gases,
The present invention provides a method for decomposing the organochlorine compound by introducing the compound into a second treatment step of treating with (C) ultraviolet light and hydrogen peroxide or (D) ultraviolet light, an ozone-containing gas and hydrogen peroxide.

In such a method, first, organic substances which easily react with ozone are decomposed and ultraviolet transmittance is improved in a first step, and in a second step, dechlorination reaction by ultraviolet rays, and ozone gas, ultraviolet rays and hydrogen peroxide are used. An oxidative decomposition reaction of an organic chlorine compound is performed by a hydroxyl radical generated as a result of a reaction of any two or more combinations. As a result, the ultraviolet ray transmittance is increased, so that dechlorination and generation of hydroxyl radicals in wastewater are promoted, and decomposition of the organic chlorine compound is efficiently performed. Further, by arranging a plurality of ultraviolet lamps horizontally in the tank as in the invention, it is possible to irradiate ultraviolet rays uniformly without using a long ultraviolet lamp which is expensive.

[0005]

However, in such a conventional technique, turbulence occurs in the treatment tank and the concentration of the hardly decomposable substance is not uniform, so that the concentration of the hardly decomposable substance in the wastewater is surely reduced. In this case, the processing tank itself must be enlarged and the processing time must be long. For this reason, there is a problem that the installation area is large, the cost is high, and the processing efficiency is poor. In order to improve the processing efficiency, it is necessary to increase the ozone dissolving efficiency, so it is necessary to employ a small-diameter pore capable of generating fine bubbles as an air diffuser for blowing the ozone-containing gas. Some wastewater may contain scale components such as calcium, magnesium, and silica, and fine solids, and also has a problem that it is easily clogged.

In order to solve the above-mentioned problems, Japanese Patent Laid-Open Publication No. Sho.
No. 22-22355. According to this invention, as shown in FIG. 10, a processing tower is constituted by stacking a plurality of units 21 each having a mercury lamp 23 and a gas-liquid mixer 24 attached thereto. The mixed wastewater 25 is supplied from the diffuser plate 26, processed while the height of the processing tower is increased, and discharged from the uppermost unit. Since the ozone dissolution efficiency depends on the height of the treatment tower or the treatment time, the dissolution efficiency of ozone is increased by increasing the treatment tower as in the above invention. In addition, in this invention, since the aluminum foil is provided inside each unit 21, ultraviolet energy can be efficiently given to the hardly decomposable substance in the wastewater. Part is improved.

However, in the above invention, each unit 20 is only separated vertically by a gas flow by a gas-liquid mixer 24, and there is a possibility that the unit 20 is circulated in the upper and lower units by a turbulent flow. It is hard to say that it will surely move upward, and it is necessary to increase the residence time to some extent. In addition, dioxins, which are one of the organic chlorine compounds, have dissolution characteristics as shown in FIG. 8, and the lower the concentration, the lower the reaction rate. Therefore, the decomposition rate of each unit must be uniform. Therefore, in order to ensure that the hardly decomposable substances are decomposed near the outlet of the treatment tower when the wastewater flows between the upper and lower parts of the unit as in the above invention, the treatment tower must be enlarged or the treatment time must be longer than necessary. No.

In order to solve the above-mentioned problems, the present invention increases the ozone dissolving efficiency and the transmittance of ultraviolet energy, and performs a process suitable for the decomposition characteristics of the hardly decomposable substance. Provided is a wastewater treatment apparatus capable of decomposing a hardly decomposable substance at a low cost, particularly, a wastewater treatment apparatus which saves space and reduces processing time.

[0009]

SUMMARY OF THE INVENTION In view of the above-mentioned problems, the present invention has proposed a wastewater treatment in accordance with the dissolution characteristics shown in FIG. First, as an invention according to claim 1, a hardly decomposable substance such as dioxins, co-PCB, and environmental hormones represented by bisphenol A contained in wastewater is converted into an oxidizing agent such as ultraviolet light, ozone, or hydrogen peroxide. In a wastewater treatment apparatus that oxidatively decomposes by using any two or more of them, a plurality of treatment sections provided with the ultraviolet irradiation means and / or the oxidant supply means are provided substantially in series and along the flow direction of the wastewater. The drainage is configured to be sequentially movable from the upstream section to the downstream section so that the concentration of the hardly decomposable substance is reduced stepwise.

[0010] In this invention, since the respective treatment areas are surely separated and are of an extrusion flow type in which turbulence of wastewater does not occur, the concentration of the hardly decomposable substance is constant in each treatment area. As shown in FIG. 8, the processing time is given in order from the upstream processing area to ΔT ₁ , ΔT ₂ ..., And the concentration of the hardly decomposable substance is decomposed stepwise as ΔD ₁ , ΔD ₂ . Thereby, the processing time is shortened in the processing tank having the minimum size, and the processing is efficiently performed.

As a specific configuration of the first aspect of the present invention, the second aspect of the invention is characterized in that the processing tank having the plurality of processing areas is vertically long, and the processing areas are vertically arranged by a perforated plate. And a plurality of stages are provided. Further, as another method for separating the processing areas, the invention according to claim 3 is characterized in that the processing tank having the plurality of processing areas is vertically long, and the processing areas are formed in a vertical direction by a straightening plate partially open. It is characterized in that it is arranged in a plurality of stages by being divided vertically.

As described above, by separating the respective treatment areas by the perforated plate or the rectifying plate, when the wastewater flows from the upstream side, it is possible to prevent the wastewater from returning to the upstream side. Rate, and can be decomposed in a small processing tank. In addition, the use of a perforated plate further improves ozone dissolving performance,
Ozone generation power can be reduced. The flow straightening plate bypasses the flow in the reaction tank by alternately installing the openings,
The mixing state in the reaction tank can be approximated to an extrusion flow. Perforated plates may be used for drainage containing less scale components and fine solid components since there is no fear of clogging, and rectifier plates may be used for drainage containing a large amount of these components. In addition, by making the processing tank vertically long, it is possible to easily approach the extrusion flow as described above, and it is possible to increase the dissolution rate of the oxidizing agent, thereby enabling an apparatus with higher processing efficiency. . The flow of the drainage may be configured to move downward from above, or may be introduced from below and moved upward.

Further, by providing the oxidizing agent supply means in all the areas in the processing tank as described in claim 4, generation of hydroxy radicals in each processing area is promoted, and more efficient. Decomposition processing can be performed well. Also,
According to a fifth aspect of the present invention, of the sections in the processing tank, the last section has a larger volume and the residence time is longer than the other sections. This is because, as described above, the decomposition rate of dioxins decreases in a quadratic curve with respect to the treatment time, so that the lower the concentration of dioxins, the lower the decomposition rate. For this reason, by extending the residence time by increasing the treatment area, it is possible to almost completely decompose and remove dioxins.

As still another method, the invention according to claim 6 is characterized in that the supply amount of the oxidizing agent in the last section in the processing tank is made larger than that in the other sections. Even in such a method, decomposition is promoted even when the concentration of dioxins is low, and the processing time can be shortened. Further, the oxidant supply amount increasing means according to claim 6 is a hydrogen peroxide supply means provided separately from the ozone supply means. As a result, the decomposition efficiency can be improved at low cost even in a treatment area having a low decomposition rate. Furthermore, as described in claim 8, a stirrer or a liquid circulation pump is provided at least in the last section in the processing tank, and the inside of the section is configured to be capable of mixing and stirring, so that the contact area between the oxidizing agent and the drainage is provided. And decomposition is promoted.

Since ozone used as an oxidizing agent is relatively expensive, an ozone circulating line is provided in the treatment tank to effectively utilize the ozone as described above. Ozone consumption can be reduced, running costs can be reduced, and exhaust gas throughput can be reduced. In the case of a drainage property containing a large amount of scale components, it is preferable that the diffuser tube in the treatment tank is of a coarse foam type so that the diffuser tube is not blocked.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be illustratively described in detail below with reference to the drawings. However, the dimensions, materials, shapes, relative arrangements, and the like of the components described in this embodiment are not intended to limit the scope of the invention thereto, unless otherwise specified, and are merely illustrative examples. Not just. FIG. 1 is a schematic configuration diagram of a wastewater treatment device according to a first embodiment of the present invention, and FIGS. 2 to 7 are schematic configuration diagrams of a wastewater treatment device showing another embodiment corresponding to FIG.
The hardly decomposable substances contained in the wastewater to be treated are hardly decomposable substances such as dioxins, co-PCB, and environmental hormones represented by bisphenol A. In the present embodiment,
In particular, it aims at treating wastewater having a relatively high concentration of dioxins. In FIG. 1, 1 is a vertically long processing tank, 2a is a perforated plate for vertically separating the processing tank 1, 3 is an ultraviolet lamp,
9 is an ozone generator and 10 is an exhaust gas treatment means.

As shown in FIG. 1, the processing tank 1 is divided into processing sections 1A, 1B, 1C and 1D in the depth direction by a perforated plate 2a. The perforated plate has a large number of holes so that gas-liquid circulation can be sufficiently performed. The shape and size of the holes can be arbitrarily set, and may be the same or different. In addition, the number of treatment zones partitioned by the perforated plate is appropriately selected according to the concentration and type of dioxins in the wastewater, and is set to be the most efficient number. An ultraviolet lamp is horizontally disposed in the processing area, and a plurality of ultraviolet lamps can be installed.

An air diffuser 4 is provided in the lowermost processing zone 1A, and ozone 6 generated by an ozone generator 9 is ejected into waste water. The diffuser tube 4 uses a large-bubble diffuser tube having a large hole diameter that is difficult to close. Thereby, even when the scale component or the fine solid is contained in the waste water, there is almost no problem of air diffuser blockage and the cost is low. The treatment area 1A is provided with a wastewater inflow portion into which wastewater containing dioxins discharged from a waste incineration facility or the like is introduced. It should be noted that the treatment area 1A may be configured such that only the ozone is supplied without installing an ultraviolet lamp according to the properties of the wastewater. This is because when a large amount of ultraviolet absorbing substances such as liquid chelates and hydroxy radical consuming substances such as organic substances and bicarbonate ions coexist in the wastewater, the decomposition of these substances should be reduced as much as possible before the combined decomposition with ozone and ultraviolet rays. This is for improving the transmittance of ultraviolet rays to improve the decomposition efficiency. Processing area 1A
And the distribution of the reaction time in the other treatment zones 1B, 1C and 1D are adjusted in accordance with the drainage properties and the target decomposition rate at the installation position of the partition perforated plate.

First, the processing flow of the processing apparatus will be described. First, the wastewater 5 introduced into the processing area 1A is mixed and stirred with ozone 6 generated by an ozone generator 9, and here, organic substances contained in the wastewater are mixed. Is decomposed while reacting with the unsaturated bond portion of ozone, and moves to the upper processing section 1B through the perforated plate 2a. In the treatment zone 1B, a dechlorination reaction of an organic chlorine compound is performed by ultraviolet rays, and an oxidative decomposition reaction of dioxins is performed by hydroxy radicals generated by a reaction between ozone gas and ultraviolet rays. Here, since the ultraviolet absorbing material and the hydroxyl radical consuming material are reduced in the processing zone 1B, the transmittance of ultraviolet light is high, and the presence of a large amount of hydroxyl radicals enables efficient decomposition treatment.

The wastewater that has stayed in the treatment area 1B for a certain period of time
Furthermore, the dioxins are guided to the upper processing section 1C through the perforated plate 2a, and are decomposed by the same reaction as in the processing section 1B, and then guided to the upper processing section 1D. As described above, the wastewater moves to the upper layer by the extrusion flow, thereby repeatedly performing the oxidative decomposition reaction of the hydroxyl radical and the like, and the concentration of dioxins in the wastewater is reduced stepwise. Uppermost processing zone 1 of such processing tank 1
In D, the treated water whose dioxin concentration has been reduced to a predetermined value or less is discharged out of the system or sent to another wastewater treatment system. In addition, the exhaust gas 8 containing ozone generated here is sent to an exhaust gas treatment unit that is treated by activated carbon decomposition or catalytic decomposition. Since the ultraviolet lamp 3 is also provided in the uppermost treatment zone 1D, the amount of ozone exhausted in the exhaust gas is minimized, and the consumption of the activated carbon and the catalyst can be minimized. .

As described above, in this treatment apparatus, by making the flow of the waste water an extrusion flow type, the concentration of dioxins can be reduced step by step, and the treatment tank is not made unnecessarily large. By making it vertically long, the ozone dissolution rate can be improved and the installation area can be reduced, so that a processing apparatus having high rationality in terms of cost and processing efficiency can be realized.

FIG. 2 is a schematic configuration diagram of a wastewater treatment apparatus according to a second embodiment of the present invention. This is another embodiment of the first embodiment shown in FIG. 1, in which each processing area is separated by using a rectifying plate 2b instead of the perforated plate 2a. Since the openings of the current plate 2b are alternately installed, the upward flow is diverted, the mixing effect is large, and the inside of the treatment area is stirred and mixed, so that the contact between the ozone bubbles and the wastewater is increased, and the oxidation is performed. Decomposition is promoted. In addition, since the opening is larger than the perforated plate, there is no danger of clogging by a solid matter. Therefore, it is preferable to use such an apparatus for treating wastewater containing a large amount of such components. In this embodiment, the ozone 6 is supplied not only to the lowermost processing area 1A but also to each processing area 1B,
Since it is also supplied to 1C and 1D, the generation amount of hydroxy radicals due to the reduction of ozone 6 is prevented, and a sufficient amount of hydroxy radicals is generated in each processing zone. Therefore, when the consumption of ozone is increased and there is a problem in terms of cost, it is preferable to return the exhaust gas 8b to the ozone diffuser separately from the exhaust gas 8a to be sent to the exhaust gas treatment device 10, and to circulate the exhaust gas.

In the third embodiment shown in FIG. 3, the processing zone 1D located above the processing tank 1 is set to be larger than the lower zone, that is, the interval between the perforated plates is increased. The residence time of the wastewater introduced into the area 1D is extended. This is because the decomposition rate of dioxins decreases as the concentration decreases, as shown in FIG.
In particular, since the decomposition rate is extremely low in the final stage of the processing step, it is necessary to take a sufficient reaction time in the uppermost processing section 1D of the processing tank, which is the final processing step. This makes it possible to minimize the concentration of dioxins in the wastewater.

Next, a fourth embodiment in which the stirring and mixing power in the upper processing zone is increased to promote the decomposition of dioxins will be described with reference to FIG. In this embodiment, the diameter of the lowermost processing zone 1A and the diameter of the processing zone having the perforated plate 2a located above are changed, and the diameter of the upper processing zone is set small. This is because, at the same ozone supply amount, the gas superficial velocity in the upper processing area is increased, so that the stirring power in the processing area is increased and the ozone dissolving performance is further improved.

In a method different from the third and fourth embodiments,
FIGS. 5, 6, and 7 show a method of increasing the processing efficiency in the upper processing area where the concentration of dioxins is low. In the fifth embodiment shown in FIG. 5, a hydrogen peroxide supply unit 12 is provided, and hydrogen peroxide 13 is supplied to the upper processing sections 1B, 1C, and 1D, so that the oxidative decomposition in the upper processing section with low decomposition efficiency is performed. Promote. At this time, the additional oxidizing agent may be ozone, but by using hydrogen peroxide, the cost can be reduced. The sixth and seventh embodiments shown in FIGS. 6 and 7 are processing apparatuses aiming to increase the stirring and mixing power in the processing area. In the sixth embodiment, the stirrers 14 are respectively provided in the upper processing area. It is effective to promote oxidative decomposition of dioxins by providing and forcibly stirring. In the seventh embodiment, the wastewater circulates in each treatment area,
A liquid circulation pump 15 is provided to stir and mix the wastewater. By these methods, the processing time can be shortened even in the upper processing area where the decomposition efficiency is low, and the volume of the processing tank can be minimized.

[0026]

As described above, according to the present invention, the treatment is performed while the wastewater is pushed out and moved in a flow manner, whereby the reaction efficiency is improved, the volume of the treatment tank can be minimized, and the oxidizing agent can be suppressed. Minimizes the amount of equipment consumed, and reduces installation and running costs.
Further, the processing time can be shortened. Further, by providing a plurality of treatment zones as compared with the case where treatment is performed in one tank, the decomposition rate of the hardly decomposable substance is dramatically increased, and the hardly decomposable substance can be reliably decomposed and removed. Further, by dividing the vertically long processing tank up and down by a perforated plate or a flow straightening plate, the dissolving efficiency of the oxidizing agent is increased and the push-flow type processing tank can be easily formed. Furthermore, by increasing the supply of oxidizing agent to the downstream treatment area, increasing the superficial tower speed, and installing a stirrer and a liquid circulation pump, it is possible to improve the efficiency of treating hardly decomposable substances in the low decomposition rate area. This makes it possible to treat the hardly decomposable substance, especially the dioxins in accordance with the decomposition characteristics.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a wastewater treatment device according to a first embodiment of the present invention.

FIG. 2 is a schematic configuration diagram of a wastewater treatment device according to a second embodiment of the present invention.

FIG. 3 is a schematic configuration diagram of a wastewater treatment device according to a third embodiment of the present invention.

FIG. 4 is a schematic configuration diagram of a wastewater treatment device according to a fourth embodiment of the present invention.

FIG. 5 is a schematic configuration diagram of a wastewater treatment device according to a fifth embodiment of the present invention.

FIG. 6 is a schematic configuration diagram of a wastewater treatment device according to a sixth embodiment of the present invention.

FIG. 7 is a schematic configuration diagram of a wastewater treatment device according to a seventh embodiment of the present invention.

FIG. 8 is a decomposition characteristic diagram showing the concentration of dioxins with respect to the processing time.

FIG. 9 is a schematic configuration diagram of a wastewater treatment apparatus according to the related art.

FIG. 10 is a schematic configuration diagram of a wastewater treatment device according to a conventional technique.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Processing tank 1A, 1B, 1C, 1D Processing area 2a Perforated plate 2b Rectifier plate 3 UV lamp 4 Ozone diffuser 11 Rectifier plate 12 Hydrogen peroxide supply device 14 Stirrer 15 Liquid circulation pump

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C07C 39/16 C07C 39/16 C07D 319/24 C07D 319/24 (72) Inventor Yoichi Kawaguchi Naka-ku, Yokohama-shi 12 at Nishikicho Mitsubishi Heavy Industries, Ltd.Yokohama Works (72) Inventor Tomotsu Egusa 12 at Nishikicho, Naka-ku, Yokohama-shi Mitsubishi Heavy Industries, Ltd.Yokohama Works (72) 1 Mitsubishi Heavy Industries, Ltd. Yokohama Laboratory (72) Inventor Noriaki Senba 1-8-1, Koura, Kanazawa-ku, Yokohama-shi 1 Mitsubishi Heavy Industries, Ltd. Yokohama Laboratory (72) Inventor Masamichi Asano 1-8-8, Koura, Kanazawa-ku, Yokohama-shi 1 Mitsubishi Heavy Industries, Ltd. Yokohama Research Laboratory F-term (reference) 4D037 AA13 AB14 AB16 BA18 BB04 BB09 CA11 CA12 4D050 AA13 AB15 AB19 BB02 B B09 BC09 BD02 BD03 BD06 4H006 AA05 AC13 AC26 BA95 BD81 BE31 BE32 EA22 FC52 FE13

Claims (10)

[Claims] 1. Dioxins contained in wastewater, co
A wastewater treatment apparatus for oxidatively decomposing hard-to-decompose substances such as environmental hormones represented by PCB and bisphenol A using two or more of oxidizing agents such as ultraviolet rays, ozone, and hydrogen peroxide; A plurality of treatment sections provided with irradiation means and / or oxidant supply means are provided in a plurality of stages substantially in series, and the wastewater is reduced so that the concentration of the hardly decomposable substance is reduced stepwise along the flow direction of the wastewater. A wastewater treatment apparatus characterized in that it is configured to be sequentially movable from an upstream area to a downstream area. 2. The processing tank having a plurality of processing zones is vertically long, and the processing zones are vertically divided by a perforated plate and arranged in a plurality of stages. Wastewater treatment equipment. 3. The processing tank having a plurality of processing zones is vertically long, and the processing zones are vertically arranged vertically in a plurality of stages by a straightening plate partially open. The wastewater treatment device according to claim 1. 4. The wastewater treatment apparatus according to claim 2, wherein said oxidizing agent supply means is provided in all areas in said treatment tank. 5. The wastewater treatment apparatus according to claim 2, wherein, among the sections in the treatment tank, the last section has a larger volume and the residence time is longer than other sections. 6. The wastewater treatment apparatus according to claim 2, wherein the supply amount of the oxidizing agent in the last section in the treatment tank is larger than that in the other sections. 7. A wastewater treatment apparatus according to claim 6, wherein said oxidant supply amount increasing means is a hydrogen peroxide supply means provided separately from said ozone supply means. 8. The apparatus according to claim 2, wherein a stirrer or a liquid circulation pump is provided at least in the last section of the processing tank, and the inside of the section can be mixed and stirred.
The wastewater treatment device as described in the above. 9. The wastewater treatment apparatus according to claim 2, wherein a circulation line for waste ozone is provided in the treatment tank, and the waste ozone is used effectively. 10. In the case of a drainage property containing a large amount of scale components, etc., the air diffuser in the treatment tank is made to have a rough foam type so as to eliminate the blockage of the air diffuser. The wastewater treatment device as described in the above.