JP6832124B2 - Amine-containing wastewater treatment method and treatment equipment - Google Patents

Description

The present invention relates to a technique for treating amine-containing wastewater and a treatment apparatus for treating amine by evaporating and concentrating amine-containing wastewater.

Amine, which is an organic nitrogen compound, is widely used industrially as a base or a ligand. There are various substances in amines, and examples thereof include aliphatic amines such as ethanolamines and heterocyclic amines such as piperazines. Ethanolamines and piperazines have high boiling points and high basicity, so they can be used as cleaning solutions for acid gas, or they can be used as bases or ligands to prevent corrosion of metal chelating agents and metal pipes. It is used as an agent.

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

Examples of piperazines include piperazine, 1-methylpiperazine, 2-methylpiperazine, etc., which are used for cleaning acid gas (for example, Patent Document 2), hardeners for epoxy resins, chelating agents, and the like. doing.

The amine is mixed with water during or after use, and is discharged as amine-containing wastewater. Amine in wastewater is composed of carbon, nitrogen, oxygen and hydrogen atoms, and carbon and nitrogen serve as COD sources and eutrophication sources and pollute rivers and lakes.

Depending on the use of amine, the concentration of amine in wastewater may be very high, and if it is high, the concentration of organic matter may be 0.1 w / v% or more. In addition, high-concentration amine-containing wastewater exhibits an alkalinity of approximately pH 9 or higher unless a large amount of acid (hydrochloric acid, sulfuric acid, etc.) for neutralization is injected.

Since high-concentration amine-containing wastewater exhibits high COD and total nitrogen (TN), it is discharged into the environment after being treated to reduce these. When discharged into the environment, 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) in Japan based on wastewater standards.

As a method for treating amine-containing wastewater, there is a method using an evaporation concentration method. For example, in Patent Document 3, ethanolamine-containing wastewater is adjusted to pH 8 or less, evaporated and concentrated, and an oxidizing agent is added to the condensed water generated by condensing the generated steam, and the temperature is 110 ° C. or less in the presence of a catalyst. A method of oxidatively decomposing ethanolamine in condensed water has been proposed. In this method, the oxidative decomposition temperature of ethanolamine is specified to be 110 ° C or lower, but in reality, the amine decomposition efficiency does not increase unless the condensed water is heated to 60 ° C or higher, so that the residual amine is small. In order to obtain treated water, a heat source for heating the condensed water to a high temperature of a certain temperature or higher is required.

Japanese Unexamined Patent Publication No. 2015-24374 Japanese Patent No. 5679995 Japanese Unexamined Patent Publication No. 10-272478

Therefore, according to the present invention, the treatment of amine-containing wastewater that can obtain treated water with a small amount of residual amine can be obtained without the need for a heat source for heating the condensed water obtained in the treatment of amine-containing wastewater by the evaporation concentration method to a high temperature. It is made for the purpose of providing a method and a processing apparatus.

The method for treating amine-containing wastewater of the present invention includes an evaporation concentration step for evaporating and concentrating amine-containing wastewater, a condensation step for condensing vapor generated in the evaporation concentration step, and an oxidizing agent for the condensed water obtained in the condensation step. with the addition of UV was irradiated with, have a, decomposing aminolysis step the amine of the condensed water, the aminolysis step, adjusting the pH of the condensed water to 6.5-7.5 It has a pH adjusting step and a conductivity measuring step of measuring the conductivity of the condensed water after pH adjustment, and establishes a preset relationship between the conductivity of the condensed water and the amount of a necessary oxidizing agent added. It is characterized in that the amount of the oxidizing agent added to the condensed water is determined from the measured conductivity.

Further, the amine-containing wastewater treatment apparatus of the present invention is used for evaporative concentration means for evaporating and concentrating amine-containing wastewater, condensing means for condensing steam generated by the evaporative concentration means, and condensed water obtained by the condensing means. with the addition of an oxidizing agent, an ultraviolet was irradiated with, have a, decomposing aminolysis means the amine of the condensed water, the amine decomposition means, the pH of the condensed water to 6.5-7.5 It has a pH adjusting means for adjusting and a conductivity measuring means for measuring the conductivity of the condensed water after pH adjustment, and a preset relationship between the conductivity of the condensed water and the amount of a necessary oxidizing agent added. The amount of the oxidizing agent added to the condensed water is determined from the measured conductivity .

According to the present invention, the treatment of amine-containing wastewater can obtain treated water with a small amount of residual amine without the need for a heat source for heating the condensed water obtained in the treatment of amine-containing wastewater by the evaporation concentration method to a high temperature. It becomes possible to provide a method and a processing apparatus.

It is a schematic diagram which shows an example of the structure of the amine-containing wastewater treatment apparatus which concerns on embodiment of this invention. It is a figure which shows the relationship between the amine concentration in condensed water at pH 7 and conductivity.

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

FIG. 1 is a schematic view showing an example of the configuration of an amine-containing wastewater treatment apparatus according to an embodiment of the present invention. The wastewater treatment device 1 shown in FIG. 1 includes a raw water tank 10, an evaporation concentrator 12 (evaporation concentration means), a concentration water tank 14, a condenser 16 (condensing means), and an amine decomposition device 18 (amine decomposition means). The evaporation concentrator 12 includes an evaporation can 22 and a heat medium supply pipe 24. The amine decomposition device 18 includes a pH adjusting device (pH adjusting tank 26, pH sensor 28 and acid agent adding pipe 30) as a pH adjusting means, a conductivity sensor 31 as a conductivity measuring means, an oxidizing agent adding pipe 33, and a line mixer. 35, a reaction tank 39 in which an ultraviolet lamp 37 is installed is provided.

The piping configuration of the wastewater treatment apparatus 1 shown in FIG. 1 will be described below. The piping configuration shown in FIG. 1 is an example and is not limited thereto.

The 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 evaporation can 22. The heat medium supply pipe 24 is connected to a heat transfer pipe 34 provided inside the evaporation can 22. One end of the heat transfer tube 34 is connected to the heat medium supply pipe 24 as described above, and the other end is connected to the drain portion 36 provided outside the evaporation can 22. One end of the drain pipe 38 is connected to the drain portion 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 a pump 40b. 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 opening 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 50a 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 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 adjusting tank 26, and the oxidant addition pipe 33 is connected to the condensed water pipe 50b.

Next, the operation of the wastewater treatment device 1 according to the present embodiment will be described.

The amine-containing wastewater to be treated is stored in the raw water tank 10. If necessary, a pH adjuster is supplied from the pH adjuster addition pipe 29, 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 evaporation can 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 tube 34, and the heat transfer tube 34 is heated. Then, the pump 40b is operated, and the amine-containing wastewater stored in the bottom of the evaporation can 22 passes through the circulation pipe 42 and is injected from the upper part of the evaporation can 22 toward the heat transfer tube 34 heated by a heating medium such as steam. To. The injected amine-containing wastewater is heated by the heat from the heat transfer tube 34, a part of the heated wastewater evaporates, and the rest is stored as amine concentrated water at the bottom of the evaporation can 22 (evaporation concentration step). The amine concentrated water concentrated to a predetermined concentration ratio in the evaporation concentration step is discharged from the evaporation can 22, passes through the circulation pipe 42 and the concentrated water pipe 44, and is stored in the concentrated water tank 14. The entire 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 rest may be distributed to the evaporation concentration by the evaporation can 22. The heat medium such as steam that has passed through the heat transfer tube 34 is stored in the drain section 36, the pump 40a is operated as needed, and the heat medium is discharged from the drain pipe 38 to the outside of the system.

Further, the vapor of the amine-containing wastewater evaporated in the evaporation can 22 is supplied to the condenser 16 through the steam recovery pipe 46. The steam supplied to the condenser 16 exchanges heat with the coolant flowing through the cooling water pipe 48 in the condenser 16 and is condensed, and is 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 is adjusted to, for example, a pH range of 6.5 to 7.5 (pH adjustment 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 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 amount of the oxidant supplied from the oxidant addition pipe 33 is adjusted according to the measured value. .. As the acid agent, for example, sulfuric acid, hydrochloric acid and the like are used.

The condensed water and the oxidant are mixed by the line mixer 35 installed in the condensed water pipe 50b, and then introduced into the reaction tank 39. At this time, ultraviolet rays are irradiated by the ultraviolet lamp 37. In the reaction vessel 39, radicals derived from the oxidizing agent are generated under ultraviolet irradiation, and the radicals decompose amines in the condensed water (amine decomposition step). The condensed water in which the amine is decomposed is discharged from the treated water pipe 52 as treated water. Since ammonium ions may remain in the treated water depending on the oxidizing agent used, 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 disassemble.

As described above, in the present embodiment, radicals derived from the oxidizing agent are generated by ultraviolet irradiation to efficiently decompose the amine, so that the condensed water does not need to be heated to a high temperature (for example, 60 ° C. or higher). May be good. Therefore, according to the present embodiment, it is possible to obtain treated water having a small amount of residual amine without requiring a heat source for heating the condensed water to a high temperature of a certain temperature or higher.

The treatment conditions for amine-containing wastewater will be described below.

The amine to be treated in the present 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 an aqueous solution of 25 ° C. Etc., 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. Ethanolamine (for example, [(HOCH ₂ CH ₂ ) ₃ N]), 2,2-methyliminodiethanol, piperazine, 1-methylpiperazin, 2-methylpiperazin and the like can be mentioned.

The amine concentration in the amine-containing wastewater is, for example, preferably several thousand to 15,000 mg / L in terms of CODMn concentration, and more preferably 5,000 to 15,000 mg / L. When the amine concentration is 15,000 mg / L or less, it is possible to obtain condensed water with a high recovery rate while concentrating the wastewater at a sufficient magnification in the evaporation concentration step. Further, the amount of amine transferred to condensed water is relatively small, and it is possible to decompose amine with a small amount of oxidizing agent added in the amine decomposition step. On the other hand, when the amine concentration exceeds 15,000 mg / L, a large amount of oxidizing agent is required to obtain good treated water quality, and the decomposition time of amine may be long.

In the treatment method of the present embodiment, when the pH of the amine-containing wastewater before the evaporation step is adjusted, it is preferable to adjust the pH to 8 or less, and more preferably 7.5 or less. As a result, the amount of amine contained in the condensed water can be reduced, so that the amount of the oxidizing agent used for decomposing the amine can be reduced. Normally, since the amine-containing wastewater has an alkalinity of pH 9 or higher, an acid agent is added to the amine-containing wastewater to adjust the pH to 8 or less. For example, a large amount of acid or the like is mixed in the amine-containing wastewater in advance, and the apparatus When the pH of the material is low (for example, pH 5 or less), which may affect the material due to corrosion or the like, an alkaline agent may be added until the pH becomes less affected (for example, more than pH 5). Further, in the treatment method of the present embodiment, the evaporation concentration step may be performed on the amine-containing wastewater exhibiting alkalinity of pH 9 or higher without adjusting the pH. This makes it possible to reduce the amount of acid and alkaline agents used.

The evaporation can 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 evaporation cans such as a type evaporation can, a forced circulation type evaporation can, a liquid film type evaporation can, and a vacuum evaporation can can be used. Among these, a vacuum evaporation can is preferable in terms of energy cost for evaporation and concentration. The vacuum evaporator is provided with a vacuum pump for depressurizing the inside of the evaporator. For example, the inside of the evaporator is depressurized to −0.05 to −0.02 MPa (gauge pressure) with the vacuum pump. As a result, the amine-containing wastewater having a high boiling point can be evaporated at a low heating temperature (for example, 60 to 90 ° C.), so that the energy cost can be suppressed.

Considering disposal, it is desirable to set the concentration ratio of the amine concentrate in the evaporation concentration step high so that the amount of water in the amine concentrate is small, but on the other hand, when the concentration ratio is increased, the condensed water The amine contained in the oxidizer may increase, and the amount of the oxidizing agent used may increase. Therefore, in terms of reducing disposal costs and the amount of oxidizing agent used, the concentration ratio of the amine concentrate in the evaporation concentration step is preferably 25 times or less, and more preferably 15 times to 25 times. .. Further, when dissolved silica is contained in the amine-containing wastewater, if the concentration proceeds, silica may precipitate in the evaporation can 22 and the heating efficiency of the amine-containing wastewater may decrease. Therefore, the silica is concentrated within a range in which the silica does not precipitate. It is desirable to set the magnification.

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

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 amine in the condensed water under ultraviolet irradiation, but for example, hydrogen peroxide. Examples thereof include ozone, sodium hypochlorite, potassium permanganate, chlorine dioxide, potassium permanganate, and sodium persulfate. Of these, hydrogen peroxide, ozone, and sodium hypochlorite are preferable in terms of amine decomposition efficiency, but since ozone requires on-site generation equipment, hydrogen peroxide and hypochlorous acid are required. Sodium is more preferred. When hydrogen peroxide or ozone is used, it is considered that hydroxyl radicals with strong oxidizing power are generated under ultraviolet irradiation, and the hydroxyl radicals decompose amines into inorganic carbon (bicarbonate ion, etc.) and ammonium ions. Be 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 (bicarbonate ion and the like) and nitrogen.

In the case of sodium hypochlorite, the amount added is larger than in the case of using hydrogen peroxide or ozone, but as described above, ammonium ions can be decomposed at the same time as amine decomposition. In the case of hydrogen peroxide and ozone, as described above, ammonium ions are generated as decomposition products of amines. Therefore, when the treated water is discharged, hypochlorite is used to decompose the regulated ammonium ions. It is desirable to use it in combination with sodium chlorite.

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 excima 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 decomposition of organic substances by the combined use of an oxidizing agent. The ultraviolet irradiation time depends on the amine concentration in the condensed water, but 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 approximately 9.0 to 11, but 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 the range of ~ 7.5 and perform amine decomposition by adding an oxidizing agent and irradiating with ultraviolet rays, because the rate of amine decomposition can be increased rather than performing amine decomposition with condensed water having a pH of 9 or higher.

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

FIG. 2 is a diagram showing the relationship between the amine concentration in the condensed water at pH 7 and the conductivity. The condensed water contains amines and their dissociated ions that have migrated from the wastewater to the condensed water side. 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 the ionic state. Therefore, in the condensed water adjusted to pH 6.5-7.5 with an acid agent, amine ions (mainly cations) and anions derived from the acid agent corresponding to their concentrations (for example, chloride ions and sulfate ions) ) Will be mainly present, so that the conductivity in the condensed water is substantially proportional to the amine concentration, for example, as shown in FIG. Therefore, for example, by setting the required amount of the oxidizing agent added to the conductivity of the condensed water in advance, the amount of the oxidizing agent to be supplied can be determined from the measured value of the conductivity of the condensed water. it can. The amount of the oxidant added depends on the type of amine and the required treated water quality, but is preferably set to be about 2 to 5 times the CODMn of the condensed water in terms of molar ratio, and is about 2 to 3 times. It is more preferable that it is set to be.

The amine decomposition apparatus 18 may include a control unit that controls the amount of the oxidizing agent added. For example, data such as a graph or a table in which the required amount of the oxidizing agent is added to the conductivity of the condensed water is stored in the control unit in advance. Then, the control unit applies the value measured by the conductivity sensor 31 to the data stored in advance to determine the required amount of the oxidizing agent added. Then, the control unit controls a valve (not shown), a pump (not shown), or the like installed in the oxidant addition pipe 33 so that the determined amount of the oxidant is added. Further, the amine decomposition apparatus 18 may include a control unit that controls the amount of the acid agent added. For example, a valve (not shown) installed in the acid agent addition pipe 30 so that the supply of the acid agent is stopped when the value measured by the pH sensor 28 reaches pH 6.5 to 7.5. Control the pump (not shown), etc.

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited to the following Examples.

<Example 1>
As the 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 wastewater dissolved in water was prepared (organic matter concentration 24 g / L). The pH of this synthetic wastewater was 11.3.

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

The pH of this synthetic wastewater 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 wastewater having a pH of 7.1 was introduced into the concentrated part flask of the rotary evaporator, and the concentrated part flask was rotated while the concentrated part flask was immersed in a hot water bath at 80 ° C. 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 the condensed water flask at the bottom and concentrated until the condensed water became 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 solution (effective concentration 30%) was added to 100 mL of condensed water after adjusting the pH so as to have a concentration _{of 80 mgH 2} O _{2 / L.} The amount of hydrogen peroxide added was 2.5 times (molar ratio) of CODMn of condensed water.

Condensed water to which hydrogen peroxide was added was put into a quartz beaker, and ultraviolet rays were irradiated for 240 minutes while stirring the condensed water. The 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.

Then, 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 wastewater was adjusted to 8.0 with hydrochloric acid (35%). The chloride ion concentration in the synthetic wastewater after adjusting the pH was 8,000 mg / L (CODMn was 13,000 mg / L, and the total nitrogen concentration (TN) was 5,700 mg / L).

500 mL of synthetic wastewater having 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 solution (effective concentration 30%) was added to 100 mL of condensed water after adjusting the pH 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>
An evaporation concentration step was performed on synthetic wastewater having a pH of 11.3 (chloride ion concentration: 150 mg / L, CODMn: 13,000 mg / L, total nitrogen concentration (TN): 5,700 mg / L). The evaporation 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 water quality of the obtained condensed water (pH, CODMn, TN, Cl) was the same. ^- 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 solution (effective concentration 30%) was added to 100 mL of condensed water after adjusting the pH so as to have a concentration _{of 2110 mgH 2} O _{2 / L.} The amount of hydrogen peroxide added 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 all of Examples 1 to 3 in which the oxidant was added and the ultraviolet irradiation was performed without heating the condensed water obtained by evaporating and concentrating the amine-containing wastewater, the CODMn in the treated water was less than 100 mg / L, which was the wastewater standard. It was a value satisfying (daily average 120 mg / L). The temperature of the condensed water at the time of adding the oxidizing agent and irradiating with ultraviolet rays was around room temperature (about 25 ° C.). Therefore, when decomposing amines in condensed water, it can be said that treated water having a small amount of residual amine could be obtained without requiring a heat source for heating the condensed water. Further, among Examples 1 to 3, Examples 1 and 2 in which the pH of the amine-containing wastewater at the time of evaporation and concentration was adjusted to 8 or less remained as compared with Example 3 in which the pH was not adjusted. It was possible to obtain treated water with a small amount of amine.

1 Wastewater treatment equipment, 10 Raw water tank, 12 Evaporation concentrator, 14 Concentration water tank, 16 Condenser, 18 Amin decomposition equipment, 22 Evaporation can, 24 Heat medium supply piping, 26 pH adjustment tank, 28 pH sensor, 29 pH adjuster Addition pipe, 30 acid agent addition pipe, 31 conductivity sensor, 32 drainage inflow pipe, 33 oxidant addition pipe, 34 heat transfer pipe, 35 line mixer, 36 drain part, 37 ultraviolet lamp, 38 drain pipe, 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 (2)

An evaporative concentration step that evaporates and concentrates amine-containing wastewater,
A condensation step that condenses the vapor generated in the evaporation concentration step, and
While adding an oxidizing agent to the condensate obtained in the condensation step, ultraviolet is irradiated with, have a, decomposing aminolysis step the amine of the condensed water,
The amine decomposition step includes a pH adjusting step of adjusting the pH of the condensed water to 6.5 to 7.5 and a conductivity measuring step of measuring the conductivity of the condensed water after adjusting the pH. It is characterized in that the amount of the oxidant to be added to the condensed water is determined from the measured conductivity by using a preset relationship between the conductivity of the condensed water and the amount of the required oxidant added. A method for treating amine-containing wastewater. Evaporative concentration means for evaporating and concentrating amine-containing wastewater,
A condensing means that condenses the steam generated by the evaporative concentration means, and
While adding an oxidizing agent to the condensate obtained in the condenser means, the ultraviolet is irradiated with, have a, decomposing aminolysis means the amine of the condensed water,
The amine decomposition means includes 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 adjusting the pH. Using the set relationship between the conductivity of the condensed water and the required amount of the oxidizing agent added, the amount of the oxidizing agent added to the condensed water is determined from the measured conductivity. Amine-containing wastewater treatment equipment.