WO2010109556A1

WO2010109556A1 - Water treatment method and water treatment system

Info

Publication number: WO2010109556A1
Application number: PCT/JP2009/005279
Authority: WO
Inventors: 比留間敏和; 木山龍均
Original assignee: 株式会社アサカ理研
Priority date: 2009-03-24
Filing date: 2009-10-09
Publication date: 2010-09-30
Also published as: JPWO2010109838A1; WO2010109838A1; SG174377A1; CN102361826B; MY155401A; KR20120002584A; KR101426925B1; CN102361826A; JP4786771B2

Abstract

Provided are a water treatment method and a water treatment system with which COD (Chemical Oxygen Demand) can be eliminated at a high elimination rate. It is possible to eliminate COD at a high elimination rate by means of a structure wherein a chlorine oxidizer is added to water that contains organic matter and that is to be treated by COD elimination; the water is then passed through a manganese filter material(62); and the organic matter is decomposed by catalytic oxidation. It is also possible to use a structure whereby after the decomposition by catalytic oxidation in this case, the water is passed through an adsorption device (7) containing active carbon (71). It is further possible to use a structure whereby a coagulant is added before the water is passed through the manganese filter material(62) and the suspended matter is removed by a filtration device (4).

Description

Water treatment method and water treatment system

The present invention relates to a water treatment method and a water treatment system, and more particularly to a water treatment method and a water treatment system for removing COD (Chemical Oxygen Demand).

COD generally used as an indicator of water quality is the amount of oxygen required to oxidize the amount of oxidizable substances in water. COD is also used as a reference value for waste water discharged from, for example, factories. From the viewpoint of environmental protection, total COD regulations are becoming stricter year by year.

As a conventional typical method for removing COD, for example, a flocculant such as aluminum sulfate, PAC, ferric chloride, ferric sulfate, polyferric sulfate or the like is added, and a filtration device or a sedimentation separation device is used. There is a coagulation separation method to separate. However, the coagulation separation method has a low COD removal rate, and it is difficult to meet the COD total amount regulations in recent years.

As another method for removing COD, there is a biological removal method in a biological reaction tank. However, this method has a problem that the removal rate of soluble hardly decomposable organic substances is low.

As still another method for removing COD, for example, there is a method of performing adsorption removal using activated carbon after performing the above-described aggregation separation and biological removal. However, activated carbon may be difficult to be adsorbed depending on the type of organic substance (for example, a substance having a strong polarity, a substance having a large molecular structure, etc.), and the removal rate is not sufficient.

That is, the COD removal rate is not sufficient with the conventional method, and it is becoming difficult to meet the recent COD emission regulations.

JP 2003-053350 A

That is, the problems to be solved by the present invention include the problems described above as an example. Accordingly, an object of the present invention is to provide a water treatment method and a water treatment system capable of solving the conventional problems and removing COD with a high removal rate.

The water treatment method and the water treatment system according to the present invention have been realized based on a novel concept that has not been achieved in the past, in which COD is removed by using a manganese-based filter material, as a result of earnest research by the present inventors. Is. Manganese-based filter media have been developed as filter media for removing manganese from water containing manganese as an impurity. However, as a result of diligent research without being bound by the prior art, the present inventors have realized a novel water treatment method and water treatment system in which COD is removed using a manganese-based filter medium. .

That is, the water treatment method of the present invention is a water treatment method for removing COD (Chemical Oxygen Demand), adding a chlorine-based oxidizing agent to water to be treated containing organic matter, passing the water through a manganese-based filter medium, and organic matter. COD is removed by catalytic oxidative decomposition.

As the chlorine-based oxidizing agent, a general chlorine-based oxidizing agent can be used. Among them, chlorine dioxide (ClO ₂ ) is most effective for removing COD.

Further, the manganese-based filter medium is preferably a filter medium in which a manganese dioxide (MnO ₂ ) crystal is supported on a particulate base material and has the following characteristics.

The water treatment method may further have a step of adsorbing and removing organic matter by passing the water to be treated after the catalytic oxidative decomposition through activated carbon, for example, when the COD regulation value is low (that is, when regulation is severe). Further, for example, when the SS concentration is high, a step of adding a flocculant to the water to be treated before passing through the manganese-based filter medium and separating and removing suspended components can be further included.

The water treatment system of the present invention is a water treatment system for removing COD (Chemical Oxygen Demand), wherein means for adding a chlorine-based oxidant to water to be treated containing organic matter, and the chlorine-based oxidant includes And a filtering device including a manganese-based filtering material that allows the added water to be treated to flow therethrough.

The water treatment system may further include an adsorption device including activated carbon that passes the water to be treated after passing through the manganese-based filter material when, for example, the COD regulation value is low (that is, when regulation is severe). . Further, for example, when the SS concentration is high, before passing through the manganese-based filter material, means for adding a flocculant to the water to be treated and other filtration for passing the water to be treated to which the flocculant is added And a device.

According to the present invention, by adding a chlorinated oxidant to water to be treated containing an organic substance and passing it through a manganese-based filter medium, the organic substance can be catalytically oxidatively decomposed to remove COD. Furthermore, by passing water through activated carbon after catalytic oxidative decomposition, it is possible to adsorb the organic components subjected to catalytic oxidative decomposition and reliably remove COD. Further, by removing suspended substances by the coagulation separation method before passing the water through the manganese-based filter medium, the contact oxidizing power of the manganese-based filter medium can be prevented from being lowered and COD can be reliably removed. It becomes possible.

It is a figure which shows the main structures of the water treatment system by preferable embodiment of this invention.

Hereinafter, a water treatment method and a water treatment system according to preferred embodiments of the present invention will be described with reference to the accompanying drawings. However, the technical scope of the present invention is not construed as being limited by the embodiments described below.

FIG. 1 shows an example of a water treatment system 1 according to a preferred embodiment of the present invention. As shown in FIG. 1, a water treatment system 1 according to the present embodiment includes a raw water tank 2 that stores organic matter-containing water (raw water) that is water to be treated, means 3 for adding a flocculant to the water to be treated, First filtration device 4 for separating suspended substances from treated water, means 5 for supplying a chlorine-based oxidizing agent to treated water, and manganese for catalytic oxidative decomposition of organic substances contained in treated water A second filtering device 6 having a system filter medium and an adsorption device 7 having activated carbon for adsorbing organic substances contained in the water to be treated are provided.

Reference numerals

21, 22, and 23 in the figure are pumps for transferring the water to be treated between the apparatuses.

Furthermore, the water treatment system 1 according to the present embodiment includes a tank 8 for storing water to be treated after being treated by the second filtration device 6. A part of the water to be treated stored in the tank 8 is a first liquid that has temporarily stopped water flow as a cleaning liquid for cleaning (so-called backwashing) the filtering material of the first and second filtering devices 4 and 6 And the wastewater after washing | cleaning supplied to the 2nd filtration apparatuses 4 and 6 is a structure returned to an upstream installation as original raw water. The return destination of the washing wastewater may be the raw water tank 2.

The first filtering device 4 has a main role of filtering and separating suspended substances in the water to be treated to which the flocculant is added by the flocculant adding means 3. As a preferred example, the first filtration device 4 has a filtration layer through which water flows in the order of anthracite 41, sand (filter material) 42, and filtration gravel 43. The water flow method may be a gravity method or a pressurization method using a pump or the like. As the anthracite 41, for example, an effective diameter of 1.2 mm and a uniformity coefficient of 1.4 or less can be used. As the sand (filter material) 42, for example, an effective diameter of 0.6 mm and a uniformity coefficient of 1.4 or less can be used. However, the average particle diameter and the uniformity coefficient are not limited to those described above. The filter gravel 43 serves as a support layer for the anthracite 41 and the sand (filter material) 42, and has a role for performing water flow and backwashing equally. However, the filtration gravel 43 can be replaced by a support member having a plurality of water holes or slits.

The second filtering device 6 has a main role of catalytically oxidizing and decomposing organic matter in the water to be treated to which the chlorinated oxidant is added by the oxidant adding means 5. As a preferred example, the second filtration device 6 has a filtration layer through which water flows in the order of anthracite 61, manganese-based filter material 62, and filtration gravel 63. The water flow method may be a gravity method or a pressurization method using a pump or the like. As the anthracite 61, for example, an effective diameter of 0.8 mm and a uniformity coefficient of 1.4 or less can be used. The anthracite 61 is provided to prevent suspended substances that could not be removed by the first filtration device 4 from adhering to the manganese-based filter material 62 and inhibiting the contact oxidation. Moreover, the filtration gravel 63 has the same role as the filtration gravel 43 described above.

That is, the catalytic oxidative decomposition of the organic substance, which is the main role of the second filtration device 6, is due to the action of the manganese-based filter material 62. The manganese-based filter medium 62 can be a filter medium in which a manganese dioxide (MnO ₂ ) crystal is supported on a particulate base material, and more preferably a filter medium having the characteristics shown in the following table. is there. Among them, SiO ₂ is preferably 72.0%, Al ₂ O ₃ is 16.0%, MnO ₂ is 3.0%, K ₂ O is 3.0%, Na ₂ O is 2.0%, Others (for example, impurities) is 4.0%.

The adsorption device 7 mainly serves to adsorb organic substances contained in the water to be treated. The adsorption device 7 has an activated carbon layer 71 formed of, for example, particulate activated carbon. As an example of the activated carbon, activated carbon (product: ACW8-32 #) manufactured by Serachem Co., Ltd. can be used. However, the type and shape of the activated carbon are not limited, and any known activated carbon can be used.

The flocculant addition means 3 and the oxidant addition means 5 connect flow paths (for example, pipes) 31 and 51 communicating with respective supply sources (not shown) to the flow path of the water to be treated. A chlorine-based oxidizing agent is configured to be added to the water to be treated. The addition amount can be adjusted by the flow rate adjusting means 32, 52 such as a valve. In order to improve the mixing property with the water to be treated, a stirring device such as a line mixer or a stirring tank may be installed. In addition, the supply place shown in FIG. 1 is an example, and is not limited to this position. The flocculant may be added at least before the supply to the first filtration device 4, and the oxidizing agent may be added at least before the supply to the second filtration device 6. Further, the addition position of the flocculant is not limited to one, and in order to effectively remove residual turbidity by the anthracite 61 of the second filtration device 6, the first filtration device 4 and the second filtration device 6 A flocculant addition means for adding a flocculant between the two may be newly added.

Examples of the flocculant include inorganic flocculants such as PAC (chemical name: polyaluminum chloride), polyiron (chemical name: polyferric sulfate), sulfate band (chemical name: aluminum sulfate), and polyacrylamide organic flocculants. Agents can be used. Among them, PAC is preferable. The flocculant is added mainly for the purpose of aggregating suspended substances in the water to be treated. The aggregated suspended solids are filtered and separated to lower the TOC (Total Organic Carbon) of the water to be treated and the suspended solids adhere to the manganese-based filter medium 62 to inhibit contact oxidation. To prevent it.

As the chlorine-based oxidizing agent, for example, chlorine dioxide (ClO ₂ ), hypochlorite such as sodium hypochlorite (NaClO), or potassium permanganate (KMnO ₄ ) can be used. The chlorine-based oxidant is added mainly for the purpose of oxidatively decomposing organic substances using the manganese-based filter material 61 as a catalyst. Thus, chlorine dioxide (ClO ₂ ) is particularly preferable as an oxidizing agent that performs oxidative decomposition of organic matter using the manganese-based filter material 61.

Next, a method for removing COD using the water treatment system 1 shown in FIG. 1 will be described. The type and quality of treated water (raw water) treated by this system is not particularly limited, and covers various organic matter-containing waters such as general wastewater, industrial wastewater, sewage, river water, groundwater, and lake water. It can be. Although not limited, the raw water treated in the examples described later had a chromaticity of 14.1, a turbidity of 14.11, and a pH of 7.65. In addition, when raw | natural water is acidic or alkaline, pH adjustment can be performed suitably as a pretreatment.

The treated water (raw water) to be treated by this system is temporarily stored in the raw water tank 2 and transferred toward the first filtration device 4 by the pump 21, and the flocculant is added by the flocculant adding means 3. Added. The addition amount of the flocculant is set to 5 to 30 mg / l, for example. The water to be treated to which the flocculant is added is supplied to the first filtration device 4, and the suspended substances are separated and removed when passing through the filter medium.

The water to be treated (separated liquid) from which the suspended substances have been separated by the first filtration device 4 is added with a chlorine-based oxidizing agent by the oxidizing agent adding means 5. The addition amount of the oxidizing agent is set to, for example, 1.25 mg / l for chlorine dioxide (ClO ₂ ) and 5 mg / l for sodium hypochlorite (NaClO). The water to be treated to which the oxidizing agent is added is supplied to the second filtration device 6, and when passing through the manganese-based filter material 61, the organic matter is oxidized and decomposed by chlorine dioxide using the manganese-based filter material 61 as a catalyst. .

The water to be treated, in which the organic matter is oxidized and decomposed by the second filtration device 6, is temporarily stored in the tank 8 and supplied to the adsorption device 7 by the pump 23. And when passing through the activated carbon layer 71 of the adsorption device 7, the organic matter is adsorbed on the activated carbon. The water to be treated from which COD has been removed in this way is sufficient COD to be discharged, as is apparent from the results of Examples described later.

As described above, according to this embodiment, a chlorine-based oxidant is added to water to be treated containing organic matter, and this is passed through the manganese-based filter material 62, whereby the organic matter is catalytically oxidized and decomposed to produce COD. Can be removed.

Furthermore, according to the present embodiment, by passing the water to be treated through activated carbon after the catalytic oxidative decomposition, it is possible to adsorb the organic components subjected to the catalytic oxidative decomposition and reliably remove COD. As already mentioned, it may be difficult to adsorb depending on the type of organic substance (for example, a substance with a strong polarity, a substance with a large molecular structure, etc.), but it decomposes into a molecule that is easily adsorbed by activated carbon by catalytic oxidative decomposition. As a result, the COD removal rate by the activated carbon can be improved.

Furthermore, according to the present embodiment, before the water is passed through the manganese-based filter media 62, the suspended solids are removed by the coagulation separation method, thereby preventing the contact oxidizing power of the manganese-based filter media 62 from being reduced. Thus, COD can be reliably removed.

Although the present invention has been described in detail with reference to specific embodiments, various substitutions, modifications, changes, etc. in form and detail are defined in the claims. It will be apparent to those skilled in the art that this can be done without departing from the spirit and scope. Therefore, the scope of the present invention should not be limited to the above-described embodiments and the accompanying drawings, but should be determined based on the description of the claims and equivalents thereof.

Hereinafter, examples performed for confirming the effects of the present invention will be described. However, the technical scope of the present invention is not construed as being limited by the examples described below.

Example 1
In this embodiment, raw water is treated according to the flow shown in FIG. The main test conditions are shown below. The raw water, the first filtration treatment, the catalytic oxidation separation, and the water to be treated after the adsorption treatment with activated carbon were sampled, and the chromaticity, turbidity, and COD were measured. Table 3 shows the measurement results. In addition, the sulfuric acid acidic potassium permanganate method was employ | adopted as the measuring method of chromaticity, turbidity, and COD.
・ First filtration: Anthracite (1.2-1.4) 300mmH
Sand (0.6-1.4) 300mmH
Filtration speed (LV) = 10 m / hr
・ Flocculant: 30 mg / l of PAC added ・ Contact oxidation: Anthracite (1.0-1.4) 200 mmH
Manganese filter material (shown in Table 3) 600mmH
Water flow rate SV = 10 / h
However, polyiron 10mg / l as flocculant before contact oxidation
Was added.
・ Activated carbon: Activated carbon 800mmH
Water flow rate SV = 10 / h

(Example 2)
This example is Example 2 in which hypochlorous acid was added as an oxidizing agent in place of the chlorine dioxide of Example 1. Other conditions are the same as in Example 1 except that the type of the oxidizing agent is changed. Table 4 shows the chromaticity, turbidity, and COD measurement results of each sampling.

(Comparative Example 1)
This comparative example is a comparative example 1 similar to the example 1 except that the catalytic oxidation was not performed. That is, the flow shown in FIG. 1 is a comparative example in which the second filtration device is omitted and the treated water subjected to the first filtration treatment is passed through activated carbon. Table 5 shows the chromaticity, turbidity, and COD measurement results of each sampling.

As is apparent from the results of Tables 3 to 5, it was confirmed that COD can be removed by passing the water to be treated to which the chlorine-based oxidizing agent has been added through the manganese-based filter medium. Furthermore, it was confirmed that COD can be reliably removed by passing the water to be treated after catalytic oxidation through activated carbon. As for the oxidizing agent, it was confirmed that NaClO is more effective when paying attention to chromaticity and turbidity, but ClO ₂ is more effective for removing COD. When ClO ₂ is used, COD after passing the activated carbon is removed to 2.4 mg / l. That is, it was confirmed that ClO ₂ can decompose organic substances so that it is more easily adsorbed by activated carbon.

DESCRIPTION OF SYMBOLS 1 Water treatment system 3 Flocculant addition means 4 1st filtration apparatus 5 Oxidizing agent addition means 6 2nd filtration apparatus 62 Manganese type filtering material 7 Adsorber 71 Activated carbon layer

Claims

In a water treatment method for removing COD (Chemical Oxygen Demand),
A water treatment method comprising removing a COD by adding a chlorine-based oxidizing agent to water to be treated containing an organic substance, passing the water through a manganese-based filter medium, and catalytically oxidizing and decomposing the organic substance.
The water treatment method according to claim 1, wherein the chlorine-based oxidizing agent is chlorine dioxide (ClO 2 ).
3. The manganese-based filter medium is a filter medium in which a manganese dioxide (MnO 2 ) crystal is supported on a particulate base material, and has the following characteristics: The water treatment method as described.
The water treatment method according to any one of claims 1 to 3, further comprising a step of passing the water to be treated after the catalytic oxidative decomposition through activated carbon to adsorb and remove organic substances.
5. The method according to claim 1, further comprising a step of adding a flocculant to the water to be treated before passing through the manganese-based filter medium, and separating and removing suspended components. Water treatment method.
A water treatment system for removing COD (Chemical Oxygen Demand),
Means for adding a chlorine-based oxidizing agent to water to be treated containing organic matter;
A filtration device comprising a manganese-based filter material for passing water to be treated to which the chlorinated oxidant is added;
A water treatment system comprising:
The water treatment system according to claim 6, further comprising an adsorption device including activated carbon that passes water to be treated after passing through the manganese-based filter material.
Before passing through the manganese-based filter material, further comprising means for adding a flocculant to the water to be treated, and another filtering device for passing the water to be treated to which the flocculant is added. The water treatment system according to claim 6 or 7, characterized in that