WO2015186590A1

WO2015186590A1 - Method for treating liquid containing organic amine compound

Info

Publication number: WO2015186590A1
Application number: PCT/JP2015/065322
Authority: WO
Inventors: 英司粟井; 和茂川村; 武田　大
Original assignee: 千代田化工建設株式会社
Priority date: 2014-06-02
Filing date: 2015-05-27
Publication date: 2015-12-10
Also published as: JP2015226889A

Abstract

Provided is a method whereby a liquid containing an organic amine compound as a hardly biologically treatable substance can be economically and stably treated. A method for treating a liquid containing an organic amine compound, said method comprising an oxidation step for introducing an oxidizing agent into the liquid containing the organic amine compound and degrading the organic amine compound, and a biological treatment step for biologically treating the liquid having been treated in the oxidation step, characterized in that, in the oxidation step, the content of nitrogen in the liquid is measured and the amount of the oxidizing agent to be introduced into the liquid is controlled on the basis of the nitrogen content.

Description

Method for treating a liquid containing an amine-based organic compound

The present invention relates to a method for treating a liquid containing an amine organic compound.

Industrial wastewater discharged from petroleum refining plants, LNG plants, etc. and wastewater from sewers are generally treated by biological treatment, which is a relatively inexpensive wastewater treatment method. However, these wastewaters may contain difficult-to-treat substances that are difficult to biologically treat. In this case, it is not preferable to treat the wastewater as it is. There are various kinds of difficult-to-treat substances, and examples thereof include dioxins, organic fluorine compounds, dioxane and amines used in solvents and the like. It is known that chemical treatment such as activated carbon adsorption method, coagulation sedimentation method, Fenton oxidation method, ozone oxidation method is effective for the treatment of these inferior biological treatment substances. In combination, it becomes possible to treat wastewater containing difficult-to-treat substances.

For example, Patent Document 1 discloses a method for removing BOD and nitrogen compounds from human wastewater and sewage organic wastewater by an accelerated oxidation method, specifically, decomposing a difficult-to-treat substance contained in wastewater with ozone. In addition, a method of biological treatment under anaerobic conditions after converting the nitrogen component to nitrate nitrogen has been proposed. Patent Document 2 and Non-Patent Document 1 describe a method for biological treatment after decomposing a difficult-to-treat substance contained in wastewater by using treatment with H ₂ O ₂ or ultraviolet irradiation and ozone treatment in combination. Proposed. Patent Document 3 proposes a method in which wastewater containing a difficult-to-treat substance is pretreated with ozone and then treated with an ion exchange resin in the subsequent stage.

Furthermore, regarding a method for treating wastewater containing an amine-based organic compound as a difficult-to-treat substance, Patent Document 4 discloses that carbon gas is produced by allowing bacteria having denitrification ability to act on ethanolamine and nitrate contained in wastewater. And a method for treating wastewater comprising a step of decomposing into ammonia and a step of nitrifying the produced ammonia under aerobic conditions in the presence of activated sludge having nitrification performance.

Japanese Unexamined Patent Publication No. 60-031895 Japanese Unexamined Patent Publication No. 05-228496 Japanese Patent Laid-Open No. 10-244280 JP 11-000693 A

Conventionally, in wastewater treatment that cannot be handled by biological treatment, chemical treatment is often performed. Furthermore, when chemical treatment is provided as a pretreatment for biological treatment, most of the difficult-to-treat substances that adversely affect the subsequent biological treatment are decomposed until carbon dioxide gas is obtained, and biological treatment is performed as the final step. Assumed. Therefore, for example, in the case of chemical treatment using ozone as an oxidizing agent, there has been a problem that the consumption of high-cost ozone is increased. Further, in chemical treatments other than ozone treatment, not only costs but also safety considerations and handling of sludge generated in large quantities may be problematic. Further, when the above-described ion exchange resin or activated carbon is used, a complicated operation such as a regeneration treatment is required, and a lot of chemicals are consumed for this, so that the cost tends to increase.

In particular, oil refining plants and LNG plants that use large amounts of amine-based organic compounds are often located in inconvenient places such as desert areas close to the mining site. In this case, there are two stages: chemical treatment and biological treatment. The chemical treatment is performed as a pretreatment for biological treatment because the disadvantages of handling waste generated in large quantities and the cost of obtaining and managing large quantities of chemicals are greater than the benefits of treatment. There were few. The present invention has been made in view of the above-described conventional problems, and an object of the present invention is to provide a method capable of economically and stably treating a liquid containing an amine-based organic compound as a difficult-to-treat material.

In order to achieve the above object, a method for treating a liquid containing an amine organic compound according to the present invention includes an oxidation treatment step of decomposing the amine organic compound by introducing an oxidant into the liquid containing the amine organic compound, And a biological treatment process for biologically treating the liquid treated in the oxidation treatment process, the liquid treatment method comprising an amine-based organic compound, wherein the oxidizing agent is based on the amount of nitrogen desorbed by the decomposition. It is characterized by controlling the amount of introduction.

According to the present invention, a liquid containing an amine organic compound can be treated economically and stably.

1 is a schematic block flow diagram showing a first embodiment of a method for treating a liquid containing an amine-based organic compound according to the present invention. It is a general block flow figure showing a 2nd embodiment of a processing method of a liquid containing an amine organic compound concerning the present invention. It is a graph which shows typically change of content of nitrogen content in a liquid in an oxidation treatment process. It is a general block flow figure showing a 3rd embodiment of a processing method of a liquid containing an amine organic compound concerning the present invention. It is a general | schematic block flow figure which shows 4th Embodiment of the processing method of the liquid containing the amine organic compound which concerns on this invention. It is a general block flow figure showing a 5th embodiment of a processing method of a liquid containing an amine organic compound concerning the present invention. It is a general | schematic block flow figure which shows 6th Embodiment of the processing method of the liquid containing the amine organic compound which concerns on this invention.

The present invention relates to an amine system having an oxidation treatment step for decomposing the organic compound by introducing an oxidant into a liquid containing an amine organic compound, and a biological treatment step for biologically treating the liquid treated in the oxidation treatment step. The present invention relates to a method for treating a liquid containing an organic compound.

First, a liquid containing an amine organic compound to be treated will be described. The amine organic compound is an organic compound containing at least one of a primary amine (—NH ₂ ), a secondary amine (—NHR), and a tertiary amine (—NRR ′). And those classified as aromatic amines or heterocyclic amines. Typical amine organic compounds include monoethanolamine, diethanolamine, triethanolamine methyl, dimethylaminoethanol, isopropylaminoethanol, acrylamide piperidine, piperazine, aniline, acrylamide and the like. A certain liquid contains one or more of these amine organic compounds.

These amine-based organic compounds are used as part of an absorption liquid for cleaning gas containing carbon dioxide and / or hydrogen sulfate in petroleum refining plants, LNG plants, and the like. The amine organic compounds are also used as an organic cleaning agent in a manufacturing facility for electronic parts such as semiconductor devices, a factory for metal processing, and a corrosion inhibitor in a nuclear power generation facility. The treatment method of the present invention can be used for the effluent discharged from these plants, equipment and factories. In addition, the waste water (drainage) discharged | emitted from these factories etc. does not necessarily show the same property always.

At these factories, wastewater containing various concentrations of amine-based organic compounds from low to high concentrations is discharged at a level of several tons or more every day, and more than several to several tens of times at regular inspections. Wastewater may be discharged at once. There are various types of amine-based organic compounds contained in these wastewaters as described above, and the amine-based organic compounds contained in the wastewater may have different decomposition paths or different appropriate decomposition agents. Furthermore, a substance that becomes an inhibitor of oxidation treatment or biological treatment may be included.

In addition, wastewater treatment equipment that treats wastewater containing amine-based organic compounds often has a significant fluctuation in the load of wastewater, and when the above-mentioned inhibitors are included, the removal rate decreases or the wastewater treatment speed decreases. Therefore, it has been difficult to stably maintain sufficient removal performance. Amine-based organic compounds can be decomposed by chemical treatment with an oxidizing agent such as ozone or hydrogen peroxide. In this case, however, it is necessary to treat the amine-based organic compound while using a large amount of a decomposing agent such as an oxidizing agent.

Therefore, the present invention includes an oxidation treatment step for decomposing the amine organic compound by introducing an oxidant into the liquid containing the amine organic compound, and a biological treatment step for biologically treating the liquid treated in the oxidation treatment step. In the method for treating a liquid containing an amine-based organic compound according to the present invention, in the oxidation treatment step, the content of nitrogen in the liquid is measured, and the amount of oxidant introduced into the liquid is determined based on the content of nitrogen. I have control.

Hereinafter, a method for treating a liquid containing the amine-based organic compound of the present invention will be specifically described. As decomposition products from amine organic compounds, carbon dioxide, nitric acid and organic nitrogen are generated in chemical treatment, and carbon dioxide and ammonia are produced in biological treatment (especially aerobic biological treatment). The inventors of the present invention introduced ozone as an oxidizing agent into wastewater containing an organic compound composed of primary amine, secondary amine, or tertiary amine, and investigated its decomposition process. As a result, at the initial stage of ozone introduction, it was first confirmed that the amino group was removed from the amine organic compound by oxidation, and this amino group formed an aspect of ammonia nitrogen or nitrate nitrogen (that is, nitrous acid or nitric acid). .

Furthermore, it has been found that the ratio of ammonia to nitrate nitrogen produced in the initial stage of oxidation treatment (hereinafter also referred to as ammonia production rate) varies depending on the primary amine, secondary amine, and tertiary amine. . Specifically, the production rate of ammonia in the oxidation treatment of the liquid containing the amine organic compound was higher in the order of primary amine> secondary amine >> tertiary amine. It has been found that ammonia nitrogen is generated by detaching particularly quickly when an oxidant acts on an amine-based organic compound, and when further oxidant acts thereafter, oxidation proceeds and shifts to nitrate nitrogen.

Furthermore, it was confirmed that the oxidation of ammonia nitrogen and nitrate nitrogen proceeded later than the elimination of nitrogen from amine organic compounds. Since these ammonia nitrogen and nitrate nitrogen can be treated in biological treatment, the present inventors have determined the timing at which the nitrogen content is desorbed from the amine organic compound (that is, the total nitrogen content in the liquid). It was found that the use of an excessive oxidizing agent can be suppressed by completing the oxidation treatment at a timing when the content of ammonia nitrogen or nitrate nitrogen is high.

On the other hand, organic compounds from which amino groups are removed increase the rate of oxidative decomposition, break carbon bonds, lower the molecular weight, and organic acids (particularly carboxylic acids such as formic acid), ketones, hydroxides, alkenes, alkanes, linear organics. A compound, an aromatic compound, and the like. It was confirmed that the organic compounds from which the amino group was removed changed quickly to carbon dioxide gas without adversely affecting the oxidation treatment and the biological treatment, although there were differences in the biological treatment speed. Moreover, it confirmed that the organic compound from which the amino group remove | deviated can be easily processed in both aerobic or anaerobic biological treatment.

Based on the above examination results, in order to suppress the oxidation reaction, the present inventors measured the nitrogen content in the liquid containing the amine-based organic compound in the oxidation treatment step, and determined the nitrogen content. Based on this, it has been found that an amine-containing liquid can be treated economically and stably by controlling the amount of the oxidizing agent introduced into the liquid containing the amine-based organic compound, and the present invention has been completed.

In other words, conventionally, the organic compound from which nitrogen has been eliminated in the oxidation treatment step is reduced in molecular weight, and further, the oxidation of the desorbed nitrogen component has progressed. Therefore, a large amount of oxidant is consumed during the oxidation treatment. It was. On the other hand, in the present invention, as described above, the nitrogen content in the liquid treated in the oxidation treatment step is measured, so that the elimination of the nitrogen content from the amine organic compound proceeds from the change over time. Determine the stage and control the amount of oxidant introduced. As a result, it can be decomposed into a structure that can be treated by biological treatment (organic compounds from which amino groups have been removed, ammonia nitrogen, nitrate nitrogen, etc.), and the use of excessive oxidizing agents in the oxidation treatment process can be suppressed. In addition, the cost for liquid processing can be reduced without placing an excessive burden on the biological treatment facility. In addition, even if the properties and flow rate of the liquid to be treated fluctuate to some extent, it is not necessary to secure a large design margin for the biological treatment equipment, and thus the economy and stability can be improved in terms of equipment. It can be compatible.

[First Embodiment]
A first embodiment of a method for treating a liquid containing an amine-based organic compound according to the present invention will be described with reference to FIG. First, after a liquid containing an amine-based organic compound is received in a water receiving tank 1 such as a pit or a tank, the liquid received in the water receiving tank 1 is supplied to the oxidation treatment tank 2 by a batch method or a continuous method. In the case of the continuous type, it is preferable that the liquid flow rate to the oxidation treatment tank 2 be constant from the viewpoint of controlling the amount of oxidant introduced later.

In the oxidation treatment tank 2, an oxidant is introduced from the oxidant supply device 3 (oxidation treatment step). The oxidation treatment tank 2 is provided with a sensor 2a for measuring the content of nitrogen in the liquid supplied from the water receiving tank 1, and the oxidation treatment tank 2 is supplied from the oxidant supply device 3 based on the measured value. The amount of the oxidizing agent introduced into the is controlled.

As the nitrogen content in the liquid, measurement may be performed with any value such as mass, mol amount or concentration thereof. Examples of the method for measuring the nitrogen content in the liquid in the oxidation treatment step include COD (chemical oxygen demand), a general method for measuring organic nitrogen, and the like. It is preferable to measure at least one of the contents of various nitrogen contents, and to control the amount of oxidant introduced based on the obtained measured values. In addition, organic nitrogen is preferable as a nitrogen content whose content is measured in the oxidation treatment step. Further, among organic nitrogen, ammonia nitrogen and nitrate nitrogen (nitrous acid, nitric acid) are preferable because of high measurement accuracy.

In particular, the formation of ammonia nitrogen from amine-based organic compounds proceeds preferentially over the formation of nitrate nitrogen, and ammonia nitrogen changes to nitrate nitrogen as oxidation proceeds. A decrease in the nitrogen content is a measure that the elimination of the amino group from the amine organic compound is complete and the liquid is ready for biological treatment. Can be controlled. The reason will be described in detail below with reference to FIG.

FIG. 3 is a graph showing the change over time in the content of nitrogen in the liquid in the oxidation treatment step. The content of ammonia nitrogen in the liquid tends to increase in the initial stage of liquid treatment, but starts to decrease with the passage of time. At the timing before and after the ammonia nitrogen content began to decrease, the increase rate of nitrate nitrogen content in the liquid increased, but this changed to nitrate nitrogen as the oxidation of ammonia nitrogen progressed It is presumed to show that. Therefore, by controlling the amount of oxidant introduced so that the content of ammonia nitrogen is generally the maximum value, the optimum amount of oxidant used can be obtained without excess or deficiency.

Here, “the content of ammonia nitrogen is generally the maximum value” means that when the content of ammonia nitrogen shows a maximum value as shown in FIG. 3, the maximum value (maximum value) is 100%, ammonia nitrogen. When the content of 0 mg / L (or 0 mol / L) is 0%, it is defined that the content of ammonia nitrogen is 65% or more. The ammonia nitrogen content is more preferably 80% or more. Thereby, the consumption of an oxidizing agent can be reduced more.

When the oxidation treatment step is a batch type, the maximum value (the maximum value of the ammonia nitrogen content) can be found by measuring the change over time in the ammonia nitrogen content. Therefore, when the ammonia nitrogen content starts to decrease after the ammonia nitrogen content reaches the maximum value, the oxidation treatment step is preferably terminated. On the other hand, when the oxidation treatment process is a continuous type, immediately after the start of the oxidation treatment process, the ratio of the amount of oxidant introduced to the supply amount of the liquid supplied to the oxidation treatment tank 2 is appropriately changed while the oxidation treatment tank 2 By measuring the content of ammonia nitrogen, it is possible to determine the introduction amount of the oxidizing agent at which the content of ammonia nitrogen shows a maximum value.

Alternatively, the oxidant is such that the total amount of ammonia nitrogen and nitrate nitrogen in the liquid after the oxidation treatment step is 50 to 90 wt%, preferably 60 to 85 wt% of the total amount of organic nitrogen in the liquid. The amount of introduction may be controlled. In any method, the use of an excessive oxidizing agent can be suppressed, and the amine organic compound can be treated with a smaller load in the biological treatment process that is the next process.

As described above, since the change in the content of ammonia nitrogen and the change in the content of nitrate nitrogen in the liquid are correlated, either the content of ammonia nitrogen or the content of nitrate nitrogen Even if only this is measured, the subject of this invention can be achieved similarly to the case where both contents are measured.

As the oxidizing agent used in the oxidation treatment step, oxygen, ozone, chlorine, hypochlorous acid, manganese dioxide, hydrogen peroxide, nitric acid and the like can be suitably used. Among these, it is particularly preferable to use ozone. Thereby, it becomes easier to produce an organic compound having an oxygen-containing functional group. In the biological treatment that follows the oxidation treatment step, the organic compound having an oxygen-containing functional group is easily decomposed and can be treated efficiently. When ozone is used as the oxidant, for example, an ozone generator using silent discharge, an apparatus for electrolyzing pure water using a platinum electrode or a lead peroxide electrode, and high-concentration oxygen are produced from air. A general ozone generator such as a PSA apparatus can be used.

Moreover, it is preferable that the oxidizing agent is gaseous. The oxidant introduced into the oxidation treatment tank 2 preferably has a form of fine bubbles called microbubbles or nanobubbles in the waste water. For this reason, for example, as shown in FIG. It is preferable to generate microbubbles and nanobubbles using a fine bubble generator 12 such as a generating nozzle. Thus, not only can the contact area be increased by blowing ozone gas into the liquid in the form of microbubbles and / or nanobubbles (these microbubbles and / or nanobubbles are also referred to as micro / nano bubbles), but also the oxidation activity due to bursting of the bubbles. The reaction efficiency can be further increased by the increase.

Although not shown in FIG. 1, a pH treatment tank is provided before the oxidation treatment step, and the pH of the liquid used for the oxidation treatment step is preferably 8.0 to 14.0, more preferably 10.0 to 13.5. It is most preferable to adjust to 12.0 to 12.5. By setting the pH of the liquid to be subjected to the oxidation treatment step within the above range, the oxidation treatment of the amine organic compound can be performed more efficiently. Examples of the alkaline agent used for the pH adjuster include sodium hydroxide (caustic soda), sodium carbonate (soda ash), calcium oxide (quick lime), calcium hydroxide (slaked lime), and calcium carbonate (limestone). Examples of the acid include sulfuric acid, hydrochloric acid, carbon dioxide and the like.

As shown in FIG. 1, it is preferable that the liquid treated in the oxidation treatment tank 2 is adjusted to a predetermined pH in the pH adjustment tank 4 and then sent to the biological treatment facility 5. In the pH adjusting tank 4, the liquid is preferably adjusted to pH 5.0 to 9.0, more preferably adjusted to pH 6.0 to 8.0, and adjusted to pH 6.5 to 7.5. Most preferred. Thereby, the biological treatment of a post process can be performed efficiently. Examples of the pH adjuster include sodium hydroxide (caustic soda), sodium carbonate (soda ash), calcium oxide (quick lime), calcium hydroxide (slaked lime), and calcium carbonate (limestone). Examples of the acid include sulfuric acid, hydrochloric acid, carbon dioxide and the like.

The treatment of the liquid sent to the biological treatment facility 5 will be described (biological treatment step). In the biological treatment facility 5, the liquid containing the organic compound can be purified by inhabiting the treatment tank with microorganisms that feed on the organic compound in the liquid. The biological treatment in the biological treatment step is roughly classified into an aerobic biological treatment and an anaerobic biological treatment, but may be performed by either one or a combination of both. Or you may perform anaerobic and aerobic alternately by 1 tank intermittently.

As aerobic biological treatment, activated sludge method that decomposes organic matter in liquid into carbon dioxide etc. by aeration and agitation while making contact with microorganisms in treatment tank, biofilm made of microorganisms on the surface of various media A biofilm method in which organic matter in a liquid is biochemically processed using the biofilm, and the activated sludge is processed and activated sludge is separated using a membrane such as a hollow fiber membrane. Examples include membrane separation activated sludge method. On the other hand, examples of the anaerobic biological treatment include an anaerobic treatment method in which an anaerobic microorganism is used and the liquid is gently flowed in a treatment tank. In addition, you may perform processes, such as a film | membrane process, ion exchange, and activated carbon adsorption, as the pre-process and post-process of the oxidation process mentioned above or a biological process.

[Second Embodiment]
Next, a second embodiment of the method for treating a liquid containing an amine-based organic compound according to the present invention will be described with reference to FIG. Note that a description of the same parts as those in the first embodiment is omitted. In the second embodiment, a volatilization process (an aeration tank 6 before oxidation treatment, an aeration tank 9 after oxidation treatment or an aeration tank 10 before biological treatment described later) is provided to volatilize volatile substances in the liquid. It is a feature. In the volatilization process, the stripping gas is supplied to the liquid containing the amine organic compound to perform the volatilization process. Thereby, since volatile substances, such as ammonia, can be discharged | emitted from the liquid before an oxidation treatment process, the introduction amount of an oxidizing agent can be reduced by reducing the process target in an oxidation treatment process.

The exhaust gas containing volatile substances such as ammonia separated by the volatilization process is subjected to combustion treatment by the combustion apparatus 8 after recovering the volatile substances such as ammonia by the recovery apparatus 7 such as a cooling device or a filling tower. Is preferred. The combustion treatment is not particularly limited, and examples thereof include a method in which natural gas as fuel and excess air are burned with a burner, and a volatile substance is burnt and oxidized by the flame. Further, ammonia contained in the exhaust gas can be used for the flue gas treatment.

In addition, also in this embodiment and other embodiments, when a gaseous oxidant (such as ozone) is used at normal temperature and pressure in the oxidation treatment step, the same effect as the volatilization treatment is obtained. By using a gaseous oxidant, it is possible to oxidize amine organic compounds and strip volatile substances at the same time, reducing the consumption of excess oxidant used for oxidizing volatile substances, and improving efficiency. Furthermore, the decomposition of the target organic compound can be promoted. The gaseous oxidant may contain a gas (oxygen, nitrogen, etc.) different from the oxidant in part. Even if the gas does not have an oxidizing action, the same effect as the above-described volatilization treatment can be obtained by stripping volatile substances present in the liquid.

[Third Embodiment]
Next, a third embodiment of the method for treating a liquid containing an amine-based organic compound according to the present invention will be described with reference to FIG. In addition, description is abbreviate | omitted about the part which overlaps with above-mentioned 1st Embodiment and 2nd Embodiment. The third embodiment is characterized in that a post-oxidation aeration tank 9 is provided after the oxidation treatment tank 2 in place of the pre-oxidation aeration tank 6 of the second embodiment, and the volatilization treatment step is performed. By sending at least a part of the liquid treated in the oxidation treatment step to the volatilization treatment step in this manner, volatile substances present in the liquid can be volatilized and removed from the liquid by the volatilization treatment using a stripping gas. it can.

Volatile substances present in the liquid are organic compounds such as ammonia, benzene, toluene, organic acids, alcohols, etc. contained in the liquid before the oxidation treatment process, as well as ammonia nitrogen and nitrate produced in the oxidation treatment process. Nitrogen, low molecular organic substances, etc. are mentioned. Since the volatile substances include compounds that are targets of oxidation treatment / biological treatment, the consumption of excess oxidant can be suppressed or the oxidation treatment process and biological substances can be reduced by reducing the content of volatile substances in the liquid. The processing speed in the processing step can be improved.

As the stripping gas, general gases such as air, nitrogen and oxygen can be used. Moreover, you may use the waste gas discharged | emitted in each process as mentioned later. In addition, when using exhaust gas as stripping gas in each process, it is preferable to use the exhaust gas discharged | emitted from the process of the back | latter stage after the process.

Furthermore, in the volatilization treatment process, the liquid treated in either the post-oxidation aeration tank 9 or the pre-biological aeration tank 10 described later) may be sent to the oxidation treatment process. Since the liquid after passing through the volatilization treatment process has a lower content of substances subject to oxidation treatment than raw water, mixing this with raw water will reduce the content of nitrogen in the liquid in the oxidation treatment process. Dilution can be performed and oxidation treatment can be performed efficiently.

Moreover, as shown in FIG. 4, it is also possible to employ a system that circulates liquid in the oxidation treatment process and the volatilization treatment process. Thereby, it is possible to improve the efficiency of a volatilization process and an oxidation process more. It is effective to perform the aeration of ammonia desorbed from amine-based organic compounds immediately after oxidation with an oxidizing agent, and to achieve more efficient oxidation with an oxidizing agent (nitrogen desorption). It is desirable to recycle a part of the liquid treated in the oxidation treatment process to the volatilization treatment process. When the ozone is used as the oxidant, the amount of liquid recycled is measured by measuring the ozone concentration in the exhaust gas discharged from the oxidation treatment tank 2 and controlling it to make this value as small as possible. Consumption can be minimized. For example, it is preferable to control the ozone gas concentration of the exhaust gas in this oxidation treatment step to 100 ppmv or less.

Since both the oxidation treatment and the volatilization treatment process are promoted in an alkaline atmosphere, a basic agent such as caustic soda may be added to the aeration tank 6 before the oxidation treatment. Thereby, volatile substances, such as ammonia and an organic acid, can be removed more efficiently, and the processing speed in an oxidation treatment process and a biological treatment process can be improved.

[Fourth Embodiment]
Next, a fourth embodiment of a method for treating a liquid containing an amine-based organic compound according to the present invention will be described with reference to FIG. Note that description of portions overlapping with any of the first to third embodiments is omitted. The fourth embodiment is characterized in that the liquid after the oxidation treatment step is supplied to the pre-oxidation aeration tank 6. Thereby, the density | concentration of the nitrogen content in the liquid supplied to an oxidation treatment process can be reduced by dilution, and oxidation treatment can be advanced efficiently in an oxidation treatment process.

Further, in the fourth embodiment, a gaseous oxidant is supplied from the oxidant supplier 3. Accordingly, the exhaust gas discharged from the oxidation treatment tank 2 contains a gaseous oxidant. By using the exhaust gas in the oxidation treatment step as a stripping gas in the volatilization treatment step (in this embodiment, the pre-oxidation step aeration tank 6), the oxidant remaining in the exhaust gas in the pre-oxidation aeration tank 6 Thus, the oxidation treatment can be performed, and the load in the subsequent oxidation treatment process can be reduced.

[Fifth Embodiment]
Next, a fifth embodiment of a method for treating a liquid containing an amine-based organic compound according to the present invention will be described with reference to FIG. Note that description of portions overlapping with any of the first to fourth embodiments is omitted. The fifth embodiment is characterized in that an ozone generator 11 with a PSA (Pressure Swing Adsorption) device is used as the oxidant supplier 3. As a result, ozone or oxygen is generated as an oxidant from the oxygen-rich gas generated by the PSA apparatus, and oxygen lean gas (that is, nitrogen-rich gas) by-produced is used as a stripping gas in the aeration tank 10 before biological treatment. Ozone and oxygen that are sent and dissolved can be volatilized. By stripping off ozone, it is possible to efficiently perform biological treatment regardless of anaerobic or aerobic. Oxygen volatilization is effective for anaerobic biological treatment. One device (ozone generator 11 with PSA device) can produce oxygen-lean stripping gas and oxidants (ozone, oxygen), making the liquid processing system more efficient and compact. . Note that the gas discharged from the pre-biological aeration tank 10 may be introduced as a stripping gas into the pre-oxidation aeration tank 6 as indicated by the one-dot chain line in FIG.

[Sixth Embodiment]
Next, a sixth embodiment of the method for treating a liquid containing an amine-based organic compound according to the present invention will be described with reference to FIG. Note that description of portions overlapping with any of the first to fifth embodiments described above is omitted. The sixth embodiment is characterized in that a diluent is mixed with a liquid to be introduced into a biological treatment process. Thereby, the density | concentration of the amine organic compound in the liquid introduce | transduced into a biological treatment process can be reduced, the process inhibition factor in the biological treatment tank 5 can be reduced, and the biological treatment tank 5 can be made highly efficient. it can. As the diluting liquid, it is possible to recycle and use waste water of other systems that do not contain a difficult-to-treat substance or liquid after the biological treatment process.

As described above, the method for treating a liquid containing an amine-based organic compound of the present invention has been described with reference to a plurality of embodiments. However, the present invention is not limited to these specific examples, and the scope of the present invention is not deviated. It can be implemented in various ways. For example, it is possible to achieve the object of the present invention by appropriately combining the components in each embodiment. That is, the technical scope of the present invention extends to the claims and their equivalents.

[Reference Example 1]
Monoethanolamine (primary amine), isopropylaminoethanol (secondary amine), methyldiethylamine (tertiary amine), and piperazine (cyclic secondary amine) as amine organic compounds that are difficult-to-treat substances Four types of samples prepared to be contained in 7 liters of pure water at a concentration of about 0.0016 mol / L were prepared. With the temperature of each sample at room temperature (25 ° C.), ozone generated from oxygen gas was introduced at a flow rate of 0.06 mol / h using a micro / nano bubble generator manufactured by Asp Corporation. In this way, a batch decomposition test using ozone-containing microbubbles was performed.

Samples were sampled at the start of ozone introduction and after 30 minutes, 60 minutes and 120 minutes from the start of COD (measurement method: chemical oxygen consumption JIS K0120-20), TOC (measurement method: organic) State nitrogen (JIS K0102-22.1), organic nitrogen (measurement method: organic nitrogen, JIS K0102-44.1 and 44.2), ammonia nitrogen (measurement method: ammoniacal nitrogen, JIS K0120-42.1 and 42) .2) and nitrate nitrogen (measurement method: nitrate nitrogen and nitrite nitrogen, JIS K0102-43.2.1). The COD decomposition rate, TOC decomposition rate, organic nitrogen decomposition rate, ammonia nitrogen decomposition rate, and nitrate nitrogen decomposition rate over time were determined. The decomposition rate can be obtained by dividing the concentration (mg / L) at each stage by the concentration (mg / L) of each component at the start of processing. The results are shown in Tables 1 to 5 below. The results in Tables 1 to 5 below are analytical values in the liquid and do not include volatile substances.

[Reference Example 2]
In addition, as simulated wastewater similar to the wastewater generated by ozone decomposition by-products, four types of samples were prepared by adding formic acid, butanol, sodium sulfide, and ammonium sulfate (ammonia) to pure water. A batch decomposition test was performed under the same conditions as in Example 1. And the decomposition rate of COD of each substance was calculated | required similarly. The results are shown in Table 6 below. The results shown in Table 6 below are analytical values in the liquid and do not include volatile substances.

As shown in Tables 1-5 above, the COD decomposition rate, TOC decomposition rate, and organic nitrogen decomposition rate are different even when the decomposition rate of the amine-based material in the simulated wastewater under the same conditions is measured. This is due to the difference in the detection rate of the amine-based substance depending on each measurement method. The inventors of the present invention have found that a method for treating a liquid containing an amine-based organic compound using as an index the nitrogen content eliminated by decomposition is effective.

From the results of Tables 4 and 5, the ratio of ammonia nitrogen to the sum of ammonia nitrogen and nitrate nitrogen was 33 / (33 + 46) = 0.42 after 30 minutes for the primary amine and 31 / after 120 minutes. (31 + 69) = 0.31. Similarly, for the secondary amine, 13 / (13 + 23) = 0.36 after 30 minutes, 25 / (25 + 54) = 0.32 after 120 minutes, and 8 minutes after 30 minutes for the tertiary amine. /(8+21)=0.28, 120 minutes later 11 / (11 + 44) = 0.20, and cyclic secondary amines 30 minutes later 20 / (20 + 25) = 0.44, 120 minutes later Is 27 / (27 + 56) = 0.33.

The timing of desorption of nitrogen varies depending on the structure of various amine organic compounds, and the progress of oxidation of ammonia nitrogen to nitrate nitrogen is caused by nitrogen desorption from amine organic compounds and decomposition byproducts (organic matter). We have found that it is slow compared to further degradation of. In other words, the ratio of ammonia nitrogen to the sum of ammonia nitrogen and nitrate nitrogen changed from a high point (a point where the ammonia nitrogen concentration becomes maximum) to a decrease (ammonia nitrogen is oxidized to nitrate nitrogen) The timing is suitable for stopping ozone supply.

Therefore, from the results in Tables 4 and 5, in the treatment conditions of Reference Example 1, in the treatment of the liquid containing the primary amine, the ratio of ammonia nitrogen to the sum of ammonia nitrogen and nitrate nitrogen is 0.3 or more. It can be seen that the supply of the oxidizing agent should be stopped at the time of Similarly, when the amine organic compound contained in the liquid is a secondary amine, the ratio is 0.3 or more, and when it is a tertiary amine, the ratio is 0.2 or more. In the case of amine, it can be seen that the supply of the oxidizing agent should be stopped when the ratio is 0.3 or more. The specific ratio of ammonia nitrogen to the sum of ammonia nitrogen and nitrate nitrogen when stopping the oxidizer employed during actual operation is the ammonia nitrogen and nitrate nitrogen measured during actual operation. It is preferable to determine based on these data.

Also, from the results of Table 6 above, it can be seen that organic substances assumed as decomposition by-products are rapidly oxidized and decomposed by continuously introducing ozone. It can be seen that if the organic matter is decomposed beyond the level capable of biological treatment, ozone is wasted, and it is important to stop the ozone decomposition promptly in order to suppress consumption. Furthermore, since oxidation of ammonia produced as a by-product proceeds gradually, suppression of ammonia oxidation is also important for suppression of ozone consumption. Therefore, by measuring the amount of nitrogen desorbed by decomposition, it is possible to predict the treatment status of a liquid containing an amine-based organic compound in the oxidation treatment process, and the oxidation treatment is performed at a timing suitable for biological treatment. The process can be terminated and the process can proceed to a biological treatment process.

[Reference Example 3]
The primary amine monoethanolamine (MEA) is 0.2 parts by mass, 0.5 parts by mass, 1.0 part by mass, 3.0 parts by mass, and 5.0 parts by mass with respect to 100 parts by mass of pure water. And 6 types of MEA solution samples added with 10 parts by mass were prepared. Each of these six types of samples was subjected to aerobic biological treatment, and the degree of inhibition of the biological treatment was examined. Specifically, in a vessel equipped with a pH meter, a dissolved oxygen concentration meter, and a stirring function, each sample of the MEA solution saturated with oxygen with air (pH adjustment near neutrality) and conditioned with a solution containing MEA Planted water containing sludge and pH buffering agent was added and treated under an air atmosphere at around 20 ° C. for 40 hours.

As a result, it was confirmed by COD measurement that a sample obtained by adding 0.2 parts by mass, 0.5 parts by mass, and 1.0 parts by mass of MEA to 100 parts by mass of pure water can be sufficiently biologically treated. Among them, the sample added with 1.0 part by mass showed a remarkable decrease in the processing speed, and the sample with 0.5 part by mass also had a lower processing speed than the sample with 0.2 part by mass. Therefore, if it is 1.0 part by mass or less, it can be processed, but 0.5 part by mass (1200 mg / L as organic nitrogen) in order to ensure an industrially compatible processing rate capable of maintaining stable performance. It was preferable that the content was 0.2 parts by mass (460 mg / L as organic nitrogen) or less.

[Example 1]
Monoethanolamine (hereinafter also referred to as MEA), which is a primary amine, is dissolved in pure water, and the MEA concentration is 0.24 mol / L (that is, 1.5 parts by mass of MEA with respect to 100 parts by mass of pure water). Simulated wastewater A (pH 10.2) containing was produced, and this was treated using a lab scale test apparatus according to the process flow comprising the oxidation treatment step, the volatilization treatment step and the biological treatment step shown in FIG.

In the oxidation treatment tank 2, the simulated waste water was supplied with a treatment amount of 1 L / h as a standard value. Moreover, 0.18 mol / h of ozone gas in the form of micro / nano bubbles generated from oxygen using an ozone generator (manufactured by Ecodesign Co., Ltd.) and a micro / nano bubble generator (manufactured by Asp Co., Ltd.) was introduced as a standard value. In the oxidation treatment tank 2, an ion selective electrode (NH4-N) manufactured by Endless Hauser was attached in order to measure the nitrogen content desorbed in the simulated wastewater. Thereby, the amount of ozone gas introduced was controlled so that the ammonia content in the simulated wastewater reached a maximum value.

Specifically, the experiment was started using the standard value of the ozone introduction amount as an initial condition, and then the ozone introduction amount was changed, and the relationship with the amount of ammonia nitrogen produced was determined. And the oxidation treatment conditions (ozone introduction amount) at which the ammonia nitrogen content becomes the maximum value were determined. Then, control the amount of ozone introduced while checking the ammonia nitrogen content with the ion selective electrode (NH4-N) so that the ammonia nitrogen content is below the maximum value and above 80% of the maximum value. Then, simulated wastewater was treated. The residence time of the simulated wastewater in the oxidation treatment tank 2 and the aeration tank 9 was set to 2 hours as a standard.

Further, an air introduction type aeration tank 9 is communicated with the oxidation treatment tank 2 so that simulated waste water is circulated at a rate of 2 L / h between the aeration tank 9 and the oxidation treatment tank 2. Further, the exhaust gas containing ozone discharged from the aeration tank 9 was released after absorbing and removing impurities contained in the packed tower using the sulfuric acid aqueous solution as the absorbing solution, and the absorbed waste solution was extracted and collected in a timely manner.

The simulated wastewater oxidized in this way is collected and stored, adjusted to a pH between 6 and 8, and then supplied to the biological treatment facility 5 equipped with an air aeration mechanism and aerobic using activated sludge. Biological treatment was performed. In the biological treatment facility 5, the biological treatment was performed so that the COD of the simulated wastewater was 50 mg / L or less, and the time taken for the biological treatment was measured.

[Comparative Example 1]
In the process flow, a method of introducing ozone gas while measuring the ozone concentration in the exhaust gas from the oxidation treatment tank without measuring the nitrogen content in the aeration tank 9 and the nitrogen content of the simulated wastewater in the oxidation treatment tank 2 is adopted. Except that, the simulated wastewater was treated in the same manner as in Example 1. Various other conditions are shown in Table 7.

[Comparative Example 2]
Except that various conditions were changed as shown in Table 7, treatment of simulated wastewater was performed in the same manner as in Comparative Example 1.

[Example 2]
In the process flow, the same method as in Example 1 was applied except that the method of introducing ozone in the oxidation treatment tank 2 was changed to a diffuser tube instead of micro / nano bubbles. Various other conditions are shown in Table 7.

[Example 3]
In the oxidation treatment step, the same procedure as in Example 1 was carried out except that air of substantially the same amount (volume ratio) as ozone was introduced simultaneously with ozone.

[Example 4]
Example 1 except that simulated waste water B having an MEA concentration of 0.80 mol / L adjusted to pH 12 to 12.5 with caustic soda (ie, about 5.0 parts by mass of MEA with respect to 100 parts by mass of pure water) was used. In the same manner as in Example 4, the treatment of Example 4 was performed.

[Example 5]
The treatment was performed in the same manner as in Example 1 except that the biological treatment process was changed as follows. In Example 5, in a biological treatment process, anaerobic biological treatment was performed after nitrogen rich gas containing 1% oxygen was aerated in wastewater, and then an aerobic biological treatment was performed.

In Comparative Example 1, the amount of ozone introduced was excessive compared to Example 1. As a result, although the load of biological treatment was smaller than that in Example 1, ozone could not be used efficiently, so that the treatment efficiency of the entire system was lower than that in Example 1. In Comparative Example 2, since the amount of ozone introduced was too small, the MEA could not be sufficiently treated in the biological treatment process, and the final simulated wastewater A COD after the biological treatment could not be reduced below the target value.

In Example 2, the COD of the simulated wastewater A after biological treatment could be reduced below the target value, but the decomposition reaction rate was slightly slower than in Example 1, and the amount of ozone introduced was large. Thereby, the superiority by having the form of the microbubble of the oxidizing agent introduced in an oxidation treatment process was confirmed.

In Example 3, the ozone introduction time (residence time) was shortened, and the ozone introduction amount could be reduced by about 10%. This is due to the fact that the air introduced simultaneously with ozone promotes the effect of aeration by ozone, which is a gaseous oxidant, and the generated ammonia is immediately volatilized.

In Example 4, compared with the simulated wastewater A used in Example 1, the ammonia concentration in the simulated wastewater in the oxidation treatment process increased after 20 minutes of treatment, despite using the simulated wastewater B having a higher MEA concentration. Was suppressed, and a downward tendency was observed after 50 minutes. As a result, the oxidation treatment process was completed in a shorter time than in Example 1. In Example 5, the nitrogen content in the simulated wastewater after the biological treatment process could be further reduced by 40%. In addition, the time required for the biological treatment process could be shortened by about 10% compared to Example 1.

DESCRIPTION OF SYMBOLS 1 Water receiving tank 2 Oxidation processing tank 2a Sensor 3 Oxidizing agent supply device 4 pH adjustment tank 5 Biological treatment equipment 5a Anaerobic processing tank 5b Aerobic processing tank 6 Aerobic tank before oxidation treatment 7 Recovery device 8 Combustion device 9 After oxidation treatment Air tank 10 Aeration tank before biological treatment 11 Ozone generator with PSA device 12 Fine bubble generator

Claims

An amine organic compound having an oxidation treatment step of decomposing the amine organic compound by introducing an oxidant into the liquid containing the amine organic compound, and a biological treatment step of biologically treating the liquid treated in the oxidation treatment step A method for treating a liquid comprising:
In the oxidation treatment step, a liquid containing an amine-based organic compound is characterized in that the nitrogen content in the liquid is measured and the amount of the oxidizing agent introduced into the liquid is controlled based on the nitrogen content. Processing method.
The method for treating a liquid containing an amine-based organic compound according to claim 1, wherein the nitrogen content in the liquid is organic nitrogen.
3. The method for treating a liquid containing an amine-based organic compound according to claim 2, wherein the organic nitrogen is ammonia nitrogen and / or nitrate nitrogen.
The method for treating a liquid containing an amine-based organic compound according to claim 3, wherein the introduction amount of the oxidizing agent is controlled so that the content of ammonia nitrogen in the liquid becomes 65% to the maximum value of the maximum value.
In the oxidation treatment step, the introduction amount of the oxidizing agent is controlled so that the total amount of ammonia nitrogen and nitrate nitrogen in the liquid is 50 to 90% of the total amount of organic nitrogen in the liquid. The processing method of the liquid containing the amine organic compound of Claim 3 or 4.
6. The method for treating a liquid containing an amine-based organic compound according to claim 2, wherein the concentration of organic nitrogen in the liquid after the oxidation treatment step is 1200 mg / L or less.
The method for treating a liquid containing an amine-based organic compound according to any one of claims 1 to 6, further comprising a volatilization treatment step to volatilize a volatile substance in the liquid.
The method for treating a liquid containing an amine-based organic compound according to any one of claims 1 to 7, wherein the oxidizing agent is gaseous.
The method for treating a liquid containing an amine-based organic compound according to claim 8, wherein the oxidizing agent is ozone.
10. The processing method according to claim 9, wherein the ozone is manufactured by a PSA apparatus, and a nitrogen-rich gas manufactured by the PSA apparatus is supplied as a stripping gas in an oxidation treatment process or a volatilization treatment process.
The method for treating a liquid containing an amine organic compound according to any one of claims 8 to 10, wherein the oxidizing agent has a form of nanobubbles and / or microbubbles.
The method for treating a liquid containing an amine-based organic compound according to any one of claims 1 to 11, wherein a diluent is mixed with the liquid to be introduced into the biological treatment step.
The treatment of a liquid containing an amine-based organic compound according to any one of claims 1 to 12, wherein the liquid containing the amine-based organic compound contains an absorption liquid used for cleaning a gas containing carbon dioxide and / or hydrogen sulfate. Method.
The method for treating a liquid containing an amine-based organic compound according to any one of claims 1 to 12, wherein the liquid containing the amine-based organic compound includes a liquid discharged from a semiconductor device manufacturing facility or a nuclear power generation facility.
The liquid containing an amine-based organic compound according to any one of claims 1 to 14, wherein the amine-based organic compound includes those classified into any one of alkanolamines, aromatic amines, and heterocyclic amines. Processing method.
An amine-based organic having an oxidation treatment tank for decomposing the amine-based organic compound by contacting an oxidant with a liquid containing the amine-based organic compound, and a biological treatment processing tank for biologically treating the liquid treated in the oxidation treatment tank A liquid treatment system comprising a compound,
The said oxidation treatment tank is equipped with the sensor which measures content of the nitrogen content in a liquid, The processing system of the liquid containing an amine organic compound characterized by the above-mentioned.
17. The amine-based organic compound according to claim 16, further comprising a volatilization treatment tank for volatilizing volatile substances contained in the liquid, and sending at least a part of the liquid treated in the oxidation treatment tank to the volatilization treatment tank. Liquid processing system.