JP5702221B2 - Method and apparatus for treating wastewater containing ethanolamine and hydrazine - Google Patents

Description

  The present invention relates to a method and apparatus for treating wastewater containing ethanolamine and hydrazine discharged from a heat exchanger or the like in a nuclear power plant or a thermal power plant.

Conventionally, hydrazine (N ₂ H ₄ ) and ammonium ion (NH ₄ ⁺ ) are used together as rust inhibitors in coolants for heat exchangers used in plants such as nuclear power plants and thermal power plants. It had been. In recent years, ethanolamine having a larger rust-preventing effect has begun to attract attention for these uses, and it is expected that ethanolamine and hydrazine are used in combination. When a rust inhibitor containing ethanolamine and hydrazine is added to the coolant that passes through the heat exchanger, ethanolamine and hydrazine are found in the blow water that is discharged from the heat exchanger regularly or unsteadily. Will be included. However, since ethanolamine and hydrazine increase the concentration of COD (chemical oxygen demand), which is an environmentally restricted substance, it is desirable to treat them in some way before discharge.

  As a method for treating ethanolamine, a method of treating with microorganisms under aerobic conditions is known. Ethanolamine is decomposed into ammonia, carbon dioxide, and water by microorganisms under aerobic conditions. However, when hydrazine coexists in the ethanolamine-containing wastewater, the activity of microorganisms, particularly aerobic microorganisms, may be greatly inhibited when the concentration is high because hydrazine is a reducing agent. Therefore, when the ethanolamine in the wastewater is decomposed by microorganisms, it is desirable to set the concentration of hydrazine below a predetermined value in advance. As a method for removing hydrazine, there has been proposed a method in which a copper compound such as copper sulfate is added as a catalyst, and oxidative decomposition is performed by aeration or addition of hydrogen peroxide (for example, see Patent Documents 1 to 3).

  According to the treatment methods such as Patent Documents 1 to 3, ethanolamine can be decomposed by the action of aerobic microorganisms after decomposing hydrazine.

Here, ammonia is generated by the decomposition of ethanolamine, and hydrazine (N ₂ H ₄ ) and ammonium ion (NH ₄ ⁺ ) are often added together as a rust preventive agent. Of ammonia will remain. Therefore, a process for removing residual ammonia is required in accordance with the nitrogen regulation at the treated water discharge destination.

  A biological treatment method can be adopted as a method for removing ammonia. That is, a nitrification step in which the nitrification bacteria are brought into contact with the nitrification bacteria under an aerobic condition, and a treatment liquid generated in the nitrification step is brought into contact with the denitrification bacteria under anaerobic conditions to thereby reduce the energy of the denitrification bacteria. Residual ammonia can be removed as nitrogen gas by combining the denitrification step of reacting while adding an organic substance such as methanol as a source and changing nitrate ions into nitrogen gas.

  However, when the present inventors tried biological treatment of treated water obtained by decomposing hydrazine using a copper compound as a catalyst and adding aeration or hydrogen peroxide in accordance with a conventional method, ethanolamine was decomposed. The present inventors have found a problem that has not been suggested so far, in which nitrification activity is significantly reduced.

Japanese Patent Laid-Open No. 10-062597 Japanese Patent Laid-Open No. 10-235392 JP 2004-351419 A

  An object of the present invention is to provide a treatment method and a treatment apparatus capable of efficiently decomposing ethanolamine by suppressing a decrease in nitrification activity in a nitrification step subsequent to the hydrazine decomposition step in wastewater containing ethanolamine and hydrazine. It is to provide.

  The present invention relates to a method for treating wastewater containing ethanolamine and hydrazine, under the conditions in which copper is not substantially present, specifically under the condition of a copper concentration of less than 0.1 mg / L, activated carbon and a manganese compound. A hydrazine decomposition step for decomposing hydrazine in the waste water using at least one catalyst selected from the above and an oxidizing agent; and a decomposition treatment solution produced in the hydrazine decomposition step is brought into contact with an aerobic microorganism to leave residual ethanolamine A biological treatment process in which ammonia generated by the decomposition of ethanolamine is further changed into nitrite ions or nitrate ions, and the nitrite ions or nitrate ions are changed to nitrogen gas by contacting with denitrifying bacteria, Is a method for treating wastewater containing ethanolamine and hydrazine.

  In the method for treating wastewater containing ethanolamine and hydrazine, it is preferable that the oxidizing agent used in the hydrazine decomposition step is oxygen or hydrogen peroxide.

  In the method for treating wastewater containing ethanolamine and hydrazine, a copper removal step for removing copper in the wastewater, a copper insolubilization step for insolubilizing copper in the wastewater, and a copper inactivation for inactivating copper in the wastewater. It is preferable to supply to the hydrazine decomposition step after performing at least one of the activation steps.

  Moreover, in the processing method of the said ethanolamine and hydrazine containing waste_water | drain, it is preferable that the said copper inactivation process adds a chelating agent and inactivates the copper in the said waste_water | drain.

  In the method for treating wastewater containing ethanolamine and hydrazine, the chelating agent is preferably ethylenediaminetetraacetic acid.

  In the method for treating wastewater containing ethanolamine and hydrazine, copper is an essential element for biological treatment. Therefore, it is preferable to add at least a copper compound to the decomposition treatment solution generated in the hydrazine decomposition step.

  In addition, the present invention is a wastewater treatment apparatus containing ethanolamine and hydrazine, and uses at least one catalyst selected from activated carbon and a manganese compound and an oxidizing agent under conditions in which copper is not substantially present. The hydrazine decomposition means for decomposing hydrazine in the waste water, the decomposition treatment liquid generated by the decomposition of the hydrazine is brought into contact with an aerobic microorganism, the remaining ethanolamine is decomposed, and the ammonia generated by the decomposition of ethanolamine is further removed. An apparatus for treating wastewater containing ethanolamine and hydrazine, comprising biological treatment means for changing to nitrite ions or nitrate ions and bringing the nitrite ions or nitrate ions into nitrogen gas by contacting with denitrifying bacteria.

  Moreover, in the said hydrazine decomposition | disassembly means in the processing apparatus of the ethanolamine and hydrazine containing waste water, it is preferable that the oxidizing agent used is oxygen or hydrogen peroxide.

  Further, in the apparatus for treating wastewater containing ethanolamine and hydrazine, a copper removing means for removing copper in the wastewater, a copper insolubilizing means for insolubilizing copper in the wastewater, and the wastewater in the front stage of the hydrazine decomposition means It is preferable to have at least one of copper deactivation means for deactivating copper.

  In the ethanolamine and hydrazine-containing wastewater treatment apparatus, the copper inactivation means preferably adds a chelating agent to inactivate copper in the wastewater.

  In the ethanolamine and hydrazine-containing wastewater treatment apparatus, the chelating agent is preferably ethylenediaminetetraacetic acid.

  The ethanolamine and hydrazine-containing wastewater treatment apparatus preferably has a copper compound addition means for adding a copper compound to the decomposition treatment liquid generated by the hydrazine decomposition means.

  In the present invention, hydrazine is decomposed in wastewater containing ethanolamine and hydrazine using at least one catalyst selected from activated carbon and a manganese compound and an oxidizing agent under the condition that copper is not substantially present. A decrease in nitrification activity in the nitrification step subsequent to the decomposition step can be suppressed, and ethanolamine can be efficiently decomposed.

It is a schematic block diagram which shows an example of the waste water treatment equipment which concerns on embodiment of this invention. It is a figure which shows transition of the ammonia concentration of the treated water in the Example 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.

  As a result of intensive studies by the present inventors, it has been found that a nitrification inhibitor is produced when wastewater in which ethanolamine and hydrazine coexist is treated in the presence of copper. This phenomenon is thought to be due to the fact that copper is the catalyst and a by-product having a strong nitrification inhibitory effect is produced from ethanolamine and hydrazine.

  Based on these facts, the present inventors added hydrazine by adding at least one catalyst selected from activated carbon and a manganese compound and an oxidizing agent to ethanolamine and hydrazine-containing waste water under the condition that copper is not substantially present. It was found that the decomposition of ethanolamine can be efficiently suppressed by suppressing the decrease in nitrification activity in the nitrification step subsequent to the hydrazine decomposition step, leading to the present invention.

  An outline of an example of a wastewater treatment apparatus according to an embodiment of the present invention is shown in FIG. The wastewater treatment apparatus 1 includes a hydrazine decomposition tank 10 as a hydrazine decomposition means, and a first aerobic decomposition tank 14, a nitrification tank 16, and a denitrification tank 18 as biological treatment means. Moreover, you may provide the 2nd aerobic decomposition tank 20 as a biological treatment means. Furthermore, the waste water treatment apparatus 1 may include the aggregating apparatus 12 having the first aggregating tank 22, the second aggregating tank 24, and the settling tank 26 as aggregating means.

  In the wastewater treatment apparatus 1 of FIG. 1, the outlet and inlet of each of the hydrazine decomposition tank 10, the agglomeration apparatus 12, the first aerobic decomposition tank 14, the nitrification tank 16, the denitrification tank 18, and the second aerobic decomposition tank 20. They are connected by piping etc. in order. The hydrazine decomposition tank 10 is provided with an oxidizer addition device 11 as an oxidizer addition means. An aeration apparatus 28 is installed in each of the first aerobic decomposition tank 14, the nitrification tank 16 and the second aerobic decomposition tank 20. In the first aggregating tank 22, the second aggregating tank 24, and the denitrification tank 18 of the aggregating apparatus 12, an agitating device 30 as an agitating unit is installed.

  The operation of the wastewater treatment method and the wastewater treatment apparatus 1 according to this embodiment will be described with reference to FIG.

  In order to prevent the secondary system cooling water of heat exchangers used in plants such as nuclear power plants and thermal power plants from flowing in and accumulating impurities during circulation and reducing heat exchange performance, Periodically clean the cooling water with ion exchange resin. Then, wastewater containing NaOH-based and HCl-based hydrazine and ethanolamine is discharged as a regeneration drainage when regenerating the ion-exchange resin with reduced performance.

  The regeneration drainage of this ion exchange resin contains hundreds to thousands mg / L of ethanolamine and hydrazine, respectively. On the other hand, if there is no route through which copper flows, the content of copper in the regeneration drainage is less than 0.1 mg / L, and it can be said that substantially no copper is contained at this point.

  And this regenerated waste water (to-be-processed water) is introduce | transduced into the hydrazine decomposition tank 10 in the waste water treatment apparatus 1 which concerns on embodiment of this invention. In the hydrazine decomposition tank 10, at least one selected from activated carbon and a manganese compound is added as a catalyst by a catalyst addition means such as a pump (not shown) while maintaining a state in which copper is not substantially present. The hydrazine decomposition is performed by supplying and reacting the oxidizing agent (hydrazine decomposition step).

  As the catalyst, at least one selected from activated carbon and a manganese compound is used from the viewpoint that hydrazine decomposition activity and the influence on microorganisms in the subsequent biological treatment are small. Activated carbon is preferable from the viewpoint of hydrazine decomposition activity.

  As the activated carbon, those in any form such as powdered activated carbon, granular activated carbon, and spherical activated carbon can be used. When granular activated carbon or spherical activated carbon is used as activated carbon, granular activated carbon or spherical activated carbon packed in an activated carbon tower is used as a hydrazine decomposition means, and water to be treated with hydrogen peroxide or the like added as an oxidizing agent can be passed through. Yes, it is not limited to these methods.

  Examples of the manganese compound include inorganic salts of manganese such as manganese oxide, manganese chloride, and manganese sulfate, and the manganese compound can be added in the form of manganese oxide powder or an aqueous solution of manganese chloride or manganese sulfate.

  The amount of at least one catalyst selected from activated carbon and a manganese compound is preferably in the range of 10 to 1,000 mg / L, and more preferably in the range of 100 to 1,000 mg / L. As the amount of the catalyst added is increased, hydrazine decomposition proceeds more rapidly, but if it is too much, the amount of sludge generated may increase.

  As the oxidizing agent, oxygen or hydrogen peroxide is preferably used, and oxygen is more preferably used. Although hydrogen peroxide is effective as an oxidant, it must be controlled in the amount of addition because it may affect the biological treatment in the subsequent stage. If oxygen is used, it is not necessary and can be easily added by aeration treatment.

  In the hydrazine decomposition step, hydrazine is decomposed under the condition that copper is not substantially present. Here, in this specification, the “condition in which copper is not substantially present” means a concentration at which copper does not function as a by-product catalyst. Is less than. Here, copper is mainly ionic copper. The concentration of copper in the water to be treated can be measured by ICP mass spectrometry (JIS K 0102) using an ICP mass spectrometer (manufactured by Perkin Elmer, ELAN DRC-e type).

  The reaction time in the hydrazine decomposition tank 10 is, for example, 2 hours to 24 hours.

  In the hydrazine decomposition step, a neutralizing agent such as sodium hydroxide is added to adjust the pH to a range of 5 to 10, and more preferably to a pH of 8 to 9. By this operation, hydrazine is decomposed into nitrogen gas and water.

  Next, there may be a case where a catalyst remains in the hydrazine decomposition treatment liquid discharged from the hydrazine decomposition tank 10. In this case, the hydrazine decomposition treatment liquid is introduced into the aggregating device 12 and decomposed with the residual catalyst. Solid-liquid separation of the treatment liquid may be performed (solid-liquid separation step). In the solid-liquid separation step, the hydrazine decomposition treatment liquid is introduced into the first flocculation tank 22, and inorganic flocculants such as ferric chloride (III) and polyaluminum chloride (PAC) are added and mixed, so that The residual catalyst is agglomerated to form a floc (floc forming step). Further, the hydrazine decomposition treatment liquid is introduced into the second flocculation tank 24, and the polymer flocculant is added and mixed to further increase the floc containing the residual catalyst formed in the first flocculation tank 22 (floc growth). Process). Next, the hydrazine decomposition treatment liquid discharged from the second coagulation tank 24 is introduced into the precipitation tank 26, and solid-liquid separation of sludge containing residual catalyst and decomposition treatment liquid is performed by gravity sedimentation or the like (solid-liquid separation step). Alternatively, the hydrazine decomposition treatment liquid discharged from the second flocculation tank 24 is introduced into a pressurized levitation tank, and fine water bubbles are generated by injecting pressurized water mixed with compressed air, and the fine air bubbles and floc are combined. By floating the floc, solid-liquid separation between the sludge containing the residual catalyst and the decomposition treatment liquid may be performed.

  Here, a part or all of the sludge separated into solid and liquid may be returned to the hydrazine decomposition tank 10 (returning step), and the amount of catalyst added may be reduced by reusing the residual catalyst in the sludge. it can.

  In the wastewater treatment apparatus 1 according to the present embodiment, for example, when copper is used in a heat exchanger or the like, the eluted copper adheres to the ion exchange resin or the like, and copper is contained in the regeneration waste liquid of the ion exchange resin. Will do. Thus, in the case where copper is substantially present in the water to be treated, copper removal means for removing copper in the water to be treated and copper insolubilization for insolubilizing copper in the water to be treated are provided on the front side of the hydrazine decomposition tank 10. It is preferable to have at least one of the means and the copper inactivation means for inactivating copper in the water to be treated. At least one of removal of copper in treated water (copper removal process), insolubilization (copper insolubilization process) and inactivation (copper inactivation process), and copper removal treatment water in the copper removal process, copper insolubilization process It is preferable to supply at least one of copper insolubilized treated water and copper inactivated treated water in the copper deactivation process to the hydrazine decomposition tank 10.

  When substantially copper is present, for example, when the concentration of copper in the water to be treated is 0.1 mg / L or more, at least one of copper removal, insolubilization and inactivation prior to the hydrazine decomposition step By carrying out this, it can be set as the conditions which copper does not exist substantially.

  As a method for removing copper, an alkali coagulation precipitation method can be generally used. In the alkali coagulation precipitation method, for example, caustic soda or slaked lime is added to the water to be treated in the coagulation tank as an alkali agent and adjusted to around pH 10 to form an inorganic salt such as copper hydroxide, which is insolubilized and generated. The copper inorganic salt is separated into solid and liquid by precipitation separation or the like in a precipitation tank.

  Further, as a heavy metal scavenger, for example, a polymer coagulant such as Olflock CL-1 (manufactured by Organo Corporation) can be added to insolubilize copper. Further, a chelating agent such as ethylenediaminetetraacetic acid (EDTA) may be added to inactivate copper.

  Next, biological treatment is performed on the decomposition treatment solution obtained after hydrazine decomposition (biological treatment step).

  The biological treatment process includes a first aerobic decomposition process in which the decomposition solution produced in the hydrazine decomposition process is brought into contact with an aerobic microorganism to decompose remaining ethanolamine, and a first aerobic process generated in the first aerobic decomposition process. The nitrification process in which the decomposition treatment liquid is brought into contact with nitrifying bacteria and ammonia generated by the decomposition of ethanolamine is changed into nitrite ions or nitrate ions, and the nitrification treatment liquid produced in the nitrification process is brought into contact with denitrifying bacteria, A denitrification step of changing ions or nitrate ions into nitrogen gas. Moreover, you may include the 2nd aerobic decomposition process which makes the denitrification process liquid produced | generated at the denitrification process contact an aerobic microorganism again.

  First, the decomposition treatment solution after hydrazine decomposition is introduced into the first aerobic decomposition tank 14 in which aerobic microorganisms such as BOD-degrading bacteria live as dominant species. In the first aerobic decomposition tank 14, for example, the pH is adjusted to a range of 6.0 to 8.5 with a neutralizing agent, and aeration is performed by the aeration apparatus 28. Other organic substances are decomposed into ammonia, carbon dioxide and water (first aerobic decomposition step).

  Next, the first aerobic decomposition treatment liquid discharged from the first aerobic decomposition tank 14 is introduced into the nitrification tank 16 where nitrifying bacteria and nitrite bacteria live. In the nitrification tank 16, for example, the pH is adjusted to a range of 6.0 to 8.5 with a neutralizing agent, and aeration is performed by the aeration device 28, so that the first aerobic is performed by the action of nitrifying bacteria or nitrite bacteria. Ammonium ions generated in the decomposition tank 14 are oxidized to nitrite ions or nitrate ions (nitrification step).

  Next, the nitrification solution discharged from the nitrification tank 16 is introduced into a denitrification tank 18 where facultative anaerobic microorganisms such as denitrifying bacteria live as dominant species. In the denitrification tank 18, for example, the pH is adjusted to a range of 6.0 to 8.5 with a neutralizing agent, and an organic substance such as methanol is added and mixed as a hydrogen donor for the denitrification reaction. The nitrite ions or nitrate ions generated in step 1 are decomposed into nitrogen gas by a biological reduction reaction (denitrification step) and released into the atmosphere.

  Next, the denitrification treatment liquid discharged from the denitrification tank 18 may be introduced into the second aerobic decomposition tank 20 where aerobic microorganisms inhabit as dominant species like the first aerobic decomposition tank 14. In the second aerobic decomposition tank 20, organic substances remaining in the liquid are decomposed without being used for metabolism by microorganisms in the organic substances added in the denitrification tank 18. In the second aerobic decomposition tank 20, for example, aeration is performed by the aeration apparatus 28, whereby the organic matter is decomposed into carbon dioxide and water by the action of aerobic microorganisms (second aerobic decomposition step). Further, a filtration device such as the submerged precision membrane filtration device 32 may be immersed in the mixed solution in the second aerobic decomposition tank 20 to perform solid-liquid separation of the treatment liquid and sludge.

  After the biological treatment, the treatment liquid is sucked or depressurized through a filtration membrane such as a microfiltration membrane as necessary to remove solid matter, and is discharged or reused after passing through the filtration membrane. The sludge remaining after the solid-liquid separation may be withdrawn at least partially and returned to the first aerobic decomposition tank 14 as a return sludge (returning step). By returning the sludge to the first aerobic decomposition tank 14, the sludge in the first aerobic decomposition tank 14 is kept as constant as possible while the remaining sludge is discharged out of the system as excess sludge. Good.

  In the present embodiment, an example in which the submerged precision membrane filtration device 32 is installed in the second aerobic decomposition tank 20 is illustrated, but an apparatus installed outside the second aerobic decomposition tank 20, A sedimentation tank or the like may be installed downstream of the aerobic decomposition tank 20 to separate the treatment liquid and sludge into solid and liquid, and the present invention is not limited to these methods.

  As treatment conditions in the first aerobic decomposition step, nitrification step, denitrification step, second aerobic decomposition step, etc. of the biological treatment step, conventional biological treatment conditions such as wastewater containing ethanolamine may be appropriately applied. .

  The wastewater treatment apparatus 1 according to the present embodiment preferably includes a copper compound addition unit that adds a copper compound to the decomposition treatment liquid generated in the hydrazine decomposition step.

  In addition to calcium, magnesium, potassium, and the like, elements other than nitrogen and phosphorus are also required for the growth of microorganisms. When these elements are insufficient in the decomposition treatment liquid generated in the hydrazine decomposition step, it is desirable to add necessary amounts. In particular, since hydrazine is decomposed in the hydrazine decomposition step under the condition that copper is not substantially present, the decomposition treatment liquid generated in the hydrazine decomposition step contains at least a trace element essential for aerobic microorganisms in the biological treatment step. It is preferable to add copper after the hydrazine decomposition step by a copper compound addition means such as a pump (not shown).

  Further, when phosphorus is insufficient in the biological treatment process, for example, a phosphorus compound such as phosphoric acid may be added so that BOD: phosphorus (weight ratio) = 100: 1.

  Examples of the mixture of trace elements necessary for microorganisms, including copper, without excess or deficiency include microbial processing performance-enhancing special nutrients such as organamine 10 (manufactured by Organo). These trace elements may be added directly to at least one of the first aerobic decomposition tank 14 and the second aerobic decomposition tank 20. In the present embodiment, by adding trace elements necessary for microorganisms after the hydrazine decomposition step, it is possible to obtain a condition in which copper is not substantially present in the hydrazine decomposition step.

  Through the above steps, almost all of the COD components such as hydrazine and ethanolamine in the waste water containing ethanolamine and hydrazine can be decomposed and removed, and there is also an inhibition in the nitrification step such as nitrification tank, denitrification step, etc. Almost all of the nitrogen in the decomposition treatment liquid can be removed with little occurrence, and the COD and total nitrogen in the treatment liquid can be reduced to below the drainage standard.

  The wastewater treatment method and wastewater treatment apparatus according to the present embodiment can be applied to wastewater containing ethanolamine and hydrazine. In particular, ethanol discharged from a heat exchanger or the like in a nuclear power plant or a thermal power plant It can be suitably applied to waste water containing amine and hydrazine.

  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.

[Hydrazine degradation activity test]
Air was aerated with respect to a system in which hydrazine was added to pure water at 200 mg / L and the catalyst concentration was the concentration shown in Table 1, and the hydrazine concentration was measured after 24 hours. The hydrazine concentration was measured by p-dimethylaminobenzaldehyde spectrophotometry using a spectrophotometer (HITACHI, U-2000A type). In particular, it was confirmed that the hydrazine decomposition activity of the system using activated carbon, manganese, cobalt and copper as a catalyst was high.

<Example 1>
Five types of wastewater not containing hydrazine as a control system were compared with those using activated carbon, manganese, cobalt, and copper as the catalyst, and the presence or absence of nitrification inhibition of the hydrazine decomposition treatment liquid by the catalyst was confirmed.

(Hydrazine decomposition conditions)
・ Test wastewater: Ion exchange resin regeneration wastewater from power plants (see Table 2 for wastewater quality)
-Control system waste water: A control system waste water was prepared by adding ethanolamine, ammonium ions, and copper to pure water so that substances other than hydrazine were equivalent to the test waste water (see Table 2). In order to confirm the influence of copper itself on nitrification inhibition, copper having the same concentration as the copper catalyst system is added.
・ Catalyst concentration: Activated carbon 200mg / L
Manganese 10mg / L (Manganese oxide added so as to be)
Cobalt 1mg / L (Cobalt chloride added so as to be)
Copper 1mg / L (added copper sulfate so as to be)
・ Hydrazine decomposition pH: 9.0
-Air aeration was performed for 24 hours to decompose hydrazine. After confirming that the hydrazine concentration was 10 mg / L or less, diluted with tap water four times and added with nutrient salts were used as raw water for the following nitrification inhibition confirmation test.

(Nitrification inhibitory confirmation test)
The hydrazine decomposition treated water was passed through an MBR (Membrane Separation Activated Sludge Method) test apparatus, and the presence or absence of a nitrification inhibitor was confirmed. The NH ₄ —N concentration (mg / L) in the treated water was measured by an indophenol blue absorptiometric method (JIS K 0102) using a spectrophotometer (manufactured by HITACHI, U-2000A type). The results are shown in FIG.
・ Reaction tank capacity: 2L
・ PVDF hollow fiber membrane ・ Water flow rate: 5.0 L / day
-Reaction vessel pH: 7.5-8.0
-Water temperature: 20-25 ° C

  Table 3 shows a summary of the evaluation results for the hydrazine decomposition activity and the nitrification activity of the decomposed water for each catalyst.

  As shown in FIG. 2, in the system in which hydrazine decomposition was performed with a copper or cobalt catalyst, the nitrification performance was lowered, and finally ammonia remained in the treated water at 200 mg / L or more. On the other hand, in the system in which hydrazine decomposition was performed using activated carbon or manganese as a catalyst, the ammonia concentration of the treated water was as good as 1 mg / L, and the nitrification performance equivalent to that of the control system was maintained. As shown in FIG. 2 and Table 3, in the treatment method for decomposing hydrazine using activated carbon or manganese as a catalyst, it is possible to decompose hydrazine without generating a nitrification inhibitory substance in the subsequent nitrification treatment. There was found.

  DESCRIPTION OF SYMBOLS 1 Waste water treatment apparatus, 10 Hydrazine decomposition tank, 11 Oxidizing agent addition apparatus, 12 Coagulation apparatus, 14 First aerobic decomposition tank, 16 Nitrification tank, 18 Denitrification tank, 20 Second aerobic decomposition tank, 22 First coagulation tank, 24 2nd aggregation tank, 26 sedimentation tank, 28 aeration apparatus, 30 stirring apparatus, 32 immersion type precision membrane filtration apparatus.

Claims (12)

A method for treating wastewater containing ethanolamine and hydrazine,
A hydrazine decomposition step of decomposing hydrazine in the waste water using at least one catalyst selected from activated carbon and a manganese compound and an oxidizing agent under a condition in which substantially no copper is present;
The decomposition treatment solution generated in the hydrazine decomposition step is brought into contact with an aerobic microorganism, the remaining ethanolamine is decomposed, and the ammonia generated by the decomposition of ethanolamine is further changed into nitrite ions or nitrate ions, A biological treatment step in which the nitrite ions or nitrate ions are changed into nitrogen gas by contacting them,
A method for treating wastewater containing ethanolamine and hydrazine, comprising: A method for treating ethanolamine and hydrazine-containing wastewater according to claim 1,
In the hydrazine decomposition step, an oxidizing agent to be used is oxygen or hydrogen peroxide, and a method for treating wastewater containing ethanolamine and hydrazine. A method for treating wastewater containing ethanolamine and hydrazine according to claim 1 or 2,
After performing at least one of a copper removal step for removing copper in the waste water, a copper insolubilization step for insolubilizing copper in the waste water, and a copper inactivation step for inactivating copper in the waste water, the hydrazine A method for treating wastewater containing ethanolamine and hydrazine, which is supplied to a decomposition step. A method for treating wastewater containing ethanolamine and hydrazine according to claim 3,
The method for treating ethanolamine and hydrazine-containing wastewater, wherein the copper inactivation step comprises adding a chelating agent to inactivate copper in the wastewater. A method for treating ethanolamine and hydrazine-containing wastewater according to claim 4,
The method for treating ethanolamine and hydrazine-containing wastewater, wherein the chelating agent is ethylenediaminetetraacetic acid. A method for treating wastewater containing ethanolamine and hydrazine according to any one of claims 1 to 5,
A method for treating ethanolamine and hydrazine-containing wastewater, wherein at least a copper compound is added to the decomposition treatment liquid produced in the hydrazine decomposition step. An apparatus for treating wastewater containing ethanolamine and hydrazine,
Hydrazine decomposition means for decomposing hydrazine in the waste water using at least one catalyst selected from activated carbon and a manganese compound and an oxidizing agent under conditions substantially free of copper;
The decomposition treatment solution generated by the decomposition of hydrazine is brought into contact with an aerobic microorganism, the remaining ethanolamine is decomposed, and the ammonia generated by the decomposition of ethanolamine is further changed into nitrite ions or nitrate ions. Biological treatment means for changing the nitrite ions or nitrate ions into nitrogen gas by contacting them,
An apparatus for treating wastewater containing ethanolamine and hydrazine, comprising: An apparatus for treating wastewater containing ethanolamine and hydrazine according to claim 7,
An apparatus for treating wastewater containing ethanolamine and hydrazine, characterized in that the oxidizing agent used in the hydrazine decomposition means is oxygen or hydrogen peroxide. An apparatus for treating wastewater containing ethanolamine and hydrazine according to claim 7 or 8,
At least a copper removing means for removing copper in the waste water, a copper insolubilizing means for insolubilizing the copper in the waste water, and a copper inactivating means for inactivating the copper in the waste water on the front side of the hydrazine decomposition means. An apparatus for treating wastewater containing ethanolamine and hydrazine, comprising any of the above. An apparatus for treating wastewater containing ethanolamine and hydrazine according to claim 9,
The said copper inactivation means adds a chelating agent and inactivates the copper in the said waste_water | drain, The processing apparatus of the ethanolamine and hydrazine containing waste_water | drain characterized by the above-mentioned. An apparatus for treating wastewater containing ethanolamine and hydrazine according to claim 10,
An apparatus for treating wastewater containing ethanolamine and hydrazine, wherein the chelating agent is ethylenediaminetetraacetic acid. The apparatus for treating wastewater containing ethanolamine and hydrazine according to any one of claims 7 to 11,
An apparatus for treating wastewater containing ethanolamine and hydrazine, comprising copper compound addition means for adding a copper compound to the decomposition treatment liquid produced by the hydrazine decomposition means.