A method and system for treating ammonia-nitrogen-containing wastewater by using integrated circuit tmaH waste liquid

Abstract

The present application relates to a kind of methods and systems for treating ammonia-nitrogen-containing wastewater using integrated circuit TMAH waste liquid, belong to wastewater treatment technical field, to solve at least one of the problems in prior art, such as high energy consumption of ammonia-nitrogen-containing wastewater treatment system, easy to produce new waste liquid, not low-carbon environmental protection, and TMAH waste liquid cannot be resource utilization.The ammonia-nitrogen-containing wastewater treatment method of the present application utilizes TMAH waste liquid, oxidizes TMAH waste liquid to obtain small molecular organic matter, uses biological method to treat ammonia-nitrogen-containing wastewater, is green and environmentally friendly, saves energy, and the wastewater treated by the method of the present application can meet the discharge standard.

Description

Technical Field

[0001] This invention relates to the field of wastewater treatment technology, and in particular to a method and system for treating ammonia-nitrogen-containing wastewater using integrated circuit TMAH wastewater. Background Technology

[0002] Tetramethylammonium hydroxide (TMAH) is widely used as a developer in industries such as integrated circuits, liquid crystal displays, and printed circuit boards. The concentration of TMAH wastewater discharged during integrated circuit manufacturing processes is typically 2.38%, and it is highly alkaline and toxic. Currently, integrated circuit factories usually mix TMAH wastewater with organic wastewater and discharge it after biological treatment. Due to the toxicity of TMAH, microorganisms are poor at decomposing it, and the TMAH content in the wastewater increases environmental pollution and harms human health. TMAH wastewater is a nitrogen-containing organic compound; its recycling and resource utilization can reduce environmental pollution.

[0003] CN111285547A discloses a method for treating developer waste liquid, which mainly consists of units such as pH adjustment, coagulation and sedimentation, concentration adjustment, anaerobic biological treatment, ammonia stripping, and acid absorption. Because TMAH is toxic, it is difficult for microorganisms to degrade it; therefore, this method cannot effectively degrade TMAH waste liquid. CN207904107U discloses a TMAH waste liquid treatment system, which, according to the process flow, includes an air flotation device, an iron-carbon microelectronic device, a Fenton oxidation device, a pH adjustment device, and an A… 2 Wastewater is treated by O-MBR units and other processing units. However, this process involves too many units, making the system overly complex and costly. Furthermore, the iron-carbon microelectronic device has an excessively long reaction time and low processing efficiency. None of the aforementioned technologies achieve resource utilization of TMAH wastewater.

[0004] Typically, the ammonia nitrogen (NH3-N) concentration in wastewater discharged from integrated circuit manufacturing processes is 300-2000 mg / L, the chemical oxygen demand (COD) concentration is 100-300 mg / L, and the pH is 8-10. This wastewater usually accounts for 5-15% of the total wastewater discharged from the factory, which is a relatively large volume. The current mainstream treatment technology involves heat-exchanging the wastewater to 50℃ and using a single-stage or two-stage stripping method. In this method, NH3-N is precipitated from the water in the stripping tower and reacts with sulfuric acid to generate ammonium sulfate waste liquid. This method can remove approximately 90%-95% of the NH3-N in the water. The wastewater after ammonia nitrogen degradation is then mixed with the factory's organic wastewater and further degraded using biological methods. However, this treatment method is energy-intensive, has high operating costs, and is not environmentally friendly. Furthermore, the NH3-N in the wastewater is not truly removed but rather transferred to generate ammonium sulfate waste liquid, which requires further treatment.

[0005] Therefore, in response to the above-mentioned technical problems, there is an urgent need to develop a treatment system and method that can both utilize TMAH waste liquid for resource recovery and treat ammonia nitrogen-containing wastewater discharged from integrated circuit manufacturing processes. This system should be highly efficient, simple in structure, cause no secondary pollution to the environment, have low operating costs, and be easy to promote and apply on a large scale in industrial applications. Summary of the Invention

[0006] Based on the above analysis, the present invention aims to provide a method and system for treating ammonia nitrogen-containing wastewater using integrated circuit TMAH waste liquid, in order to solve at least one of the following problems in the existing ammonia nitrogen-containing wastewater treatment system: high energy consumption, generation of new waste liquid, lack of low carbon and environmental protection, and inability to utilize TMAH waste liquid for resource recovery.

[0007] In a first aspect, the present invention provides a method for treating ammonia-nitrogen-containing wastewater using integrated circuit TMAH waste liquid, comprising the following steps:

[0008] Step S1: After adjusting the pH value of the TMAH waste liquid for the first time, add some ammonia nitrogen-containing wastewater and reagents to perform the first homogenization treatment and TMAH oxidation treatment in sequence to obtain the oxidized TMAH waste liquid;

[0009] Step S2: After filtering another portion of the ammonia nitrogen-containing wastewater, add the oxidized TMAH waste liquid to perform a second homogenization treatment and a second pH adjustment treatment to obtain the pretreated ammonia nitrogen-containing wastewater.

[0010] Step S3: The pretreated ammonia nitrogen-containing wastewater is subjected to a first denitrification treatment, a first nitrification treatment, a second denitrification treatment, a second nitrification treatment, and a sedimentation treatment in sequence to separate the wastewater and sludge.

[0011] Furthermore, in step S1, the pH value is adjusted to 4-7 using acid.

[0012] Furthermore, in step S1, the reagent includes ferrous iron, a complexing agent, and persulfate.

[0013] Furthermore, the divalent iron includes one or more of ferrous sulfate, ferrous nitrate, or ferrous chloride;

[0014] The complexing agent is one or more of ethylenediaminetetraacetic acid, N-N'-ethylenediaminedisuccinic acid, hypozinotriacetic acid, and citric acid;

[0015] The persulfate mentioned is permonosulfate and / or perdisulfate.

[0016] Furthermore, the dosage of ferrous iron is 200-2000 mg / L, the dosage of the complexing agent is 1-30 mg / L, and the dosage of persulfate is 500-5000 mg / L.

[0017] Furthermore, in step S1, the volume ratio of TMAH waste liquid to ammonia nitrogen-containing wastewater is 1:10 to 1:250.

[0018] Furthermore, the volume ratio of TMAH waste liquid in step S1 to ammonia nitrogen-containing wastewater in step S2 is 1:2 to 1:20.

[0019] Furthermore, in step S2, the pH value is adjusted to 7-7.5.

[0020] Furthermore, in step S3, part of the sludge is returned to the first denitrification treatment to enhance the denitrification effect, and the remaining sludge is discharged for treatment.

[0021] Furthermore, in step S3, the first denitrification treatment, the first nitrification treatment, the second denitrification treatment, and the second nitrification treatment are carried out sequentially in the first anoxic tank, the first aerobic tank, the second anoxic tank, and the second aerobic tank.

[0022] Secondly, the present invention provides a system for treating ammonia-nitrogen-containing wastewater using integrated circuit TMAH waste liquid. The system includes a TMAH waste liquid pretreatment unit and an ammonia-nitrogen-containing wastewater treatment unit. The TMAH waste liquid, after being treated by the TMAH waste liquid pretreatment unit, enters the ammonia-nitrogen-containing wastewater treatment unit as a carbon raw material for treating ammonia-nitrogen-containing wastewater.

[0023] Furthermore, the TMAH waste liquid pretreatment unit includes, according to the process flow, a waste liquid tank, a first pH adjustment tank, a first homogenization tank, and a reaction tank connected in sequence.

[0024] Furthermore, the ammonia nitrogen-containing wastewater treatment unit includes, in accordance with the process flow, a raw water tank, a manganese sand filter, a second equalization tank, a second pH adjustment tank, a first anoxic tank, a first aerobic tank, a second anoxic tank, a second aerobic tank, and a sedimentation tank connected in sequence.

[0025] Furthermore, the raw water tank is also connected to the first homogenization tank, the reaction tank is also connected to the second homogenization tank, and the sedimentation tank is also connected to the first anoxic tank.

[0026] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects:

[0027] (1) The ammonia nitrogen wastewater treatment method of the present invention utilizes TMAH waste liquid for resource utilization, oxidizes TMAH waste liquid to obtain small molecule organic matter, and uses small molecule organic matter as carbon raw material for treating ammonia nitrogen wastewater. The ammonia nitrogen wastewater is treated by biological method, which is green and environmentally friendly and saves energy. The wastewater can meet the discharge standards after treatment by the method of the present invention.

[0028] (2) By adding Fe(II), a complexing agent, and persulfate, this invention constructs two advanced oxidation systems within the reaction system: the complexing agent-Fe(II)-H2O2 system and the Fe(II)-persulfate system. On one hand, in the complexing agent-Fe(II)-H2O2 system, H2O2 and Fe(II) undergo electron transfer to generate hydroxyl radicals, while Fe(II) is oxidized to Fe(III). The complexing agent reacts with Fe(II) and Fe(III) to generate Fe(II)L and Fe(III)L, which enhances the reaction between Fe(II) / Fe(III) and H2O2. Hydroxyl radicals possess strong oxidizing properties and can break the molecular chains of organic compounds. On the other hand, in the Fe(II)-persulfate system, Fe(II) and Fe(III) can act as donors, activating persulfate through single-electron transfer to generate sulfate radicals. Sulfate radicals possess strong oxidizing properties and can break the molecular chains of organic compounds. The intermediate products of TMAH oxidation are amine organic compounds such as trimethylamine, dimethylamine, and methylamine. Sulfate radicals have a better oxidizing effect on the NH bonds in amine groups than hydroxyl radicals. Therefore, hydroxyl radicals and sulfate radicals have a synergistic effect, resulting in better degradation of TMAH wastewater and reducing the dosage of complexing agents, Fe(II), persulfate, and other reagents. TMAH molecules undergo chain scission degradation into easily biodegradable small-molecule organic compounds. These small-molecule organic compounds serve as carbon sources, and ammonia nitrogen as a nitrogen source. Under the action of anoxic and aerobic microorganisms, denitrification and nitrification reactions occur, respectively, degrading ammonia nitrogen and organic matter in the wastewater. The treated wastewater meets emission standards for NH3-N, total nitrogen (TN), and COD.

[0029] (3) The system of the present invention saves equipment investment and operating costs, is simple to operate, is environmentally friendly, and is easy to promote and apply on a large scale in industrial applications.

[0030] In this invention, the above-described technical solutions can be combined with each other to achieve more preferred combinations. Other features and advantages of this invention will be set forth in the following description, and some advantages may become apparent from the description or be learned by practicing the invention. The objects and other advantages of this invention can be realized and obtained from what is particularly pointed out in the description and drawings. Attached Figure Description

[0031] The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Throughout the drawings, the same reference numerals denote the same parts.

[0032] Figure 1 This is a process flow diagram of treating ammonia nitrogen-containing wastewater using integrated circuit TMAH waste liquid according to the present invention;

[0033] Figure 2 This is a graph showing the degradation rate of TMAH over time in Experimental Example 2 of this invention. Detailed Implementation

[0034] The preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings, which constitute a part of the present invention and are used together with the embodiments of the present invention to illustrate the principles of the present invention, but are not intended to limit the scope of the present invention.

[0035] A specific embodiment of the present invention discloses a method for treating ammonia-nitrogen-containing wastewater using integrated circuit TMAH waste liquid, comprising the following steps:

[0036] Step S1: After adjusting the pH value of the TMAH waste liquid for the first time, add some ammonia nitrogen-containing wastewater and reagents to perform the first homogenization treatment and TMAH oxidation treatment in sequence to obtain the oxidized TMAH waste liquid;

[0037] Step S2: After filtering another portion of the ammonia nitrogen-containing wastewater, add the oxidized TMAH waste liquid to perform a second homogenization treatment and a second pH adjustment treatment to obtain the pretreated ammonia nitrogen-containing wastewater.

[0038] Step S3: The pretreated ammonia nitrogen-containing wastewater is subjected to a first denitrification treatment, a first nitrification treatment, a second denitrification treatment, a second nitrification treatment, and a sedimentation treatment in sequence to separate the wastewater and sludge.

[0039] Compared with the prior art, the ammonia nitrogen wastewater treatment method of the present invention utilizes TMAH waste liquid for resource recovery. The TMAH waste liquid is oxidized to obtain small molecule organic matter, which is used as carbon raw material for treating ammonia nitrogen wastewater. The ammonia nitrogen wastewater is treated by biological method, which is green and environmentally friendly, saves energy, and the wastewater treated by the method of the present invention can meet the discharge standards.

[0040] Because ammonia solution with a ratio of NH3:H2O2:H2O of 1:1:5 is typically used in integrated circuit manufacturing processes to clean microparticles from chip surfaces, the resulting ammonia nitrogen wastewater usually contains H2O2 at a concentration of 500-5000 mg / L. This invention first adds a portion of the ammonia nitrogen-containing wastewater to the TMAH waste liquid. The H2O2 in the ammonia nitrogen-containing wastewater forms an advanced oxidation system with the reagent, generating hydroxyl radicals and sulfate radicals. These two types of radicals have a synergistic effect, efficiently degrading TMAH molecules into easily biodegradable small-molecule organic compounds, thus reducing the amount of reagent required.

[0041] Specifically, in step S1, the pH value is adjusted to 4-7 using acid. At pH values ​​within this range, the advanced oxidation system exhibits high reaction efficiency and good degradation effect on TMAH.

[0042] Preferably, the acid is one or more of hydrochloric acid, sulfuric acid, or nitric acid.

[0043] Specifically, in step S1, the reagent includes ferrous iron (Fe(II)), a complexing agent, and persulfate.

[0044] Preferably, the divalent iron (Fe(II)) includes one or more of ferrous sulfate, ferrous nitrate or ferrous chloride;

[0045] The complexing agent is one or more of ethylenediaminetetraacetic acid (EDTA), N-N'-ethylenediaminedisuccinic acid (EDDS), nitrotriacetic acid (NTA), and citric acid;

[0046] The persulfate is permonosulfate (PMS) and / or perdisulfate (PDS).

[0047] It should be noted that, by adding Fe(II), a complexing agent, and persulfate, this invention constructs two advanced oxidation systems within the reaction system: the complexing agent-Fe(II)-H₂O₂ system and the Fe(II)-persulfate system. On one hand, in the complexing agent-Fe(II)-H₂O₂ system, electron transfer occurs between H₂O₂ and Fe(II) to generate hydroxyl radicals, while Fe(II) is oxidized to Fe(III). The complexing agent reacts with Fe(II) and Fe(III) to generate Fe(II)L and Fe(III)L, which enhances the reaction between Fe(II) / Fe(III) and H₂O₂. Hydroxyl radicals possess strong oxidizing properties and can break the molecular chains of organic compounds. On the other hand, in the Fe(II)-persulfate system, Fe(II) and Fe(III) can act as donors, activating persulfate through single-electron transfer to generate sulfate radicals. Sulfate radicals also possess strong oxidizing properties and can break the molecular chains of organic compounds. The intermediate products of TMAH oxidation are amine organic compounds such as trimethylamine, dimethylamine, and methylamine. Sulfate radicals have a better oxidizing effect on the NH bonds in amine groups than hydroxyl radicals. Therefore, hydroxyl radicals and sulfate radicals have a synergistic effect, resulting in better degradation of TMAH wastewater and reducing the dosage of complexing agents, Fe(II), persulfate, and other reagents. TMAH molecules undergo chain scission degradation into easily biodegradable small-molecule organic compounds. These small-molecule organic compounds serve as carbon sources, and ammonia nitrogen as a nitrogen source. Under the action of anoxic and aerobic microorganisms, respectively, denitrification and nitrification reactions occur, degrading ammonia nitrogen and organic matter in the wastewater. The treated wastewater meets emission standards for NH3-N, total nitrogen (TN), and chemical oxygen demand (COD).

[0048] The complexing agent, Fe(II), and persulfate used in this invention do not cause secondary pollution to the environment, are inexpensive and readily available, non-toxic and harmless, and easy to use.

[0049] Preferably, the dosage of Fe(II) is 200-2000 mg / L, for example, 200 mg / L, 400 mg / L, 600 mg / L, 800 mg / L, 1000 mg / L, 1200 mg / L, 1400 mg / L, 1600 mg / L, 1800 mg / L, 2000 mg / L; and the dosage of the complexing agent is 1-30 mg / L, for example, 1 mg / L, 3 mg / L, 5 mg / L, 7 mg / L, 9 mg / L, 11 mg / L, 13 mg / L, 15 mg / L, 17 mg / L, 19 mg / L, 21 mg / L, 23 mg / L, 25 mg / L, 27 mg / L, 29 mg / L, 30 mg / L. The persulfate dosage is 500-5000 mg / L, for example, 500 mg / L, 700 mg / L, 900 mg / L, 1100 mg / L, 1300 mg / L, 1500 mg / L, 1700 mg / L, 1900 mg / L, 2100 mg / L, 2300 mg / L, 2500 mg / L, 2700 mg / L, 2900 mg / L, 3100 mg / L, 3300 mg / L, 3500 mg / L, 3700 mg / L, 3900 mg / L, 4100 mg / L, 4300 mg / L, 4500 mg / L, 4700 mg / L, 4900 mg / L, and 5000 mg / L.

[0050] Through extensive testing, this invention has found that when the dosages of Fe(II), complexing agent, and persulfate are within the above-mentioned ranges, the oxidation effect of TMAH is better.

[0051] Specifically, in step S1, the volume ratio of TMAH waste liquid to ammonia nitrogen-containing wastewater is 1:10 to 1:250, for example, 1:10, 1:20, 1:30, 1:40, 1:50, 1:60, 1:70, 1:80, 1:90, 1:100, 1:110, 1:120, 1:130, 1:140, 1:150, 1:160, 1:170, 1:180, 1:190, 1:200, 1:210, 1:220, 1:230, 1:240, and 1:250.

[0052] It should be noted that when the volume ratio of TMAH waste liquid to ammonia nitrogen-containing wastewater is within the above range, the advanced oxidation reaction can proceed; outside this range, the advanced oxidation reaction cannot proceed.

[0053] Specifically, the volume ratio of TMAH waste liquid in step S1 to ammonia nitrogen-containing wastewater in step S2 is 1:2 to 1:20, for example, 1:2, 1:3, 1:4, 1:5, 1:6, 1:7, 1:8, 1:9, 1:10, 1:11, 1:12, 1:13, 1:14, 1:15, 1:16, 1:17, 1:18, 1:19, 1:20.

[0054] It should be noted that when the volume ratio of TMAH waste liquid in step S1 to ammonia nitrogen-containing wastewater in step S2 is within the above range, the subsequent denitrification reaction can proceed. If it exceeds this range, the denitrification reaction cannot proceed.

[0055] Specifically, in step S2, the pH value is adjusted to 7-7.5, for example, 7, 7.1, 7.2, 7.3, 7.4, or 7.5.

[0056] It should be noted that denitrifying bacteria have high activity and good denitrification effect when the pH value is in the range of 7-7.5.

[0057] Preferably, the pH value is adjusted using an acid or a base. More preferably, the acid is one or more of hydrochloric acid, sulfuric acid, or nitric acid, and the base is sodium hydroxide or potassium hydroxide.

[0058] It should be noted that in step S2, the filtration uses a manganese sand filter, which can remove H2O2 from the ammonia nitrogen wastewater. Since H2O2 has strong oxidizing properties, it will affect the activity of denitrifying and nitrifying bacteria in step S3.

[0059] Specifically, in step S3, part of the sludge is returned to the first denitrification treatment to enhance the denitrification effect, and the remaining sludge is discharged for treatment.

[0060] Specifically, in step S3, the first denitrification treatment, the first nitrification treatment, the second denitrification treatment, and the second nitrification treatment are carried out sequentially in the first anoxic tank, the first aerobic tank, the second anoxic tank, and the second aerobic tank.

[0061] Preferably, a portion of the mixed liquor from the first aerobic tank is recycled to the first anoxic tank by providing nitrates (NO3). - As an electron acceptor, it enhances the denitrification efficiency of the anoxic pond.

[0062] It should be noted that the water entering the first anoxic tank is wastewater whose pH has been adjusted a second time. Under anoxic conditions, denitrification occurs. Denitrifying bacteria use small organic molecules degraded by TMAH molecules as a carbon source and oxygen from nitrates in the return liquid from the first aerobic tank as an electron acceptor, carrying out respiration and life activities to reduce nitrate nitrogen to gaseous nitrogen. The first aerobic tank receives the wastewater after denitrification from the first anoxic tank and undergoes nitrification under aerobic conditions, degrading ammonia nitrogen and organic matter in the wastewater. A portion of the mixed liquid from the first aerobic tank is returned to the first anoxic tank. The second anoxic tank receives the wastewater after ammonia nitrogen degradation from the first aerobic tank and undergoes denitrification again under anoxic conditions for further biological denitrification, reducing the nitrogen content in the wastewater. The second aerobic tank receives the wastewater after denitrification from the second anoxic tank and undergoes nitrification again under aerobic conditions to further remove ammonia nitrogen and organic matter from the wastewater.

[0063] Sedimentation is carried out in a sedimentation tank. A portion of the sludge is returned to the first anoxic tank, while the remainder is discharged as excess sludge. After treatment using the method of this invention, the TMAH wastewater is fully utilized as a resource. The NH3-N, TN, and COD of the ammonia nitrogen wastewater all meet the indirect discharge standards of the current national standard "Electronic Industry Water Pollutant Discharge Standard" GB39731, namely NH3-N ≤ 45 mg / L, TN ≤ 70 mg / L, and COD ≤ 500 mg / L.

[0064] Another specific embodiment of the present invention, such as Figure 1 As shown, a system for treating ammonia-nitrogen-containing wastewater using integrated circuit TMAH waste liquid is disclosed. The system includes a TMAH waste liquid pretreatment unit and an ammonia-nitrogen-containing wastewater treatment unit. The TMAH waste liquid is treated by the TMAH waste liquid pretreatment unit and then enters the ammonia-nitrogen-containing wastewater treatment unit as a carbon raw material for treating ammonia-nitrogen-containing wastewater.

[0065] Specifically, the TMAH waste liquid pretreatment unit includes, according to the process flow, a waste liquid tank, a first pH adjustment tank, a first homogenization tank, and a reaction tank connected in sequence.

[0066] Specifically, the ammonia nitrogen-containing wastewater treatment unit includes, in sequence, a raw water tank, a manganese sand filter, a second equalization tank, a second pH adjustment tank, a first anoxic tank, a first aerobic tank, a second anoxic tank, a second aerobic tank, and a sedimentation tank.

[0067] Specifically, the raw water tank is also connected to the first homogenization tank, the reaction tank is also connected to the second homogenization tank, and the sedimentation tank is also connected to the first anoxic tank.

[0068] It should be noted that the waste liquid tank receives TMAH waste liquid discharged from the production process and adjusts the waste liquid volume; the first pH adjustment tank is used to adjust the pH value of the TMAH waste liquid. After the pH value is adjusted, the wastewater is added to the first homogenization tank with reagents. Part of the ammonia nitrogen-containing wastewater in the raw water tank is added to the first homogenization tank for uniform mixing; the uniformly mixed wastewater enters the reaction tank for reaction, and the TMAH waste liquid is degraded in the reaction tank.

[0069] The raw water tank receives ammonia-nitrogen-containing wastewater discharged from the production process. This wastewater then enters a manganese sand filter for treatment, removing H2O2. The TMAH waste liquid, after degradation treatment to obtain small-molecule organic matter, enters the second homogenization tank from the reaction tank and is uniformly mixed with the H2O2-removed ammonia-nitrogen-containing wastewater. It then enters the second pH adjustment tank to adjust the pH value, and subsequently enters the first anoxic tank for denitrification. Denitrifying bacteria reduce nitrate and nitrite nitrogen in the wastewater to N2. The first aerobic tank undergoes nitrification in an aerobic environment, where nitrifying bacteria degrade ammonia nitrogen in the wastewater into nitrate and nitrite nitrogen, while simultaneously degrading organic matter. The second anoxic tank undergoes a second denitrification reaction in an anaerobic environment, further degrading nitrate and nitrite nitrogen in the wastewater. The second aerobic tank undergoes another nitrification reaction in an aerobic environment, further degrading ammonia nitrogen and organic matter in the wastewater. The sedimentation tank separates the mixed liquid from the second aerobic tank into mud and water, and the supernatant is discharged.

[0070] A portion of the sludge in the sedimentation tank is returned to the first anoxic tank, while the other portion is discharged from the system as excess sludge.

[0071] The system of this invention saves on equipment investment and operating costs, is simple to operate, environmentally friendly, and is easy to promote and apply on a large scale in industrial applications.

[0072] The technical solution of the present invention will be further explained below with reference to specific embodiments.

[0073] Example 1

[0074] like Figure 1 As shown in this embodiment, a system for treating ammonia nitrogen-containing wastewater using integrated circuit TMAH waste liquid is provided. The system includes a TMAH waste liquid pretreatment unit and an ammonia nitrogen-containing wastewater treatment unit. The TMAH waste liquid is treated by the TMAH waste liquid pretreatment unit and then enters the ammonia nitrogen-containing wastewater treatment unit as a carbon raw material for treating ammonia nitrogen-containing wastewater.

[0075] Specifically, the TMAH waste liquid pretreatment unit includes, according to the process flow, a waste liquid tank, a first pH adjustment tank, a first homogenization tank, and a reaction tank connected in sequence.

[0076] The ammonia nitrogen wastewater treatment unit, according to the process flow, includes a raw water tank, a manganese sand filter, a second equalization tank, a second pH adjustment tank, a first anoxic tank, a first aerobic tank, a second anoxic tank, a second aerobic tank, and a sedimentation tank connected in sequence.

[0077] The raw water tank is also connected to the first homogenization tank, the reaction tank is also connected to the second homogenization tank, and the sedimentation tank is also connected to the first anoxic tank.

[0078] Example 2

[0079] A method for treating ammonia nitrogen-containing wastewater using the system of Example 1 includes the following steps:

[0080] Step S1: Collect the TMAH waste liquid discharged from the production process in the waste liquid pool. After the pH value of the TMAH waste liquid is adjusted by adding hydrochloric acid in the first pH adjustment pool to a pH of 4.5-5, add some ammonia nitrogen-containing wastewater and reagents and perform first homogenization treatment in the first homogenization pool and TMAH oxidation treatment in the reaction pool to obtain oxidized TMAH waste liquid.

[0081] The reagents include ferrous sulfate, EDTA and PDS. The dosage of ferrous sulfate is 1200 mg / L, the dosage of EDTA is 12 mg / L, the dosage of PDS is 3200 mg / L, and the volume ratio of TMAH waste liquid to ammonia nitrogen-containing wastewater is 1:90.

[0082] Step S2: After filtering another portion of the ammonia nitrogen-containing wastewater through a manganese sand filter, add the oxidized TMAH waste liquid to the second homogenization tank for a second homogenization treatment, and add HCl or NaOH to the second pH adjustment tank for a second pH adjustment to 7-7.5 to obtain the pretreated ammonia nitrogen-containing wastewater.

[0083] In step S1, the volume ratio of TMAH waste liquid to ammonia nitrogen-containing wastewater in step S2 is 1:5.

[0084] Step S3: The pretreated ammonia nitrogen-containing wastewater is sequentially subjected to first denitrification in the first anoxic tank, first nitrification in the second aerobic tank, second denitrification in the second anoxic tank, second nitrification in the second aerobic tank, and sedimentation in the sedimentation tank to separate the wastewater and sludge.

[0085] In this process, a portion of the mixed liquor from the first aerobic tank is returned to the first anoxic tank, a portion of the sludge from the sedimentation tank is returned to the first anoxic tank, and the other portion is discharged from the system as excess sludge.

[0086] Example 3

[0087] The method for treating ammonia nitrogen-containing wastewater in this embodiment is similar to that in Embodiment 2, except that...

[0088] In step S1, the reagents include ferrous chloride, EDDS and PMS. The dosage of ferrous chloride is 200 mg / L, the dosage of EDDS is 30 mg / L, the dosage of PMS is 500 mg / L, and the volume ratio of TMAH waste liquid to ammonia nitrogen-containing wastewater is 1:250.

[0089] In step S1, the volume ratio of TMAH waste liquid to ammonia nitrogen-containing wastewater in step S2 is 1:20.

[0090] Example 4

[0091] The method for treating ammonia nitrogen-containing wastewater in this embodiment is similar to that in Embodiment 2, except that...

[0092] In step S1, the reagents include ferrous sulfate, NTA and PDS. The dosage of ferrous sulfate is 2000 mg / L, the dosage of NTA is 1 mg / L, the dosage of PDS is 5000 mg / L, and the volume ratio of TMAH waste liquid to ammonia nitrogen-containing wastewater is 1:10.

[0093] In step S1, the volume ratio of TMAH waste liquid to ammonia nitrogen-containing wastewater in step S2 is 1:2.

[0094] Comparative Example 1

[0095] The method for treating ammonia nitrogen-containing wastewater in this comparative example is similar to that in Example 2, except that in step S1, the volume ratio of TMAH waste liquid to ammonia nitrogen-containing wastewater is 1:5.

[0096] Comparative Example 2

[0097] The method for treating ammonia nitrogen-containing wastewater in this comparative example is similar to that in Example 2, except that the dosage of ferrous sulfate in step S1 is 100 mg / L.

[0098] Comparative Example 3

[0099] The method for treating ammonia nitrogen-containing wastewater in this comparative example is similar to that in Example 2, except that the dosage of EDTA in step S1 is 0.5 mg / L.

[0100] Comparative Example 4

[0101] The method for treating ammonia nitrogen-containing wastewater in this comparative example is similar to that in Example 2, except that the dosage of PDS in step S1 is 400 mg / L.

[0102] Comparative Example 5

[0103] The method for treating ammonia nitrogen-containing wastewater in this comparative example is similar to that in Example 2, except that the volume ratio of TMAH waste liquid in step S1 to ammonia nitrogen-containing wastewater in step S2 is 1:1.

[0104] Experimental Example 1

[0105] Wastewater from a 12-inch integrated circuit factory was treated using the methods described in Examples 2-4 and Comparative Examples 1-5, respectively. The TMAH wastewater concentration was 2.38%, and the discharge volume was 5.5 m³. 3 / h, pH 9-10. Ammonia nitrogen wastewater volume is 650m³. 3 / h, NH3-N concentration is 350-400mg / L, H2O2 concentration is 3800-4000mg / L, COD is 120-130mg / L.

[0106] The results of testing the NH3-N content, TN content, and COD content in the treated wastewater are shown in Table 1.

[0107] Table 1

[0108] Example 2 21 24 162 Example 3 38 42 255 Example 4 42 47 272 Comparative Example 1 363 585 642 Comparative Example 2 355 540 618 Comparative Example 3 360 590 622 Comparative Example 4 345 565 640 Comparative Example 5 348 573 635

[0109] According to the data in Table 1, when the dosages of ferrous sulfate, EDTA, and PDS, and the volume ratio of TMAH waste liquid to ammonia nitrogen-containing wastewater are all within the limits specified in this invention, the NH3-N, TN, and COD values ​​of the treated effluent are low, meeting the emission standards. When the dosage of one of the three agents is lower than the minimum value within the limits specified in this invention, and the volume ratio of waste liquid to wastewater exceeds the maximum value within the limits specified, the NH3-N, TN, and COD values ​​of the treated effluent will increase significantly, failing to meet the emission standards.

[0110] Therefore, we can conclude that for a certain concentration of TMAH waste liquid and ammonia nitrogen-containing wastewater, when the dosages of ferrous sulfate, EDTA, and PDS are within the specified range, the effluent NH3-N, TN, and COD values ​​meet the discharge standards. When the dosage of a certain agent is reduced to near the specified range, the number of free radicals generated by the advanced oxidation system decreases, the TMAH waste liquid cannot be completely degraded into small molecule organic matter, and it cannot provide enough carbon source for the ammonia nitrogen-containing wastewater. Microorganisms cannot effectively degrade the ammonia nitrogen-containing wastewater, and the effluent NH3-N, TN, and COD values ​​increase after treatment, but still meet the discharge standards. When the dosage of a certain agent is reduced below the minimum value within the specified range, or when the volume ratio of TMAH waste liquid to ammonia nitrogen-containing wastewater is higher than the specified range, the advanced oxidation reaction can hardly proceed, microorganisms have difficulty degrading the ammonia nitrogen-containing wastewater, and the effluent NH3-N, TN, and COD values ​​do not meet the discharge standards after treatment.

[0111] Experimental Example 2

[0112] The degradation rate of TMAH waste liquid was compared with that of different reaction times in different oxidation systems.

[0113] The first oxidation system is Fe(II)-PDS, that is, the added reagents are ferrous sulfate and PDS;

[0114] The second oxidation system is EDDS-Fe(II)-H2O2, that is, the added reagents are: ferrous sulfate, EDDS and H2O2;

[0115] The third oxidation system is EDDS-Fe(II)-H2O2+Fe(II)-PDS, that is, the added reagents are ferrous sulfate, EDDS, PDS and H2O2.

[0116] The test method is as follows:

[0117] At room temperature, TMAH solution is prepared in the raw water tank. The solution enters the mixing tank, and the above three groups of reagents are added to the mixing tank. After thorough stirring, the solution enters the reaction tank and is discharged after exiting the reaction tank.

[0118] Specific experimental steps:

[0119] S1: Prepare a 2.38% TMAH solution in the original water tank, stir well, and adjust the pH of the solution to 5 with HCl;

[0120] S2: Add three sets of reagents to the mixing tank respectively, stir the reagents evenly, and then the solution enters the reaction tank;

[0121] Group 1: FeSO4 1500 mg / L, PDS 3800 mg / L;

[0122] Group 2: EDDS 25 mg / L, FeSO4 1500 mg / L, H2O 2 4000 mg / L;

[0123] Group 3: EDDS 18 mg / L, FeSO4 1200 mg / L, H2O2 4000 mg / L, PDS 2600 mg / L;

[0124] S3: Within 120 min of the start of the reaction, take a sample every 20 min to determine the TMAH concentration.

[0125] The degradation effects of the three oxidation systems on TMAH in water are shown in Table 2. The degradation effect changes with reaction time as follows: Figure 2 As shown, C0 is the initial concentration of the TMAH solution, and C is the concentration after a period of reaction.

[0126] Table 2

[0127] 0 0 0 0 20 11 18 45 40 22 34 67 60 34 49 82 80 42 59 91 100 46 64 97 120 48 66 100

[0128] From Table 2 and Figure 2 It can be seen that when FeSO4 is added at 1500 mg / L and PDS at 3800 mg / L, the Fe(II)-PDS system has a certain degradation effect on TMAH, and the removal rate of TMAH is 48% at 120 min.

[0129] When EDDS 25 mg / L, FeSO4 1500 mg / L, and H2O2 4000 mg / L were added, the EDDS-Fe(II)-H2O2 system showed good degradation effect on TMAH, with a removal rate of 66% at 120 min.

[0130] When EDDS 18 mg / L, FeSO4 1200 mg / L, H2O2 4000 mg / L, and PDS 2600 mg / L were added, the Fe(II)-PDS+EDDS-Fe(II)-H2O2 system significantly improved the effect, and the removal rate of TMAH could reach 100% at 120 min.

[0131] The above experimental examples demonstrate that the hydroxyl radicals and sulfate radicals generated by the EDDS-Fe(II)-H2O2+Fe(II)-PDS advanced oxidation system provided by this invention have a synergistic effect, which can reduce the dosage of reagents and make the method for degrading TMAH in water more effective.

[0132] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for treating ammonia-nitrogen-containing wastewater discharged from integrated circuit manufacturing processes using integrated circuit TMAH waste liquid, characterized in that, The concentration of H2O2 in the ammonia nitrogen wastewater is 500-5000 mg / L, and the process includes the following steps: Step S1: After adjusting the pH value of the TMAH waste liquid for the first time, add some ammonia nitrogen-containing wastewater and reagents to perform the first homogenization treatment and TMAH oxidation treatment in sequence to obtain the oxidized TMAH waste liquid; The reagents include ferrous iron, a complexing agent, and persulfate. The reaction system constructs two advanced oxidation systems: complexing agent-Fe(II)-H2O2 and Fe(II)-persulfate, generating hydroxyl radicals and sulfate radicals. The hydroxyl radicals and sulfate radicals have a synergistic effect, which can reduce the amount of reagents added and has a better degradation effect on TMAH waste liquid. Step S2: After filtering another portion of the ammonia nitrogen-containing wastewater, add the oxidized TMAH waste liquid to perform a second homogenization treatment and a second pH adjustment treatment to obtain the pretreated ammonia nitrogen-containing wastewater. Step S3: The pretreated ammonia nitrogen-containing wastewater is subjected to a first denitrification treatment, a first nitrification treatment, a second denitrification treatment, a second nitrification treatment, and a sedimentation treatment in sequence to separate the wastewater and sludge.

2. The method for treating ammonia-nitrogen-containing wastewater discharged from integrated circuit manufacturing processes using integrated circuit TMAH waste liquid according to claim 1, characterized in that, In step S1, the pH value is adjusted to 4-7 using acid.

3. The method for treating ammonia-nitrogen-containing wastewater discharged from integrated circuit manufacturing processes using integrated circuit TMAH waste liquid according to claim 1, characterized in that, The divalent iron mentioned includes one or more of ferrous sulfate, ferrous nitrate, or ferrous chloride; The complexing agent is ethylenediaminetetraacetic acid (EDTA) or N2O. N' One or more of ethylenediaminedisuccinic acid, hypozinotriacetic acid, and citric acid; The persulfate mentioned is permonosulfate and / or perdisulfate.

4. The method for treating ammonia-nitrogen-containing wastewater discharged from integrated circuit manufacturing processes using integrated circuit TMAH waste liquid according to claim 1, characterized in that, The dosage of ferrous iron is 200-2000 mg / L, the dosage of the complexing agent is 1-30 mg / L, and the dosage of persulfate is 500-5000 mg / L.

5. A method for treating ammonia-nitrogen-containing wastewater discharged from integrated circuit manufacturing processes using integrated circuit TMAH waste liquid according to any one of claims 1-4, characterized in that, In step S1, the volume ratio of TMAH waste liquid to ammonia nitrogen-containing wastewater is 1:10 to 1:

250.

6. A method for treating ammonia-nitrogen-containing wastewater discharged from integrated circuit manufacturing processes using integrated circuit TMAH waste liquid according to any one of claims 1-4, characterized in that, The volume ratio of TMAH waste liquid in step S1 to ammonia nitrogen-containing wastewater in step S2 is 1:2 to 1:

20.

7. A method for treating ammonia-nitrogen-containing wastewater discharged from integrated circuit manufacturing processes using integrated circuit TMAH waste liquid according to any one of claims 1-4, characterized in that, In step S2, adjust the pH value to 7~7.

5.

8. The method for treating ammonia-nitrogen-containing wastewater discharged from integrated circuit manufacturing processes using integrated circuit TMAH waste liquid according to claim 1, characterized in that, In step S3, part of the sludge is returned to the first denitrification treatment to enhance the denitrification effect, and the remaining sludge is discharged for treatment.

9. A method for treating ammonia-nitrogen-containing wastewater discharged from integrated circuit manufacturing processes using integrated circuit TMAH waste liquid according to claim 1, characterized in that, In step S3, the first denitrification treatment, the first nitrification treatment, the second denitrification treatment, and the second nitrification treatment are carried out sequentially in the first anoxic tank, the first aerobic tank, the second anoxic tank, and the second aerobic tank.

10. A system for treating ammonia-nitrogen-containing wastewater discharged from integrated circuit manufacturing processes using integrated circuit TMAH waste liquid according to any one of claims 1-9, characterized in that, The system includes a TMAH waste liquid pretreatment unit and an ammonia nitrogen-containing wastewater treatment unit. The TMAH waste liquid is treated by the TMAH waste liquid pretreatment unit and then enters the ammonia nitrogen-containing wastewater treatment unit as a carbon raw material for treating ammonia nitrogen-containing wastewater. The TMAH wastewater pretreatment unit, according to the process flow, includes a wastewater tank, a first pH adjustment tank, a first homogenization tank, and a reaction tank connected in sequence. The wastewater tank receives TMAH wastewater discharged from the production process. The ammonia nitrogen-containing wastewater treatment unit, according to the process flow, includes a raw water tank, a manganese sand filter, a second homogenization tank, a second pH adjustment tank, a first anoxic tank, a first aerobic tank, a second anoxic tank, a second aerobic tank, and a sedimentation tank connected in sequence. The raw water tank receives ammonia nitrogen-containing wastewater discharged from the production process, and a portion of the ammonia nitrogen-containing wastewater in the raw water tank is added to the first homogenization tank for uniform mixing. The raw water tank is also connected to the first homogenization tank, the reaction tank is also connected to the second homogenization tank, and the sedimentation tank is also connected to the first anoxic tank. The TMAH waste liquid is degraded to obtain small molecule organic matter, which enters the second homogenization tank from the reaction tank and is uniformly mixed with the ammonia nitrogen-containing wastewater from which H2O2 has been removed.

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