Wastewater treatment processes and ammonia nitrogen-containing wastewater treatment systems

Abstract

A wastewater treatment process involves real-time monitoring of the ammonia nitrogen concentration in the wastewater and comparing it with a preset threshold. Based on the ammonia nitrogen concentration, a first wastewater treatment method is used to treat wastewater with high ammonia nitrogen concentrations, and a second wastewater treatment method is used to treat wastewater with low ammonia nitrogen concentrations. After the first and second wastewater treatments, the wastewater from both methods is mixed and homogenized. This process reduces energy and reagent consumption while ensuring the treated ammonia nitrogen-containing wastewater meets emission standards. Furthermore, the wastewater treatment process provided by this invention can adapt to changes in the ammonia nitrogen concentration of the wastewater and adjust the treatment method accordingly, allowing for more flexible wastewater treatment.

Description

Technical Field

[0001] This invention relates to the field of semiconductor manufacturing, and more particularly to a wastewater treatment process and a system for treating ammonia-nitrogen-containing wastewater. Background Technology

[0002] Ammonia nitrogen is a key contributor to eutrophication in water bodies. Direct discharge of ammonia-nitrogen-containing wastewater stimulates algae growth, depletes dissolved oxygen, and causes fish and other aquatic organisms to suffocate and die. Simultaneously, ammonia nitrogen transforms into toxic substances such as nitrites in water, directly poisoning aquatic life, disrupting the food chain balance of aquatic ecosystems, and causing poisoning or even death in fish and other aquatic organisms due to high concentrations of ammonia-nitrogen-containing wastewater. Therefore, the treatment of ammonia-nitrogen-containing wastewater is an essential requirement for pollution control and a core component of water resource recycling, ecological security maintenance, and green industrial transformation, possessing significant environmental and economic value.

[0003] In the semiconductor manufacturing process, some processes (such as chemical mechanical polishing and metal-organic chemical vapor deposition) generate ammonia-nitrogen-containing wastewater. To ensure that production activities comply with environmental protection standards, the ammonia-nitrogen-containing wastewater generated in the semiconductor manufacturing process needs to be treated so that the ammonia nitrogen concentration, acidity, alkalinity and other indicators of the treated ammonia-nitrogen-containing wastewater meet the emission standards.

[0004] However, existing ammonia nitrogen wastewater treatment processes suffer from high energy consumption. Summary of the Invention

[0005] The problem solved by the embodiments of the present invention is to provide a wastewater treatment process and an ammonia nitrogen-containing wastewater treatment system that reduces the energy consumption of treating ammonia nitrogen-containing wastewater while treating the wastewater.

[0006] To address the aforementioned problems, this invention provides a wastewater treatment process for treating wastewater containing ammonia nitrogen, comprising: real-time monitoring of the ammonia nitrogen concentration of the wastewater; comparing the ammonia nitrogen concentration of the wastewater with a preset threshold; when the ammonia nitrogen concentration of the wastewater is greater than or equal to the preset threshold, performing a first wastewater treatment on the wastewater with an ammonia nitrogen concentration greater than or equal to the threshold; when the ammonia nitrogen concentration of the wastewater is less than the preset threshold, performing a second wastewater treatment on the wastewater with an ammonia nitrogen concentration less than the preset threshold; mixing the wastewater after the first wastewater treatment and the wastewater after the second wastewater treatment, and performing homogenization adjustment.

[0007] Optionally, the step of performing a first wastewater treatment on the wastewater with an ammonia nitrogen concentration higher than or equal to the preset threshold includes: conveying the wastewater to an ammonia stripping unit for ammonia removal treatment.

[0008] Optionally, the step of performing a second wastewater treatment on the wastewater with an ammonia nitrogen concentration lower than the preset threshold includes: transporting the wastewater to an acid-base reaction tank and adding an acidic liquid to the acid-base reaction tank to neutralize the alkalinity of the wastewater.

[0009] Optionally, the acidic liquid includes waste acid from cation bed regeneration.

[0010] Optionally, in the step of transporting the wastewater to the acid-base reaction tank, the pH value of the wastewater is 10.5-11.5; after adding acidic liquid to the acid-base reaction tank, the pH value of the wastewater drops to 5.5-6.5.

[0011] Optionally, the preset threshold is 35 mg / L to 45 mg / L.

[0012] Optionally, in the step of real-time monitoring of the ammonia nitrogen concentration of the wastewater, the wastewater is located in an ammonia-containing equalization tank, and a monitoring instrument for monitoring the ammonia nitrogen concentration of the wastewater is installed on the output pipeline of the ammonia-containing equalization tank, and the monitoring instrument is connected to an automatic control valve.

[0013] Optionally, in the step of comparing the ammonia nitrogen concentration of the wastewater with a preset threshold, when the ammonia nitrogen concentration of the wastewater is greater than or equal to the preset threshold, the automatic control valve guides the wastewater through the output pipeline and then through the first pipeline to the ammonia stripping unit; when the ammonia nitrogen concentration of the wastewater is less than the preset threshold, the automatic control valve guides the wastewater through the output pipeline and then through the second pipeline to the acid-base reaction tank.

[0014] Optionally, the wastewater treatment process further includes: before real-time monitoring of the ammonia nitrogen concentration in the wastewater, collecting the ammonia nitrogen-containing wastewater in an ammonia-containing equalization tank for water quality homogenization treatment.

[0015] This invention also provides an ammonia-nitrogen-containing wastewater treatment system, comprising: an ammonia-containing equalization tank for receiving and homogenizing ammonia-nitrogen-containing wastewater; an ammonia-nitrogen monitoring instrument installed on the output pipeline of the ammonia-containing equalization tank for real-time monitoring of the ammonia-nitrogen concentration of the wastewater flowing out of the ammonia-containing equalization tank; an automatic control valve connected to the ammonia-nitrogen monitoring instrument for switching the wastewater treatment path based on a comparison result of the ammonia-nitrogen concentration and a preset threshold; an ammonia stripping unit connected to the automatic control valve via a first pipeline for receiving wastewater with an ammonia-nitrogen concentration greater than or equal to the preset threshold and performing ammonia stripping treatment; an acid-base reaction tank connected to the automatic control valve via a second pipeline for receiving wastewater with an ammonia-nitrogen concentration less than the preset threshold, the acid-base reaction tank also having an acidic liquid inlet for receiving acidic liquid to neutralize the alkalinity of the received wastewater; and an acid-base equalization tank connected to the outlet of the ammonia stripping unit and the outlet of the acid-base reaction tank, respectively, for receiving the wastewater treated by the ammonia stripping unit and the acid-base reaction tank and performing mixing, homogenization, and equalization.

[0016] Compared with the prior art, the technical solution of the embodiments of the present invention has the following advantages: In the wastewater treatment process provided by this invention embodiment, the ammonia nitrogen concentration of the wastewater is monitored in real time and compared with a preset threshold. Based on the ammonia nitrogen concentration, a first wastewater treatment method is used to treat wastewater with high ammonia nitrogen concentration, and a second wastewater treatment method is used to treat wastewater with low ammonia nitrogen concentration. After the first and second wastewater treatments, the wastewater treated by the first and second wastewater treatments is mixed and homogenized. Under the premise that the treated ammonia nitrogen-containing wastewater meets emission standards, the energy and reagent consumption in the wastewater treatment process is reduced. Furthermore, the wastewater treatment process provided by this invention embodiment can also cope with changes in the ammonia nitrogen concentration of the wastewater and adjust the wastewater treatment method according to these changes, enabling more flexible wastewater treatment.

[0017] The ammonia nitrogen-containing wastewater treatment system provided in this embodiment of the invention includes: an ammonia-containing equalization tank for storing and homogenizing ammonia nitrogen-containing wastewater; an ammonia nitrogen monitoring instrument installed on the output pipeline of the ammonia-containing equalization tank for real-time monitoring of the ammonia nitrogen concentration in the ammonia nitrogen-containing wastewater flowing out of the ammonia-containing equalization tank; and an automatic control valve connected to the ammonia nitrogen monitoring instrument, which automatically switches the wastewater treatment path based on a comparison between the value of the ammonia nitrogen monitoring instrument and a preset threshold. When the value of the ammonia nitrogen monitoring instrument is greater than or equal to the preset threshold, the automatic control valve opens the first pipeline connected to the automatic control valve to transport the ammonia nitrogen-containing wastewater into an ammonia stripping unit; when the value of the ammonia nitrogen monitoring instrument is lower than the preset threshold, the automatic control valve opens the second pipeline connected to the automatic control valve to transport the ammonia nitrogen-containing wastewater into an acid-base reaction tank. The treated wastewater from the ammonia stripping unit and the acid-base reaction tank is sent to the acid-base equalization tank and mixed and homogenized. The ammonia nitrogen wastewater treatment system provided in this embodiment of the invention reduces the energy and chemical reagent consumption of the system while ensuring that the treated wastewater meets the discharge standards. Furthermore, the ammonia nitrogen wastewater treatment system provided in this embodiment of the invention can also cope with changes in the ammonia nitrogen concentration of the wastewater and adjust the treatment site and corresponding treatment method according to the changes in the ammonia nitrogen concentration, thus treating the wastewater in a more flexible manner. Attached Figure Description

[0018] Figure 1 This is a flowchart of the wastewater treatment process according to an embodiment of the present invention; Figure 2 This is a structural block diagram of an ammonia nitrogen-containing wastewater treatment system according to an embodiment of the present invention. Detailed Implementation

[0019] As can be seen from the background technology, existing ammonia nitrogen-containing wastewater treatment processes have the problem of high energy consumption.

[0020] Specifically, the ammonia nitrogen component in the ammonia nitrogen-containing wastewater generated during semiconductor manufacturing processes includes water-soluble ammonia molecules and ammonium ions. Existing technologies often employ ammonia stripping processes to treat this ammonia nitrogen-containing wastewater. The ammonia stripping process creates a strongly alkaline environment by adding an alkaline solution, thereby forcing a large number of ammonium ions in the ammonia nitrogen-containing wastewater to be converted into ammonia molecules. Then, air is blown into the bottom of the ammonia stripping unit, and the ammonia nitrogen-containing wastewater is sprayed from the top of the ammonia stripping unit. The ammonia nitrogen-containing wastewater and the air come into countercurrent contact in the middle of the ammonia stripping unit, causing the ammonia molecules in the ammonia nitrogen-containing wastewater to be transferred into the air.

[0021] Although existing technologies can reduce the ammonia nitrogen concentration in the ammonia nitrogen-containing wastewater to some extent, they often use fixed parameters when treating the ammonia nitrogen-containing wastewater, which can cause unnecessary losses in actual production processes.

[0022] Specifically, existing technologies employ the aforementioned ammonia stripping process for both high- and low-concentration ammonia-nitrogen wastewater. While suitable for treating high-concentration ammonia-nitrogen wastewater, the ammonia stripping process is less cost-effective for reducing the ammonia nitrogen concentration in low-concentration wastewater, and it involves waste of energy and chemicals. Therefore, treating low-concentration ammonia-nitrogen wastewater requires alternative treatment methods that consume less energy and chemicals.

[0023] To address the aforementioned technical problem, the wastewater treatment process provided in this embodiment of the invention involves real-time monitoring of the ammonia nitrogen concentration in the wastewater and comparing it with a preset threshold. Based on the ammonia nitrogen concentration, a first wastewater treatment process is used to treat wastewater with high ammonia nitrogen concentrations, while a second wastewater treatment process is used to treat wastewater with low ammonia nitrogen concentrations. After both the first and second wastewater treatments, the treated wastewater is mixed and homogenized. This process reduces energy and reagent consumption while ensuring the treated ammonia nitrogen-containing wastewater meets emission standards. Furthermore, the wastewater treatment process provided in this embodiment can also adapt to changes in the ammonia nitrogen concentration of the wastewater and adjust the treatment method accordingly, enabling more flexible wastewater treatment.

[0024] The technical solutions in the disclosed embodiments will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the invention, and not all embodiments. Based on the embodiments of the invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the invention.

[0025] refer to Figure 1 A wastewater treatment process for treating wastewater containing ammonia nitrogen includes: Step S1: Real-time monitoring of the ammonia nitrogen concentration in the wastewater.

[0026] It should be noted that the wastewater is stored in an ammonia-containing equalization tank, which continuously discharges wastewater. Due to different process applications, the wastewater discharged into the ammonia-containing equalization tank has varying ammonia nitrogen concentrations. Therefore, the wastewater discharged into the ammonia-containing equalization tank will change the ammonia nitrogen concentration of the wastewater in the equalization tank. In other words, the ammonia nitrogen concentration of the wastewater in the equalization tank is constantly changing. The wastewater treatment process provided in this embodiment monitors the ammonia nitrogen concentration of the wastewater in real time to ensure the accuracy of comparing the ammonia nitrogen concentration in the wastewater with a preset threshold. This improves the accuracy of subsequent judgments on the first wastewater treatment of wastewater with high ammonia nitrogen concentration and the second wastewater treatment of ammonia-containing wastewater with low ammonia nitrogen concentration. This is beneficial for reducing the energy and reagent consumption in the wastewater treatment process while ensuring that the treated wastewater meets the discharge standards.

[0027] In some embodiments, during the step of real-time monitoring of the ammonia nitrogen concentration in the wastewater, the wastewater is in an ammonia-containing equalization tank, and a monitoring instrument for monitoring the ammonia nitrogen concentration in the wastewater is installed on the output pipeline of the ammonia-containing equalization tank. The monitoring instrument is connected to an automatic control valve.

[0028] The ammonia-containing equalization tank is used to store and homogenize the wastewater. The output pipeline of the ammonia-containing equalization tank is used to transport the wastewater out of the ammonia-containing equalization tank. A monitoring instrument is installed on the output pipeline of the ammonia-containing equalization tank. The monitoring instrument accurately measures the ammonia nitrogen concentration of the wastewater. The automatic control valve is connected to the monitoring instrument. Subsequently, the ammonia nitrogen concentration of the wastewater is compared with a preset threshold, and the valve is switched to adjust the inflow location of the wastewater in the ammonia-containing equalization tank and the treatment method of the wastewater leaving the ammonia-containing equalization tank.

[0029] In some embodiments, the wastewater treatment process further includes: before real-time monitoring of the ammonia nitrogen concentration in the wastewater, collecting the ammonia nitrogen-containing wastewater in an ammonia-containing equalization tank for water quality homogenization treatment.

[0030] The wastewater containing ammonia nitrogen is collected in an ammonia-containing equalization tank for water quality homogenization treatment. This is to ensure that the wastewater in the equalization tank has a relatively uniform acidity / alkalinity and ammonia nitrogen concentration, which is beneficial for subsequent centralized treatment of wastewater containing ammonia nitrogen with low or high ammonia nitrogen concentrations.

[0031] In some embodiments, the ammonia nitrogen concentration of the wastewater is measured, and the wastewater is treated based on the ammonia nitrogen concentration.

[0032] It should be noted that, according to the ammonia nitrogen concentration, the embodiments of the present invention employ different treatment methods to treat wastewater with high ammonia nitrogen concentration and wastewater with low ammonia nitrogen concentration respectively. On the basis of ensuring that the treated wastewater meets the discharge standards, the consumption of energy and chemical agents in the wastewater treatment process is reduced. In addition, the embodiments of the present invention can also cope with changes in the ammonia nitrogen concentration of the wastewater and adjust the wastewater treatment method according to the changes in the ammonia nitrogen concentration of the wastewater, so as to treat the wastewater in a more flexible manner.

[0033] In some embodiments, step S2: compare the ammonia nitrogen concentration in the wastewater with a preset threshold; step S2.1: when the ammonia nitrogen concentration in the wastewater is greater than or equal to the preset threshold, perform a first wastewater treatment on the wastewater with an ammonia nitrogen concentration greater than or equal to the preset threshold; step S2.2: when the ammonia nitrogen concentration in the wastewater is less than the preset threshold, perform a second wastewater treatment on the wastewater with an ammonia nitrogen concentration less than the preset threshold.

[0034] The ammonia nitrogen concentration of the wastewater is measured in real time and compared with a preset threshold. The wastewater with an ammonia nitrogen concentration higher than or equal to the preset threshold is subjected to first wastewater treatment, and the wastewater with an ammonia nitrogen concentration lower than the preset threshold is subjected to second wastewater treatment. This allows for adjustments to the wastewater treatment method based on changes in the ammonia nitrogen concentration of the wastewater, enabling more flexible wastewater treatment.

[0035] In some embodiments, the preset threshold is 35 mg / L to 45 mg / L.

[0036] It should be noted that the preset threshold value should not be set too high or too low. If the preset threshold value is too high, the wastewater treatment process will perform second wastewater treatment on some of the high ammonia nitrogen concentration wastewater that should have undergone the first wastewater treatment. Since the second wastewater treatment is not suitable for high ammonia nitrogen concentration wastewater, the treated wastewater will still have a high ammonia nitrogen concentration, resulting in a high ammonia nitrogen concentration in the final discharged wastewater, which may fail to meet the standards. If the preset threshold value is too low, the wastewater treatment process will perform first wastewater treatment on some of the low ammonia nitrogen concentration wastewater that could have undergone the second wastewater treatment. The first wastewater treatment will waste energy and chemical agents when treating low ammonia nitrogen concentration wastewater, resulting in no significant energy and chemical agent savings compared to existing technologies.

[0037] In some embodiments, in the step of comparing the ammonia nitrogen concentration of the wastewater with a preset threshold, when the ammonia nitrogen concentration of the wastewater is greater than or equal to the preset threshold, the automatic control valve guides the wastewater through the output pipeline and then through the first pipeline to the ammonia stripping unit; when the ammonia nitrogen concentration of the wastewater is less than the preset threshold, the automatic control valve guides the wastewater through the output pipeline and then through the second pipeline to the acid-base reaction tank.

[0038] As an example, the automatic control valve is an electric three-way ball valve. The input end of the automatic control valve is connected to the output pipeline of the ammonia-containing equalization tank. The automatic control valve is driven by a monitoring instrument with a relay output. The controller inside the monitoring instrument or connected to the monitoring instrument compares the ammonia nitrogen concentration of the wastewater with a preset threshold. If the ammonia nitrogen concentration of the wastewater is greater than or equal to the preset threshold, the automatic control valve connects the output pipeline of the ammonia-containing equalization tank to a first pipeline, guiding the wastewater to the ammonia stripping unit. If the ammonia nitrogen concentration of the wastewater is lower than the preset threshold, the automatic control valve connects the output pipeline of the ammonia-containing equalization tank to a second pipeline, guiding the wastewater to the acid-base reaction tank.

[0039] In some embodiments, the step of performing a first wastewater treatment on the wastewater with an ammonia nitrogen concentration higher than or equal to the preset threshold includes: conveying the wastewater to an ammonia stripping unit for ammonia removal treatment.

[0040] The ammonia removal process creates a strongly alkaline environment by adding an alkaline solution, thereby forcing a large number of ammonium ions in the wastewater to be converted into ammonia molecules. Then, air is blown into the bottom of the ammonia stripping unit, and the wastewater is sprayed from the top of the ammonia stripping unit. The wastewater and the air come into countercurrent contact in the middle of the ammonia stripping unit, so that the ammonia molecules in the wastewater are transferred into the air.

[0041] In some embodiments, the step of performing a second wastewater treatment on the wastewater with an ammonia nitrogen concentration lower than the preset threshold includes: transporting the wastewater to an acid-base reaction tank and adding an acidic liquid to the acid-base reaction tank to neutralize the alkalinity of the wastewater.

[0042] The wastewater is alkaline before being transported to the acid-base reaction tank. Therefore, in order to adjust the acidity or alkalinity of the wastewater in the acid-base reaction tank to neutralize the alkalinity of the wastewater, an acidic liquid needs to be added to the acid-base reaction tank.

[0043] The second wastewater treatment is suitable for treating wastewater with low ammonia nitrogen concentration. Compared with the first wastewater treatment, the second wastewater treatment only treats the acidity and alkalinity of the wastewater, so that the acidity and alkalinity index of the wastewater meets the discharge standards.

[0044] It should be noted that the second wastewater treatment is applicable to wastewater whose ammonia nitrogen concentration is already lower than the emission standard. In other words, for wastewater whose ammonia nitrogen concentration is already lower than the emission standard, further reducing the ammonia nitrogen concentration of the wastewater is not cost-effective and not very meaningful. Treating only the acidity or alkalinity of the wastewater is sufficient to make the wastewater meet the emission standard as a whole.

[0045] In some embodiments, the acidic liquid comprises waste acid from cation exchange bed regeneration.

[0046] To prepare ultrapure water for cleaning semiconductor structures, hydrogen ions on the cation exchange resin in the cation exchange bed are replaced by metal cations in the water. When the hydrogen ions on the cation exchange resin are completely replaced by metal cations, the cation exchange resin becomes ineffective. For the ineffective cation exchange resin, a high-concentration acid can be used to replace the metal cations adsorbed on the cation exchange resin to regenerate the resin, so that the cation exchange resin can continue to replace metal cations in the water to prepare ultrapure water. The waste liquid discharged during the process of replacing the metal cations adsorbed on the cation exchange resin with a high-concentration acid is called cation bed regeneration waste acid. In other words, the cation bed regeneration waste acid is the acidic waste liquid generated in the process of preparing ultrapure water.

[0047] Using the cation bed regeneration waste acid as an acidic liquid to adjust the wastewater with low ammonia nitrogen concentration can reduce the dosage of chemical agents consumed in the second wastewater treatment. Furthermore, the cation bed regeneration waste acid, as an acidic waste liquid, replaces fresh acidic chemical agents in adjusting the wastewater with low ammonia nitrogen concentration, which is beneficial for resource recycling.

[0048] In some embodiments, in the step of conveying the wastewater to the acid-base reaction tank, the pH value of the wastewater is 10.5-11.5.

[0049] The wastewater transported to the acid-base reaction tank has a low ammonia nitrogen concentration, and the hydrolysis of ammonia molecules has little effect on the pH value of the wastewater, so the wastewater is alkaline.

[0050] In some embodiments, after adding an acidic liquid to the acid-base reaction tank, the pH value of the wastewater drops to 5.5-6.5. This pH range is generally considered to be neutral and meets most discharge standards. Subsequently, the wastewater in the acid-base reaction tank is mixed with the wastewater in the ammonia stripping unit and homogenized to further adjust the acidity or alkalinity of the wastewater.

[0051] In some embodiments, step S3: the wastewater after the first wastewater treatment and the wastewater after the second wastewater treatment are mixed and homogenized.

[0052] Specifically, the wastewater after the first wastewater treatment is alkaline, while the wastewater after the second wastewater treatment is acidic. Furthermore, under some typical operating conditions, the wastewater discharged into the ammonia-containing equalization tank contains more wastewater with high ammonia nitrogen concentrations than low ammonia nitrogen concentrations. Therefore, after the wastewater from the first and second wastewater treatments is discharged into the acid-base equalization tank, the overall wastewater in the tank is alkaline. Subsequently, the acidity or alkalinity of the wastewater in the equalization tank needs to be adjusted by adding an acidic solution to ensure that the acidity or alkalinity of the wastewater in the equalization tank meets the discharge standards.

[0053] As an example, sulfuric acid is used to balance the acid-base balance of the wastewater in the acid-base adjustment tank.

[0054] Sulfuric acid, as an acidic solution for treating wastewater containing ammonia nitrogen, has a low cost. The ammonium sulfate solution generated by neutralizing the ammonia nitrogen wastewater with sulfuric acid is stable, does not easily volatilize, and can be used as a process by-product (such as fertilizer), which is beneficial to the recycling of resources.

[0055] refer to Figure 2 This invention also provides an ammonia nitrogen-containing wastewater treatment system, comprising: an ammonia-containing equalization tank 100 for storing and homogenizing ammonia nitrogen-containing wastewater; an ammonia nitrogen monitoring instrument 200 installed on the output pipeline of the ammonia-containing equalization tank 100 for real-time monitoring of the ammonia nitrogen concentration of the ammonia nitrogen-containing wastewater flowing out of the ammonia-containing equalization tank 100; and an automatic control valve 800 connected to the ammonia nitrogen monitoring instrument 200 for automatically switching the wastewater treatment path based on the comparison result of the value of the ammonia nitrogen monitoring instrument 200 with a preset threshold. When the value of the ammonia nitrogen monitoring instrument 200 is greater than or equal to a preset threshold, the automatic control valve 800 opens the first pipeline 300 connected to the automatic control valve 800, conveying the ammonia nitrogen-containing wastewater into the ammonia stripping unit 500; when the value of the ammonia nitrogen monitoring instrument 200 is lower than the preset threshold, the automatic control valve 800 opens the second pipeline 400 connected to the automatic control valve 800, conveying the ammonia nitrogen-containing wastewater into the acid-base reaction tank 600. The wastewater treated in the ammonia stripping unit 500 and the acid-base reaction tank 600 is sent to the acid-base adjustment tank 700 and mixed and homogenized. The ammonia nitrogen wastewater treatment system provided in this embodiment of the invention reduces the energy and chemical reagent consumption of the system while ensuring that the treated wastewater meets the discharge standards. Furthermore, the ammonia nitrogen wastewater treatment system provided in this embodiment of the invention can also cope with changes in the ammonia nitrogen concentration of the wastewater and adjust the treatment site and corresponding treatment method according to the changes in the ammonia nitrogen concentration, thus treating the wastewater in a more flexible manner.

[0056] refer to Figure 2A wastewater treatment system containing ammonia nitrogen includes: an ammonia equalization tank 100 for receiving and homogenizing wastewater containing ammonia nitrogen.

[0057] The wastewater is collected in the ammonia-containing equalization tank 100 for water quality homogenization treatment so that the wastewater in the ammonia-containing equalization tank 100 has a uniform acidity / alkalinity and ammonia nitrogen concentration, which is beneficial for centralized treatment of ammonia-containing wastewater with low or high ammonia nitrogen concentrations.

[0058] In some embodiments, an ammonia nitrogen monitoring instrument 200 is installed on the output pipeline of the ammonia-containing conditioning tank 100 to monitor the ammonia nitrogen concentration of the wastewater flowing out of the ammonia-containing conditioning tank 100 in real time.

[0059] The ammonia-containing equalization tank 100 is used to store and homogenize the wastewater. The output pipeline of the ammonia-containing equalization tank 100 is used to transport the wastewater away from the equalization tank. An ammonia nitrogen monitoring instrument 200 is installed on the output pipeline of the ammonia-containing equalization tank 100. The ammonia nitrogen monitoring instrument 200 accurately measures the ammonia nitrogen concentration of the wastewater, which is beneficial for the automatic control valve 800 to accurately switch the wastewater treatment path according to the ammonia nitrogen concentration of the wastewater.

[0060] In some embodiments, an automatic control valve 800 is connected to the ammonia nitrogen monitoring instrument 200 and is used to switch the wastewater treatment path based on the comparison result of the ammonia nitrogen concentration and a preset threshold.

[0061] As an example, the automatic control valve 800 is an electric three-way ball valve. The input end of the automatic control valve 800 is connected to the output pipeline of the ammonia-containing equalization tank 100. The automatic control valve 800 is driven by an ammonia nitrogen monitoring instrument 200 with a relay output. The ammonia nitrogen monitoring instrument 200, internally or connected to a controller, compares the ammonia nitrogen concentration of the wastewater with a preset threshold. If the ammonia nitrogen concentration of the wastewater is greater than or equal to the preset threshold, the automatic control valve 800 connects the output pipeline of the ammonia-containing equalization tank 100 to the first pipeline 300, guiding the wastewater to the ammonia stripping unit 500. If the ammonia nitrogen concentration of the wastewater is lower than the preset threshold, the automatic control valve 800 connects the output pipeline of the ammonia-containing equalization tank 100 to the second pipeline 400, guiding the wastewater to the acid-base reaction tank 600.

[0062] In some embodiments, the ammonia stripping unit 500 is connected to the automatic control valve 800 via a first pipeline 300, and is used to receive wastewater with an ammonia nitrogen concentration greater than or equal to the preset threshold and perform ammonia stripping treatment.

[0063] The ammonia stripping unit 500 performs ammonia removal by adding an alkaline liquid to create a strongly alkaline environment, thereby forcing a large number of ammonium ions in the wastewater to be converted into ammonia molecules. Then, air is blown into the bottom of the ammonia stripping unit 500, and the wastewater is sprayed from the top of the ammonia stripping unit 500. The wastewater and the air come into countercurrent contact in the middle of the ammonia stripping unit 500, so that the ammonia molecules in the wastewater are transferred into the air, thereby reducing the ammonia nitrogen concentration of the wastewater.

[0064] In some embodiments, the acid-base reaction tank 600 is connected to the automatic control valve 800 via a second pipeline 400 for receiving wastewater with an ammonia nitrogen concentration less than the preset threshold. The acid-base reaction tank 600 also has an acidic liquid inlet for receiving acidic liquid to neutralize the alkalinity of the received wastewater.

[0065] The wastewater is alkaline before being transported to the acid-base reaction tank 600. Therefore, in order to adjust the acidity or alkalinity of the wastewater in the acid-base reaction tank 600 to neutralize the alkalinity of the wastewater, an acidic liquid needs to be added to the acid-base reaction tank 600. As an example, cation bed regeneration waste acid is selected as the acidic liquid to neutralize the alkalinity of the received wastewater. The cation bed regeneration waste acid is an acidic waste liquid generated in the process of preparing ultrapure water for cleaning semiconductor equipment. Its utilization is conducive to the recycling of resources and further reduces the energy and chemical consumption of the wastewater treatment system.

[0066] In some embodiments, the acid-base conditioning tank 700 is connected to the outlet of the ammonia stripping unit 500 and the outlet of the acid-base reaction tank 600, respectively, for receiving the treated wastewater and mixing and homogenizing it.

[0067] The acid-base adjustment tank 700 receives wastewater from the outlet of the ammonia stripping unit 500 and the outlet of the acid-base reaction tank 600, and adjusts the acidity or alkalinity of the wastewater discharged into the acid-base adjustment tank 700. The wastewater discharged from the ammonia stripping unit 500 is strongly alkaline, while the wastewater in the acid-base reaction tank 600 is acidic. In actual production, the volume of wastewater with high ammonia nitrogen concentration is greater than that with low ammonia nitrogen concentration. Therefore, the overall wastewater mixed in the acid-base adjustment tank 700 is alkaline. To ensure that the acidity or alkalinity of the wastewater in the acid-base adjustment tank 700 meets the discharge standards, an acidic liquid needs to be added to the acid-base adjustment tank 700.

[0068] While the embodiments of the present invention have been disclosed above, the invention is not limited thereto. Any person skilled in the art can make various modifications and alterations without departing from the spirit and scope of the invention; therefore, the scope of protection of the invention should be determined by the scope defined in the claims.

Claims

1. A wastewater treatment process for treating wastewater containing ammonia nitrogen, characterized in that, include: Real-time monitoring of ammonia nitrogen concentration in the wastewater; The ammonia nitrogen concentration in the wastewater is compared with a preset threshold. When the ammonia nitrogen concentration in the wastewater is greater than or equal to the preset threshold, the wastewater with the ammonia nitrogen concentration greater than or equal to the preset threshold is subjected to first wastewater treatment. When the ammonia nitrogen concentration of the wastewater is less than the preset threshold, the wastewater with the ammonia nitrogen concentration lower than the preset threshold is subjected to a second wastewater treatment. The wastewater after the first wastewater treatment and the wastewater after the second wastewater treatment are mixed and homogenized.

2. The wastewater treatment process as described in claim 1, characterized in that, The first wastewater treatment step for the wastewater with an ammonia nitrogen concentration higher than or equal to the threshold includes: conveying the wastewater to an ammonia stripping unit for ammonia removal treatment.

3. The wastewater treatment process as described in claim 1, characterized in that, The step of performing a second wastewater treatment on the wastewater with an ammonia nitrogen concentration lower than the threshold includes: transporting the wastewater to an acid-base reaction tank and adding an acidic liquid to the acid-base reaction tank to neutralize the alkalinity of the wastewater.

4. The wastewater treatment process as described in claim 3, characterized in that, The acidic liquid includes waste acid from cation exchange bed regeneration.

5. The wastewater treatment process as described in claim 3, characterized in that, In the step of transporting the wastewater to the acid-base reaction tank, the pH value of the wastewater is 10.5-11.5; After adding acidic liquid to the acid-base reaction tank, the pH value of the wastewater drops to 5.5-6.

5.

6. The wastewater treatment process as described in claim 1, characterized in that, The preset threshold is 35 mg / L to 45 mg / L.

7. The wastewater treatment process as described in claim 1, characterized in that, In the step of real-time monitoring of the ammonia nitrogen concentration of the wastewater, the wastewater is in an ammonia-containing equalization tank, and a monitoring instrument for monitoring the ammonia nitrogen concentration of the wastewater is installed on the output pipeline of the ammonia-containing equalization tank. The monitoring instrument is connected to an automatic control valve.

8. The wastewater treatment process as described in claim 7, characterized in that, In the step of comparing the ammonia nitrogen concentration of the wastewater with a preset threshold, when the ammonia nitrogen concentration of the wastewater is greater than or equal to the preset threshold, the automatic control valve guides the wastewater through the output pipeline and then through the first pipeline to the ammonia stripping unit; when the ammonia nitrogen concentration of the wastewater is less than the preset threshold, the automatic control valve guides the wastewater through the output pipeline and then through the second pipeline to the acid-base reaction tank.

9. The wastewater treatment process as described in claim 1, characterized in that, The wastewater treatment process further includes: before real-time monitoring of the ammonia nitrogen concentration in the wastewater, collecting the ammonia nitrogen-containing wastewater in an ammonia-containing equalization tank for water quality homogenization treatment.

10. A wastewater treatment system containing ammonia nitrogen, characterized in that, include: An ammonia equalization tank is used to receive and homogenize wastewater containing ammonia nitrogen. An ammonia nitrogen monitoring instrument is installed on the output pipeline of the ammonia-containing equalization tank to monitor the ammonia nitrogen concentration of the wastewater flowing out of the ammonia-containing equalization tank in real time. An automatic control valve is connected to the ammonia nitrogen monitoring instrument signal and is used to switch the wastewater treatment path based on the comparison result of the ammonia nitrogen concentration and the preset threshold. The ammonia stripping unit is connected to the automatic control valve through a first pipeline and is used to receive wastewater with an ammonia nitrogen concentration greater than or equal to the preset threshold and perform ammonia stripping treatment. An acid-base reaction tank is connected to the automatic control valve via a second pipeline. It is used to receive wastewater with an ammonia nitrogen concentration lower than the preset threshold. The acid-base reaction tank also has an acidic liquid inlet for receiving acidic liquid to neutralize the alkalinity of the received wastewater. An acid-base conditioning tank is connected to the outlet of the ammonia stripping unit and the outlet of the acid-base reaction tank, respectively, and is used to receive the wastewater treated by the ammonia stripping unit and the acid-base reaction tank and to mix, homogenize and condition it.

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