JP3468619B2 - Method for removing organic halogen compounds and petroleum hydrocarbons from tap water or well water - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for removing trace amounts of organic halogen compounds and petroleum hydrocarbons dissolved in tap water, well water, industrial water, and the like. Electronics industry that manufactures semiconductors and liquid crystals as drinking water,
The present invention relates to a method for efficiently removing trace amounts of organic halogen compounds and petroleum hydrocarbons dissolved in tap water, well water, and the like used in nuclear power plants, pharmaceutical manufacturing plants, and the like. 2. Description of the Related Art In recent years, a large amount of nutrients such as phosphorus and nitrogen from urban wastewater, industrial wastewater, agricultural wastewater, etc., flows into rivers, lakes and marshes. A large amount of algae such as phytoplankton are generated.
Algae such as phytoplankton generate large amounts of organic substances by themselves or by metabolites, and increase the concentration of organic substances in water such as rivers and lakes. Therefore, when tap water is used to purify raw water from eutrophic rivers and lakes, a large amount of chlorine is added for sanitary, sterilization, or purification purposes because organic substances cannot be completely removed. Must. However, if a large amount of chlorine is added to tap water having a high organic substance concentration, the organic substance reacts with chlorine to produce trihalomethanes (organic halogen compounds such as chloroform and three halogen substances bonded to carbon). The trihalomethanes and the like thus produced have high carcinogenicity and teratogenicity, and when dissolved in tap water, pose a serious problem in hygiene. Further, chloroethane and chloroethylene such as 1,1,1-trichloroethane, 1,2-dichloroethane, trichloroethylene and tetrachloroethylene which are used as a degreasing agent for dry cleaning and machinery also have carcinogenicity. Teratogenic. Therefore, although these are usually used in a closed system, even a small amount of water penetrates underground from a part of the closed system and becomes a serious problem when mixed with groundwater. Furthermore, petroleum hydrocarbons such as benzene, toluene, and xylene may penetrate underground and mix into groundwater from factory wastewater from factories that handle dyes, synthetic polymer materials, etc., and agricultural wastewater contaminated with pesticides. . In fact, even in the well water, volatile organic halogen compounds and petroleum hydrocarbons are dissolved in trace amounts, which is a problem in hygiene. [0004] When such tap water or well water is used as raw water of ultrapure water widely used in electronic industries for manufacturing semiconductor devices and liquid crystals, nuclear power plants, pharmaceutical manufacturing plants, etc. Unremoved organic halogen compounds and petroleum hydrocarbons reduce the efficiency of organic substance decomposition in the organic substance decomposer installed in the ultrapure water production equipment, and consequently the water quality of ultrapure water, thereby lowering product yield. And so on. Conventionally, methods for removing organic halogen compounds dissolved in water include (1) an adsorption treatment method in which an organic halogen compound is adsorbed and removed by a substance (adsorbent) having an adsorbing action such as activated carbon; ) A photodecomposition method in which an organic halogen compound is decomposed by a photoreaction using a semiconductor catalyst such as titanium oxide, and (3) a metal powder such as iron serving as a reduction catalyst converts, for example, trichlorethylene into chlorine gas and ethylene gas which is chemically stable. (4) a biological treatment method for biodegrading an organic halogen compound by living organisms constituting activated sludge, etc .; and (5) an organic halogen compound dissolved in water by boiling is pushed toward the gas phase. (6) A large amount of gas is sent into water, and the organic halogen compound dissolved in the liquid phase is moved to the gas phase by the gas partial pressure difference. Aerated how to drive out to, and the like have been studied. However, the method (1) requires a large amount of the adsorbent due to the adsorbing ability of the adsorbent, which is costly and has a higher affinity for the adsorbent than the target substance. When a substance having high affinity is present in the vicinity of the adsorbent, the adsorbent releases a target substance, and there is a problem that a substance having a higher affinity for the adsorbent is adsorbed. In the photodecomposition method (2), the turbid components (fine particles and the like) present in the water block the transmission of light. There was a problem that required. Further, in the reduction treatment method (3), it is difficult to maintain the catalytic activity of the metal powder as the reduction catalyst, and there is a problem that the metal powder is mixed into the water to be treated. In the biological treatment method (4), the treatment speed is slow, so the apparatus must be large. In the boiling method (5), a large amount of energy is required for boiling.
There has been a problem that operating costs are high. Also,
In the aeration method (6), there is a problem that an organic substance having a strong interaction with water in an aqueous solution such as trihalomethane cannot be efficiently removed. Further, conventionally, as a method for removing petroleum hydrocarbons dissolved in water, (7) the petroleum hydrocarbons dissolved in the liquid phase are moved to the gas phase by aeration,
An aeration method for removing petroleum hydrocarbons, and (8) an ultraviolet ray decomposition method for decomposing petroleum hydrocarbons into carbon dioxide by ultraviolet rays have been studied. However, in the aeration method (7), petroleum hydrocarbons cannot be removed efficiently, and in the ultraviolet decomposition method (8), turbid components (fine particles and the like) existing in water block transmission of ultraviolet light. , It takes a long reaction time to decompose petroleum hydrocarbons by irradiating ultraviolet rays uniformly,
Further, there is a problem in that the operation cost is increased in the decomposition by irradiation with ultraviolet rays. SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned conventional problems, and is intended for drinking water or for the electronics industry for producing semiconductor devices and liquid crystals, for nuclear power plants, for pharmaceutical production. An object of the present invention is to provide a method of removing trace amounts of organic halogen compounds and petroleum hydrocarbons dissolved in tap water or well water used in factories and the like at low cost, stably with time, and with high efficiency. I do. [0010] According to the present invention, tap water or
Method for removing organic halogen compounds and petroleum hydrocarbon well water, organic halogen compounds traces and petroleum coal
Tap water or well water in which hydrogen hydride is dissolved has a pH of 2.0
A first step of adjusting to 3.0 , aerated air and the water to be treated are brought into countercurrent contact, and a small amount of organic halogen compounds and petroleum hydrocarbons dissolved in the water to be treated are forcibly transferred to the aerated air. The second step is performed in order. In the present invention, the organic halogen compounds to be removed include, for example, trihalomethanes such as chloroform, dichlorobromoform, chlorodibromoform, and broloform, 1,1,1-trichloroethane, 1,2-dichloroethane, and the like. Chloroethanes such as trichloroethylene and tetrachloroethylene and chloroethylenes are mentioned, and petroleum hydrocarbons include organic solvents such as benzene, toluene and xylene. [0012] In the present invention, in order to remove the organic halogen compound or a petroleum hydrocarbon traces of dissolved in tap water or well water, Piita of the water to be treated is 2.0 to 3.0 two tone
Is adjusted . The treated water whose p た has been adjusted to the acidic side is brought into countercurrent contact with aerated air, and trace organic halogen compounds and petroleum hydrocarbons present in the treated water are forcibly transferred to the aerated air and efficiently removed. You. In the present invention, by adjusting the water to be treated to be acidic, it is considered that the interaction between the organic halogen compound or petroleum hydrocarbon and water is weakened.
As a result of the aeration treatment, organic halogen compounds and petroleum hydrocarbons are more likely to move to the gas phase side, and it is estimated that trace amounts of organic halogen compounds and petroleum hydrocarbons present in the water to be treated can be removed efficiently. . In the present invention, to adjust the water to be treated to be acidic, a method of adding an acid such as hydrochloric acid or sulfuric acid to the water to be treated, a method of passing the water to be treated through a cation exchange apparatus, or a method of these methods And the like are used in combination,
There is no particular limitation as long as the water to be treated can be adjusted to be acidic. [0015] In addition, when the aerated air and the water to be treated are brought into countercurrent contact with each other to forcibly transfer trace organic halogen compounds and petroleum hydrocarbons dissolved in the water to be treated to the aerated air, it is necessary to use terraret, Raschig ring or the like. The water to be treated is supplied from the upper part of the packed bed filled with the filler having a large surface area,
A Jojo deaerator that introduces air from the lower part of the packed bed by a blower or the like can be suitably used. However, if the aerated air and the water to be treated are brought into countercurrent contact with each other and a small amount of organic halogen compounds and petroleum hydrocarbons dissolved in the water to be treated can be forcibly transferred to the aerated air, it is particularly preferable to use Jojo degassing. It is not limited to a device. Further, in the present invention, there are no particular restrictions on the capacity of the packed bed, the filler, the composition of the aerated air, and the like. There is no particular limitation on the flow rate of the water to be treated, the supply amount of the aerated air, and the like. That is, the capacity of the packed bed, the filler, the composition of the aerated air, the flow rate of the water to be treated, the supply amount of the aerated air, and the like are determined by the concentrations of the organic halogen compounds and petroleum hydrocarbons dissolved in the water to be treated and the organic halogen. It is appropriately determined according to the type of the compound and the petroleum hydrocarbon. Embodiments of the present invention will be described below in detail with reference to the drawings. (Example 1, Example 2, and Comparative Example 1) FIG. 1 is a view showing one example of a method for removing an organic halogen compound and a petroleum hydrocarbon in water according to the present invention. In FIG. 1, reference numeral 1 denotes an acid addition device for adding hydrochloric acid to the water to be treated, and 2 denotes a normal-pressure degassing device installed on a storage tank 3 for storing the water to be treated. Type (Nippon Steel Chemical Co., Ltd., filling diameter 450mm,
(Filling layer height 1800 mm). Reference numeral 4 denotes a filtration device for filtering air supplied to the atmospheric deaerator 2 by a filter, and 5 denotes a blower (Hitachi, Ltd.) for supplying the air filtered by the filter 4 to the atmospheric deaerator 2. ), V
B-030-E), and 6 is a transfer pump for sending the water to be treated stored in the storage tank 3 to a subsequent stage. Reference numeral 7 denotes a line for supplying the water to be treated to the upper part of the atmospheric deaerator 2, and reference numeral 8 denotes a line for supplying the air filtered by the filter 4 to the lower part of the atmospheric deaerator 2. Reference numerals 9 and 9 denote a line for discharging the air to which the trace amounts of volatile organic halogen compounds and petroleum hydrocarbons dissolved in the water to be treated have been transferred from the atmospheric deaerator 2. Reference numerals 11 and 12 indicate a line 7 for collecting water to be treated.
And a sampling cock installed on the line 10. Next, the operation steps of an embodiment according to the present invention will be described with reference to FIG. First, the water to be treated is supplied to the upper part of the atmospheric deaerator 2 at a flow rate of 3 m ³ / h through a line 7. In this process, the water to be treated is subjected to the addition of hydrochloric acid by the acid addition device 1 so that the pH is adjusted to 2.0 to 3.0 and supplied to the atmospheric deaeration device 2. On the other hand, the air filtered in the filtering device 4 is supplied to the lower part of the atmospheric degassing device 2 through the line 8 at a flow rate of 2.5 m ³ / min. The falling water to be treated and the ascending air are brought into countercurrent contact with each other in the atmospheric degassing device 2, and the organic halogen compounds and petroleum hydrocarbons contained in the water to be treated are transferred to air. . The water to be treated, from which the organic halogen compounds and petroleum hydrocarbons have been removed, flows into the storage tank 3 and is sent to the subsequent stage through the line 10 by the power of the transfer pump 6. The air into which the organic halogen compound and the petroleum hydrocarbon have been transferred is discharged to the outside of the atmospheric deaerator 2 through a line 9. Further, the water to be treated is collected from the sampling cocks 11 and 12 as necessary,
Water quality is analyzed. Next, a description will be given of Example 1 and Comparative Example 1, which were carried out using the embodiment of the present invention configured as described above. The water to be treated has a pH of 7.1 and a water temperature of 22.
Using the Atsugi water ° C., more addition of hydrochloric acid <br/> from acid addition apparatus 1, treatment water pH adjusted to 2.7 (Example
1) As a control, Atsugi City Water (Comparative Example 1) having a pH of 7.1 without adding hydrochloric acid was supplied to the atmospheric deaerator 2 to remove organic halogen compounds and petroleum hydrocarbons in the water. Then, the removal efficiency was examined. In Examples and Comparative Examples, the concentrations of organic halogen compounds and petroleum hydrocarbons in water were analyzed by GC-MS with purge and trap. Table 1 shows the analysis results of the concentration of each organic halogen compound and petroleum hydrocarbon contained in the water to be treated, Atsugi-shi water, and the water to be treated after the removal treatment in Example 1 and Comparative Example 1. 2 shows the results of analysis of the concentration of each organic halogen compound and petroleum hydrocarbon and the removal rate. [Table 1] Table from 1 results clear as, the Ru a pH of the water to be treated is low <br/>, the concentration of each organic halogen compounds and petroleum hydrocarbons contained in the water to be treated is reduced, often they effectively It can be seen that it has been removed. In particular, when the pH was adjusted to 2.7 (Example 1 ), each organic halogen compound contained in the water to be treated and a petroleum-based compound were compared with the control (Comparative Example 1) in which the pH remained 7.1. The total concentration of hydrocarbons is 10
% Or less, and highly efficient removal of organic halogen compounds and petroleum hydrocarbons has been achieved. (Example 2 and Comparative Example 2) FIG. 2 is a view showing another embodiment of the method for removing organic halogen compounds and petroleum hydrocarbons in water according to the present invention. In addition, about the same structure as FIG. 1, the same code | symbol as FIG. 1 is attached | subjected and detailed description is abbreviate | omitted. In FIG. 2, reference numeral 13 denotes a strongly acidic cation exchange resin duolite C which has been regenerated and converted into type Η in advance.
This is a cation exchange device filled with 56 liters of -20 (Rome & Haas). The ion exchange capacity of the cation exchange device 13 is 0.9 equivalent / liter-Resin. The route Α is a bypass line installed to bypass the cation exchange device 13,
The selection of the path is performed by opening and closing the control valves 14 to 17. That is, when the water to be treated is passed through the cation exchange device 13, the control valves 14 and 16
Is opened and the control valves 15 and 17 are closed. When the water to be treated is bypassed by the cation exchange device 13 by the path A, the control valves 14 and 16 are closed and the control valves 15 and 17 are opened. It is supposed to be. Next, the operation steps of another embodiment according to the present invention will be described with reference to FIG. First, the water to be treated is cation-exchanged in a cation exchange device 13 to adjust the pH to 2 to 6.5, and then is supplied to a line 7 at a flow rate of 3 m ³ / h at a normal pressure deaeration device 2.
To the top of the The air filtered by the filter 4 is supplied to the lower part of the atmospheric deaerator 2 at a flow rate of 2.5 m ³ / min through a line 8. The falling water to be treated and the ascending air are brought into countercurrent contact with each other in the atmospheric degassing device 2, and the organic halogen compounds and petroleum hydrocarbons contained in the water to be treated are transferred to air. . The water to be treated, from which the organic halogen compounds and petroleum hydrocarbons have been removed, flows into the storage tank 3 and is sent to the subsequent stage through the line 10 by the power of the transfer pump 6. The air into which the organic halogen compound and the petroleum hydrocarbon have been transferred is discharged to the outside of the atmospheric deaerator 2 through the line 9. Further, the water to be treated is collected from the sampling cocks 11 and 12 as necessary,
Water quality is analyzed. Next, the thus configured for Example 2 and Comparative Example 2 were performed with another embodiment of the present invention will be described. The water to be treated has a pH of 6.8 and a water temperature of 19
The water to be treated whose pH was adjusted to 2.6 by passing the well water through the cation exchange device 13 to exchange cations using the well water at a temperature of 0 ° C. (Example 2 ). PH 6.8
The as-well water (Comparative Example 2) was supplied to the atmospheric deaerator 2 to remove organic halogen compounds and petroleum hydrocarbons in the water, and the removal efficiency was examined. In this example and the comparative example, as in the example 1 and the comparative example 1, the concentrations of the organic halogen compound and the petroleum hydrocarbon in the water were determined by GC-MS with purge and trap. Table 2 shows the analysis results of the concentration of each organic halogen compound and petroleum hydrocarbon contained in the well water as the water to be treated, and the respective concentrations in the water after the removal treatment in Example 2 and Comparative Example 2. The analysis result of the concentration of the organic halogen compound and the petroleum hydrocarbon and the removal rate are shown. [Table 2] As is clear from the results in Table 2, by lowering the pH of the water to be treated, the concentration of each organic halogen compound and petroleum hydrocarbon contained in the water to be treated is reduced, and these are efficiently removed. You can see that. When the pH was adjusted to 2.6 (Example 2 ), each organic halogen compound and petroleum hydrocarbon contained in the water to be treated were compared with the control (Comparative Example 1) in which the pH remained 6.8. Has been reduced to about 5%, and highly efficient removal of organic halogen compounds and petroleum hydrocarbons has been achieved. According to the present invention, the water to be treated is adjusted to be acidic and then brought into countercurrent contact with the aerated air, so that trace amounts of organic halogen compounds and petroleum-based carbon present in the water to be treated are present. Hydrogen easily migrates to aerated air and is efficiently removed. According to the present invention, when removing trace amounts of organic halogen compounds and petroleum hydrocarbons present in the water to be treated, the water to be treated may be adjusted to be acidic and brought into countercurrent contact with aerated air. Therefore, (1) the problem of high cost due to the use of a large amount of adsorbent and the problem of re-elution of the organic halogen compound from the adsorbent are avoided. (2) Since there is no need to irradiate light, the method can be applied to water to be treated which has a large amount of turbid components (fine particles and the like), and the organic halogen compound can be removed in a short treatment time. Furthermore, unlike (3) a reaction using a catalyst, it is stable over time, (4) the processing speed is high, a small apparatus is required, and (5) the water temperature does not need to be particularly increased, so that space is saved. In addition, the organic halogen compound being processed can be removed at a low operating cost. Further, (6) it is considered that the interaction between water and an organic halogen compound such as trihalomethane during treatment is reduced, and as a result, an organic halogen compound having a strong interaction with water can be efficiently removed. (7) It is considered that the interaction between water and a petroleum hydrocarbon such as toluene during the treatment is also reduced, and the petroleum hydrocarbon can be efficiently removed. Also,
(8) Since there is no need to irradiate ultraviolet rays, the method can be applied to water to be treated which has a large amount of turbid components (fine particles and the like), and petroleum hydrocarbons can be removed in a short treatment time, and the operating cost is reduced. As described above, according to the present invention, trace amounts of organic substances dissolved in tap water or well water used as drinking water or in the electronics industry, nuclear power plants, pharmaceutical manufacturing factories, and the like for manufacturing semiconductor devices and liquid crystals. Halogen compounds and petroleum hydrocarbons can be removed at low cost, with stability over time, and with high efficiency.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a view showing one embodiment of a method for removing organic halogen compounds and petroleum hydrocarbons in water according to the present invention. FIG. 2 is a view showing another embodiment of the method for removing organic halogen compounds and petroleum hydrocarbons in water according to the present invention. [Description of Signs] 1... Acid adding device 2... Normal pressure deaerator 3... Storage tank 4... Filtration device 5... Blower 6. ... Line 11 ... Sampling cock 12 ... Sampling cock 13 ... Cation exchange device

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Masahiko Kogure 2-9-8 Okada, Atsugi-shi, Kanagawa Prefecture Nomura MicroSciences Co., Ltd. (72) Inventor Shuichi Chino 2-9-1-8 Okada, Atsugi-shi, Kanagawa Prefecture No. Nomura Micro Science Co., Ltd. (56) References JP-A-5-317846 (JP, A) JP-A-5-212371 (JP, A) JP-A-7-682269 (JP, A) (58) Field surveyed (Int.Cl. ⁷ , DB name) C02F 1/20

Claims (1)

(57) [Claims] [Claim 1] Trace amounts of organic halogen compounds and petroleum
Treated water consisting of tap water or well water in which hydrocarbons are dissolved
A first step of adjusting the pH to 2.0 to 3.0, and contacting aerated air with the water to be treated in countercurrent to remove trace amounts of organic halogen compounds and petroleum hydrocarbons dissolved in the water to be treated. a second step the organic halogen compounds in tap water or well water to a characterized in that the sequentially performed and a method of removing the petroleum hydrocarbon to force migrated to the aeration air.