JP2018065098A - Processing method and processing device for amine-containing drainage water - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of processing amine-containing drainage water capable of providing processing water with low residual amine, while restraining the amount of chemicals used in processing of amine-containing drainage water.SOLUTION: A method of processing amine-containing drainage water comprises an evaporative concentration process of evaporating and concentrating amine-containing drainage water via an evaporative concentrator 12, a condensation process of condensing steam generated in the evaporative concentration process with a condenser 16, a pH adjustment process of adjusting a condensate resulting from the condensation process to pH8 or lower with a pH adjustment device 18, and a reverse osmosis membrane processing process of separating the condensate adjusted to pH8 or lower into permeable water and concentrated water at a reverse osmosis membrane module 20.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a method for treating amine-containing wastewater and evaporating the amine-containing wastewater to treat it with amine.

  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.

  For example, Patent Document 3 proposes a wastewater treatment method in which wastewater containing an organic nitrogen compound such as amine is wet-oxidized using air as an oxidizing agent in the presence of a metal-supported catalyst. However, in this method, the reaction temperature needs to be 100 to 300 ° C., and the operation pressure needs to be 0.2 to 5 MPa or more. For this reason, the energy cost required for heating and pressurization is increased, and an apparatus capable of withstanding high temperature and high pressure is required, resulting in an increase in apparatus cost.

  Further, as a method for treating amine-containing wastewater, there is a method using an evaporation concentration method. For example, Patent Document 4 proposes a method in which ethanolamine-containing wastewater containing a high concentration is adjusted to pH 8 or less, and then distilled using an evaporation concentrator and oxidatively decomposes ethanolamine transferred to condensed water using a catalyst. ing. According to this method, it is possible to reduce the amount of ethanolamine evaporation and obtain condensed water with relatively little residual amine by evaporating and concentrating the ethanolamine-containing wastewater to pH 8 or lower. However, a large amount of acid is required to adjust the ethanolamine-containing wastewater to be evaporated to a pH of 8 or less (that is, a large amount of acid is necessary to neutralize the basic amine), and residual amine in the condensed water When oxidizing and decomposing, a large amount of oxidant is required, and thus there is a problem that chemical costs are increased.

JP 2015-24374 A Japanese Patent No. 5679995 JP 2011-224547 A Japanese Patent Laid-Open No. 10-272478

  Therefore, the present invention provides an amine-containing wastewater treatment method and a treatment apparatus capable of obtaining treated water with little residual amine while suppressing the amount of chemicals used in the treatment of amine-containing wastewater by the evaporation concentration method. It was made as a purpose.

  The method for treating amine-containing wastewater of the present invention includes an evaporation concentration step for evaporating and condensing amine-containing wastewater, a condensation step for condensing steam generated in the evaporation concentration step, and a condensed water obtained in the condensation step having a pH of 8 or less. And a reverse osmosis membrane treatment step of passing the condensed water adjusted to pH 8 or lower through a reverse osmosis membrane and separating it into permeate and concentrated water.

  In the method for treating amine-containing wastewater, the concentrated water obtained in the reverse osmosis membrane treatment step is preferably supplied to the amine-containing wastewater.

  In the method for treating amine-containing wastewater, the amine concentration in the amine-containing wastewater is preferably 35000 mg / L or less in terms of total organic carbon concentration.

  The amine-containing wastewater treatment apparatus according to the present invention includes an evaporative concentration means for evaporating and condensing the amine-containing wastewater, a condensing means for condensing steam generated by the evaporative concentration means, and condensed water obtained by the condensing means. pH adjusting means for adjusting the pH to 8 or less, and reverse osmosis membrane treatment means for providing a reverse osmosis membrane, allowing the condensed water adjusted to pH 8 or less to flow through the reverse osmosis membrane and separating it into permeated water and concentrated water. It is characterized by having.

  The amine-containing wastewater treatment apparatus preferably includes supply means for supplying concentrated water obtained by the reverse osmosis membrane treatment means to the amine-containing wastewater.

  In the above-described amine-containing wastewater treatment apparatus, the amine concentration in the amine-containing wastewater is preferably 35000 mg / L or less in terms of total organic carbon concentration.

  According to the present invention, there is provided an amine-containing wastewater treatment method and a treatment apparatus capable of obtaining treated water with little residual amine while suppressing the amount of chemicals used in the treatment of amine-containing wastewater by the evaporation concentration method. It becomes possible.

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.

  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 waste water 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), a pH adjusting device 18 (pH adjusting means), and a reverse osmosis membrane module. 20 (reverse osmosis membrane processing means). The evaporative concentrator 12 includes an evaporator 22 and a heat medium supply pipe 24. The pH adjusting device 18 includes a pH adjusting tank 26, a pH sensor 28, and a pH adjusting agent adding pipe 30.

  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.

  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 50b is connected to the outlet of the pH adjustment tank 26, and the other end is connected to the inlet of the reverse osmosis membrane module 20 via the pump 40c. A treated water pipe 52 is connected to the permeate outlet of the reverse osmosis membrane module 20. One end of the concentrated water supply pipe 54 (concentrated water supply means) is connected to the concentrated water outlet of the reverse osmosis membrane module 20, and the other end is connected to the concentrated water inlet of the raw water tank 10.

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

  The amine-containing wastewater stored 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).

  The condensed water is supplied from the condensed water pipe 50a to the pH adjusting tank 26 and adjusted to pH 8 or less (pH adjusting step). Specifically, the pH of the condensed water in the pH adjusting tank 26 is measured by the pH sensor 28, and the amount of the pH adjusting agent supplied from the pH adjusting agent adding pipe 30 is adjusted according to the measured value. To a pH of 8 or less. Here, the condensed water contains amine evaporated in the evaporation concentration step. The concentration of the amine contained in the condensed water is, for example, 1/10 or less of the raw water (amine-containing wastewater) although it depends on the recovery rate of the condensed water in the evaporation concentration step. Therefore, since the amount of the pH adjuster to be added is, for example, 1/10 or less when the pH of the raw water is 8 or less, the amount of chemicals used in the treatment of amine-containing wastewater by the evaporation concentration method is remarkably increased. It becomes possible to reduce. In addition, since the pH of the condensed water containing an amine exhibits alkalinity, an acid agent such as sulfuric acid or hydrochloric acid is usually used as a pH adjuster.

Condensed water adjusted to pH 8 or less (containing amine) is passed from the condensed water pipe 50b to the reverse osmosis membrane module 20 by the pump 40c. The condensed water is separated by the reverse osmosis membrane in the reverse osmosis membrane module 20 into permeated water from which the amine has been removed and concentrated water from which the amine has been concentrated. The permeated water is discharged from the treated water pipe 52 as treated water, and the concentrated water is supplied from the concentrated water supply pipe 54 to the raw water tank 10. Thus, by setting the pH of the condensed water (containing amine) to 8 or less, most of the amine in the condensed water exists as an ionized substance such as R-NH ₃ ^+. Can be removed, and treated water with little residual amine can be obtained. Further, when oxidative decomposition of amine-containing condensed water with an oxidation catalyst, a large amount of oxidant is required, but according to the reverse osmosis membrane treatment, it is not necessary to add an oxidant. It is possible to significantly reduce the amount of chemicals used in the treatment of contained wastewater. In addition, in the oxidative decomposition of condensed water, it is necessary to heat the condensed water to around 100 ° C. However, according to the reverse osmosis membrane treatment, the condensed water can be processed without being heated, so the energy cost is also reduced. It is beneficial.

  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 that satisfies the above physical property values tends to be relatively little even if it is alkaline in the evaporative concentration step, so the amount of the pH adjuster used for adjusting the pH of the condensed water is adjusted to the pH of the wastewater. Less than the amount required for Therefore, if wastewater containing amine that satisfies the above physical property values is applied to the treatment method of this embodiment, the amount of chemicals used in the treatment of amine-containing wastewater by the evaporation concentration method can be further reduced.

  The amine concentration in the amine-containing wastewater is, for example, preferably 35000 mg / L or less in terms of total organic carbon concentration, and preferably in the range of 5000 to 35000 mg / L. Although it is possible to treat wastewater with an amine concentration exceeding 35000 mg / L, it may be necessary to install multiple stages of reverse osmosis membranes in order to obtain good treated water quality. The energy cost required for filtration may increase.

  In the treatment method of the present embodiment, pH adjustment may be performed on the amine-containing wastewater before the evaporation and concentration step. Usually, amine-containing wastewater is alkaline with a pH of 9 or more.For example, if the wastewater has a low pH that may affect the material of the device due to a large amount of acid or the like mixed in advance, An alkaline agent may be added until the pH is less affected. In addition, for amine-containing wastewater having an alkalinity of pH 9 or higher, it is desirable to perform the evaporation and concentration step without adding an acid agent, but an acid agent may be added to adjust the pH to less than 9. By adjusting the amine-containing wastewater to less than pH 9 and performing the evaporation and concentration step, the amount of amine transferred to the steam side can be reduced, reducing the load on the reverse osmosis membrane and reducing the equipment cost and energy required for filtration. In some cases, costs can be reduced. Even if the pH of the amine-containing wastewater is adjusted, according to the treatment method of the present embodiment, the reverse osmosis membrane treatment makes it unnecessary to add an oxidizing agent. Reduction of the amount of chemicals used is guaranteed.

  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. As the amine contained in the water increases, the amount of the pH adjusting agent necessary for adjusting the pH of the condensed water may increase. 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 reduce the disposal costs and the amount of pH adjuster used. preferable.

  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. .

Although the pH of the condensed water obtained by the condenser 16 should just be adjusted to 8 or less, Preferably it is 7.5 or less, More preferably, it adjusts in the range of 6.5-7.5. By setting the pH of the condensed water to 8 or less, the ratio of amine ionized substances (for example, R-NH ₃ ⁺ ) in the condensed water can be increased, so that the amine is efficiently removed by the reverse osmosis membrane treatment in the subsequent stage. It becomes possible to do. If the pH of the condensed water is too acidic (for example, pH 4 or less), the inside of the apparatus may be corroded.

When the condensed water is passed through the reverse osmosis membrane, it is desirable to apply a pressure according to the characteristics of the membrane to be used, and to take out a certain proportion of the amount of water passed as concentrated water. The amount of water discharged as concentrated water varies depending on the characteristics of the reverse osmosis membrane and the inflowing water quality, but is generally preferably 70 to 90% of the amount of water flowing into the membrane. Pressure when passed through the reverse osmosis membrane, depending on the characteristics of the film, for example, in the range of a few ^{kg / cm 2 ~70kg / cm 2} .

  The reverse osmosis membrane used in the present embodiment is not particularly limited. For example, polyamide-based, polyvinylidene fluoride (PVDF), polyvinyl chloride (PVC), polyethersulfone (PES), cellulose acetate ( Examples thereof include organic films such as CA) and inorganic films made of ceramic. The shape of the reverse osmosis membrane is not particularly limited, and examples thereof include a hollow fiber membrane, a tubular membrane, a flat membrane, and a spiral. In addition, as the water flow method for the reverse osmosis membrane, any water flow method such as an internal pressure type and an external pressure type can be applied.

The amine concentration in the concentrated water obtained by the reverse osmosis membrane treatment is, for example, about several thousand to 20,000 mg / L in terms of the total organic carbon concentration. It is preferable to return to the waste water). Thereby, it becomes possible to raise the recovery rate of treated water. In addition, since the acid added in the pH adjustment step remains in the concentrated water obtained by the reverse osmosis membrane treatment (the acid added in the pH adjustment step hardly permeates the reverse osmosis membrane), it is concentrated in the raw water before the evaporation concentration step. By supplying water, the pH of the raw water can be lowered. As a result, the ratio of amine ionized substances (for example, R—NH ₃ ⁺ ) in the raw water is increased, and the amount of amine transferred to the vapor side in the evaporative concentration step is reduced. It becomes possible to further reduce the amount of the adjusting agent. Note that the concentrated water obtained by the reverse osmosis membrane treatment may be supplied to the concentrated water tank 14.

  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.

<Examples 1-1 to 1-3>
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. The pH of this synthetic wastewater was adjusted to 7.1 with hydrochloric acid (35%) and measured, the total organic carbon concentration (TOC) was 11,500 mg / L, and the total nitrogen concentration (TN) was 6,200 mg / L. CODMn was 13,000 mg / L. In addition, although TOC and TN in synthetic | combination waste_water | drain were measured with the Shimadzu total organic carbon and nitrogen measuring apparatus, since it is necessary to measure in neutral vicinity, pH adjustment with the above hydrochloric acid was performed. In the following wastewater treatment, synthetic wastewater (pH 11.3) that is not pH-adjusted is used.

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

  500 mL of synthetic waste water having a pH of 11.3 was introduced into a concentrator flask of a rotary evaporator, and the concentrator flask was rotated with the concentrator flask 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, TOC, TN, CODMn) of condensed water (1425 mL) and concentrated water (75 mL) obtained by performing this distillation operation three times was measured.

  Next, the condensed water was divided into 4 × 300 mL, and hydrochloric acid was added to 3 of them, and the pH was adjusted to 4.0, 7.1, and 8.0, respectively (Examples 1-1, 1-2). 1-3) The amount of hydrochloric acid added for adjustment was recorded. The remaining one was not adjusted for pH (pH 10.5, Comparative Example 1).

  A reverse osmosis membrane (manufactured by Nitto Denko, LFC-3) is arranged at the bottom of the pressure vessel (internal capacity 300 mL), and the above-mentioned pH adjusted condensed water or pH non-adjusted condensed water is introduced and sealed in the container, While rotating the stirring blade, compressed nitrogen was introduced into the container to make the internal pressure 1 MPa, and filtration was continued until the permeated water reached 252 mL (recovery rate 84%). The quality of the obtained permeated water (TOC, TN, CODMn) was measured. In addition, the ratio (recovery rate) of the permeated water amount (treated water amount) to the synthetic waste water amount is 80% (95% × 84%).

  Table 2 shows the water quality results of Examples 1-1 to 1-3 and Comparative Example 1.

  As in Examples 1-1 to 1-3, the pH of the condensed water obtained by evaporation and concentration was adjusted to 8 or less, and the pH of the condensed water as in Comparative Example 1 was subjected to reverse osmosis membrane filtration treatment. Compared to the case where the water content was not adjusted to 8 or less, permeated water (treated water) with good water quality could be obtained. That is, permeated water (treated water) with little residual amine could be obtained.

<Example 2>
The concentrated water after the reverse osmosis membrane treatment obtained by performing the same operation as in Example 1-2 and the residual liquid of the concentrated water after the reverse osmosis membrane treatment of Example 1-2 were mixed, and 76 mL (one time) Concentrated water A (16% of condensed water obtained by evaporative concentration operation) was mixed with 500 mL of synthetic waste water. 576 mL of this mixed water was evaporated and concentrated to obtain 551 mL of condensed water B. A part of the condensed water B is subjected to analysis, and 800 mg HCl / L hydrochloric acid is added to 300 mL of the remaining condensed water B to adjust to pH 7.1, and the reverse osmosis membrane is operated in the same manner as in Example 1-2. Processing was performed to obtain 252 mL of permeated water C (84% of condensed water B). The water quality of the concentrated water A, condensed water B and permeated water C was measured, and the results are shown in Table 3.

  The quality of the permeated water C of Example 2 was slightly higher than that of Example 1-2, which was the same amount of acid added in the pH adjustment step, but the drainage standard was sufficiently satisfied. In Example 2, 463 mL of permeated water (treated water) could be recovered from 500 mL of synthetic waste water. That is, the recovery rate of Example 2 was 93%, which was higher than that of Examples 1-1 to 1-3.

<Comparative example 2>
Hydrochloric acid was added to the synthetic waste water to adjust the pH to 8.6, and the amount of hydrochloric acid added at this time was recorded (in Table 4, expressed as the amount added per liter). Synthetic waste water 500 mL after pH adjustment was introduced into a concentration flask of a rotary evaporator, and concentrated about 6 times (= condensate recovery rate 84%) by the same evaporation concentration operation as in Examples 1-1 to 1-3. . The quality of the condensed water obtained was measured, and the results are shown in Table 4.

  In Comparative Example 2, water quality condensed water (treated water) satisfying drainage standards (T-N 60 mg / L, CODMn 120 mg / L) is obtained, but the amount of hydrochloric acid required for pH adjustment is 6700 mg / L, It was 6.5 to 10.3 times of each Example. In other words, it was shown that, in the example, the amount of acid used can be remarkably reduced and the chemical cost can be greatly reduced in order to obtain treated water with better water quality than Comparative Example 2.

<Example 3>
As amine-containing wastewater, synthetic wastewater was prepared by dissolving 2-aminoethanol 18 g / L, 2,2-iminodiethanol 18 g / L, piperazine 18 g / L, and 2-methylpiperazine 18 g / L in tap water (organic concentration). 72 g / L). The pH of this synthetic wastewater was 11.6, and the total organic carbon concentration (TOC) measured by adjusting the pH to 7.1 with hydrochloric acid (35%) was 34,600 mg / L, and the total nitrogen concentration (T- N) was 18,500 mg / L and CODMn was 38,700 mg / L.

  500 mL of synthetic waste water having a pH of 11.6 was introduced into a concentrator flask of a rotary evaporator, and the concentrator flask was rotated with the concentrator flask immersed in an 80 ° C. hot water bath from the bottom to about half. The vacuum pump was operated while passing cooling water at 22 ° C. through the condensing part, 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 a condensate flask at the bottom and concentrated until the condensed water reached 425 mL (condensed water recovery rate 85%). The quality of the condensed water obtained (pH, TOC, TN and CODMn) was measured.

  Hydrochloric acid was added to 300 mL of condensed water to adjust the pH to 7.1, and the amount of hydrochloric acid added required for the adjustment was recorded. Thereafter, as in Example 1-2, a reverse osmosis membrane (manufactured by Nitto Denko, LFC-3) is arranged at the bottom of the pressure vessel, and condensed water whose pH is adjusted is introduced into the vessel and sealed, and the vessel is sealed. Pressure nitrogen was introduced to adjust the internal pressure to 1.1 MPa, and filtration was continued until the filtrate water reached 252 mL (recovery rate 84%). The quality of the obtained permeated water was measured.

  Table 5 shows the water quality results of Example 3.

  As shown in Table 5, treated water (permeated water) satisfying the drainage standard was obtained for both CODMn and TN even for synthetic wastewater containing TOC 34500 mg / L amine. The treated water quality of Example 3 was better than that of Comparative Example 2 in which synthetic wastewater having a lower organic matter concentration than the synthetic wastewater of Example 3 was treated. In addition, the amount of hydrochloric acid added in Example 3 was lower than that in Comparative Example 2, indicating that the amount of chemical used can be reduced.

DESCRIPTION OF SYMBOLS 1 Waste water treatment apparatus, 10 Raw water tank, 12 Evaporation concentration machine, 14 Concentration water tank, 16 Condenser, 18 pH adjustment apparatus, 20 Reverse osmosis membrane module, 22 Evaporator, 24 Heat medium supply piping, 26 pH adjustment tank, 28 pH Sensor, 30 pH adjuster addition pipe, 32 Drain inflow pipe, 34 Heat transfer pipe, 36 Drain part, 38 Drain pipe, 40a-40c Pump, 42 Circulation pipe, 44 Concentrated water pipe, 46 Steam recovery pipe, 48 Cooling water pipe, 50a-50b Condensate water piping, 52 treated water piping, 54 concentrated water supply piping.

Claims (6)

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 pH adjustment step of adjusting the condensed water obtained in the condensation step to pH 8 or less;
and a reverse osmosis membrane treatment step of passing the condensed water adjusted to pH 8 or lower through a reverse osmosis membrane and separating it into permeated water and concentrated water.   The method for treating amine-containing wastewater according to claim 1, wherein the concentrated water obtained in the reverse osmosis membrane treatment step is supplied to the amine-containing wastewater.   The method for treating amine-containing wastewater according to claim 1 or 2, wherein the amine concentration in the amine-containing wastewater is 35000 mg / L or less in terms of total organic carbon concentration. Evaporative concentration means for evaporating and condensing amine-containing wastewater;
Condensing means for condensing the vapor generated by the evaporative concentration means;
PH adjusting means for adjusting the condensed water obtained by the condensing means to pH 8 or less;
A reverse osmosis membrane treatment means comprising a reverse osmosis membrane and passing the condensed water adjusted to pH 8 or less through the reverse osmosis membrane and separating it into permeated water and concentrated water. Wastewater treatment equipment.   5. The amine-containing wastewater treatment apparatus according to claim 4, further comprising a supply unit that supplies the concentrated water obtained by the reverse osmosis membrane treatment unit to the amine-containing wastewater. The amine concentration in the amine-containing wastewater is 35000 mg / L or less in terms of total organic carbon concentration, and the amine-containing wastewater treatment apparatus according to claim 4 or 5.

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