JP2007244930A - Method and apparatus for treating wastewater containing organic matter - Google Patents

Abstract

[PROBLEMS] To prevent a decrease in flux and biofouling due to the adhesion of organic matter on the membrane surface in an RO membrane separator when treating and collecting waste water containing organic matter using an RO membrane separator, and COD of RO concentrated water Efficiently reduce the value to prevent adverse effects on wastewater treatment etc. of RO concentrated water.
A scale inhibitor is added to an organic matter-containing wastewater, and an alkali is added to adjust the pH to 9.5 or higher, and water is passed through an RO membrane separator. A sulfur compound containing a peroxide group is added to the RO concentrated water, and oxidation treatment is performed by UV irradiation. By setting the pH of the RO water supply to 9.5 or higher, biofouling in the RO membrane separation device is prevented, and adhesion of the nonionic surfactant to the membrane surface is prevented, thereby preventing a decrease in flux. Addition of the scale inhibitor suppresses membrane surface clogging due to calcium carbonate scale under high pH conditions. Addition of sulfur compounds and UV irradiation generate sulfuric acid radicals with very high oxidizing power, decompose organic substances in concentrated water into carbon dioxide and nitrogen gas, and remove them from the water.
[Selection] Figure 1

Description

  In the present invention, when wastewater containing high or low concentration organic matter (TOC) discharged from an electronic device manufacturing factory or the like is treated and recovered using a reverse osmosis (RO) membrane separator, organic matter in the RO membrane separator Prevents decrease in flux due to adhesion of membrane surface and prevents bio-fouling for long-term stable treatment, and at the same time, efficiently reduces TOC concentration in water to obtain high-quality treated water, and RO membrane separation The present invention relates to a processing method and a processing apparatus for organic matter-containing wastewater that easily and efficiently treats concentrated water of the apparatus.

  In recent years, environmental standards and water quality standards tend to be stricter, and it is desired to purify discharged water to a high degree. On the other hand, for the purpose of eliminating water shortage, development of advanced water treatment technology is also desired in order to collect and reuse various wastewater.

  Under such circumstances, RO membrane separation treatment can effectively remove impurities (ions, organic substances, fine particles, etc.) in water, and has recently been used in many fields. It was. For example, when recovering and recycling wastewater containing high-concentration TOC or low-concentration TOC containing acetone, isopropyl alcohol, etc. discharged from the semiconductor manufacturing process, this is first biologically treated to remove the TOC component, A method of purifying by RO membrane treatment is widely adopted (for example, JP-A-2002-336886).

  However, in recent years, when biological treatment wastewater is passed through the RO membrane separation device, the problem that the membrane surface of the RO membrane is clogged and the flux decreases due to biological metabolites generated by the decomposition of organic matter by microorganisms begins to become apparent. It has become like this.

  On the other hand, when these TOC-containing wastewater is directly passed through the RO membrane separator without using biological treatment, the TOC concentration flowing into the RO membrane separator is high, so that microorganisms propagate in the RO membrane separator. Easy environment. Therefore, for the purpose of suppressing biofouling in the RO membrane separation apparatus, a large amount of slime control agent is usually added to TOC-containing wastewater. However, since the slime control agent is expensive, it is cheaper. There is a need for a new biofouling suppression method.

  In addition, the wastewater discharged from the electronic device manufacturing factory may be mixed with a nonionic surfactant that may adhere to the membrane surface of the RO membrane separator and reduce the flux. RO membrane separation treatment could not be applied to such nonionic surfactant-containing wastewater.

  When solving such problems and treating and collecting wastewater containing high or low concentration organic matter discharged from electronic device manufacturing factories and other various fields using RO membrane separators, As a technology to obtain high-quality treated water by efficiently reducing the TOC concentration in water while simultaneously performing stable treatment over a long period of time by preventing flux reduction and biofouling due to the adhesion of the organic material to the film surface First, add to the organic matter-containing wastewater an alkali to the organic matter-containing wastewater as well as adding a scale inhibitor at least 5 times the weight of calcium ions in the organic matter-containing wastewater. Thus, a method and apparatus for adjusting the pH to 9.5 or higher and then performing RO separation treatment have been proposed (Japanese Patent Laid-Open No. 2005-169372).

  In this way, RO membrane separation is performed by adding a predetermined amount of scale inhibitor to the water to be treated (hereinafter sometimes referred to as “RO feed water”) introduced into the RO membrane separation device and adjusting the pH to 9.5 or higher. By passing the water through the device, the following actions and effects can be performed for a long period of time to prevent a decrease in flux due to adhesion of the membrane surface of organic matter in the RO membrane separator and biofouling, and to perform stable treatment over a long period of time. It is possible to efficiently reduce the TOC concentration in water and obtain high quality treated water.

(1) The following effects can be obtained by adjusting the pH of the RO water supply to 9.5 or higher.
Microorganisms cannot live in alkaline areas. Therefore, by adjusting the pH of the RO feed water to 9.5 or more, it becomes possible to create an environment in which there are nutrient sources but microorganisms cannot live in the RO membrane separation device. Biofouling in the RO membrane separator can be suppressed without the need for addition.
In addition, nonionic surfactants that may lower the flux are known to be desorbed from the membrane surface in the alkaline region. By increasing the pH of the RO water supply to 9.5 or higher, these are applied to the RO membrane surface. It becomes possible to suppress adhesion of these components.

(2) The following effects can be obtained by adding a scale inhibitor 5 times or more times the calcium ion in the RO water supply to the RO water supply.
In rare cases, calcium ions, which are the basis of scale, may be mixed in TOC-containing wastewater discharged from an electronic device manufacturing factory or the like. Under high pH RO operating conditions where the pH of the RO feed water is 9.5 or higher, scales such as calcium carbonate are generated even when a very small amount of calcium ions are mixed, and the RO membrane is immediately blocked. Therefore, for the purpose of suppressing the membrane surface clogging due to such scale, a scale inhibitor is added to the RO water supply at least 5 times the weight of calcium ions in the RO water supply to prevent the generation of scale.
JP 2002-336886 A JP 2005-169372 A

  According to the technique described in Japanese Patent Application Laid-Open No. 2005-169372, wastewater containing high or low concentration organic substances discharged from electronic device manufacturing factories and other various fields, particularly wastewater containing nonionic surfactants, is RO membrane. When processing / recovering using a separator, the TOC concentration in the water is efficient while at the same time providing stable treatment over a long period of time by preventing flux reduction and biofouling due to the adhesion of the organic matter in the RO membrane separator. However, there are the following problems.

  That is, in accordance with the technique described in JP-A-2005-169372, concentrated water obtained by adding a scale inhibitor to RO water supply and performing RO membrane separation treatment (hereinafter sometimes referred to as “RO concentrated water”). Concentrates the added scale inhibitor, so that it contains a large amount of the scale inhibitor that is a COD component. That is, since the scale inhibitor does not permeate the RO membrane, it is concentrated on the concentrated water side. In particular, according to the technique of Japanese Patent Application Laid-Open No. 2005-169372, a large amount is contained in the RO concentrated water obtained by adding a large amount of scale inhibitor more than 5 times the weight of calcium ions in the RO feed water and subjecting it to RO membrane separation treatment. The scale preventive agent is included.

  Usually, RO concentrated water is transferred to a wastewater treatment process and discharged through biological treatment and coagulation sedimentation treatment. In general, scale inhibitors are difficult to remove by coagulation sedimentation treatment and biological treatment. The inhibitor also inhibits the aggregation reaction. Therefore, when RO concentrated water containing a large amount of scale inhibitor is transferred to the wastewater treatment process, the load of the wastewater treatment process is increased and the COD value in the discharged water is increased, thereby reducing the water quality. There is a fear.

  Accordingly, an object of the present invention is to provide an organic matter-containing wastewater treatment method and treatment apparatus that efficiently reduce the COD value of the RO concentrate water and prevent adverse effects on the wastewater treatment and the like of the RO concentrate water. To do.

  The treatment method for organic matter-containing wastewater according to the present invention (Claim 1) includes a scale inhibitor addition step for adding a scale inhibitor to the organic matter-containing wastewater, and a reverse osmosis membrane separation apparatus for treating the organic matter-containing wastewater to which the scale inhibitor is added. The organic matter having a reverse osmosis membrane separation step that is separated into permeated water and concentrated water, and a pH adjustment step that adjusts the pH of the organic matter-containing wastewater supplied to the reverse osmosis membrane separation device to 9.5 or higher In the method for treating contained wastewater, a sulfur compound containing a peroxide group is added to the concentrated water, and the concentrated water is irradiated with ultraviolet rays to oxidize the concentrated water.

  The method for treating wastewater containing organic matter according to claim 2 is characterized in that, in claim 1, the amount of the sulfur compound added is 40 times or more the TOC concentration of the concentrated water.

The method for treating wastewater containing organic matter according to claim 3 is characterized in that, in claim 1 or 2, the irradiation amount of the ultraviolet rays is 0.2 kwh / m ³ or more per 1 m ^{3 of the} concentrated water.

  The method for treating organic matter-containing wastewater according to claim 4 is the method according to any one of claims 1 to 3, wherein, in the scale inhibitor addition step, the organic matter-containing wastewater is added 5 times as much as calcium ions in the organic matter-containing wastewater. The above scale inhibitor is added.

  The method for treating organic matter-containing wastewater according to claim 5 is the method according to claim 4, wherein, in the scale inhibitor adding step, the organic matter-containing wastewater is added with a scale inhibitor 5 to 50 times as much as calcium ions in the organic matter-containing wastewater. It is characterized by adding.

  The method for treating organic matter-containing wastewater according to claim 6 is the method according to any one of claims 1 to 5, wherein the reverse osmosis membrane of the reverse osmosis membrane separator is 1500 mg / L of saline at 1.47 MPa, 25 ° C. It is a reverse osmosis membrane for low fouling of polyvinyl alcohol having a salt rejection rate of 95% or more when a reverse osmosis membrane separation treatment is performed under the condition of pH 7.

  The organic matter-containing wastewater treatment method according to claim 7 is characterized in that, in any one of claims 1 to 6, the pH of the organic matter-containing wastewater is adjusted to 10.5 to 12 in the pH adjustment step. .

  The method for treating wastewater containing organic matter according to claim 8 is characterized in that in any one of claims 1 to 7, the wastewater containing organic matter is subjected to cation exchange treatment prior to the addition of the scale inhibitor.

  The processing apparatus for organic matter-containing wastewater according to the present invention (claim 9) comprises a scale inhibitor addition means for adding a scale inhibitor to the organic matter-containing wastewater, and an organic matter-containing wastewater to which the scale inhibitor has been added. In the processing apparatus for organic matter-containing wastewater, comprising the reverse osmosis membrane separation device and the pH adjusting means for adjusting the pH of the organic matter-containing wastewater supplied to the reverse osmosis membrane separation device to 9.5 or more, the concentrated water And a sulfur compound adding means for adding a sulfur compound containing a peroxide group, and means for irradiating the concentrated water with ultraviolet light in the presence of the sulfur compound.

  An apparatus for treating organic matter-containing wastewater according to claim 10 is characterized in that, in claim 9, the amount of sulfur compound added by the sulfur compound addition means is 40 times or more the TOC concentration of the concentrated water.

An organic substance-containing wastewater treatment apparatus according to an eleventh aspect is characterized in that, in the ninth or tenth aspect, the ultraviolet irradiation amount of the ultraviolet irradiation means is 0.2 kwh / m ³ or more per 1 m ^{3 of the} concentrated water.

  The organic matter-containing wastewater treatment apparatus according to claim 12 is the processing apparatus according to any one of claims 9 to 11, wherein, in the scale inhibitor addition means, the organic matter-containing wastewater is 5 times as much as calcium ions in the organic matter-containing wastewater. The above scale inhibitor is added.

  An apparatus for treating organic matter-containing wastewater according to claim 13 is characterized in that, in claim 12, in the scale inhibitor addition means, the organic matter-containing wastewater is provided with a scale inhibitor 5 to 50 times as much as calcium ions in the organic matter-containing wastewater. It is characterized by adding.

  The organic matter-containing wastewater treatment device according to claim 14 is the treatment device according to any one of claims 9 to 13, wherein the reverse osmosis membrane of the reverse osmosis membrane separation device is 1500 mg / L of saline at 1.47 MPa, 25 ° C. It is a reverse osmosis membrane for low fouling of polyvinyl alcohol having a salt rejection rate of 95% or more when a reverse osmosis membrane separation treatment is performed under the condition of pH 7.

  The organic matter-containing wastewater treatment apparatus according to claim 15 is characterized in that, in any one of claims 9 to 14, the pH adjusting means adjusts the pH of the organic matter-containing wastewater to 10.5 to 12. .

  The organic matter-containing wastewater treatment apparatus according to claim 16 is provided with a cation exchange tower for cation exchange treatment of the organic matter-containing wastewater supplied to the scale inhibitor addition means according to any one of claims 9 to 15. And

  According to the method and apparatus for treating organic matter-containing wastewater of the present invention, wastewater containing high-concentration or low-concentration organic matter discharged from an electronic device manufacturing factory and other various fields, particularly wastewater containing a nonionic surfactant. When processing / recovering using RO membrane separators, the TOC concentration in the water is reduced at the same time as performing stable treatment over a long period of time by preventing flux reduction and biofouling due to organic membrane adhesion in the RO membrane separator. Can be efficiently reduced to obtain high-quality treated water. Moreover, it is possible to easily and efficiently treat the organic substance containing the scale inhibitor in the RO concentrated water to reduce the load on the subsequent wastewater treatment process.

  That is, in the present invention, since the scale inhibitor is added to the RO water supply and the pH is adjusted to 9.5 or higher and water is passed through the RO membrane separator, as described above, biofouling in the RO membrane separator is performed. In addition, it is possible to suppress clogging of the film surface due to the scale.

  In addition, it is derived from the scale inhibitor in RO concentrated water by adding a sulfur compound containing a peroxide group to the RO concentrated water obtained by adding the scale inhibitor to the RO water supply and irradiating with ultraviolet rays (UV). It is possible to efficiently remove organic substances in the concentrated water including the COD component.

  That is, when a predetermined amount of a sulfur compound containing a peroxide group is added to RO concentrated water and irradiated with UV, sulfuric acid radicals having very high oxidizing power are generated, and the organic substances in the concentrated water are converted into carbon dioxide gas or nitrogen by the sulfuric acid radicals. It can be oxidatively decomposed to gas and removed from water. This sulfuric acid radical has a much higher oxidizing power than the case of an oxidizing agent alone or UV irradiation alone, and can also decompose a scale inhibitor that is difficult to oxidatively decompose.

  In the present invention, if the amount of the sulfur compound containing a peroxide group to the RO concentrated water is too small, the generation of the sulfate radicals is insufficient, and a sufficient COD or TOC removal effect cannot be obtained. The compound addition amount is preferably 40 times or more the TOC concentration of concentrated water (claims 2 and 10).

On the other hand, if the UV irradiation amount is too small, the generation of OH radicals, which are the basis for the generation of sulfuric acid radicals, will be insufficient, and a sufficient COD or TOC removal effect cannot be obtained, so 0.2 kwh / m per unit concentrated water amount. It is preferably ³ or more (claims 3 and 11).

In addition, if the amount of the scale inhibitor added to the organic matter-containing wastewater is too small, a sufficient scale prevention effect cannot be obtained. Therefore, the amount of the scale inhibitor added to the organic matter-containing wastewater is the amount of calcium ions in the RO water supply. It is preferable that the weight be 5 times or more (claims 4 and 12).
In the present invention, the amount of the scale inhibitor added is a value converted in the form of an acid even when the scale inhibitor is a salt such as a sodium salt.

  In the present invention, in particular, as the RO membrane, a salt rejection rate (hereinafter simply referred to as “salt exclusion rate”) when the RO membrane separation treatment is performed with 1500 mg / L of saline under the conditions of 1.47 MPa, 25 ° C., and pH 7. The membrane separation treatment is preferably performed using a polyvinyl alcohol-based low-fouling RO membrane having a desalting performance of 95% or more. The reason why it is preferable to use such a low fouling RO membrane is as follows.

  That is, the low-fouling RO membrane is superior in contamination resistance because it eliminates the chargeability of the membrane surface and improves the hydrophilicity as compared with a commonly used aromatic polyamide membrane. However, with respect to water containing a large amount of nonionic surfactant, its antifouling effect is reduced, and the flux decreases with time.

  On the other hand, in the present invention, by adjusting the pH of the RO water supply to 9.5 or higher, the nonionic surfactant that may lower the RO membrane flux is desorbed from the membrane surface, so that an aromatic system that is usually used is used. Even when a polyamide film is used, it is possible to suppress an extreme decrease in flux. However, when the nonionic surfactant concentration in the RO water supply is high, the effect is also reduced, and the flux is lowered in the long term.

  Therefore, in the present invention, in order to solve such problems, preferably, the polyvinyl alcohol-based RO membrane for low fouling having the above-mentioned specific desalting performance and the pH of the RO water supply are 9.5 or more. In combination with the conditions for passing water, it is possible to perform stable operation over a long period of time without causing a decrease in flux even for RO water containing a high concentration of nonionic surfactant.

In the present invention, it is preferable to employ the following conditions in order to perform more efficient processing.
(1) The RO feedwater pH is preferably 10.5 or more, particularly 10.5 to 12 (claims 7 and 15).
(2) The addition amount of the scale inhibitor is 5 to 50 times the calcium ion concentration (Claims 5 and 13).
(3) When the calcium ion concentration of the RO feed water is high, cation exchange treatment is performed as a pretreatment for adding the scale inhibitor to remove calcium (claims 2 and 16).

  DESCRIPTION OF EMBODIMENTS Embodiments of a method and apparatus for treating organic matter-containing wastewater according to the present invention will be described in detail below with reference to the drawings.

  FIG. 1 is a system diagram showing an embodiment of the method and apparatus for treating wastewater containing organic matter according to the present invention.

  In FIG. 1, after adding a scale inhibitor to raw water (organic matter-containing wastewater) introduced through the tank 1, the pH is adjusted to 9.5 or higher by adding an alkali, and then introduced into the RO membrane separation device 2 to return to the RO membrane. Separated.

  As the scale inhibitor to be added to the raw water, chelate-based scale inhibitors such as ethylenediaminetetraacetic acid (EDTA) and nitrilotriacetic acid (NTA), which easily dissociate in the alkaline region and form a complex with metal ions, are preferably used. Other low molecular weight polymers such as (meth) acrylic acid polymer and salts thereof, maleic acid polymer and salts thereof, ethylenediaminetetramethylenephosphonic acid and salts thereof, hydroxyethylidene diphosphonic acid and salts thereof, nitrilotrimethylenephosphonic acid and salts thereof Phosphonic acids and phosphonates such as salts, phosphonobutanetricarboxylic acid and salts thereof, hexametaphosphoric acid and salts thereof, inorganic polymer phosphoric acid and inorganic polymer phosphate such as tripolyphosphoric acid and salts thereof, and the like can be used. These scale inhibitors may be used individually by 1 type, and may use 2 or more types together.

  In the present invention, the addition amount of the scale inhibitor is preferably at least 5 times the calcium ion concentration in the raw water (water to which the scale inhibitor is added). If the addition amount of the scale inhibitor is less than 5 times the calcium ion concentration in the raw water, the effect of adding the scale inhibitor cannot be sufficiently obtained. Even if the scale inhibitor is added in an excessively large amount, it is not preferable in terms of drug cost. Therefore, the scale inhibitor is preferably 5 to 50 times the calcium ion concentration in the raw water.

  The raw water to which the scale inhibitor has been added is then adjusted to pH 9.5 or higher, preferably 10 or higher, more preferably 10.5 to 12, for example pH 10.5 to 11 by adding an alkaline agent to the RO membrane separator 2. To introduce. The alkaline agent used here is not particularly limited as long as it is an inorganic alkaline agent that can adjust the pH of raw water to 9.5 or higher, such as sodium hydroxide and potassium hydroxide.

  Examples of the RO membrane of the RO membrane separation apparatus 2 include those having alkali resistance, for example, polyetheramide composite membrane, polyvinyl alcohol composite membrane, aromatic polyamide membrane, etc., preferably for the above reasons, the salt rejection rate A low-fouling RO membrane of 95% or more of polyvinyl alcohol is used. This RO membrane may be of any type such as a spiral type, a hollow fiber type, and a tubular type.

  Next, the permeated water of the RO membrane separation device 2 is adjusted to pH 4 to 8 by adding an acid, and further subjected to activated carbon treatment or the like as necessary, and then reused or discharged. There is no restriction | limiting in particular as an acid used here, Mineral acids, such as hydrochloric acid and a sulfuric acid, are mentioned.

  On the other hand, the concentrated water of the RO membrane separation device 2 contains a sulfur compound containing a peroxide group (hereinafter sometimes referred to as “peroxide-based sulfur compound”) and then passes through the UV oxidation device 3 to be contained. After COD or TOC is decomposed and removed, it is discharged out of the system.

  The peroxide-based sulfur compound added to the RO concentrated water may be any sulfur compound containing a peroxide group such as peroxydisulfate such as sodium peroxydisulfate, ammonium peroxydisulfate, and potassium peroxydisulfate. Don't do it. These peroxide-based sulfur compounds may be used alone or in combination of two or more.

  The added amount of the peroxide-based sulfur compound is preferably 40 times by weight or more, particularly preferably 100 to 200 times by weight, relative to the TOC concentration of the RO concentrated water. If the added amount of the peroxide-based sulfur compound is less than 40 times the TOC concentration of the concentrated water, the generation of sulfur radicals is not sufficient, and the TOC removal rate is extremely reduced. If the amount of peroxide-based sulfur compound added is too large, a large amount of sulfate ions will be generated by radical reaction, the pH of the treated water will be extremely lowered, and the amount of neutralizing agent for wastewater treatment, which is the destination of the treated water, will increase. This is inconvenient, so the above range.

Further, the UV irradiation amount is preferably 0.2 kwh / m ³ or more per unit amount of concentrated water. When this UV irradiation amount is less than 0.2 kwh / m ³ , the generation of OH radicals that are the basis for the generation of sulfuric acid radicals is not sufficient, and the TOC removal rate is extremely lowered. From the viewpoint of UV irradiation cost and processing efficiency, the UV irradiation amount is preferably 0.5 to 2 kwh / m ³ .

  The addition of the peroxide-based sulfur compound and the UV irradiation can be performed at a high pH without particularly adjusting the pH of the concentrated water, but the pH of the concentrated water is adjusted to around 5 to 8 neutral. You can go after that.

  Since the TOC concentration of the RO concentrated water obtained in this way is sufficiently reduced, it may be discharged as it is or after adjusting the pH by adding an acid if necessary. You may mix with and send to a wastewater treatment process and process. Alternatively, this can be passed through a deionizer and recovered as deionized water.

  In addition, in the case where peroxide-based sulfur compounds remain in the oxidized water, it is desirable to remove them in order to eliminate adverse effects on the latter stage. Bisulfite is used as a means for removing residual peroxide-based sulfur compounds. There is addition of a reducing agent such as sodium or water flow to an activated carbon tower packed with activated carbon or a catalyst tower packed with a catalyst such as platinum or palladium.

  As shown in FIG. 1, by adding a predetermined amount of scale inhibitor to raw water and adjusting the pH to 9.5 or higher and then performing RO membrane separation treatment, long-term reduction in flux in the RO membrane separation device is caused without causing a decrease in flux. It is possible to obtain a high-quality treated water from which TOC is highly removed by performing a stable treatment over a period of time. Moreover, the organic substance in concentrated water can be highly oxidatively decomposed and removed by adding a peroxide sulfur compound to the RO concentrated water obtained by this RO membrane separation treatment and irradiating with UV.

  FIG. 1 shows an example of an embodiment of the present invention, and the present invention is not limited to the illustrated one as long as the gist thereof is not exceeded. In FIG. 1, after adding the scale inhibitor to the raw water, the alkali is added to adjust the pH, but after adding the alkali to the raw water and adjusting the pH, the scale inhibitor may be added. You may perform pH adjustment and the addition of a scale inhibitor simultaneously. Further, the process by the RO membrane separation apparatus is not limited to a single stage process, and may be a multistage process having two or more stages. In addition, in TOC-containing wastewater discharged from electronic device manufacturing factories, there are few cases where calcium ions, etc., which cause scales are basically mixed, but when calcium ions, etc. are mixed in raw water, scale prevention Prior to the addition of the agent, a cation exchange tower for removing calcium ions may be provided to remove calcium in advance. Furthermore, you may provide the mixing tank for pH adjustment and the addition of a scale inhibitor.

  Moreover, you may provide the stirring tank which adds and stirs a peroxide type sulfur compound in the process of RO concentrated water. In addition, when multistage treatment of two or more stages is performed by the RO membrane separation apparatus, such oxidative decomposition treatment may be performed only for the RO concentrated water of the first stage RO membrane separation apparatus, and for other RO concentrated water A similar process may be performed.

  Hereinafter, the present invention will be described in more detail with reference to Examples, Comparative Examples and Reference Examples.

Example 1
Wastewater with a TOC concentration of 3 mg / L and calcium ion concentration of 10 mg / L is used as raw water, and EDTA-based scale inhibitor (ethylenediaminetetraacetic acid sodium salt) is added to the raw water as 5 times the calcium ion concentration of the raw water and then NaOH is added. Then, the pH was set to 10.5, and RO membrane separation treatment was performed with a RO membrane separator (Nitto Denko's low-pressure aromatic polyamide RO membrane “ES-10”) under conditions of a water flow rate of 80 L / h and a recovery rate of 75%.

The change over time in the rate of decrease of the membrane flux (25 ° C., 1.47 MPa) of the RO membrane separator at this time was examined, and the results are shown in Table 1.
Further, after adding sodium peroxydisulfate (Na ₂ S ₂ O ₈ ) to the RO concentrated water obtained by this RO membrane separation treatment so as to be 40 times the TOC concentration of the concentrated water, it is passed through a UV oxidizer. It was water-oxidized with a UV irradiation amount of 0.2 kwh / m ³ per unit amount of concentrated water.
The removal rate of TOC in the RO concentrated water by addition of the peroxide sulfur compound and UV irradiation was examined, and the results are shown in Table 1.

Example 2
In Example 1, raw water and RO concentrated water were treated in the same manner except that an acrylic acid-based scale inhibitor (polyacrylic acid) was added to the raw water as a scale inhibitor, and the results are shown in Table 1.

Comparative Examples 1 and 2
In Example 1, the raw water was treated in the same manner except that the pH of the RO water supply was set to 7 (Comparative Example 1) or 5 (Comparative Example 2). The results are shown in Table 1.

Reference examples 1 and 2
In Example 1, the raw water was treated in the same manner except that the addition amount of the scale inhibitor was 1 times the calcium ion concentration of the raw water (Reference Example 1), or 3 times (Reference Example 2). The results are shown in Table 1.

Examples 3-5
In Example 1, the amount of sodium peroxydisulfate added was 10 times (Example 3), 30 times (Example 4), or 200 times (Example 5) the TOC concentration of concentrated water. The raw water and RO concentrated water were treated in the same manner, and the results are shown in Table 1.

Examples 6-8
In Example 1, the UV irradiation amount was 0.1 kwh / m ³ (Example 6), 0.15 kwh / m ³ (Example 7), or 0.3 kwh / m ³ (Example 8) per unit amount of concentrated water. The raw water and the RO concentrated water were treated in the same manner except for the above, and the results are shown in Table 1.

From Table 1, the following is clear.
<RO membrane separation treatment of raw water>
In any of the Examples, the decrease in membrane flux could be prevented over a long period of time by adding a scale inhibitor to adjust the pH of the RO feed water. On the other hand, in Comparative Examples 1 and 2, it became clear that the membrane flux decreased to about 20% of the initial membrane flux in 20 days from the start of operation. Adsorption of organic substances was observed from the closed film surface. On the other hand, from Reference Examples 1 and 2, it is clear that the membrane flux decreases more slowly as the scale dispersant is added, but the membrane surface is clogged if it is not added more than 5 times the calcium ion concentration of the raw water. became. When this closed membrane surface was analyzed, precipitation of CaCO ₃ scale was observed.

<Oxidation treatment of RO concentrated water>
From Examples 1 to 8, the TOC removal rate is improved as the amount of sodium peroxydisulfate added and the amount of UV irradiation per unit concentrated water increase, but the amount of sodium peroxydisulfate added is reduced to 40% of the TOC concentration of concentrated water. It was revealed that the removal rate was 90% or more when the UV irradiation amount per unit concentrated water was 0.2 kwh / m ³ or more by weight times or more.
Moreover, it was confirmed that the addition of the peroxide-based sulfur compound and the oxidation treatment by UV irradiation are effective for both the EDTA-based scale inhibitor and the acrylic acid-based scale inhibitor.

  INDUSTRIAL APPLICABILITY The present invention is effectively applied to water treatment for discharging, collecting or reusing wastewater containing high or low concentration TOC discharged in the electronic device manufacturing field, semiconductor manufacturing field, and other various industrial fields.

It is a systematic diagram which shows embodiment of the processing method and processing apparatus of the organic substance containing waste_water | drain of this invention.

Explanation of symbols

1 Tank 2 RO membrane separator 3 UV oxidation system

Claims (16)

A scale inhibitor addition process for adding a scale inhibitor to wastewater containing organic matter,
A reverse osmosis membrane separation step of supplying organic matter-containing wastewater to which the scale inhibitor has been added to a reverse osmosis membrane separation device and separating the permeated water and concentrated water;
In the method for treating organic matter-containing wastewater, the pH adjustment step of adjusting the pH of the organic matter-containing wastewater supplied to the reverse osmosis membrane separation device to 9.5 or more,
A method for treating organic matter-containing wastewater, wherein a sulfur compound containing a peroxide group is added to the concentrated water, and the concentrated water is oxidized by irradiating with ultraviolet rays.   In Claim 1, the addition amount of the said sulfur compound is 40 weight times or more of the TOC density | concentration of the said concentrated water, The processing method of the organic substance containing waste_water | drain characterized by the above-mentioned. ^{3. The} method for treating organic matter-containing wastewater according to claim 1, wherein an irradiation amount of the ultraviolet rays is 0.2 kwh / m ³ or more per 1 m ^{3 of the} concentrated water.   In any 1 item | term of Claim 1 thru | or 3, In the said scale inhibitor addition process, the scale inhibitor more than 5 weight times of the calcium ion in this organic matter containing waste water is added to the said organic matter containing waste water, It is characterized by the above-mentioned. To treat organic wastewater.   5. The treatment of organic matter-containing wastewater according to claim 4, wherein, in the scale inhibitor addition step, a scale inhibitor that is 5 to 50 times the calcium ion in the organic matter-containing wastewater is added to the organic matter-containing wastewater. Method.   The reverse osmosis membrane according to any one of claims 1 to 5, wherein the reverse osmosis membrane of the reverse osmosis membrane separation device is obtained by subjecting 1500 mg / L saline to reverse osmosis membrane separation under the conditions of 1.47 MPa, 25 ° C, and pH 7. An organic matter-containing wastewater treatment method comprising a polyvinyl alcohol-based low fouling reverse osmosis membrane having a desalting performance with a salt rejection rate of 95% or more.   The method for treating organic matter-containing wastewater according to any one of claims 1 to 6, wherein in the pH adjustment step, the pH of the organic matter-containing wastewater is adjusted to 10.5 to 12.   The method for treating organic matter-containing wastewater according to any one of claims 1 to 7, wherein the organic matter-containing wastewater is subjected to cation exchange treatment prior to the addition of the scale inhibitor. A scale inhibitor addition means for adding a scale inhibitor to organic matter-containing wastewater,
A reverse osmosis membrane separation device that separates organic matter-containing wastewater to which the scale inhibitor is added into permeated water and concentrated water;
In a treatment apparatus for organic matter-containing wastewater having pH adjusting means for adjusting the pH of the organic matter-containing wastewater supplied to the reverse osmosis membrane separation device to 9.5 or more,
An organic matter-containing wastewater treatment apparatus comprising: a sulfur compound addition means for adding a sulfur compound containing a peroxide group to the concentrated water; and a means for irradiating the concentrated water with ultraviolet light in the presence of the sulfur compound. .   10. The apparatus for treating organic matter-containing wastewater according to claim 9, wherein an addition amount of the sulfur compound of the sulfur compound addition means is 40 times or more the TOC concentration of the concentrated water. The apparatus for treating wastewater containing organic matter according to claim 9 or 10, wherein the ultraviolet irradiation amount of the ultraviolet irradiation means is 0.2 kwh / m ³ or more per 1 m ^{3 of the} concentrated water.   In any one of Claims 9 thru | or 11, In the said scale inhibitor addition means, the scale inhibitor more than 5 weight times of the calcium ion in this organic matter containing waste water is added to the said organic matter containing waste water, It is characterized by the above-mentioned. Organic wastewater treatment equipment.   13. The treatment of organic matter-containing wastewater according to claim 12, wherein in the scale inhibitor addition means, the organic matter-containing wastewater is added with a scale inhibitor 5 to 50 times the calcium ion in the organic matter-containing wastewater. apparatus.   The reverse osmosis membrane according to any one of claims 9 to 13, wherein the reverse osmosis membrane of the reverse osmosis membrane separation device is obtained by subjecting 1500 mg / L saline to reverse osmosis membrane separation under the conditions of 1.47 MPa, 25 ° C, and pH 7. An organic matter-containing wastewater treatment apparatus, which is a polyvinyl alcohol-based low fouling reverse osmosis membrane having a salt rejection of 95% or more.   15. The apparatus for treating organic matter-containing wastewater according to any one of claims 9 to 14, wherein the pH adjusting means adjusts the pH of the organic matter-containing wastewater to 10.5 to 12.   The apparatus for treating organic matter-containing wastewater according to any one of claims 9 to 15, further comprising a cation exchange tower for subjecting the organic matter-containing wastewater supplied to the scale inhibitor addition means to cation exchange treatment.

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