JP2018065112A - Method and apparatus for treating amine-containing wastewater - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for treating amine-containing wastewater, which produces treated water containing less amount of residue amine, requiring no heat source to heat condensed water that is produced during a treatment process of amine-containing wastewater by an evaporative concentration method.SOLUTION: There is provided a method of treating amine-containing wastewater, the method comprising: an evaporation concentration step of evaporating and concentrating amine-containing wastewater by an evaporation concentrator 12; a condensation step by a condenser 16 of condensing the steam generated during the evaporation concentration step; and an amine decomposition step of adding an oxidizing agent to the condensed water which is obtained during the condensation step and of decomposing amines contained in the condensed water by irradiating the condensed water with ultraviolet rays by an amine decomposition apparatus 18.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an amine-containing wastewater treatment method and a processing apparatus technology for treating amine by evaporating and concentrating amine-containing wastewater.

  Amines that are organic nitrogen compounds are widely used industrially as bases or ligands. There are various types of amines, and examples thereof include aliphatic amines such as ethanolamines and heterocyclic amines such as piperazines. Since ethanolamines and piperazines have high boiling points and high basicity, they are used in acid gas cleaning solutions, or because of their properties of bases or ligands, such as metal chelating agents and metal pipes. It is used as an agent.

  Examples of ethanolamines include monoethanolamine (2-aminoethanol), diethanolamine (2,2-iminodiethanol), triethanolamine, and 2,2-methyliminodiethanol. For example, ethanolamine may be added as an anticorrosive agent to the steam generation piping of a power plant. Further, in recent years, from the viewpoint of suppressing the emission of carbon dioxide generated during fossil fuel combustion, the carbon dioxide in the exhaust gas is brought into contact with a carbon dioxide absorbent containing various ethanolamines (for example, see Patent Document 1). Is also absorbed.

  Piperazines include, for example, piperazine, 1-methylpiperazine, 2-methylpiperazine, etc., and are used for cleaning acidic gas (for example, Patent Document 2), used as an epoxy resin curing agent, chelating agent, etc. doing.

  The amine is, for example, mixed in water at the time of use or after use and discharged as amine-containing waste water. The amine in the wastewater is composed of carbon, nitrogen, oxygen and hydrogen atoms, and carbon and nitrogen become COD sources and eutrophication sources and pollute rivers and lakes.

  Depending on the use of the amine, the amine concentration in the waste water may be very high. If it is high, the organic matter concentration may be 0.1 w / v% or more. High-concentration amine-containing wastewater generally exhibits an alkalinity of pH 9 or higher unless a large amount of neutralizing acid (hydrochloric acid, sulfuric acid, etc.) is injected.

  And since high concentration amine containing waste water shows high COD and total nitrogen (TN), after performing the process which reduces these, it is discharged | emitted in the environment. When discharged into the environment, in Japan, it is necessary to reduce CODMn to 120 mg / L or less (daily average) and total nitrogen to 60 mg / L or less (daily average) based on wastewater standards.

  As a method for treating amine-containing wastewater, there is a method using an evaporation concentration method. For example, Patent Document 3 discloses that ethanolamine-containing wastewater is adjusted to pH 8 or lower, evaporated and concentrated, and an oxidizing agent is added to condensed water generated by condensing the generated steam, and 110 ° C. or lower in the presence of a catalyst. Has proposed a method for oxidizing and decomposing ethanolamine in condensed water. Although this method stipulates that the oxidative decomposition temperature of ethanolamine is 110 ° C. or lower, in practice, if the condensed water is not heated to 60 ° C. or higher, the amine decomposition efficiency does not increase, so there is little residual amine. In order to obtain treated water, a heat source for heating the condensed water to a high temperature above a certain temperature is required.

JP 2015-24374 A Japanese Patent No. 5679995 Japanese Patent Laid-Open No. 10-272478

  Therefore, the present invention is a treatment of amine-containing wastewater that can obtain treated water with little residual amine without requiring a heat source for heating condensed water obtained in the treatment of amine-containing wastewater by the evaporative concentration method. It was made for the purpose of providing a method and a processing apparatus.

  The method for treating amine-containing wastewater according to the present invention includes an evaporation and concentration step for evaporating and condensing amine-containing wastewater, a condensation step for condensing steam generated in the evaporation and concentration step, and an oxidant in the condensed water obtained in the condensation step. And an amine decomposition step of decomposing amine in the condensed water by irradiating with ultraviolet rays.

  In the method for treating amine-containing wastewater, in the amine decomposition step, the pH adjustment step for adjusting the pH of the condensed water to 6.5 to 7.5, and the conductivity of the condensed water after pH adjustment are measured. It is preferable to adjust the addition amount of the oxidizing agent according to the measured conductivity value.

  The amine-containing wastewater treatment apparatus of the present invention includes an evaporative concentration means for evaporating and condensing the amine-containing wastewater, a condensing means for condensing vapor generated by the evaporative concentration means, and condensed water obtained by the condensing means. And an amine decomposing means for decomposing amines in the condensed water by irradiating with ultraviolet rays while adding an oxidizing agent.

  In the amine-containing wastewater treatment apparatus, the amine decomposing means measures the pH adjusting means for adjusting the pH of the condensed water to 6.5 to 7.5, and the conductivity of the condensed water after the pH adjustment. It is preferable to have an electrical conductivity measuring means and adjust the addition amount of the oxidizing agent according to the measured electrical conductivity value.

  ADVANTAGE OF THE INVENTION According to this invention, the treatment of the amine containing waste_water | drain which can obtain the treated water with few residual amines, without requiring the heat source for heating the condensed water obtained in the treatment of the amine containing waste_water | drain by the evaporative concentration method to high temperature A method and a processing apparatus can be provided.

It is a schematic diagram which shows an example of a structure of the processing apparatus of the amine containing waste water which concerns on embodiment of this invention. It is a figure which shows the relationship between the amine density | concentration in condensed water in pH7, and electrical conductivity.

  Embodiments of the present invention will be described below. This embodiment is an example for carrying out the present invention, and the present invention is not limited to this embodiment.

  Drawing 1 is a mimetic diagram showing an example of the composition of the processing device of the amine content drainage concerning the embodiment of the present invention. The wastewater treatment apparatus 1 shown in FIG. 1 includes a raw water tank 10, an evaporative concentrator 12 (evaporating and concentrating means), a concentrated water tank 14, a condenser 16 (condensing means), and an amine decomposing apparatus 18 (amine decomposing means). The evaporative concentrator 12 includes an evaporator 22 and a heat medium supply pipe 24. The amine decomposing apparatus 18 includes a pH adjusting device (pH adjusting tank 26, pH sensor 28 and acid agent adding pipe 30) as pH adjusting means, a conductivity sensor 31 as an electric conductivity measuring means, an oxidizing agent adding pipe 33, a line mixer. 35 and a reaction tank 39 in which an ultraviolet lamp 37 is installed.

  Below, the piping structure of the waste water treatment apparatus 1 shown in FIG. 1 is demonstrated. The piping configuration shown in FIG. 1 is an example, and the present invention is not limited to this.

  A pH adjuster addition pipe 29 is connected to the raw water tank 10. One end of the drainage inflow pipe 32 is connected to the drainage outlet of the raw water tank 10, and the other end is connected to the drainage inlet on the side surface of the evaporator 22. The heat medium supply pipe 24 is connected to a heat transfer pipe 34 provided inside the evaporator 22. As described above, one end of the heat transfer tube 34 is connected to the heat medium supply pipe 24, and the other end is connected to a drain portion 36 provided outside the evaporator 22. One end of the drain pipe 38 is connected to the drain part 36, and the other end is connected to, for example, a water tank provided outside the system via a pump 40a. One end of the circulation pipe 42 is connected to the lower outlet of the evaporator 22, and the other end is connected to the upper inlet of the evaporator 22 via the pump 40 b. One end of the concentrated water pipe 44 is connected to the circulation pipe 42, and the other end is connected to the concentrated water tank 14. One end of the steam recovery pipe 46 is connected to the upper side port of the evaporator 22, and the other end is connected to the steam inlet of the condenser 16. A cooling water pipe 48 is installed in the condenser 16. One end of the condensed water pipe 50 a is connected to the condensed water outlet of the condenser 16, and the other end is connected to the inlet of the pH adjusting tank 26. One end of the condensed water pipe 50 b is connected to the outlet of the pH adjusting tank 26, and the other end is connected to the inlet of the reaction tank 39 via the line mixer 35. A treated water pipe 52 is connected to the outlet of the reaction tank 39. The acid agent addition pipe 30 is connected to the pH adjustment tank 26, and the oxidant addition pipe 33 is connected to the condensed water pipe 50b.

  Next, the operation of the waste water treatment apparatus 1 according to this embodiment will be described.

  The amine-containing wastewater to be treated is stored in the raw water tank 10. A pH adjuster is supplied from the pH adjuster addition pipe 29 as necessary, and the pH of the amine-containing wastewater is adjusted to 8 or less. The amine-containing wastewater in the raw water tank 10 passes through the wastewater inflow pipe 32 and is supplied to the evaporator 22 of the evaporation concentrator 12. Further, a heat medium such as steam is supplied from the heat medium supply pipe 24 to the heat transfer pipe 34, and the heat transfer pipe 34 is heated. Then, the pump 40b is operated, and the amine-containing wastewater stored at the bottom of the evaporator 22 passes through the circulation pipe 42 and is sprayed from the upper part of the evaporator 22 toward the heat transfer tube 34 heated by a heating medium such as steam. The The injected amine-containing waste water is heated by heat from the heat transfer pipe 34, a part of the heated waste water evaporates, and the remainder is stored as amine concentrated water at the bottom of the evaporator 22 (evaporation concentration step). The amine concentrated water concentrated at a predetermined concentration rate in the evaporation concentration step is discharged from the evaporator 22 and stored in the concentrated water tank 14 through the circulation pipe 42 and the concentrated water pipe 44. The total amount of the amine concentrated water may be supplied to the concentrated water tank 14, or a part of the amine concentrated water may be supplied to the concentrated water tank 14 and the remaining part may be distributed to the evaporation concentration by the evaporator 22. Note that the heat medium such as steam that has passed through the heat transfer pipe 34 is stored in the drain portion 36, and the pump 40 a is operated as necessary, and is discharged out of the system from the drain pipe 38.

  The amine-containing waste water vapor evaporated by the evaporator 22 is supplied to the condenser 16 through the steam recovery pipe 46. The steam supplied to the condenser 16 is condensed by exchanging heat with the coolant flowing through the cooling water pipe 48 in the condenser 16 and discharged as condensed water from the condensed water pipe 50a (condensing step).

  Condensed water is supplied from the condensed water piping 50a to the pH adjusting tank 26, and is adjusted to a range of, for example, pH 6.5 to 7.5 (pH adjusting step). Specifically, the pH of the condensed water in the pH adjustment tank 26 is measured by the pH sensor 28, and the amount of the acid agent supplied from the acid agent addition pipe 30 is adjusted according to the measured value, and the pH of the condensed water is adjusted. Is adjusted. Further, the conductivity of the condensed water after pH adjustment is measured by the conductivity sensor 31 (conductivity measurement step), and the addition amount of the oxidizing agent supplied from the oxidizing agent addition pipe 33 is adjusted according to the measured value. . As the acid agent, for example, sulfuric acid, hydrochloric acid or the like is used.

  The condensed water and the oxidizing agent are mixed by the line mixer 35 installed in the condensed water pipe 50 b and then introduced into the reaction tank 39. At this time, ultraviolet rays are irradiated by the ultraviolet lamp 37. In the reaction tank 39, radicals derived from the oxidizing agent are generated under ultraviolet irradiation, and the amine in the condensed water is decomposed by the radicals (amine decomposition step). The condensed water in which the amine has been decomposed is discharged from the treated water pipe 52 as treated water. Depending on the oxidizing agent used, ammonium ions may remain in the treated water. For example, an ammonium ion decomposing agent such as sodium hypochlorite is added to the reaction tank 39 or the treated water pipe 52 to convert it to nitrogen. It is desirable to decompose.

  As described above, in this embodiment, radicals derived from an oxidant are generated by ultraviolet irradiation to efficiently decompose the amine, so that the condensed water does not have to be heated to a high temperature (for example, 60 ° C. or higher). Also good. Therefore, according to this embodiment, treated water with little residual amine can be obtained without requiring a heat source for heating the condensed water to a high temperature of a certain temperature or higher.

  Below, the process conditions of an amine containing waste_water | drain are demonstrated.

The amine to be treated in this embodiment is not particularly limited, but is a substance having a boiling point of 130 ° C. or higher under atmospheric pressure and an acid dissociation constant pKa of 8.5 or higher in a 25 ° C. aqueous solution. For example, monoethanolamine (for example, 2-aminoethanol [HOCH ₂ CH ₂ NH ₂ ]), diethanolamine (for example, 2,2-iminodiethanol [(HOCH ₂ CH ₂ ) ₂ NH]), tri Examples include ethanolamine (for example, [(HOCH ₂ CH ₂ ) ₃ N]), 2,2-methyliminodiethanol, piperazine, 1-methylpiperazine, 2-methylpiperazine and the like.

  The amine concentration in the amine-containing wastewater is, for example, preferably several thousand to 15000 mg / L, more preferably 5000 to 15000 mg / L in terms of CODMn concentration. When the amine concentration is 15000 mg / L or less, it is possible to obtain condensed water with a high recovery rate while concentrating the waste water at a sufficient magnification in the evaporation concentration step. Furthermore, the amount of amine transferred to the condensed water is relatively small, and the amine can be decomposed with a small amount of oxidizing agent in the amine decomposition step. On the other hand, if the amine concentration exceeds 15000 mg / L, a large amount of oxidizing agent is required to obtain good treated water quality, and the decomposition time of the amine may be prolonged.

  In the treatment method of the present embodiment, when pH adjustment is performed on the amine-containing wastewater before the evaporation step, the pH is preferably adjusted to 8 or less, and more preferably adjusted to 7.5 or less. Thereby, since the amount of amine contained in condensed water can be reduced, it becomes possible to reduce the usage-amount of the oxidizing agent for decomposing | disassembling an amine. Usually, amine-containing wastewater exhibits an alkalinity of pH 9 or higher, so an acid agent is added to amine-containing wastewater and adjusted to pH 8 or lower. For example, a large amount of acid or the like is mixed in the amine-containing wastewater in advance. When the pH is low (for example, pH 5 or less) that may affect the material such as corrosion, an alkaline agent may be added until the pH (for example, exceeding pH 5) is considered to be less affected. Moreover, in the processing method of this embodiment, you may perform an evaporation concentration process, without performing pH adjustment with respect to the amine containing waste water which shows alkalinity more than pH9. Thereby, it becomes possible to reduce the usage-amount of an acid agent and an alkali agent.

  The evaporator 22 used in the present embodiment is not particularly limited as long as it has a structure capable of heating and evaporating the amine-containing wastewater and concentrating the amine-containing wastewater. For example, natural circulation Conventionally known evaporators such as a type evaporator, a forced circulation evaporator, a liquid film evaporator, and a vacuum evaporator can be used. Among these, vacuum evaporators are preferable from the viewpoint of energy cost for evaporation and concentration. The vacuum evaporator is equipped with a vacuum pump that depressurizes the inside of the evaporator. For example, the inside of the evaporator is reduced to -0.05 to -0.02 MPa (gauge pressure) with the vacuum pump. Thereby, it becomes possible to evaporate the amine-containing wastewater having a high boiling point at a low heating temperature (for example, 60 to 90 ° C.), so that the energy cost can be suppressed.

  In consideration of disposal, it is desirable to set the concentration rate of the amine concentrate in the evaporation concentration process higher so that the amount of water in the amine concentrate is reduced. May increase the amount of amine contained in the oxidizer and increase the amount of oxidizing agent used. Therefore, the concentration ratio of the amine concentrate in the evaporative concentration step is preferably 25 times or less, more preferably in the range of 15 times to 25 times, in order to suppress disposal costs and the amount of oxidant used. . Moreover, when dissolved silica is contained in the amine-containing wastewater, if the concentration proceeds, silica may precipitate in the evaporator 22 and the heating efficiency of the amine-containing wastewater may be reduced. It is desirable to set the magnification.

  The amine concentrated water obtained by the evaporative concentration step may be disposed of as waste, for example, or may be decomposed into carbon dioxide and nitrogen by burning the amine at a high temperature while blowing oxygen in the combustion apparatus. .

  The oxidizing agent added to the condensed water obtained by the condenser 16 is not particularly limited as long as it is a substance capable of decomposing amines in the condensed water under ultraviolet irradiation. Examples include ozone, sodium hypochlorite, potassium permanganate, chlorine dioxide, potassium permanganate, and sodium persulfate. Among these, hydrogen peroxide, ozone, and sodium hypochlorite are preferred from the viewpoint of amine decomposition efficiency, but ozone requires an on-site generation facility, so hydrogen peroxide, hypochlorous acid. Sodium is more preferred. When hydrogen peroxide or ozone is used, hydroxyl radicals with strong oxidizing power are generated under ultraviolet irradiation, and the hydroxyl radicals are considered to decompose amines into inorganic carbon (such as bicarbonate ions) and ammonium ions. It is done. When hypochlorous acid is used, it is considered that chloric acid radicals and the like are generated under ultraviolet irradiation, and the chloric acid radicals decompose amines into inorganic carbon (such as bicarbonate ions) and nitrogen.

  In the case of sodium hypochlorite, the amount added is larger than when hydrogen peroxide or ozone is used, but as described above, ammonium ions can be decomposed together with the decomposition of the amine. In the case of hydrogen peroxide and ozone, as described above, ammonium ions are generated as the decomposition products of amines. Therefore, when treating water is discharged, hypochlorite ions are decomposed in order to decompose the regulated ammonium ions. Use in combination with sodium chlorate is desirable.

  The ultraviolet lamp 37 used in the present embodiment is not particularly limited, and examples thereof include a low-pressure ultraviolet lamp, a medium-pressure ultraviolet lamp, an amalgam lamp, an excimer lamp, a xenon lamp, an electrodeless lamp, and an ultraviolet LED. . The wavelength of ultraviolet rays emitted from the ultraviolet lamp 37 includes a wavelength of 254 nm suitable for the decomposition of organic substances by the combined use of an oxidizing agent. Although the ultraviolet irradiation time depends on the amine concentration in the condensed water, for example, it is preferably in the range of several tens of minutes to 5 hours, and more preferably in the range of 2 hours to 4 hours.

  The pH of the condensed water obtained by the condenser 16 is about 9.0 to about 11. However, when decomposing the amine of the condensed water, an acid agent or the like is added to the condensed water to adjust the pH to 6.5. It is preferable to adjust to a range of ˜7.5, and to perform amine decomposition by adding an oxidant and irradiating with ultraviolet rays in that the amine decomposition rate can be increased rather than amine decomposition with condensed water having a pH of 9 or higher.

  The amount of oxidant added is appropriately set according to the amine concentration in the condensed water, but the amine concentration in the condensed water varies depending on the amine concentration in the waste water and the concentration ratio in the evaporation concentration process. To adjust the amount, it is necessary to measure the amine concentration in the condensed water. Here, the amine concentration in water can be generally measured with a COD meter or a TN meter, but since these cannot be measured in real time, oxidation is performed according to changes in the amine concentration in condensed water. It is difficult to adjust the addition amount of the agent. However, as explained below, since the electrical conductivity in water and the amine concentration are in a proportional relationship, the electrical conductivity in the condensed water is measured, and the addition amount of the oxidizing agent is adjusted according to the measured electrical conductivity. It is possible to cope with fluctuations in the amine concentration in the condensed water.

  FIG. 2 is a graph showing the relationship between the amine concentration in the condensed water at pH 7 and the electrical conductivity. The condensed water contains an amine that has moved from the waste water to the condensed water side and its dissociated ions. In particular, amines with a pKa of 8.5 or higher have a pH of 7.5 or lower and at least 90% of all amine molecules are in an ionic state. Therefore, the condensed water adjusted to pH 6.5 to 7.5 with an acid agent contains amine ions (mainly cations) and anions derived from acid agents corresponding to the concentration (for example, chloride ions, sulfate ions). ) Mainly exists, the conductivity in the condensed water is substantially proportional to the amine concentration, as shown in FIG. 2, for example. Therefore, for example, by setting in advance the amount of oxidant necessary for the conductivity of the condensed water, the amount of oxidant to be supplied can be determined from the measured value of the conductivity of the condensed water. it can. The addition amount of the oxidizing agent depends on the type of amine and the required treatment water quality, but is preferably set to be about 2 to 5 times that of condensed water CODMn in terms of a molar ratio, for example, about 2 to 3 times. It is more preferable to set so that.

  The amine decomposing apparatus 18 may include a control unit that controls the addition amount of the oxidizing agent. For example, data such as a graph or a table in which the amount of oxidant added necessary for the conductivity of the condensed water is set is stored in the control unit in advance. And a control part applies the value measured by the conductivity sensor 31 to the data memorize | stored previously, and determines the addition amount of a required oxidizing agent. And a control part controls the valve | bulb (not shown), the pump (not shown), etc. which were installed in the oxidant addition piping 33 so that it may become the determined addition amount of oxidant. In addition, the amine decomposing apparatus 18 may include a control unit that controls the amount of acid agent added. For example, when a value measured by the pH sensor 28 reaches pH 6.5 to 7.5, a valve (not shown) installed in the acid agent addition pipe 30 so that the supply of the acid agent is stopped. Controls a pump (not shown) and the like.

  Hereinafter, although an example and a comparative example are given and the present invention is explained more concretely in detail, the present invention is not limited to the following examples.

<Example 1>
As amine-containing wastewater, 2-aminoethanol 6 g / L, 2,2-iminodiethanol 6 g / L, piperazine 6 g / L, and 2-methylpiperazine 6 g / L, which are widely used among the above-exemplified amines, are used as tap water. Synthetic waste water dissolved in water was prepared (organic matter concentration 24 g / L). The pH of this synthetic waste water was 11.3.

  Table 1 shows the boiling point (760 mmHg) and pKa (25 ° C.) of each amine in the synthetic waste water.

  The pH of this synthetic waste water was adjusted to 7.1 with hydrochloric acid (35%). The pH-adjusted wastewater had a CODMn of 13,000 mg / L, a total nitrogen concentration (TN) of 5,700 mg / L, and a chloride ion concentration of 8,900 mg / L. The CODMn, TN, and chloride ion concentrations in the synthetic wastewater were measured by a method based on JIS K0102.

500 mL of synthetic waste water having pH of 7.1 was introduced into a concentration evaporator flask of a rotary evaporator, and the concentration flask was rotated in a state in which the concentration flask was immersed in an 80 ° C. hot water bath from the bottom to about half. While passing cooling water of 22 ° C. through the condensing part, the vacuum pump was operated, and the pressure inside the evaporator including the concentrating part flask was adjusted to −0.07 MPa. The condensed water cooled in the condensing part was collected in the bottom condensate flask and concentrated until the condensed water reached 475 mL (condensed water recovery rate 95%). The water quality (pH, CODMn, TN, Cl ⁻ concentration) of this condensed water was measured. The results are shown in Table 2.

  Next, the pH of the condensed water was adjusted to 7.3 with hydrochloric acid, and the conductivity was measured. The results are shown in Table 2.

Hydrogen peroxide water (effective concentration 30%) was added to 100 mL of condensed water after pH adjustment so as to have a concentration of 80 mgH ₂ O ₂ / L. In addition, the hydrogen peroxide addition amount was 2.5 times (molar ratio) of CODMn of condensed water.

  The condensed water to which hydrogen peroxide was added was put into a quartz beaker and irradiated with ultraviolet rays for 240 minutes while stirring the condensed water. Ultraviolet irradiation was performed by a low-pressure ultraviolet lamp installed at a position 72 mm away from the quartz beaker (center). The irradiation intensity was 2 mW / cm.

  Thereafter, a sodium hypochlorite solution (effective concentration 4%) was added so that chlorine remained at 0.3 to 0.5 mg / L. Using this as treated water, CODMn and TN were measured. The results are shown in Table 2.

<Example 2>
The pH of the synthetic waste water was adjusted to 8.0 with hydrochloric acid (35%). The chloride ion concentration in the synthetic waste water after pH adjustment was 8,000 mg / L (note that CODMn was 13,000 mg / L and total nitrogen concentration (TN) was 5,700 mg / L).

500 mL of synthetic wastewater with a pH of 8.0 was evaporated and concentrated in the same manner as in Example 1 to obtain condensed water. The water quality (pH, CODMn, TN, Cl ⁻ concentration) of this condensed water was measured. The results are shown in Table 2.

  Next, the pH of the condensed water was adjusted to 7.5 with hydrochloric acid, and the conductivity was measured. The results are shown in Table 2.

Hydrogen peroxide water (effective concentration 30%) was added to 100 mL of condensed water after pH adjustment so as to have a concentration of 325 mgH ₂ O ₂ / L. The amount of hydrogen peroxide added was 2.8 times (molar ratio) of CODMn of condensed water.

  The condensed water to which hydrogen peroxide was added was irradiated with ultraviolet rays in the same manner as in Example 1, and then sodium hypochlorite was added. Using this as treated water, CODMn and TN were measured. The results are shown in Table 2.

<Example 3>
The evaporative concentration step was carried out on synthetic wastewater of pH 11.3 (chloride ion concentration 150 mg / L, CODMn 13,000 mg / L, total nitrogen concentration (TN) 5,700 mg / L). The evaporative concentration step was the same as in Example 1 except that the condensed water was concentrated to 333 mL (condensed water recovery rate 67%), and the quality of the obtained condensed water (pH, CODMn, TN, Cl ^- concentration) was measured. The results are shown in Table 2.

  Next, the pH of the condensed water was adjusted to 7.5 with hydrochloric acid, and the conductivity was measured. The results are shown in Table 2.

Hydrogen peroxide water (effective concentration 30%) was added to 100 mL of condensed water after pH adjustment so as to have a concentration of 2110 mgH ₂ O ₂ / L. In addition, the hydrogen peroxide addition amount was 2.5 times (molar ratio) of CODMn of condensed water.

  The condensed water to which hydrogen peroxide was added was irradiated with ultraviolet rays in the same manner as in Example 1, and then sodium hypochlorite was added. Using this as treated water, CODMn and TN were measured. The results are shown in Table 2.

  In Examples 1 to 3 in which the oxidant was added and ultraviolet irradiation was performed without heating the condensed water obtained by evaporating and condensing the amine-containing wastewater, the CODMn in the treated water was less than 100 mg / L, and the wastewater standard It was a value satisfying (daily average 120 mg / L). The temperature of the condensed water during the addition of the oxidizing agent and the ultraviolet irradiation was around room temperature (about 25 ° C.). Therefore, when decomposing the amine in the condensed water, it can be said that treated water with little residual amine could be obtained without requiring a heat source for heating the condensed water. Moreover, in Examples 1-3, the direction of Examples 1-2 which adjusted pH of the amine containing waste_water | drain at the time of evaporative concentration to 8 or less compared with Example 3 which is not pH-adjusted. Treated water with less amine could be obtained.

  DESCRIPTION OF SYMBOLS 1 Waste water treatment apparatus, 10 Raw water tank, 12 Evaporation concentrator, 14 Concentrated water tank, 16 Condenser, 18 Amine decomposition apparatus, 22 Evaporator, 24 Heat medium supply piping, 26 pH adjustment tank, 28 pH sensor, 29 pH adjuster Addition piping, 30 Acid agent addition piping, 31 Conductivity sensor, 32 Drainage inflow piping, 33 Oxidant addition piping, 34 Heat transfer tube, 35 Line mixer, 36 Drain section, 37 UV lamp, 38 Drain piping, 39 Reaction tank, 40a , 40b Pump, 42 Circulation piping, 44 Concentrated water piping, 46 Steam recovery piping, 48 Cooling water piping, 50a, 50b Condensed water piping, 52 Treated water piping.

Claims (4)

An evaporation concentration process for evaporating and condensing amine-containing wastewater;
A condensation step of condensing the vapor generated in the evaporation concentration step;
A method for treating amine-containing wastewater, comprising adding an oxidant to the condensed water obtained in the condensation step and irradiating ultraviolet rays to decompose the amine in the condensed water.   The amine decomposition step has a pH adjustment step for adjusting the pH of the condensed water to 6.5 to 7.5, and a conductivity measurement step for measuring the conductivity of the condensed water after pH adjustment. The method for treating amine-containing wastewater according to claim 1, wherein the amount of the oxidizing agent added is adjusted in accordance with a conductivity value. Evaporative concentration means for evaporating and condensing amine-containing wastewater;
Condensing means for condensing the vapor generated by the evaporative concentration means;
An amine-containing wastewater treatment apparatus, comprising: an amine decomposition means for decomposing an amine in the condensed water by adding an oxidizing agent to the condensed water obtained by the condensing means and irradiating ultraviolet rays.   The amine decomposing means has a pH adjusting means for adjusting the pH of the condensed water to 6.5 to 7.5, and a conductivity measuring means for measuring the conductivity of the condensed water after pH adjustment. 4. The amine-containing wastewater treatment apparatus according to claim 3, wherein the amount of the oxidizing agent added is adjusted according to a conductivity value.