A low ammonia-nitrogen wastewater treatment system and a treatment method

Abstract

The present application relates to wastewater treatment and reuse technical field, particularly to a low ammonia nitrogen wastewater treatment system and treatment method, the low ammonia nitrogen wastewater treatment method of the present application, through the oxidation treatment of low ammonia nitrogen wastewater under the cooperation of trichloroisocyanuric acid and sodium hypochlorite, while removing ammonia nitrogen, the use of sodium hypochlorite reagent is reduced, the conductivity of the liquid after treatment does not rise too fast, reduces corrosion, at the same time, according to the automatic control of liquid backflow, direct delivery and filtration according to the residual chlorine online monitoring result and the chloride ion online monitoring result, reduces the use of reduction device, avoids more reagent and energy consumption caused by increasing reduction device, realizes the efficient treatment of low ammonia nitrogen wastewater, reduces the processing cost. The low ammonia nitrogen wastewater treatment system of the present application cooperates with the slow-release tank containing trichloroisocyanuric acid and the chlorine folding reaction mechanism, reduces the use of reduction device, can ensure the water quality requirement of circulating water pool, realizes the efficient and low-cost treatment of low ammonia nitrogen wastewater.

Description

Technical Field

[0001] The present invention relates to the technical field of wastewater treatment and reuse, and in particular to a low-ammonia nitrogen wastewater treatment system and a treatment method. Background Art

[0002] At present, due to the continuous accumulation of foaming factors above C10 in diesel and reagent components in upstream batch operations in the amine liquid system of the natural gas purification plant, the anti-foaming performance of the amine liquid has decreased, resulting in the amine liquid being carried by acid gas into tail units such as sour water stripping, and ultimately causing the ammonia nitrogen content of the sour water stripping purified water to exceed the standard. This part of low ammonia nitrogen wastewater generally needs to be treated and reused in the circulating water field as circulating water makeup or discharged. However, since the ammonia nitrogen content (NH3-N <50mg / L) exceeds the ammonia nitrogen content requirements for circulating water and external discharge, it cannot be directly discharged or reused and requires further treatment.

[0003] For the treatment of the above-mentioned low-ammonia nitrogen wastewater, the current mainstream disposal methods include traditional biochemical methods and membrane methods (reverse osmosis membrane or degassing membrane method). A small number of factories use electrochemical methods or breakpoint chlorination methods. However, the traditional biochemical method has the problem that the turbidity and suspended solids of the effluent do not meet the requirements of recycled water; the degassing membrane or reverse osmosis membrane method does not remove ammonia nitrogen but only transfers ammonia nitrogen, and still requires subsequent treatment technology, and the investment and operating costs are extremely high; and the breakpoint chlorination method generally requires the addition of chlorine-containing agents for reaction. Due to the large amount of chlorine-containing agents added, the residual chlorine and salt content of the effluent are difficult to control, which can easily lead to ultra-high conductivity of the liquid after the reaction. Generally, a reduction device is also required to avoid corrosion and scaling problems caused by excessive conductivity on the equipment, resulting in high equipment investment costs, and it is still easy for the residual chlorine to exceed the standard, resulting in high equipment preparation and operating costs. Summary of the Invention

[0004] The purpose of the present invention is to overcome the technical problems of poor treatment effect and high cost of existing low ammonia nitrogen wastewater in the prior art, and to provide a low ammonia nitrogen wastewater treatment system and treatment method.

[0005] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0006] In a first aspect, the present invention provides a method for treating low-ammonia nitrogen wastewater, comprising:

[0007] Step 1: Input the wastewater to be treated into the buffer tank for buffering;

[0008] Step 2: The wastewater in the buffer tank is input into a slow-release tank for oxidation treatment under the action of trichloroisocyanuric acid;

[0009] Step 3, adjusting the pH of the liquid treated in step 2;

[0010] Step 4: sending the liquid treated in step 3 to a chlorine reduction reaction mechanism for oxidation treatment under the action of sodium hypochlorite;

[0011] Step 5. According to the online monitoring results of the residual chlorine in the effluent of the chlorine-bearing reaction mechanism, part of the liquid is adjusted to flow back to the chlorine-bearing reaction mechanism to continue the oxidation treatment under the action of sodium hypochlorite, so that the residual chlorine in the effluent is controlled below 0.5 mg / L; according to the online monitoring results of the chloride ion influent of the circulating water pool, part of the effluent of the chlorine-bearing reaction mechanism is adjusted to be input into the reverse osmosis membrane mechanism for filtration treatment before being input into the circulating water pool for use, and part of the liquid is directly input into the circulating water pool from the chlorine-bearing reaction mechanism for use, so that the chloride ion content of the influent of the circulating water pool is controlled below 50 mg / L.

[0012] The invention discloses a method for treating low-ammonia nitrogen wastewater. The method comprises the following steps: subjecting the low-ammonia nitrogen wastewater to oxidation treatment under the action of trichloroisocyanuric acid and oxidation treatment under the action of sodium hypochlorite. Since the solubility of trichloroisocyanuric acid in water is lower than that of sodium hypochlorite in water, the oxidation treatment with trichloroisocyanuric acid has little effect on the conductivity of the treated liquid. The oxidation treatment of the low-ammonia nitrogen wastewater with the combination of trichloroisocyanuric acid and sodium hypochlorite is achieved, and the use of sodium hypochlorite is reduced while removing ammonia nitrogen. The conductivity of the treated liquid does not increase too quickly, thereby avoiding corrosion caused by excessively high conductivity of the treated liquid.

[0013] At the same time, the reflux, direct transmission and filtration volumes of the effluent from the chlorine reduction reaction mechanism are automatically controlled based on the online monitoring results of residual chlorine and chloride ions, so that the residual chlorine and chloride ion contents of the liquid entering the circulating water pool meet the set requirements, reducing the use of reduction devices and avoiding the additional reagent and energy consumption caused by adding reduction devices, thus achieving efficient treatment of low-ammonia nitrogen wastewater and reducing treatment costs.

[0014] In addition, the treated liquid is sent to the circulating water pool for use, realizing the efficient recycling of low ammonia nitrogen wastewater, further reducing the treatment cost of low ammonia nitrogen wastewater.

[0015] As a preferred embodiment of the present invention, in step 2, trichloroisocyanuric acid is filled into the slow-release tank. After the wastewater enters the slow-release tank, it remains in the tank for at least 20 minutes before being discharged. The liquid is fully exposed to the trichloroisocyanuric acid in the slow-release tank, which removes some ammonia nitrogen, reduces the amount of sodium hypochlorite added later, and prevents the conductivity of the treated liquid from increasing too rapidly.

[0016] As a preferred scheme of the present application, it further comprises: step 6, according to the residual chlorine online monitoring result of the effluent of the chloramine reaction mechanism, adding ammonium sulfite reagent to the liquid entering the reverse osmosis membrane mechanism for reduction treatment under the action of ammonium sulfite. By adding ammonium sulfite reagent to remove the residual chlorine of the liquid entering the reverse osmosis membrane mechanism, the damage of residual chlorine to the reverse osmosis membrane mechanism is reduced, and the service life of the reverse osmosis membrane mechanism is prolonged.

[0017] In the second aspect, the present application provides a low ammonia-nitrogen wastewater treatment system, which adopts a low ammonia-nitrogen wastewater treatment method as described above, comprising:

[0018] The buffer tank, the slow-release tank, the acid-base adjusting mechanism, the chloramine reaction mechanism and the reverse osmosis membrane mechanism are connected in sequence by pipelines, and the chloramine reaction mechanism and the reverse osmosis membrane mechanism are further connected to the circulating water pool;

[0019] The slow-release tank is filled with trichloroisocyanuric acid for pre-oxidation treatment of the wastewater to be treated under the action of trichloroisocyanuric acid; and the chloramine reaction mechanism is filled with sodium hypochlorite reagent for oxidation treatment of the liquid after acid-base adjustment under the action of sodium hypochlorite;

[0020] The buffer tank is provided with an ammonia-nitrogen monitor;

[0021] The effluent position of the chloramine reaction mechanism is provided with a first residual chlorine monitor;

[0022] The circulating water pool is provided with a chlorine ion online monitor and a second residual chlorine monitor.

[0023] The low ammonia-nitrogen wastewater treatment system of the present application realizes the control of the conductivity of the low ammonia-nitrogen wastewater after treatment through the cooperation of the slow-release tank filled with trichloroisocyanuric acid and the chloramine reaction mechanism, avoiding the corrosion problem caused by the high conductivity of the wastewater after treatment.

[0024] Meanwhile, through the residual chlorine online monitoring result and the chlorine ion online monitoring result, based on the connection relationship between the chloramine reaction mechanism and the reverse osmosis membrane mechanism and the circulating water pool, the liquid passing through the chloramine reaction mechanism can be partially filtered in the reverse osmosis membrane mechanism and partially directly input into the circulating water pool for use, reducing the use of the reduction device and ensuring the water quality requirement of the circulating water pool, realizing the efficient and low-cost treatment of the low ammonia-nitrogen wastewater.

[0025] As a preferred scheme of the present application, the chloramine reaction mechanism is provided with a direct feeding branch and a filtering branch;

[0026] One end of the direct feeding branch is in communication with the chloramine reaction mechanism, and the other end is in communication with the circulating water pool; one end of the filtering branch is in communication with the chloramine reaction mechanism, and the other end is in communication with the reverse osmosis membrane mechanism;

[0027] The filtering branch is provided with a first regulating valve, and the first regulating valve is connected in cascade with the chloride ion online monitor.

[0028] The first regulating valve is used to automatically control the on-off and size adjustment of the filter branch according to the chloride ion content in the circulating water pool, that is, to control the amount of liquid entering the filter branch. Through the setting of the first regulating valve, automatic control of the water outlet of the chlorine-breaking reaction mechanism is achieved, so that part of the liquid output from the chlorine-breaking reaction mechanism is input into the circulating water pool for use, and part is filtered through the reverse osmosis membrane mechanism to make the chloride ion content in the circulating water pool meet the use requirements.

[0029] As a preferred embodiment of the present invention, the chlorine-reducing reaction mechanism is provided with a reflux branch, one end of the reflux branch is connected to the outlet side of the chlorine-reducing reaction mechanism, and the other end is connected to the inlet side of the chlorine-reducing reaction mechanism. The reflux branch is provided with a second regulating valve, and the second regulating valve is connected in cascade with the first residual chlorine monitor.

[0030] The second regulating valve is used to automatically control the on-off and size adjustment of the reflux branch according to the online monitoring results of the residual chlorine in the effluent of the chlorine-reducing reaction mechanism, that is, to control the amount of liquid entering the reflux branch. Through the setting of the second regulating valve, the automatic control of the reflux of the effluent of the chlorine-reducing reaction mechanism is realized, so that part of the liquid output from the chlorine-reducing reaction mechanism is returned to the chlorine-reducing reaction mechanism for continued oxidation treatment, thereby avoiding excessive residual chlorine content and further ensuring that the water quality in the circulating water pool meets the use requirements.

[0031] As a preferred embodiment of the present invention, an ammonium sulfite injection mechanism is provided between the first regulating valve and the reverse osmosis membrane mechanism, and the sodium sulfite injection mechanism is connected in series with the first residual chlorine monitor. Based on the online monitoring results of the residual chlorine in the effluent of the chlorine conversion reaction mechanism, ammonium sulfite is dynamically added to the liquid to remove the residual chlorine that enters the reverse osmosis membrane mechanism, thereby reducing damage to the reverse osmosis membrane caused by the residual chlorine.

[0032] As a preferred embodiment of the present invention, the chlorine-bending reaction mechanism includes a box body, a plurality of baffles are provided in the box body, adjacent baffles are staggered to form a baffle channel, a stirring chamber is provided on one side of the box body close to the inlet, a stirring mechanism is provided in the stirring chamber, and a sodium hypochlorite agent filling mechanism is provided in the stirring chamber.

[0033] By forming a baffle channel through the staggered baffles, the flow distance of the liquid in the chlorination reaction mechanism is extended to ensure that the liquid is fully oxidized. At the same time, by setting a stirring mechanism, the liquid oxidation process is accelerated and the processing time is shortened.

[0034] As a preferred embodiment of the present invention, the slow-release tank is filled with trichloroisocyanuric acid, the inlet of the slow-release tank is located below the top surface of the trichloroisocyanuric acid tank, and the outlet of the slow-release tank is located above the top surface of the trichloroisocyanuric acid tank. The liquid in the slow-release tank is discharged in an overflow manner. The liquid passes through the filled trichloroisocyanuric acid from bottom to top before overflowing and being discharged. The liquid is fully oxidized by the trichloroisocyanuric acid, partially removing ammonia nitrogen, reducing the subsequent amount of sodium hypochlorite added, and avoiding corrosion problems caused by excessively high conductivity of the effluent water.

[0035] As a preferred embodiment of the present invention, the slow-release tank is equipped with an online pH monitor, which is connected in series with the acid-base adjustment mechanism. The acid-base adjustment mechanism includes a NaOH agent injection mechanism and an HCl agent injection mechanism, which are arranged in sequence. A mixer is provided between the NaOH agent injection mechanism and the HCl agent injection mechanism, and a mixer is provided between the HCl agent injection mechanism and the chlorination reaction mechanism. The acid-base adjustment mechanism maintains the pH of the liquid entering the chlorination reaction mechanism at 6-9, ensuring that the pH of the liquid in the chlorination reaction mechanism meets the treatment requirements, improving the treatment effect, and allowing the acid-base adjustment process to be carried out step by step. In conjunction with the mixer, the acid-base adjustment effect and efficiency are improved.

[0036] Compared with the prior art, the present invention has the following beneficial effects:

[0037] 1. A low-ammonia nitrogen wastewater treatment method of the present invention subjects the low-ammonia nitrogen wastewater to oxidation treatment under the action of trichloroisocyanuric acid and oxidation treatment under the action of sodium hypochlorite, thereby achieving oxidation treatment of the low-ammonia nitrogen wastewater under the combination of trichloroisocyanuric acid and sodium hypochlorite, while removing ammonia nitrogen, reducing the use of sodium hypochlorite reagent, so that the conductivity of the treated liquid does not increase too quickly, avoiding corrosion caused by excessively high conductivity;

[0038] 2. A low-ammonia nitrogen wastewater treatment method of the present invention automatically controls the reflux, direct transfer and filtration amounts of the effluent from the chlorine conversion reaction mechanism according to the online monitoring results of residual chlorine and chloride ions, so that the residual chlorine and chloride ion contents of the liquid entering the circulating water pool meet the requirements, reduces the use of reduction devices, avoids the additional reagent and energy consumption caused by adding reduction devices, achieves efficient treatment of low-ammonia nitrogen wastewater, and reduces treatment costs;

[0039] 3. In the low-ammonia nitrogen wastewater treatment method of the present invention, the treated liquid is sent to a circulating water pool for use, thereby realizing the recycling and waste-free treatment of the low-ammonia nitrogen wastewater, further reducing the treatment cost of the low-ammonia nitrogen wastewater;

[0040] 4. The low ammonia-nitrogen wastewater treatment system of the present application, through the cooperation of the slow-release tank containing trichloroisocyanuric acid and the chlorine folding reaction mechanism, realizes the control of the conductivity of the low ammonia-nitrogen wastewater after treatment, and avoids the corrosion problem caused by the excessively high conductivity of the wastewater after treatment;

[0041] 5. The low ammonia-nitrogen wastewater treatment system of the present application, through the residual chlorine online monitoring result and the chlorine ion online monitoring result, based on the connection relationship between the chlorine folding reaction mechanism and the reverse osmosis membrane mechanism and the circulating water pool, the liquid passing through the chlorine folding reaction mechanism can partially enter the reverse osmosis membrane mechanism for filtration treatment, and part of the liquid can be directly input into the circulating water pool for use, reducing the use of the reduction device, and ensuring the water quality requirement of the circulating water pool, realizing the efficient and low-cost treatment of the low ammonia-nitrogen wastewater. BRIEF DESCRIPTION OF DRAWINGS

[0042] Figure 1 It is a flowchart of the low ammonia-nitrogen wastewater treatment method of embodiment 1;

[0043] Figure 2 It is a flowchart of the low ammonia-nitrogen wastewater treatment method of embodiment 2;

[0044] Figure 3 It is a structural schematic diagram of the low ammonia-nitrogen wastewater treatment system of embodiment 3;

[0045] Figure 4 It is a structural schematic diagram of the low ammonia-nitrogen wastewater treatment system of embodiment 4.

[0046] Markings in the figure: 1-buffer tank, 2-slow-release tank, 3-chlorine folding reaction mechanism, 31-box, 32-baffle, 33-baffle passage, 34-stirring cavity, 35-stirring mechanism, 4-sodium hypochlorite medicament adding mechanism, 5-reverse osmosis membrane mechanism, 6-circulating water pool, 7-acid-base adjusting mechanism, 71-pH online monitor, 72-NaOH medicament adding mechanism, 73-HCl medicament adding mechanism, 74-mixer, 81-first residual chlorine monitor, 82-chlorine ion online monitor, 83-ammonia-nitrogen monitor, 84-second residual chlorine monitor, 91-direct input branch, 92-filtration branch, 93-reflux branch, 94-first adjusting valve, 95-second adjusting valve, 10-ammonium sulfite medicament adding mechanism. DETAILED DESCRIPTION

[0047] The present application will be further described in detail below in combination with test examples and specific embodiments. However, it should not be understood that the scope of the above-mentioned subject matter of the present application is limited to the following examples only, and any technology realized based on the content of the present application belongs to the scope of the present application.

[0048] In the description of specific embodiments of the present application, the terms of orientation or positional relationship such as "upper", "lower", "left", "right", "center", "inner", "outer" and the like are expressed based on the orientation or positional relationship shown in the drawings or the orientation or positional relationship in which the product / device / apparatus of the present application is usually used, unless otherwise specified. These terms of orientation or positional relationship are only for the convenience of describing the present application or simplifying the description in specific embodiments, for the purpose of facilitating the understanding of the scheme by the skilled person, and therefore cannot be understood as indicating or implying that a specific device / component / element must have a specific orientation or be constructed and operated in a specific positional relationship, and therefore cannot be understood as limiting the present application.

[0049] In addition, the terms "horizontal", "vertical", "overhanging", "parallel" and the like do not mean that the corresponding device / component / element must be absolutely horizontal or vertical or overhanging or parallel, but can be slightly inclined or deviated. For example, "horizontal" only means that its direction is more horizontal relative to "vertical", and does not mean that the structure must be completely horizontal, but can be slightly inclined. Alternatively, it can be simplified to mean that the corresponding device / component / element is arranged in the direction of "horizontal", "vertical", "overhanging", "parallel" and the like, and can have an error / deviation of ±10% with respect to the corresponding direction, more preferably an error / deviation of ±8% or less, more preferably an error / deviation of ±6% or less, more preferably an error / deviation of ±5% or less, and more preferably an error / deviation of ±4% or less. As long as the corresponding device / component / element is within the error / deviation range, it can still achieve its role in the scheme of the present application.

[0050] In addition, the terms "first", "second", "third" and the like in the description of the present application are only used to distinguish the same or similar components, and should not be understood as emphasizing or implying the relative importance of the specific components.

[0051] In addition, in the description of the embodiments of the present application, "several", "a plurality of", "several" represent at least 2. It can be 2, 3, 4, 5, 6, 7, 8, 9, etc. in any case, and even more than 9.

[0052] In addition, in the description of the technical scheme of the present application, unless otherwise specified / limited / limited, the terms "arrangement", "installation", "connection", "connection", "provided with", "laid", "arrangement" should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or it can be integrally connected, such as welding, riveting, bolting, screwing and other commonly used connection means in the art. The connection can be mechanical connection, electrical connection or communication connection; it can be directly connected or indirectly connected through an intermediate medium; it can be the communication between two elements.

[0053] Example 1

[0054] As shown in Figure 1 A low ammonia nitrogen wastewater treatment method, comprising:

[0055] Step 1, input the wastewater to be treated into the buffer tank 1 for buffering;

[0056] Step 2, input the wastewater in the buffer tank 1 into the slow-release tank 2 for oxidation treatment under the action of trichloroisocyanuric acid;

[0057] Step 3, adjust the pH of the liquid after step 2 treatment;

[0058] Step 4, input the liquid after step 3 treatment into the chloramine reaction mechanism 3 for oxidation treatment under the action of sodium hypochlorite;

[0059] Step 5, according to the online monitoring results of the residual chlorine of the effluent from the chloramine reaction mechanism 3, adjust part of the liquid to flow back to the chloramine reaction mechanism 3 for further oxidation treatment under the action of sodium hypochlorite, so that the residual chlorine of the effluent is controlled below 0.5 mg / L; according to the online monitoring results of the chloride ion of the influent of the circulating water tank 6, adjust part of the effluent from the chloramine reaction mechanism 3 to input into the reverse osmosis membrane mechanism 5 for filtration treatment and then input into the circulating water tank 6 for use, and part of the liquid is directly input from the chloramine reaction mechanism 3 into the circulating water tank 6 for use, so that the chloride ion content of the influent of the circulating water tank 6 is controlled below 50 mg / L.

[0060] In one or several embodiments, in step 1, the buffer tank 1 and the slow-release tank 2 are both vertical storage tank structures. By inputting the wastewater to be treated into the buffer tank 1 for buffering, the wastewater to be treated can be transported at a relatively low and uniform starting speed, so that the flow rate of the liquid entering the slow-release tank 2 is low, and the trichloroisocyanuric acid crystals will not be displaced by impact. The wastewater to be treated can immerse the trichloroisocyanuric acid filled in the slow-release tank 2, and the trichloroisocyanuric acid in the slow-release tank 2 can oxidize the wastewater to be treated to remove part of the ammonia nitrogen, reduce the use of subsequent sodium hypochlorite reagent, reduce the addition of salt, and prevent the conductivity of the treated liquid from rising too fast.

[0061] In one or more embodiments, in step 2, the slow-release tank 2 is filled with trichloroisocyanuric acid crystals, wastewater enters the slow-release tank 2 from the bottom of the slow-release tank 2, and after staying in the slow-release tank 2 for at least 20 minutes, it is output from the top of the slow-release tank 2. Preferably, the wastewater in the buffer tank 1 is transported into the slow-release tank 2 through a combination of pump and pipeline. Since the solubility of trichloroisocyanuric acid crystals is lower than that of sodium hypochlorite, by immersing trichloroisocyanuric acid crystals in wastewater for a certain period of time, the removal of ammonia nitrogen in low ammonia nitrogen wastewater is achieved, and the subsequent addition amount of sodium hypochlorite medicament is reduced. At the same time, the wastewater inlet of the buffer tank 1 is located at a relatively low position, and the wastewater outlet of the buffer tank 1 is located at a relatively high position, so that the wastewater in the buffer tank 1 is transported into the slow-release tank 2 in an overflow manner through the pipeline. There is a height difference between the wastewater outlet of the buffer tank 1 and the inlet of the slow-release tank 2, so that the liquid can smoothly enter the slow-release tank 2. After two consecutive overflow treatments, the residence time of the liquid in the buffer tank 1 and the slow-release tank 2 can be prolonged, so as to improve the oxidation treatment effect and improve the ammonia nitrogen removal effect.

[0062] In one or more embodiments, in step 3, the pH value of the liquid after trichloroisocyanuric acid oxidation treatment is adjusted to 6-9.

[0063] In one or more embodiments, in step 4, the addition amount of sodium hypochlorite is determined according to the online monitoring result of the ammonia nitrogen in the liquid in the buffer tank 1. The addition of an appropriate amount of sodium hypochlorite medicament removes most of the ammonia nitrogen in the liquid, so as to ensure the ammonia nitrogen treatment effect of the wastewater.

[0064] In an optional embodiment, the sodium hypochlorite medicament can be added in the form of a solution. Preferably, the concentration of the sodium hypochlorite solution is 10%, the unit of the addition amount of the sodium hypochlorite solution is g, and the unit of the online monitoring result of the ammonia nitrogen in the liquid in the buffer tank 1 is mg / L. By obtaining the total amount of ammonia nitrogen in a certain volume of liquid, the addition amount of the sodium hypochlorite solution can be determined.

[0065] Preferably, the total amount of ammonia nitrogen used to calculate the addition amount of the sodium hypochlorite solution is determined by monitoring the volume of the liquid entering the buffer tank 1 within a certain period of time and combining the online monitoring result.

[0066] Preferably, the mass ratio of the addition amount of the sodium hypochlorite medicament to the total amount of ammonia nitrogen monitored in the liquid in the buffer tank 1 within a certain period of time is (0.085-0.088):1. By adding an appropriate amount of sodium hypochlorite medicament, 99% of the ammonia nitrogen in the liquid can be removed, and the ammonia nitrogen treatment effect of the wastewater can be improved.

[0067] In an optional embodiment, sodium hypochlorite is added to the inlet side of the chlorine-reducing reaction mechanism 3. The wastewater liquid that has been oxidized with trichloroisocyanuric acid and adjusted in pH value is oxidized by sodium hypochlorite in the chlorine-reducing reaction mechanism 3. Since the liquid has already undergone the oxidation reaction with trichloroisocyanuric acid, some ammonia nitrogen has been removed. Therefore, under the same water quality requirements, the corresponding amount of sodium hypochlorite added can be reduced. As a result, the free chlorine in the liquid output after treatment by the chlorine-reducing reaction mechanism 3 will be correspondingly reduced, thereby achieving the effect of reducing the conductivity of the effluent water.

[0068] In one or more embodiments, in step 5, the liquid is automatically controlled to be refluxed, directly transported and filtered according to the online monitoring results of residual chlorine and chloride ions, so as to realize dynamic control of the low ammonia nitrogen wastewater treatment process, so that the residual chlorine and chloride ion contents of the liquid entering the circulating water pool 6 for use meet the requirements, reduce the use of the reduction device, avoid adding more reagents and energy consumption of the reduction device, realize efficient treatment of low ammonia nitrogen wastewater, and reduce treatment costs.

[0069] In an optional embodiment, a residual chlorine monitor is provided at the outlet of the chlorine-reducing reaction mechanism 3 to monitor the residual chlorine content of the liquid of the chlorine-reducing reaction mechanism 3 excluding the reflux portion. The reflux amount is adjusted according to the online monitoring result of the residual chlorine of the outlet water of the chlorine-reducing reaction mechanism 3. When the residual chlorine content is too high, the reflux amount is increased to control the residual chlorine content of the outlet water of the chlorine-reducing reaction mechanism 3 excluding the reflux portion of the liquid to be below 0.5 mg / L.

[0070] In an optional embodiment, a chloride ion monitor is provided at the water inlet of the circulating water pool 6 to monitor the total chloride ion content of the liquid entering the circulating water pool 6, including the direct feed and filtration parts. When the chloride ion content is too high, the amount of liquid passing through the reverse osmosis membrane mechanism 5 is increased so that the total chloride ion content of the liquid entering the circulating water pool 6, including the direct feed and filtration parts, is controlled below 50 mg / L.

[0071] Specifically, when the chloride ion content of the effluent from the chlorine-bearing reaction mechanism 3 is 200 mg / L, since the reverse osmosis membrane mechanism 5 can generally remove more than 98% of the chloride ions in the liquid passing through it, in order to ensure that the chloride ions in the circulating water pool 6 are controlled below 50 mg / L, about 80% of the total amount of liquid output from the chlorine-bearing reaction mechanism 3 is filtered through the reverse osmosis membrane mechanism 5, and the remaining part is directly input from the chlorine-bearing reaction mechanism 3 into the circulating water pool 6 for use.

[0072] Generally, wastewater with an ammonia nitrogen content of less than 50 mg / L is considered low ammonia nitrogen wastewater, which is higher than the requirements of the wastewater discharge index of 15 mg / L and the reuse circulating water index of 5 mg / L. It needs to be treated before it can be used. However, the addition of a large amount of sodium hypochlorite will significantly affect the conductivity of the treated liquid and cannot be used directly. Therefore, a low ammonia nitrogen wastewater treatment method of this embodiment is to subject the low ammonia nitrogen wastewater to oxidation treatment under the action of trichloroisocyanuric acid and oxidation treatment under the action of sodium hypochlorite, thereby achieving oxidation treatment of the low ammonia nitrogen wastewater under the combination of trichloroisocyanuric acid and sodium hypochlorite, while removing ammonia nitrogen and reducing the use of sodium hypochlorite reagent. The conductivity of the treated liquid will not rise too quickly, avoiding corrosion caused by excessively high conductivity. At the same time, the liquid is automatically controlled to be refluxed, directly transported and filtered according to the online monitoring results of residual chlorine and chloride ions, so that the residual chlorine and chloride ion contents of the liquid entering the circulating water pool 6 for use meet the requirements, reducing the use of the reduction device, avoiding the increase in reagents and energy consumption caused by adding the reduction device, achieving efficient treatment of low-ammonia nitrogen wastewater, and reducing treatment costs. In addition, the treated liquid is sent to the circulating water pool 6 for use, realizing the recycling and waste-free treatment of low-ammonia nitrogen wastewater, and further reducing the treatment cost of low-ammonia nitrogen wastewater.

[0073] Example 2

[0074] like Figure 2 As shown, a low ammonia nitrogen wastewater treatment method of this embodiment is similar to Example 1, except that: it also includes step 6, according to the online monitoring result of the residual chlorine in the effluent of the chlorine reduction reaction mechanism 3, adding ammonium sulfite agent to the liquid entering the reverse osmosis membrane mechanism 5, and performing reduction treatment under the action of ammonium sulfite.

[0075] In a low-ammonia nitrogen wastewater treatment method of this embodiment, when the residual chlorine in the effluent of the chlorine reduction reaction mechanism 3 is high, the residual chlorine in the liquid entering the reverse osmosis membrane mechanism 5 is removed by adding ammonium sulfite reagent to reduce the damage of the residual chlorine to the reverse osmosis membrane mechanism 5 and extend the service life of the reverse osmosis membrane mechanism 5.

[0076] In an optional embodiment, the ammonium sulfite agent is added in the form of a solution, the concentration of the ammonium sulfite solution is 10%, the unit of the amount of ammonium sulfite solution added is g, the unit of the online monitoring result of the residual chlorine in the water outlet of the chlorine reaction mechanism 3 is mg / L, and the amount of ammonium sulfite solution added is determined by obtaining the total amount of residual chlorine in a certain volume of liquid.

[0077] Preferably, the total amount of residual chlorine used to calculate the amount of ammonium sulfite solution to be added is determined by monitoring the volume of water discharged from the chlorine reduction reaction mechanism 3 within a certain period of time and combining it with the online monitoring result of residual chlorine.

[0078] Preferably, the mass ratio of the added amount of the ammonium sulfite solution to the total amount of residual chlorine in the effluent from the chloramine folding mechanism is (0.09-0.1):1.

[0079] Embodiment 3

[0080] As shown in Figure 1-Figure 2 , a low ammonia-nitrogen wastewater treatment system according to the low ammonia-nitrogen wastewater treatment method of embodiment 1 comprises: a buffer tank 1, a slow-release tank 2, an acid-base adjusting mechanism 7, a chloramine folding mechanism 3 and a reverse osmosis membrane mechanism 5 connected in sequence through pipelines; the chloramine folding mechanism 3 and the reverse osmosis membrane mechanism 5 are connected to a circulating water pool 6; the slow-release tank 2 is filled with trichloroisocyanuric acid, which is used for oxidation treatment of the wastewater to be treated under the action of trichloroisocyanuric acid; the chloramine folding mechanism 3 is filled with sodium hypochlorite, which is used for oxidation treatment of the liquid after acid-base adjustment under the action of sodium hypochlorite;

[0081] The buffer tank 1 is provided with an ammonia-nitrogen monitor 83;

[0082] The effluent position of the chloramine folding mechanism 3 is provided with a first residual chlorine monitor 81;

[0083] The circulating water pool 6 is provided with a chlorine ion online monitor 82 and a second residual chlorine monitor 84;

[0084] The chloramine folding mechanism 3 is provided with a direct delivery branch 91 and a filtration branch 92;

[0085] One end of the direct delivery branch 91 communicates with the chloramine folding mechanism 3, and the other end communicates with the circulating water pool 6; one end of the filtration branch 92 communicates with the chloramine folding mechanism 3, and the other end communicates with the reverse osmosis membrane mechanism 5; the filtration branch 92 is provided with a first adjusting valve 94, and the first adjusting valve 94 is in cascade connection with the chlorine ion online monitor 82;

[0086] The chloramine folding mechanism 3 is provided with a reflux branch 93;

[0087] One end of the reflux branch 93 communicates with the chloramine folding mechanism 3, and the other end communicates with the inlet of the chloramine folding mechanism 3; the reflux branch 93 is provided with a second adjusting valve 95, and the second adjusting valve 95 is in cascade connection with the first residual chlorine monitor 81.

[0088] In an optional embodiment, each component of the low ammonia-nitrogen wastewater treatment system is placed and installed in a skid-mounted form, each structure is connected through a pipeline, a valve is correspondingly arranged on the pipeline, each valve is in cascade connection with each monitor, automatic control is realized, and continuous, efficient and low-cost treatment of low ammonia-nitrogen wastewater is realized.

[0089] In an optional embodiment, the slow-release tank 2 is filled with trichloroisocyanuric acid, the inlet of the slow-release tank 2 is arranged below the top surface of the filled trichloroisocyanuric acid, the outlet of the slow-release tank 2 is arranged above the top surface of the filled trichloroisocyanuric acid, the liquid in the slow-release tank 2 is output in an overflow manner, and the liquid in the slow-release tank 2 flows from bottom to top through the filled trichloroisocyanuric acid and is then output in an overflow manner. The liquid is fully treated by trichloroisocyanuric acid, the increase of the conductivity of the effluent water is reduced, and the treatment effect is improved.

[0090] In an optional embodiment, the slow-release tank 2 is provided with a pH on-line monitor 71, and the pH on-line monitor 71 is connected in cascade with the acid-base adjusting mechanism 7. The liquid entering the chlor-amine reaction mechanism 3 meets the treatment requirements in terms of the acid-base degree.

[0091] In an optional embodiment, the acid-base adjusting mechanism 7 comprises a NaOH medicament filling mechanism 72 and an HCl medicament filling mechanism 73 arranged in sequence, a mixer 74 is arranged between the NaOH medicament filling mechanism 72 and the HCl medicament filling mechanism 73, and the mixer 74 is arranged between the HCl medicament filling mechanism 73 and the chlor-amine reaction mechanism 3. The acid-base adjusting process is carried out in steps, and the mixer 74 is used to improve the acid-base adjusting effect.

[0092] In an optional embodiment, the chlor-amine reaction mechanism 3 comprises a box body 31, a plurality of baffles 32 are arranged in the box body 31, adjacent baffles 32 are arranged in a staggered manner to form a baffle passage 33, a stirring cavity 34 is arranged on one side of the box body 31 close to the inlet, a stirring mechanism 35 is arranged in the stirring cavity 34, and a sodium hypochlorite medicament filling mechanism 4 is arranged in the stirring cavity 34. The baffle passage 33 is formed by the baffles 32 arranged in a staggered manner, the flow distance of the liquid in the chlor-amine reaction mechanism 3 is prolonged, the liquid is ensured to be fully oxidized, and the stirring mechanism 35 is arranged to accelerate the oxidation process of the liquid and shorten the treatment time.

[0093] In an optional embodiment, the second residual chlorine monitor 84 arranged in the circulating pool 6 is used to provide data support for the addition of oxidants in the subsequent use of the circulating pool 6.

[0094] A low-ammonia nitrogen wastewater treatment system of the present embodiment, based on the connection relationship between the chlorine-reducing reaction mechanism and the reverse osmosis membrane mechanism 5 and the circulating water pool 6, is configured through the provision of a direct transmission branch 91 and a filtration branch 92, so that part of the liquid output from the chlorine-reducing reaction mechanism 3 is input into the circulating water pool 6 for use, and part is filtered through the reverse osmosis membrane mechanism 5 to ensure that the chloride ion content in the circulating water pool 6 meets the use requirements. Through the provision of a reflux branch 93, part of the liquid output from the chlorine-reducing reaction mechanism 3 is returned to the chlorine-reducing reaction mechanism 3 for further oxidation treatment, thereby avoiding excessive residual chlorine content and further ensuring that the water quality in the circulating water pool 6 meets the use requirements. Through the use of trichloroisocyanuric acid, the amount of sodium hypochlorite used is effectively reduced, the free chlorine in the effluent water is effectively reduced, and the effluent water conductivity is reduced. At the same time, the use of reduction devices is reduced, thereby achieving low-cost treatment of low-ammonia nitrogen wastewater.

[0095] During the specific implementation process, the ammonia nitrogen content of the wastewater to be treated is 18-30 mg / L. After being treated by a low ammonia nitrogen wastewater treatment system of this embodiment, the ammonia nitrogen content of the influent of the circulating water pool 6 is maintained below 1 mg / L. During the treatment process, when no reflux is performed, the ammonia nitrogen content of the influent of the circulating water pool 6 is maintained at about 2 mg / L, and the residual chlorine content is about 0.5 mg / L. When the reverse osmosis membrane mechanism 5 is not filtered, the chloride ion content of the effluent of the chlorine reaction mechanism 3 excluding the reflux part is 200-220 mg / L. When the reverse osmosis membrane mechanism 5 is filtered, the chloride ion content of the influent of the circulating water pool 6 is about 40 mg / L.

[0096] Example 4

[0097] The low ammonia nitrogen wastewater treatment system of this embodiment has a structure similar to that of Example 1, except that an ammonium sulfite agent filling mechanism 10 is provided between the first regulating valve 94 and the reverse osmosis membrane mechanism 5 , and the sodium sulfite agent filling mechanism 10 is connected in series with the first residual chlorine monitor 81 .

[0098] A low-ammonia nitrogen wastewater treatment system in this embodiment further adds an ammonium sulfite agent injection mechanism 10 on the basis of Example 3, so that according to the online monitoring results of the residual chlorine in the water outlet of the chlorine reduction reaction mechanism 3, ammonium sulfite agent is dynamically added to the liquid to remove the residual chlorine entering the reverse osmosis membrane mechanism 5, thereby reducing the damage of the residual chlorine to the reverse osmosis membrane. At the same time, the use of dynamic addition can avoid the use of large-scale reduction equipment, making wastewater treatment more economical.

[0099] In an optional embodiment, a mixer 73 is provided between the ammonium sulfite agent filling mechanism 10 and the reverse osmosis membrane mechanism 5 .

[0100] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for treating low ammonia nitrogen wastewater, characterized in that: include: Step 1: inputting the wastewater to be treated into a buffer tank (1) for buffering; Step 2: The wastewater in the buffer tank (1) is input into the slow-release tank (2) for oxidation treatment under the action of trichloroisocyanuric acid; Step 3, adjusting the pH of the liquid treated in step 2; Step 4: sending the liquid treated in step 3 to the chlorine reduction reaction mechanism (3) for oxidation treatment under the action of sodium hypochlorite; Step 5: According to the online monitoring result of the residual chlorine of the effluent from the chlorine-reducing reaction mechanism (3), a portion of the liquid is adjusted to flow back to the chlorine-reducing reaction mechanism (3) to continue the oxidation treatment under the action of sodium hypochlorite, so that the residual chlorine in the effluent is controlled below 0.5 mg / L; according to the online monitoring result of the chloride ion influent from the circulating water pool, a portion of the effluent from the chlorine-reducing reaction mechanism (3) is adjusted to be input to the reverse osmosis membrane mechanism (5) for filtration treatment before being input to the circulating water pool (6) for use, and a portion of the liquid is directly input from the chlorine-reducing reaction mechanism (3) to the circulating water pool (6) for use, so that the chloride ion content of the influent from the circulating water pool (6) is controlled below 50 mg / L.

2. A method for treating low-ammonia nitrogen wastewater according to claim 1, characterized in that: In step 2, trichloroisocyanuric acid is filled into the slow-release tank (2), and after the wastewater enters the slow-release tank (2), it stays in the slow-release tank (2) for at least 20 minutes before being discharged.

3. A method for treating low-ammonia nitrogen wastewater according to claim 1, characterized in that: The method further comprises: step 6, adding ammonium sulfite reagent to the liquid entering the reverse osmosis membrane mechanism (5) according to the online monitoring result of the residual chlorine in the effluent of the chlorine reduction reaction mechanism (3), and performing reduction treatment under the action of ammonium sulfite.

4. A low ammonia nitrogen wastewater treatment system, characterized in that: A method for treating low-ammonia nitrogen wastewater according to any one of claims 1 to 3, comprising: A buffer tank (1), a slow-release tank (2), an acid-base adjustment mechanism (7), a chlorine-converting reaction mechanism (3), and a reverse osmosis membrane mechanism (5) are sequentially connected via pipelines, wherein the chlorine-converting reaction mechanism (3) and the reverse osmosis membrane mechanism (5) are further connected to a circulating water pool (6); The slow-release tank (2) is filled with trichloroisocyanuric acid for performing oxidation treatment on the wastewater to be treated by trichloroisocyanuric acid; the chlorine reduction reaction mechanism (3) is filled with sodium hypochlorite for performing oxidation treatment on the liquid after the acid-base adjustment treatment by sodium hypochlorite; The buffer tank (1) is provided with an ammonia nitrogen monitor (83); A first residual chlorine monitor (81) is provided at the water outlet of the chlorine reduction reaction mechanism (3); The circulating water pool (6) is provided with a chloride ion online monitor (82) and a second residual chlorine monitor (84).

5. A low ammonia nitrogen wastewater treatment system according to claim 4, characterized in that: The chlorine reduction reaction mechanism (3) is provided with a direct transmission branch (91) and a filtering branch (92); One end of the direct transmission branch (91) is in communication with the chlorine-reducing reaction mechanism (3), and the other end is in communication with the circulating water pool (6); one end of the filtration branch (92) is in communication with the chlorine-reducing reaction mechanism (3), and the other end is in communication with the reverse osmosis membrane mechanism (5); The filtering branch (92) is provided with a first regulating valve (94), and the first regulating valve (94) is connected in cascade with the chloride ion online monitor (82).

6. A low ammonia nitrogen wastewater treatment system according to claim 5, characterized in that: The chlorine-reducing reaction mechanism (3) is provided with a reflux branch (93), one end of which is in communication with the outlet side of the chlorine-reducing reaction mechanism (3), and the other end of which is in communication with the inlet side of the chlorine-reducing reaction mechanism (3); The reflux branch (93) is provided with a second regulating valve (95), and the second regulating valve (95) is connected in cascade with the first residual chlorine monitor (81).

7. A low ammonia nitrogen wastewater treatment system according to claim 5, characterized in that: An ammonium sulfite agent injection mechanism (10) is provided between the first regulating valve (94) and the reverse osmosis membrane mechanism (5), and the ammonium sulfite agent injection mechanism (10) is connected in cascade with the first residual chlorine monitor (81).

8. A low ammonia nitrogen wastewater treatment system according to claim 4, characterized in that: The chlorine-reducing reaction mechanism (3) comprises a box (31), a plurality of baffles (32) are provided in the box (31), adjacent baffles (32) are staggered to form a baffle channel (33), a stirring chamber (34) is provided on one side of the box (31) close to the inlet, a stirring mechanism (35) is provided in the stirring chamber (34), and a sodium hypochlorite agent filling mechanism (4) is provided in the stirring chamber (34).

9. A low ammonia nitrogen wastewater treatment system according to claim 4, characterized in that: The slow-release tank (2) is filled with trichloroisocyanuric acid, the inlet of the slow-release tank (2) is arranged below the top surface of the trichloroisocyanuric acid filling, the outlet of the slow-release tank (2) is arranged above the top surface of the trichloroisocyanuric acid filling, and the liquid in the slow-release tank (2) is discharged in an overflow manner.

10. A low ammonia nitrogen wastewater treatment system according to claim 4, characterized in that: The slow-release tank (2) is provided with a pH online monitor (71), and the pH online monitor (71) is connected in cascade with the acid-base regulating mechanism (7); The acid-base adjustment mechanism (7) comprises a NaOH agent filling mechanism (72) and an HCl agent filling mechanism (73) which are arranged in sequence; A mixer (74) is provided between the NaOH agent injection mechanism (72) and the HCl agent injection mechanism (73), and a mixer (74) is provided between the HCl agent injection mechanism (73) and the chlorine reduction reaction mechanism (3).

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