JP4113851B2 - Concentration measuring method and concentration measuring apparatus - Google Patents

Description

  The present invention relates to a method and apparatus for measuring the concentration of a hardly decomposable organic compound in a treatment technique for a hardly decomposable organic compound such as dioxins in a liquid, and a decomposition apparatus and method for an organic compound of a hardly decomposable organic compound. .

  Industrial wastewater, sewage, leachate from waste landfills, and the like contain various persistent organic compounds, which can cause pollution of the water environment if discharged with insufficient treatment. Typical examples of such hardly decomposable harmful pollutants are well known, for example, agricultural chemicals, organic chlorine compounds such as dioxins, plastic additives such as phthalate esters and bisphenol A, and the like.

  Among these, dioxins, phthalates and the like are said to be endocrine disrupting substances, and there is concern that even a trace amount (very low concentration) may adversely affect organisms and ecosystems. Therefore, for the discharged water to the outside world, the treatment is such that the concentration of the hardly decomposable harmful pollutant is extremely low from ppt (1 trillionth) to ppq (1 trillionth). Water quality may be required.

  As a conventional technique for processing the hardly decomposable organic compounds contained in these liquids, ozone gas is blown into the liquid to be treated and ultraviolet rays are irradiated to generate active oxygen such as hydroxy radicals by an antichemical reaction or a chemical reaction. An accelerated oxidation method (hereinafter abbreviated as AOP method), which is a method of generating, is known.

  By the way, a hardly decomposable organic compound such as dioxin is not present alone in the waste water, but is present in the liquid together with other organic compounds that coexist. In addition, as shown in the graph described in Non-Patent Document 1 (this graph is shown in FIG. 7), the total organic compound is the total of the persistent organic compound (dioxin) and the coexisting organic compound present in the liquid. There is no correlation between the compound (COD) and the amount of the hardly decomposable organic compound (dioxin). That is, just because the total amount of organic compounds (COD) in the wastewater is large, it does not necessarily contain a lot of persistent organic compounds. The composition is usually greatly different depending on various factors such as the existence.

  When wastewater containing a hardly decomposable organic compound such as dioxin and a coexisting organic compound is treated by the AOP method, there is a problem that the coexisting organic compound shields the ultraviolet rays and the ultraviolet rays do not sufficiently penetrate into the wastewater. As a result, the treatment of the hardly decomposable organic compound tends to be insufficient. Further, when the decomposition by the AOP method is performed, in order to decompose most of the dioxins that become the emission standard, it is necessary to perform the AOP method for a long time, and there is a problem that the running cost and the processing time become long.

  In order to solve the problem that the organic compound contained in the COD component inhibits the decomposition of the organic chlorine compound (dioxin) in view of this problem, Patent Document 1 oxidizes the COD component and the like by injecting ozone as an oxidizing agent. Disclosed is a technology that decomposes organic chlorine compounds such as dioxin contained in wastewater by performing AOP treatment after contacting with an adsorbing medium such as activated carbon to remove most COD components. ing. That is, even if wastewater containing a large amount of coexisting organic compounds is treated by the AOP method using ultraviolet irradiation, the ultraviolet rays do not sufficiently penetrate into the wastewater, and dioxins and other difficult-to-decompose organic compounds are treated in areas far from the ultraviolet lamp. Since it is discharged as it is, after decomposing substances that can be decomposed with an oxidizing agent such as ozone in advance, and removing most of the organic compounds that were not decomposed with the oxidizing agent, the remaining trace amount of dioxins, etc. An organic chlorine compound is to be treated by the AOP method.

  On the other hand, when these wastewaters are decomposed by the AOP method, as shown in FIG. 8, the hardly-decomposable organic compounds and the total organic compounds in the wastewater are not necessarily decomposed at a fixed ratio, and the decomposition rate of both Changes from treatment to treatment under the influence of various factors such as the type of coexisting organic compound and the treatment method. Therefore, even if this liquid to be treated is directly decomposed by the AOP method, the ratio of the hard-to-decompose organic compound in the total organic compound is unclear in the liquid after the treatment. The total organic compound concentration cannot be correlated.

Moreover, in the measurement of the density | concentration of the hardly decomposable organic compound in waste_water | drain, since it receives to the influence of a coexisting organic compound, it is difficult to measure directly with visible light or an ultraviolet light absorbency. However, it is extremely important to measure the concentration of dioxin in the wastewater to determine whether it is at a level that allows waste liquid to be discharged to the outside. In order to solve these problems, in Patent Document 2, when the wastewater is AOP treated with ozone, the dissolved ozone concentration is measured by measuring the dissolved ozone concentration in the wastewater, and the dissolved ozone concentration is measured as an alternative index. It is disclosed that the concentration of harmful substances such as dioxin is estimated.
JP 2003-47980 A JP 2003-24958 A About the report of the Central Environment Council concerning the “Environment and Maintenance Standards for Waste Disposal Sites Based on the Act on Special Measures against Dioxins” on the Environment Agency website [online] December 10, 1999 [Search January 2004], Internet <URL: http://www.env.go.jp/press/file_view.php3?serial=1394&hou_id=1900>, P.36-37 (4. Dioxins and others) Correlation with other substances) Sota Nakagawa et al., Technical Information Center Co., Ltd. Technical Seminar Text “Effective Treatment of Organic and Trace Hazardous Substances in Water by Accelerated Oxidation Method (AOP)” February 20, 2003, p. 8-9

  However, the technique of the cited document 1 has a problem that a large amount of harmful substances such as dioxin is adsorbed by an adsorbing substance such as activated carbon and is not decomposed, so that treatment of dioxin adsorbed on activated carbon or the like is necessary and costly. is there. In addition, in order to measure the concentration of difficult-to-decompose substances such as dioxin in treated wastewater, it is difficult to estimate the concentration accurately by absorbance measurement as described above, so it is difficult to constantly monitor the concentration. Therefore, it is difficult to find the end point of processing by the AOP method online. In addition, since the AOP method irradiates ultraviolet rays while adding ozone, the running cost is high, and the end point of the processing becomes unclear. If the processing is continued for an unnecessarily long time, unnecessary costs are increased. .

  In addition, since the technique of the cited document 2 uses an expensive dissolved ozone meter, the cost of the apparatus is high, and the concentration of the hardly decomposable organic compound is not directly measured, and the ozone concentration is used as an alternative index. Therefore, it is difficult to obtain high accuracy for the measured value. In addition, it is assumed that the decomposition rate of other organic compounds coexisting with the decomposition rate of a hardly decomposable organic compound (a trace amount of harmful substances) is assumed to have a certain relationship, for example, one-to-one. Since the reaction rate with the OH radical that functions as an oxidant in the method varies greatly depending on the chemical substance, the ratio varies depending on the chemical substance contained in the liquid to be treated. Therefore, this technique has a large error in estimated density, and it is difficult to perform highly accurate density measurement.

  Further, since it is necessary to measure the ozone concentration in a state where ozone gas is supplied in the liquid, there is also a problem that it is easily influenced by the amount of supplied ozone gas, and the detection standard of the end point tends to vary.

Furthermore, when ozone is added to the wastewater to decompose the organic compound, as disclosed in Non-Patent Document 2, ozone reacts with water in the processing liquid to self-decompose, generating HO ₂ radicals, decomposed into OH radicals and oxygen the HO ₂ radicals react with ozone. The generated OH radical oxidizes and decomposes the organic compound. However, since this OH radical reacts with ozone to generate HO ₂ radical and oxygen, the concentration of dissolved ozone in the treatment liquid increases so that it cannot be decomposed by the generated HO ₂ radical and OH radical. The amount of ozone is dissolved in the liquid. Therefore, using ozone as an alternative index as a hardly decomposable organic compound and using the ozone concentration as a reaction end point detection cannot be expected from a chemical standpoint.

  Therefore, the technical problem to be solved by the present invention is to provide a low-cost method for measuring the concentration of a hardly-decomposable organic compound that can directly measure the concentration of the hardly-decomposable organic compound with high accuracy.

  The present inventor has measured the concentration of a hardly decomposable organic compound using absorbance measurement for a liquid to be treated containing an easily decomposable organic chemical that can be decomposed by ozone and a hardly decomposable organic compound that is not decomposed by ozone. In view of the problem that easily decomposable organic chemicals affect the absorbance value, when the easily decomposable organic compound in the liquid to be treated is removed and decomposed, the absorbance of the liquid after the treatment is different from that of the hardly decomposable organic compound. The knowledge that it correlates was obtained. In order to detect that the readily decomposable organic compound has been removed and decomposed, hydrogen peroxide is generated in the liquid to be treated when there is no organic compound in the liquid that can be easily decomposed by ozone treatment. Focusing on starting, the present invention has been completed. That is, as a means for detecting that most of the liquid-decomposable organic compound in the liquid to be treated has been decomposed and removed, the hydrogen peroxide concentration in the liquid to be treated is equal to or higher than a reference value.

That is, the present invention is a method for measuring the concentration of a hardly decomposable organic compound in a liquid to be treated, comprising a hardly decomposable organic compound that is not decomposed by ozone and a readily decomposable organic compound that can be decomposed by ozone,
The ozone gas is supplied to the liquid to be treated within perform concentration measurement of hydrogen peroxide starts the decomposition of easily decomposable organic compounds, decompose hydrogen peroxide concentration of the liquid to be treated inside of the easily decomposable organic compound And a concentration measuring method for measuring the concentration of the hardly decomposable organic compound in the liquid to be treated by measuring absorbance after the sample is retained until it reaches a reference value indicating that the process is substantially completed.

Further, the present invention is an apparatus for measuring the concentration of a hardly decomposable organic compound in a liquid to be treated, comprising a hardly decomposable organic compound that is not decomposed by ozone and a readily decomposable organic compound that can be decomposed by ozone,
An ozone decomposition treatment apparatus comprising an ozone treatment tank for accumulating the liquid to be treated and an ozone supply device for supplying ozone to the liquid to be treated accumulated in the treatment tank;
A first concentration measuring device for measuring a hydrogen peroxide concentration in the liquid to be treated accumulated in the ozonolysis treatment device;
A treatment liquid discharge pipe that discharges a liquid to be treated that contains the hydrogen peroxide measured by the first concentration measuring apparatus above a reference value indicating that the decomposition of the readily decomposable organic compound is substantially completed;
There is provided a concentration measuring device comprising: a second concentration measuring device that measures the concentration of the hardly decomposable organic compound in the liquid to be treated by measuring absorbance of the processing liquid discharged from the processing liquid discharge pipe.

According to the present invention, ozone gas is supplied to a liquid to be treated containing a hardly decomposable organic compound and a readily decomposable organic compound, and the easily decomposable organic compound is oxidized and decomposed. At this time, the decomposition mechanism is that ozone gas decomposes easily decomposable organic compounds into fatty acids via ozonides or self-decomposes to generate OH radicals, which attack organic compounds and decompose easily decomposable organic compounds. . The oxidative decomposition reaction of the liquid to be treated at this time may be a continuous type or a batch type. Further, a circulation type may be used in which the material is once discharged into the processing tank and then supplied to the processing tank again. The readily decomposable organic compound in the present invention is a direct decomposition reaction in which ozone gas is dissolved in a solution and dissolved in ozone, and an indirect decomposition by OH radicals generated by ozone self-decomposition. It means an organic compound that has a high reaction rate and can be decomposed relatively easily by adding ozone. Specific examples thereof include phenols and polycyclic aromatic hydrocarbons. When the decomposition of the readily decomposable organic compound proceeds to a certain extent and the attack target of the OH radical generated by the self-decomposition of ozone decreases, the OH radical becomes excessive in the liquid to be treated. OH radicals generate hydrogen peroxide H ₂ O ₂ by reaction between OH radicals, and HO ₂ radicals generated by reaction of OH radicals and ozone also react to generate hydrogen peroxide. When OH radicals become excessive in the liquid to be treated, hydrogen peroxide increases.

  That is, if it is detected that hydrogen peroxide is generated in the liquid to be treated above a reference value indicating that the decomposition of the easily decomposable organic compound is almost completed, most of the easily decomposable organic compound is decomposed, Most of the organic compounds remaining in the liquid to be treated are hardly decomposable organic compounds that are not decomposed by ozone. The reference value indicating that the decomposition of the readily decomposable organic compound is almost completed depends on the concentration of the easily decomposable organic compound contained in the liquid to be treated. For example, when hydrogen peroxide starts to be generated and accumulated When the hydrogen peroxide concentration exceeds the reference value, etc., or when it begins to accumulate other than this, or when a predetermined time elapses after it exceeds the reference value, etc. it can. In addition, the hardly decomposable organic compound in the present invention is an organic compound which has a relatively slow reaction rate of direct decomposition reaction and indirect decomposition reaction when ozone gas is blown into the liquid and dissolved, and is difficult to decompose by this method. Specifically, dioxins, organochlorine compounds such as PCB, humic substances, diethyl phthalate and the like are exemplified. These are substances that can be decomposed by the AOP method in which ozone is added to the liquid and irradiated with ultraviolet rays.

  Thus, when hydrogen peroxide is detected in the liquid to be treated above the reference value, most of the organic compounds present in the liquid to be treated are hardly decomposable organic compounds that are difficult to decompose by ozone treatment. Therefore, by measuring this by measuring the absorbance, the concentration of the hardly decomposable organic compound can be measured without being affected by the easily decomposable organic compound.

  When measuring a hardly decomposable organic compound by absorbance measurement, the measurement wavelength used is, in the case of a hardly decomposable organic compound, the measurement wavelength is 230 to 300 nm, and at least three points within the range where the ultraviolet absorption spectrum of ozone exhibits a peak. It is preferable to measure using the information of the light absorbency.

  In addition, in order to detect whether the hydrogen peroxide in a to-be-processed liquid became more than a reference value, it can carry out by a titration method or an absorbance measurement. The determination as to whether or not the hydrogen peroxide in the measurement using the absorbance measurement has exceeded the reference value can be made using the absorbance value as it is. Since hydrogen peroxide has an absorption wavelength at 180 nm, the liquid to be treated containing hydrogen peroxide is affected by absorbance at a wavelength of approximately 180 to 230 nm. Here, the wavelength up to 200 nm is strongly absorbed by air and has a great influence on the concentration measurement by the spectrometer. Therefore, if the measurement wavelength is 230 nm, for example, the concentration of hydrogen peroxide can be detected by absorbance measurement.

  In addition, by removing hydrogen peroxide in advance, the influence of hydrogen peroxide can be eliminated in the measurement of the concentration of the hardly decomposable organic compound, so that the accuracy of the concentration measurement of the hardly decomposable organic compound can be improved. . In order to remove hydrogen peroxide, the liquid to be treated may be irradiated with ultraviolet rays or an enzyme for removing hydrogen peroxide may be added.

Further, the present invention is an organic compound decomposition apparatus that oxidatively decomposes a hardly decomposable organic compound that is not decomposed by ozone contained in a liquid to be treated and an easily decomposable organic compound that can be decomposed by ozone, Ozone provided with a supply pipe for supplying a liquid, an ozone treatment tank for accumulating the liquid to be treated supplied from the supply pipe, and an ozone supply device for supplying ozone to the liquid to be treated accumulated in the ozone treatment tank A decomposition processing device;
A first concentration measuring device for measuring a hydrogen peroxide concentration in the liquid to be treated accumulated in the ozonolysis treatment device;
A first treatment liquid discharge pipe for discharging a liquid to be treated that contains the hydrogen peroxide measured by the first concentration measuring apparatus above a reference value indicating that the decomposition of the readily decomposable organic compound is substantially completed;
An ultraviolet treatment tank for accumulating the liquid to be treated supplied from the treatment liquid discharge pipe, and an ultraviolet irradiation device for irradiating the liquid to be treated accumulated in the treatment tank with ultraviolet rays, and accumulated in the ultraviolet treatment tank. An accelerated oxidation treatment apparatus capable of supplying ozone to the liquid to be treated;
A second concentration measuring device for measuring the concentration of the hardly decomposable organic compound in the liquid to be treated by measuring the absorbance in the liquid to be treated accumulated in the ultraviolet treatment tank;
An organic compound decomposing apparatus comprising: a second processing liquid discharge pipe for discharging the liquid to be processed to the outside when the absorbance of the second concentration measuring apparatus becomes a reference value or less.

  According to the present invention, in the ozone treatment tank, ozone gas is supplied to the liquid to be treated containing the hardly decomposable organic compound and the easily decomposable organic compound to decompose the easily decomposable organic compound. The treatment method of the ozone treatment tank may be any of continuous type, batch type, and circulation type. When the decomposition of the readily decomposable organic compound proceeds to a certain extent and the attack target of OH radicals due to ozone self-decomposition decreases, the OH radicals become excessive in the liquid to be treated. If the first concentration measuring device finds that the hydrogen peroxide concentration in the liquid to be treated is equal to or higher than the reference value, the liquid to be treated is accumulated in the ultraviolet treatment tank via the first treatment liquid discharge pipe. .

  In the ultraviolet treatment tank, ultraviolet light is irradiated while ozone gas is supplied to decompose the hardly decomposable organic compound by the AOP method. As described above, the hydrogen peroxide concentration is higher than the reference value, and the liquid to be treated discharged from the ozone treatment tank contains almost no easily decomposable organic compound and is irradiated to the ultraviolet treatment tank. Ultraviolet rays reach a hardly decomposable organic compound without being shielded, and the AOP method proceeds with high efficiency. The treatment method of the ultraviolet treatment tank may be any of continuous type, batch type, and circulation type. The concentration of the hardly decomposable organic compound in the liquid to be treated in the ultraviolet treatment tank is measured by absorbance measurement using a second concentration measuring device. As described above, the liquid to be treated in the ultraviolet treatment tank contains almost no easily decomposable organic compound and is hardly affected by the absorbance of the easily decomposable organic compound.

  When the absorbance of the liquid to be processed is equal to or lower than the reference value by the second concentration measuring device, the liquid to be processed is discharged to the outside through the second processing liquid discharge pipe. The reference value at this time can be set to a desired value such as a level at which the hardly decomposable organic compound can be discharged to the outside or a level that does not adversely affect living organisms and ecosystems.

  Thus, when hydrogen peroxide is detected in the liquid to be treated above the reference value, the organic compounds present in the liquid to be treated are mostly hardly decomposable organic compounds. In the case of AOP treatment by UV, ultraviolet rays reach the hardly-decomposable organic compound without being blocked by the easily-decomposable organic compound, and can improve the decomposition efficiency of AOP. The accuracy of compound concentration measurement can be increased.

In addition, the present invention provides an organic compound that is subjected to accelerated oxidative decomposition treatment by simultaneously performing ozone supply and ultraviolet irradiation on a liquid to be treated containing a hardly decomposable organic compound that is not decomposed by ozone and an easily decomposable organic compound that can be decomposed by ozone. A decomposition method,
Ozone gas is supplied into the liquid to be treated to start decomposing the easily decomposable organic compound, and hydrogen peroxide in the liquid to be treated is equal to or higher than a reference value indicating that the decomposition of the easily decomposable organic compound is almost completed. There is provided an organic compound decomposition method in which the liquid to be treated which has been retained until becomes an accelerated oxidative decomposition treatment directly.

  According to the concentration measuring method and the concentration measuring apparatus according to the present invention, it is possible to measure the concentration by measuring the absorbance of the hardly-decomposable organic compound without being affected by the easily-decomposable organic compound, and therefore it is possible to monitor constantly. The accuracy of concentration measurement can be improved. Further, an inexpensive absorption densitometer can be used for concentration measurement, and the cost can be reduced. In addition, by using the hydrogen peroxide concentration as an indicator that most of the readily decomposable organic compounds have been decomposed, it is possible to make a high-precision and quick determination, without performing unnecessary ozone treatment for a long time. , Running costs can be reduced.

  Further, according to the organic compound decomposition apparatus and method of the present invention, the end point of the removal of the easily decomposable organic compound that affects the AOP method is determined based on the amount of hydrogen peroxide in the liquid to be treated. Moreover, this can be determined with high accuracy, and pretreatment by ozone treatment does not become excessive or insufficient. Therefore, it is possible to decompose and remove a sufficiently easily decomposable organic compound without performing an unnecessary process between the ozone treatment and the AOP treatment using ultraviolet rays, and the running cost of the apparatus can be suppressed. Moreover, since the discharge | emission parameter | index of a hardly decomposable organic compound can be measured by an absorbance measurement, a density | concentration can be measured by continuous monitoring and the process by a continuous type and a circulation type is attained.

(First embodiment)
Hereinafter, specific configuration examples of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing a schematic configuration of a concentration measuring apparatus of the present invention having a circulation type processing tank. The concentration measuring apparatus 1 includes an ozone treatment tank 2 that communicates with a treatment liquid supply pipe LI that supplies a treatment liquid, an ozone supply apparatus 5 that supplies ozone gas to the treatment liquid stored in the ozone treatment tank 2, and A first concentration meter provided in the treatment liquid discharge pipe L1 for discharging the treatment liquid in the ozone treatment tank 2 and an external discharge pipe LO provided on the downstream side of the first concentration meter for discharging the treatment liquid to the outside. A switching valve 6 is provided for switching between sending or returning to the circulation pipe L2 for returning to the ozone treatment tank.

  The ozone supply device 5 includes an ozonizer 10 and a nozzle 11 that supplies ozone gas generated by the ozonizer 10 to the liquid 100 to be processed. Ozone gas is supplied from the nozzle 11 provided on the bottom surface of the ozone treatment tank 2 to the liquid to be treated in the ozone treatment tank 2 by the ozone supply device 5, and the ozone gas is dissolved in the liquid to be treated. The liquid to be treated discharged from the ozone treatment tank 2 through the treatment liquid discharge pipe L1 is measured for the hydrogen peroxide concentration by the first concentration meter 3. If the hydrogen peroxide concentration is below the reference value, the circulation pipe It returns to the ozone treatment tank 2 through L2, and circulates between the ozone treatment tank 2 and the treatment liquid discharge pipe L1.

The liquid to be treated is a waste liquid containing dioxin and contains both dioxins that are difficult to decompose by ozone and easily decomposed organic compounds such as phenols that are easily decomposed by ozone. It is out. By supplying ozone gas in the ozone treatment tank 2, the easily decomposable organic compound is oxidized and decomposed by ozone. Oxidation / decomposition reaction at this time includes direct decomposition reaction in which ozonide is formed by ozone and decomposes into lower fatty acids by reacting with organic substances, and oxidation of HO ₂ radical and OH radical generated in the process of ozone self-decomposition reaction. It is an indirect decomposition reaction by force. The indirect decomposition reaction is represented by the following chemical formulas (1) to (7), and decomposes an easily decomposable organic compound and a lower fatty acid produced by the direct decomposition reaction.

Thus, when the organic compound in the liquid to be treated is oxidized and decomposed by ozone in the ozone treatment tank 2, the number of OH radicals attacked by the self-decomposition of ozone decreases, and OH radicals are excessive in the liquid to be treated. (See formula (1) to formula (4)). OH radicals are generated by the reaction of OH radicals as shown in formula (7) to generate hydrogen peroxide H ₂ O ₂ , and the OH radicals and ozone react as shown in formula (5). Since HO ₂ radicals also react with each other to generate hydrogen peroxide, hydrogen peroxide increases when OH radicals are excessive in the liquid to be treated. The first concentration meter 3 measures the concentration of hydrogen peroxide in the liquid to be treated generated by the mechanism.

  The first concentration meter 3 is a concentration meter that measures hydrogen peroxide by measuring absorbance. The first concentration meter 3 simultaneously measures the concentration of hydrogen peroxide and the concentration of organic compound (COD component) in the liquid to be treated. The concentration measurement method disclosed in Japanese Patent Application No. 2003-074091 (not disclosed at the time of filing this application) is used for the measurement of the concentration of hydrogen peroxide and the concentration of the organic compound (COD component) performed in the first concentration meter 3.

  The first concentration meter 3 measures the hydrogen peroxide concentration and the organic compound (COD component) concentration as follows.

  The first densitometer uses the measurement wavelengths of 230 nm, 260 nm, and 290 nm, and simultaneously measures the hydrogen peroxide concentration and the organic compound concentration from these absorbance values by the following method. In addition, the light of these measurement wavelengths used for an absorbance measurement can be selected by passing the light of a wavelength of 200-300 nm through an interference filter, for example.

  The first densitometer stores absorbance data at 230, 260, and 290 nm of the liquid to be treated, respectively, and compares the reference ozone spectrum with a known concentration and the reference organic substance (hydrogen peroxide, organic compound) spectrum, and calculates the following: The hydrogen peroxide concentration and the organic compound (COD) concentration are measured by the formula. Here, the reference ozone spectrum means a reference ultraviolet spectrum having a known ozone concentration and containing no organic matter. The reference organic matter spectrum means a reference ultraviolet spectrum in which the organic matter (hydrogen peroxide, organic compound) concentration is a constant value and does not contain ozone.

  The respective absorbance values measured at 230, 260, and 290 nm are substituted into Equation (8), and the ozone concentration is first calculated.

式（８）中、Ｄ_Ｏ３はオゾン濃度、Ａ₂₃₀，Ａ₂₆₀，Ａ₂₉₀は、それぞれ２３０，２６０，２９０ｎｍ近傍での吸光度、Ｐは係数を示す。

In Equation (8), D _O3 is the ozone concentration, A ₂₃₀ , A ₂₆₀ and A ₂₉₀ are the absorbances near ₂₃₀ , ₂₆₀ and ₂₉₀ nm, respectively, and P is a coefficient.

  As described above, the liquid to be treated decomposes an organic compound by supplying ozone, and contains ozone, hydrogen peroxide, and an organic compound. Therefore, in liquid component measurement by absorbance, the Lambert-Beer law is used. Therefore, it is necessary to exclude the influence of other components when measuring each component. That is, the absorbance at each wavelength is expressed as the sum of values expressed based on the concentrations of ozone, organic compound, and hydrogen peroxide.

  On the other hand, using the fact that ozone has an absorption spectrum (Hartley band) peaking at 254 nm in the ultraviolet region of 200 to 300 nm, the change in absorbance given to the liquid to be treated in the wavelength range is mainly due to ozone. We can guess that there is. That is, by using the absorbance at 230 and 290 nm, which is a wavelength located outside the wavelength range of the rise of the spectrum in the Hartley band of the ozone ultraviolet spectrum, as a baseline, hydrogen peroxide and ozone interference measurement components The ozone concentration can be measured by eliminating the absorbance of COD. The coefficient P is calculated by using the least square method based on the ultraviolet spectrum of a reference sample with a known concentration stored in the storage unit.

  When the ozone concentration is derived, the absorbance data at 230 and 290 nm are substituted into the equations (9) and (10), and the concentration of the organic compound and the concentration of hydrogen peroxide are calculated, respectively.

式（９），（１０）中、Ｄ_CODは有機化合物濃度、D_H2O2は過酸化水素濃度、Ｑ，Ｒ，Ｓ，Ｔ，Ｕはそれぞれ係数を示す。

In the formulas (9) and (10), D _COD is an organic compound concentration, _{DH 2 O 2} is a hydrogen peroxide concentration, and Q, R, S, T, and U are coefficients.

  The concentration of the organic compound is generally measured for absorbance at a wavelength of 250 to 260 nm. In this liquid to be treated, the absorbance of hydrogen peroxide has an effect, so the absorbance is measured using 290 nm. .

  The coefficients Q, R, S, T, and U are calculated by using the least square method based on the organic compound of the reference sample having a known concentration and the ultraviolet spectrum of hydrogen peroxide. The coefficients R, T, and U have negative values based on the Lambert-Beer law.

  According to the concentration measuring apparatus according to the present embodiment, the hydrogen peroxide concentration and the organic matter concentration can be measured simultaneously by measuring the ultraviolet spectrum of the liquid to be treated only once.

  When the first concentration meter 3 detects that the hydrogen peroxide concentration is equal to or higher than the reference value, the first switching valve 6 is switched, and the processing liquid discharge pipe L1 communicates with the external discharge pipe LO. As described above, the concentration of the organic compound at this time is 1st because most of the readily decomposable organic compound that can be decomposed by ozone is decomposed by supplying ozone in the ozone treatment tank 2. The organic compound measured by the densitometer 3 is dioxins which are hardly decomposable organic compounds, and has a correlation between the absorbance and the concentration of the organic compound. Therefore, the concentration of dioxins in the liquid to be treated can be measured by measuring the absorbance. In this embodiment, since the hydrogen peroxide concentration and the organic compound concentration can be measured simultaneously as described above, the concentration of the organic compound at the time when it is clear that a predetermined amount of hydrogen peroxide is generated is used. Thus, the concentration of the hardly decomposable organic compound can be estimated.

(Second Embodiment)
Next, a second embodiment of the present invention will be described with reference to the drawings. FIG. 2 is a block diagram showing a schematic configuration of the organic compound decomposition apparatus of the present invention having a circulation type treatment tank. The organic compound decomposition apparatus 20 includes an ozone treatment tank 2 that communicates with a treatment liquid supply pipe LI that supplies a treatment liquid, an ozone supply apparatus 5 that supplies ozone gas to the treatment liquid, and a treatment in the ozone treatment tank 2. A first concentration meter provided in the treatment liquid discharge pipe L1 for discharging the liquid, and a circulation provided on the downstream side of the first concentration meter for sending the treatment liquid to the ultraviolet treatment tank 21 or returning it to the ozone treatment tank A first switching valve 6 that switches whether to return to the pipe L2, an ultraviolet treatment tank 21 having an ultraviolet lamp 22 that irradiates the treatment liquid 101 with ultraviolet rays and oxidizes and decomposes by the AOP method, and a treatment in the ultraviolet treatment tank 21 The second concentration meter 4 provided in the treatment liquid discharge pipe L4 for discharging the liquid 101, and an ultraviolet treatment tank provided on the downstream side of the first concentration meter and sent to an external discharge pipe LO for discharging the liquid to be processed to the outside Return to the circulation pipe L5 to return to 21 And a second switching valve 7 for switching.

  The ozone supply device 5 includes an ozonizer 10, a nozzle 11 that supplies ozone gas generated by the ozonizer 10 to the liquid 100 to be processed in the ozone treatment tank 2, and a nozzle that supplies ozone gas to the liquid 101 to be processed in the ultraviolet treatment tank 21. 12.

  Ozone gas is supplied from the nozzle 11 provided on the bottom surface of the ozone treatment tank 2 to the liquid 100 to be treated in the ozone treatment tank 2 by the ozone supply device 5, and the ozone gas is dissolved in the liquid to be treated. The liquid to be treated discharged from the ozone treatment tank 2 through the treatment liquid discharge pipe L1 is measured for the hydrogen peroxide concentration by the first concentration meter 3. If the hydrogen peroxide concentration is below the reference value, the circulation pipe It returns to the ozone treatment tank through L2 and circulates between the ozone treatment tank 2 and the treatment liquid discharge pipe L1.

  The first densitometer performs concentration measurement using absorbance in order to measure the amount of hydrogen peroxide in the liquid to be treated. The measurement wavelength at this time was 180 to 230 nm.

  When the absorbance value of the first concentration meter exceeds a predetermined value, that is, when it is detected that the hydrogen peroxide concentration is higher than the reference value, the first switching valve 6 is switched, and the treatment liquid discharge pipe L1 and the ultraviolet ray treatment are switched. The liquid to be processed is fed to the ultraviolet processing tank 21 by communicating with the tank supply pipe L3. In the present embodiment, the first switching valve is switched when it is detected that hydrogen peroxide is generated in the liquid to be treated. At this time, in order to remove hydrogen peroxide in the liquid to be treated, an erasing enzyme that removes hydrogen peroxide is added to the supply pipe L3 for the ultraviolet treatment tank. Examples of the erasing enzyme include peroxidase and catalase. Catalase is an enzyme that breaks down hydrogen peroxide into water and oxygen. Specific examples of these include hydrogen peroxide-degrading enzyme “Aqua Super” (trade name) manufactured by Mitsubishi Gas Chemical Company.

  In the ultraviolet treatment tank, ozone generated by the ozonizer 10 is supplied to the liquid 101 in the ultraviolet treatment tank 21 via the nozzle 12 and irradiated with ultraviolet rays by the ultraviolet lamp 22, and is then treated in the liquid to be treated by the AOP method. The organic compounds are oxidized and decomposed. As described above, since most of the organic compounds contained in the ultraviolet treatment tank 21 are dioxins which are hardly decomposable organic compounds, the easily decomposable organic compounds block ultraviolet rays and inhibit the AOP treatment of dioxins. Therefore, AOP processing can be performed efficiently.

  The concentration of the organic compound in the liquid 101 to be treated in the ultraviolet irradiation tank 21 is measured by measuring the ultraviolet absorbance with the second densitometer 4 provided in the treatment liquid discharge pipe L4. The concentration measurement of the organic compound by the second densitometer 4 is performed as follows.

  The second densitometer measures the concentration of the organic compound in the liquid to be treated by measuring the absorbance. In the present embodiment, the measurement wavelength is 260 nm. Although 260 nm is in common with the absorption bands of ozone and hydrogen peroxide, it is considered that this effect is hardly affected. With regard to ozone, the concentration of organic compounds to be decomposed is reduced and the concentration increases when continuously supplied. Therefore, if the amount of hydrogen peroxide is used, the timing for switching between treatments can be determined. It can be measured before the ozone concentration in the liquid to be treated increases, and has almost no influence on the absorbance measurement of the organic compound. As for hydrogen peroxide, since an erasing enzyme for removing hydrogen peroxide is added for the above-mentioned purpose, it is considered that the hydrogen peroxide is decomposed and hardly affects the absorbance measurement of the organic compound.

  When the absorbance is lower than a predetermined value by the second densitometer, when the organic compound in the liquid to be treated, that is, the dioxins that are difficult-to-decompose organic compounds, is decomposed to a concentration that can be discharged, The second switching valve 8 is switched, the processing liquid discharge pipe L1 communicates with the external discharge pipe LO, and the liquid to be processed is discharged to the outside.

  As described above, the organic compound decomposition apparatus according to the present embodiment can convert the organic compound contained in the liquid to be treated to AOP treatment into dioxins that are hardly decomposable organic compounds and is discharged from the ultraviolet treatment tank. The absorbance value indicating the organic compound concentration in the liquid to be treated has a correlation with the dioxin concentration, and the dioxin concentration in the liquid to be treated can be measured by measuring the absorbance.

(Example 1)
Using the apparatus shown in FIG. 1, wastewater containing dioxins was treated under the following conditions. That is, ozone having a concentration of 167 g / Nm ³ was supplied at 0.3 L / min in an ozone treatment tank having a storage water volume of 20 L, and the absorbance of the concentration meter 3 liquid to be treated was measured. While measuring the density | concentration of the organic compound in process with the measurement wavelength of 260 nm, the change of hydrogen peroxide was evaluated by the light absorbency of the measurement wavelength of 230 nm. Further, the treatment liquid was sampled, the hydrogen peroxide concentration was measured using a test paper (manufactured by Mitsubishi Gas Chemical Co., Ltd., hydrogen peroxide test paper), and the COD value was measured using a pack test (manufactured by Kyoritsu Riken). The results are as shown in Table 1 and FIG. In the table, “over” indicates that the absorbance exceeds 5, and “−” indicates that measurement is not performed.

  As processing proceeds, organic compound concentrations decrease and COD and absorbance at 260 nm also decrease. After the treatment time of 15 minutes, the COD and absorbance do not change and the hydrogen peroxide concentration increases. The absorbance at 230 nm also decreases with the treatment, but after the treatment time of 15 minutes, the absorbance starts to increase due to the increase in hydrogen peroxide. From this result, the point at which the change in absorbance at 230 nm starts from decreasing can be set as the end point.

(Example 2)
In order to measure the amount of dioxins in the organic compound of the liquid to be treated after the ozone treatment, the following experiment was conducted. That is, the waste water containing dioxins was processed using the apparatus shown in FIG. In an ozone treatment tank with a stored water amount of 7 m ³ , ozone having a concentration of 150 g / Nm ³ was supplied at 10 L / min, and the absorbance of the liquid to be treated was measured by the densitometer 3. The concentration of the organic compound in the treatment liquid was measured at a measurement wavelength of 260 nm, the treatment liquid was sampled, and the hydrogen peroxide concentration was measured using a test paper (hydrogen peroxide test paper manufactured by Mitsubishi Gas Chemical). The results are as shown in Table 2 and FIG.

  As the process proceeds, the organic matter concentration decreases and the absorbance at 260 nm also decreases. After the treatment time of 24 hours, the absorbance no longer changed and the hydrogen peroxide concentration increased, so the ozone treatment was terminated.

Subsequently, AOP treatment was performed. That is, the liquid to be treated was sent to the ultraviolet treatment tank shown in FIG. 2 to perform accelerated oxidation treatment. In an ultraviolet treatment tank having a reserved water amount of 7 m ³ , ozone having a concentration of 150 g / Nm ³ was supplied at 10 L / min, the ultraviolet lamp 22 was turned on, and the absorbance of the liquid to be treated was measured by the densitometer 4. While measuring the concentration of the organic compound in the treatment liquid at a measurement wavelength of 260 nm, the treatment liquid was sampled and the dioxin concentration was measured. (Measured by rapid analysis method of Environmental Techno Co., Ltd.) The results are as shown in Table 3 and FIG. A similar experiment was performed again, and the results are shown in Table 4.

  Of the above results, a graph showing the relationship between the absorbance in Table 3 and the dioxin concentration is shown in FIG. As apparent from FIG. 6, there is a correlation between the absorbance and the dioxin concentration, and it can be seen that the dioxin concentration can be estimated by measuring the absorbance.

  As described above, according to the concentration measurement method of the present invention, it is possible to provide a correlation between the total organic compound concentration which does not originally have a correlation and the hardly decomposable organic compound concentration. The concentration of a hardly decomposable organic compound such as dioxins in the liquid to be treated can be estimated. In addition, in order to detect the end point of oxidation / decomposition of easily decomposable organic compounds that can be decomposed by ozone treatment, the timing of the end point is clarified by using the amount of hydrogen peroxide in the liquid to be treated. An efficient treatment is possible without causing excessive or insufficient oxidation / decomposition of the organic compound.

  In addition, this invention is not limited to the said embodiment, It can implement in another various aspect. For example, in the above embodiment, the ozone treatment and the ultraviolet treatment were performed by the circulation method, but the present invention is not limited to this, and any of a batch method and a continuous method can be performed.

It is a block diagram which shows the structure of the density | concentration measuring apparatus concerning 1st Embodiment of this invention. It is a block diagram which shows the structure of the organic compound decomposition | disassembly apparatus concerning 2nd Embodiment of this invention. It is a graph which shows the time-dependent change in the processing time in the ozone treatment of Example 1, an absorbance, and a hydrogen peroxide concentration. It is a graph which shows the time-dependent change in the processing time in the ozone processing of Example 2, and a light absorbency and hydrogen peroxide concentration. It is a graph which shows the time-dependent change in the processing time in the AOP process of Example 1, and a light absorbency and a dioxin density | concentration. It is a graph which shows the relationship of the density | concentration of the organic compound and dioxin of the to-be-processed liquid in the AOP process of Example 2. FIG. It is a graph which shows the correlation of COD and dioxin density | concentration. It is a figure explaining the ratio of the oxidative decomposition of the easily decomposable organic compound and the hardly decomposable organic compound in the liquid to be treated.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Concentration measuring device 2 Ozone processing tank 3 1st concentration meter 4 2nd concentration meter 5 Ozone supply device 6,7 Switching valve 10 Ozonizer 11,12 Nozzle 21 Ultraviolet processing tank 22 Ultraviolet lamp 100,101 Processed liquid

Claims (15)

A method for measuring the concentration of a hardly decomposable organic compound in a liquid to be treated, comprising a hardly decomposable organic compound not decomposed by ozone and an easily decomposable organic compound decomposable by ozone,
The ozone gas is supplied to the liquid to be treated within perform concentration measurement of hydrogen peroxide starts the decomposition of easily decomposable organic compounds, decompose hydrogen peroxide concentration of the liquid to be treated inside of the easily decomposable organic compound A concentration measuring method, wherein the concentration of the hardly decomposable organic compound in the liquid to be treated is measured by measuring the absorbance after the sample is retained until it reaches a reference value indicating that the liquid is substantially finished.   2. The concentration measurement according to claim 1, wherein the hydrogen peroxide is generated when most of the readily decomposable organic compound is decomposed and excess OH radicals generated from ozone react with each other. Method.   The concentration measuring method according to claim 1, wherein the hardly decomposable organic compound is dioxins.   The concentration measuring method according to claim 3, further comprising removing hydrogen peroxide in the liquid to be treated before measuring the absorbance.   The measurement wavelength used for measuring the absorbance of the hardly decomposable organic compound is 230 to 300 nm, and the measurement is performed using information on absorbance at least three points within a range where the ultraviolet absorption spectrum of ozone exhibits a peak, The density | concentration measuring method as described in any one of Claim 1 to 4. Concentration measurements before Symbol hydrogen peroxide is characterized by dividing lines by the absorbance measurement, concentration measurement method according to any one of claims 1 5. An apparatus for measuring the concentration of a hardly decomposable organic compound in a liquid to be treated, comprising a hardly decomposable organic compound that is not decomposed by ozone and a readily decomposable organic compound that can be decomposed by ozone,
An ozone decomposition treatment apparatus comprising an ozone treatment tank for accumulating the liquid to be treated and an ozone supply device for supplying ozone to the liquid to be treated accumulated in the treatment tank;
A first concentration measuring device for measuring a hydrogen peroxide concentration in the liquid to be treated accumulated in the ozonolysis treatment device;
A treatment liquid discharge pipe that discharges a liquid to be treated that contains the hydrogen peroxide measured by the first concentration measuring apparatus above a reference value indicating that the decomposition of the readily decomposable organic compound is substantially completed;
And a second concentration measuring device for measuring the concentration of the hardly decomposable organic compound in the liquid to be treated by measuring absorbance of the processing liquid discharged from the processing liquid discharge pipe. apparatus.   The concentration measuring apparatus according to claim 7, wherein the hardly decomposable organic compound is dioxins.   The measurement wavelength of the second concentration measuring device is 230 to 300 nm, and measurement is performed using information on absorbance at least three points within a range in which the ultraviolet absorption spectrum of ozone exhibits a peak. The concentration measuring apparatus according to 1.   8. The apparatus according to claim 7, further comprising a hydrogen peroxide removing device that removes hydrogen peroxide in the liquid to be treated at a position upstream of the second concentration measuring device of the treatment liquid discharge pipe. To 9. The concentration measuring device according to any one of 9 to 9.   The concentration measurement apparatus according to claim 10, wherein the hydrogen peroxide removing apparatus is an ultraviolet irradiation apparatus that irradiates the liquid to be treated with ultraviolet rays.   The concentration measuring apparatus according to claim 10, wherein the hydrogen peroxide removing apparatus is an erasing enzyme adding apparatus that adds an erasing enzyme that removes hydrogen peroxide to the liquid to be treated.   The concentration measuring device according to claim 7, wherein the first concentration measuring device is a device that measures a concentration by measuring absorbance. An organic compound decomposing apparatus that oxidizes and decomposes a hardly decomposable organic compound that is not decomposed by ozone contained in a liquid to be treated and an easily decomposable organic compound that can be decomposed by ozone, and supplies the liquid to be treated An ozone treatment tank that accumulates the liquid to be treated supplied from the supply pipe, and an ozone decomposition treatment apparatus that includes an ozone supply device that supplies ozone to the liquid to be treated accumulated in the ozone treatment tank;
A first concentration measuring device for measuring a hydrogen peroxide concentration in the liquid to be treated accumulated in the ozonolysis treatment device;
A first treatment liquid discharge pipe for discharging a liquid to be treated that contains the hydrogen peroxide measured by the first concentration measuring apparatus above a reference value indicating that the decomposition of the readily decomposable organic compound is substantially completed;
An ultraviolet treatment tank for accumulating the liquid to be treated supplied from the treatment liquid discharge pipe, and an ultraviolet irradiation device for irradiating the liquid to be treated accumulated in the treatment tank with ultraviolet rays, and accumulated in the ultraviolet treatment tank. An accelerated oxidation treatment apparatus capable of supplying ozone to the liquid to be treated;
A second concentration measuring device for measuring the concentration of the hardly decomposable organic compound in the liquid to be treated by measuring the absorbance in the liquid to be treated accumulated in the ultraviolet treatment tank;
An organic compound decomposing apparatus comprising: a second processing liquid discharge pipe that discharges the liquid to be processed to the outside when the absorbance of the second concentration measuring apparatus becomes a reference value or less.   The organic compound decomposing apparatus according to claim 14, further comprising a hydrogen peroxide removing device that removes hydrogen peroxide in the liquid to be treated in the first treatment liquid discharge pipe.

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