A resource treatment method for high-salt, high-total nitrogen, and high-TOC dye wastewater

Abstract

The present application discloses a method for resource treatment of dye wastewater with high salt, high total nitrogen, and high TOC. According to the difference of the influent C 氨氮 / C 总氮 , an ozone oxidation, ultraviolet photocatalysis, ammonia nitrogen membrane separation, breakpoint chlorination, and electrocatalysis combined process is selectively used to treat the wastewater. In this process, high-efficiency removal of TOC and partial removal of nitrate nitrogen are achieved through ozone oxidation and photocatalysis first, then ammonia nitrogen removal is realized through ammonia nitrogen membrane separation and breakpoint chlorination, and finally the remaining nitrate nitrogen in the wastewater is further removed by a special electrocatalytic electrode, which is converted into nitrogen gas while reducing the total nitrogen content in the wastewater. The qualified brine can meet the standard of ion-exchange membrane caustic soda brine. The ammonia nitrogen membrane separation process is used to recover the ammonia nitrogen in the wastewater during the treatment process, and the ammonium sulfate produced can be sold externally to bring economic benefits. The whole process creates economic benefits for the enterprise while not generating secondary pollution, implementing the development concepts of clean production and circular economy.

Description

Technical Field

[0001] The present invention belongs to the technical field of resource treatment of dye wastewater, and particularly relates to a treatment method for high-salt, high-total nitrogen, and high-TOC dye wastewater. Background Art

[0002] Dyes and dye intermediates belong to fine chemicals. The high-salt organic wastewater generated during their production processes is characterized by high salt content, high TOC (total organic carbon), high total nitrogen, and complex components. It is difficult to treat, and the disposal of crystalline waste salt also requires additional costs. How to efficiently treat such wastewater has become a problem restricting the green, sustainable, and high-quality development of related fine chemical enterprises.

[0003] In the prior art, a Chinese invention patent with the publication number CN116265401A discloses a comprehensive treatment method for high-salt and high-ammonia-nitrogen wastewater. The steps are as follows: After neutralizing the wastewater, it is sent to an MVR evaporation system for solid-liquid separation to recover by-product salt; the evaporation condensate is treated by an ammonia-nitrogen stripping device to generate by-product ammonium sulfate, and the wastewater treated by the ammonia-nitrogen stripping unit is sent to subsequent treatment sections. When treating wastewater using this method, on the one hand, the investment and operation costs are high, and on the other hand, the mother liquor generated by evaporation needs secondary treatment.

[0004] A Chinese invention with the publication number CN105565546A discloses a method for removing ammonia nitrogen and nitrate nitrogen from high-salt wastewater. Its technical feature is to place the high-salt nitrogen-containing wastewater in an acid- and alkali-resistant container 1, adjust the pH value of the wastewater in container 1, add a zinc sheet bent into a roll to this container, and add cadmium chloride solution. React under the conditions of being isolated from the external air and stirring. After the reaction is completed, solid-liquid separation is carried out, and the supernatant is collected for standby; the supernatant is transferred to an acid- and alkali-resistant, high-temperature-resistant, and high-pressure-resistant reaction kettle 2, and a wet oxidation reaction is carried out under certain conditions. The effluent after filtration is the required effluent. This invention combines the composite metal catalytic reduction technology and the wet oxidation technology to remove the total nitrogen in the wastewater. Although the total nitrogen removal effect is improved to a certain extent, no resource utilization is carried out, and the wet oxidation requires high-temperature and high-pressure conditions, which is relatively costly compared to other oxidation processes.

[0005] A Chinese invention patent with the publication number CN109437445A discloses a method for resource recycling of high-salt and high-organic matter wastewater. The wastewater is treated by a nanofiltration + reverse osmosis combined process. The divalent salts are intercepted by the nanofiltration unit, and the nanofiltration effluent enters the reverse osmosis membrane for treatment. The reverse osmosis membrane effluent can be recycled, and the reverse osmosis concentrate can be treated secondarily to recover salts. This invention can efficiently separate the organic matter and sodium chloride in high-salt wastewater, and high-purity sodium chloride can be obtained, which can be used in the chlor-alkali industry to prepare high-concentration sodium hydroxide solution, but the concentrate separated by membrane concentration needs secondary treatment.

[0006] The above-mentioned existing technologies for the resource utilization of high-salt wastewater all have problems such as incomplete removal of total nitrogen and TOC, high operating costs, and secondary pollution. Therefore, how to cleanly, efficiently, and low-costly treat total nitrogen and TOC has become a difficult problem to be solved urgently in the resource utilization of high-salt, high-total-nitrogen, and high-TOC wastewater. Summary of the Invention

[0007] The present invention provides a method for the resource treatment of high-salt, high-total-nitrogen, and high-TOC dye wastewater aiming at how to efficiently treat high-salt, high-total-nitrogen, and high-TOC dye wastewater. The treatment method selectively adopts several combined processes of ozone oxidation, ultraviolet photocatalysis, ammonia nitrogen membrane separation, breakpoint chlorination, and electrocatalysis according to different ratios of influent C 氨氮 / C 总氮 to remove the organic matter and total nitrogen in the wastewater in an efficient and low-cost manner.

[0008] After treating the high-salt, high-total-nitrogen, and high-TOC dye wastewater generated in the production process of the dye industry by the method of the present invention, the qualified brine is applied to the ion-exchange membrane caustic soda production process, realizing the resource utilization of high-salt, high-total-nitrogen, and high-TOC dye wastewater while avoiding the generation of secondary pollution.

[0009] To solve the above problems, the technical solutions adopted in the present application are as follows:

[0010] A method for the resource treatment of high-salt, high-total-nitrogen, and high-TOC dye wastewater selectively adopts a combined process of ozone oxidation, ultraviolet photocatalysis, ammonia nitrogen membrane separation, breakpoint chlorination, and electrocatalysis to treat the wastewater according to different influent C 氨氮 / C 总氮 , and specifically includes the following steps:

[0011] S1: Measure the TOC, total nitrogen content, and ammonia nitrogen content of the wastewater;

[0012] S2: Select the treatment method according to the following conditions

[0013] (i) When the value of C 氨氮 / C 总氮 is between 0.8 and 1, sequentially adopt a combined process of ozone oxidation, ultraviolet photocatalysis, ammonia nitrogen membrane separation, and breakpoint chlorination for treatment;

[0014] (ii) When the value of C 氨氮 / C 总氮 is between 0 and 0.8, sequentially adopt a combined process of ozone oxidation, ultraviolet photocatalysis, ammonia nitrogen membrane separation, breakpoint chlorination, and electrocatalysis for treatment.

[0015] In a preferred embodiment of the present invention, in the ozone oxidation section, ozone and hydrogen peroxide are used for synergistic oxidation treatment. The ozone generation amount is 1 - 3 g / L / h, the hydrogen peroxide dosage is 0.1 - 0.5%, and the treatment time is 10 - 30 min.

[0016] In a preferred embodiment of the present invention, in the ultraviolet photocatalysis section, the ultraviolet irradiation intensity is 20 - 100 mw / cm 2 , the wavelength is 254 nm; the oxidant used is one or two of hydrogen peroxide and sodium hypochlorite solution; the catalyst for removing nitrate nitrogen is SrFexTi1 - xO rich in Lewis acid 3 / TiO 2 .

[0017] In a preferred embodiment of the present invention, in the ammonia nitrogen membrane separation section, the influent requirements are SS ≤ 10 ppm, temperature 35 - 45 °C, pH ≥ 10, and the absorbent for removing ammonia nitrogen is sulfuric acid with a concentration of 5 - 15 wt%.

[0018] In a preferred embodiment of the present invention, in the breakpoint chlorination section, the reagent used is sodium hypochlorite, and the pH value is 6 - 7, which can achieve deep removal of ammonia nitrogen.

[0019] In a preferred embodiment of the present invention, in the electrocatalysis section, the electrode uses a Cu - Zn bimetallic electrode, the current density is 10 - 30 mA / cm 2 , and the pH value is 6 - 9, which can achieve the removal of high - concentration nitrate nitrogen.

[0020] In a preferred embodiment of the present invention, after treatment, the TOC, ammonia nitrogen, and total nitrogen in the wastewater are controlled within 10 mg / L, 1 mg / L, and 4 mg / L respectively.

[0021] In a preferred embodiment of the present invention, the method further includes the step of the treated wastewater (brine) entering the ion - exchange membrane caustic soda unit for resource utilization.

[0022] Compared with the prior art, the beneficial effects of this application are as follows:

[0023] (1) A resource - based treatment method for high - salt, high - total - nitrogen, and high - TOC dye wastewater provided by this application is proposed by the applicant based on a large amount of actual industrial high - salt wastewater resource - based treatment work. This process first realizes the efficient removal of TOC and partial removal of nitrate nitrogen in the wastewater through ozone oxidation and ultraviolet photocatalytic oxidation, then realizes the removal of ammonia nitrogen in the wastewater through ammonia nitrogen membrane separation and breakpoint chlorination, and finally realizes the further removal of the remaining nitrate nitrogen in the wastewater through a special electrocatalytic electrode, converting it into nitrogen and reducing the total nitrogen content in the wastewater. According to the influent C 氨氮 / C 总氮is different. When the C 氨氮 / C 总氮 value ranges from 0.8 to 1, an ozone oxidation, ultraviolet photocatalysis, ammonia nitrogen membrane separation, breakpoint chlorination combined process is used for treatment; when the C 氨氮 / C 总氮 value ranges from 0 to 0.8, an ozone oxidation, ultraviolet photocatalysis, ammonia nitrogen membrane separation, breakpoint chlorination, electrocatalysis combined process is used for treatment.

[0024] (2) A method for resource treatment of high-salt, high-total nitrogen, high-TOC dye wastewater provided by this application uses C 氨氮 / C 总氮 in the dye wastewater as a standard to measure the difficulty of wastewater resource treatment. For different ranges of C 氨氮 / C 总氮 , different process combinations are used to remove organic matter and total nitrogen in the wastewater in an efficient and low-cost manner. After treating the high-salt, high-total nitrogen, high-TOC dye wastewater generated in the production process of the dye industry by the method of this application, the qualified brine is applied to the ion membrane caustic soda production process to realize the resource utilization of the wastewater.

[0025] (3) A method for resource treatment of high-salt, high-total nitrogen, high-TOC dye wastewater provided by this application is compared with the processes of single ozone, photocatalytic advanced oxidation followed by stripping, and resin adsorption denitrification, and then compared with deleting a certain process alone, indicating the irreplaceability and indispensability of ultraviolet photocatalysis, ammonia nitrogen membrane separation, breakpoint chlorination, and electrocatalysis in each section used. In addition, by comparing the effluent effects after replacing the process sequence, it shows that the sequence of the combined process cannot be replaced. This application effectively improves the final effluent effect. In addition, this application effectively avoids the generation of secondary pollution and promotes the development of the enterprise's circular economy. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 is the process flow chart of the solution in Embodiment 1. DETAILED DESCRIPTION OF THE INVENTION

[0027] The following further describes this application with specific embodiments.

[0028] It should be noted that the terms such as "upper", "lower", "left", "right", "middle" cited in this specification are only for the convenience of description and are not used to limit the scope that can be implemented. The change or adjustment of their relative relationship shall also be regarded as the scope that can be implemented by this application without substantial change in the technical content.

[0029] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs; the term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0030] For those not specified in the examples, they are carried out under conventional conditions or conditions recommended by the manufacturer. For reagents or instruments whose manufacturers are not specified, they are all conventional products that can be obtained through commercial purchase.

[0031] As used herein, the term "about" is used to provide flexibility and imprecision associated with a given term, measurement, or value. Those skilled in the art can easily determine the degree of flexibility of a specific variable.

[0032] As used herein, the term "at least one of..." is intended to be synonymous with "one or more of...". For example, "at least one of A, B, and C" clearly includes only A, only B, only C, and their respective combinations.

[0033] Concentrations, amounts, and other numerical data may be presented in range format herein. It should be understood that such range formats are used only for convenience and brevity and should be interpreted flexibly as including not only the numerical values explicitly recited as the limits of the range, but also all individual numerical values or sub-ranges subsumed within the stated range, as if each numerical value and sub-range were explicitly recited. For example, a numerical range of about 1 to about 4.5 should be interpreted as including not only the explicitly recited limit values of 1 to about 4.5, but also the individual numbers (such as 2, 3, 4) and sub-ranges (such as 1 to 3, 2 to 4, etc.). The same principle applies to ranges that recite only one numerical value, such as "less than about 4.5", which should be interpreted as including all of the above values and ranges. In addition, this interpretation should apply regardless of the breadth of the range or feature described.

[0034] The present invention combines a large amount of experimental data and comprehensively compares the removal effects and treatment costs of different process combinations in the wastewater of each C 氨氮 / C 总氮 and will adopt the best combined process according to different ranges of wastewater C 氨氮 / C 总氮 to efficiently remove TOC and total nitrogen in the wastewater on the basis of reducing costs.

[0035] Example 1

[0036] Combined Figure 1 , this example provides a method for resource treatment of high-salt, high-total nitrogen, and high-TOC dye wastewater, which specifically includes the following steps:

[0037] A resource treatment method for high-salt, high-total nitrogen, and high-TOC dye wastewater. According to the influent C 氨氮 / C 总氮 differences, several processes such as ozone oxidation, ultraviolet photocatalysis, ammonia nitrogen membrane separation, breakpoint chlorination, and electrocatalysis are selectively used for combined treatment of the wastewater. The specific steps are as follows:

[0038] S1: Measure the TOC, total nitrogen, and ammonia nitrogen contents of the wastewater;

[0039] S2: Select the treatment method according to the following conditions

[0040] (i) When the C 氨氮 / C 总氮 value is between 0.8 and 1, use the combined process of ozone oxidation, ultraviolet photocatalysis, ammonia nitrogen membrane separation, and breakpoint chlorination for treatment;

[0041] (ii) When the C 氨氮 / C 总氮 value is between 0 and 0.8, use the combined process of ozone oxidation, ultraviolet photocatalysis, ammonia nitrogen membrane separation, breakpoint chlorination, and electrocatalysis for treatment;

[0042] The sample is taken from the dye wastewater of an enterprise. This wastewater is high-salt, high-total nitrogen, and high-TOC dye wastewater. After testing, TOC = 1796.3 mg / L, ammonia nitrogen = 1120.7 mg / L, total nitrogen = 1227.9 mg / L, C 氨氮 / C 总氮 = 0.93. Therefore, (i) is adopted, that is, the combined process of ozone oxidation, ultraviolet photocatalysis, ammonia nitrogen membrane separation, and breakpoint chlorination is used for treatment. Specifically:

[0043] The ozone generation amount of the ozone oxidation unit is 1 g / L / h, the dosage of hydrogen peroxide is 0.2%, and the reaction time is 20 min. The wavelength of the ultraviolet photocatalysis unit is 254 nm, the oxidant is hydrogen peroxide, and the catalyst is SrFexTi1-xO rich in Lewis acid 3 / TiO 2 , and the ultraviolet light intensity is controlled at 40 mw / cm 2, the dosage of the oxidant was controlled at 1.5% (mass ratio), and the advanced oxidation reaction time was 60 min. The absorbent of the ammonia nitrogen membrane separation unit was a sulfuric acid solution with a concentration of wt = 10%, the influent SS ≤ 10 ppm, the temperature was 35 - 45 °C, and the pH ≥ 10. The dosing agent in the breakpoint chlorination section was a sodium hypochlorite solution with wt = 10%, and the influent pH was 6 - 7. After treatment, the TOC was reduced to 5.8 mg / L, the ammonia nitrogen was reduced to 0.4 mg / L, and the total nitrogen was reduced to 2.4 mg / L. It met the requirements for entering the ion-exchange membrane caustic soda production, so the treated brine entered the ion-exchange membrane caustic soda unit for resource utilization. The resource treatment of high-salt, high-total nitrogen, and high-TOC dye wastewater was realized.

[0044] Comparative Example 1A

[0045] For comparison, other treatment conditions were the same as those in Example 1, treating the same wastewater. The difference was that: the stripping process was used instead of the ammonia nitrogen membrane separation and breakpoint chlorination denitrification processes in Example 1 for treatment. The specific steps and conditions were: adjusting the pH of the wastewater to 9, controlling the temperature at 90 °C, and aerating for 90 min.

[0046] After detection, after treating the wastewater for denitrification using the stripping process in this comparative example, the TOC was reduced to 7.6 mg / L, the ammonia nitrogen was reduced to 419.4 mg / L, and the total nitrogen was reduced to 453.5 mg / L. It did not meet the requirements for entering the ion-exchange membrane caustic soda production.

[0047] Comparative Example 1B

[0048] For comparison, other treatment conditions were the same as those in Example 1, treating the same wastewater. The difference was that: the resin adsorption process was used instead of the ammonia nitrogen membrane separation and breakpoint chlorination denitrification processes in Example 1 for treatment. The specific steps and conditions were: adjusting the pH of the wastewater to 3, using GC-15 type resin, controlling the flow rate at 1 BV / h, and conducting an adsorption experiment.

[0049] After detection, after treating the wastewater for denitrification using the stripping process in this comparative example, the TOC was reduced to 8.1 mg / L, the ammonia nitrogen was reduced to 526.4 mg / L, and the total nitrogen was reduced to 556.1 mg / L. It did not meet the requirements for entering the ion-exchange membrane caustic soda production.

[0050] Comparative Example 1C

[0051] For comparison, other treatment conditions were the same as those in Example 1, treating the same wastewater. The difference was that the ultraviolet photocatalysis process in Example 1 was deleted.

[0052] After detection, after removing the ultraviolet photocatalysis process, the TOC was reduced to 1397.6 mg / L, the ammonia nitrogen was reduced to 1.9 mg / L, and the total nitrogen was reduced to 103.5 mg / L. It did not meet the requirements for entering the ion-exchange membrane caustic soda production.

[0053] Comparative Example 1D

[0054] As a comparison, other treatment conditions are the same as those in Example 1, treating the same wastewater, except that the ammonia nitrogen membrane separation process in Example 1 is deleted.

[0055] After detection, after treating the wastewater by deleting the ammonia nitrogen membrane separation process, the TOC is reduced to 8.2 mg / L, the ammonia nitrogen is reduced to 1023.4 mg / L, and the total nitrogen is reduced to 1023.7 mg / L. It does not meet the requirements for entering the ion-exchange membrane caustic soda production.

[0056] Comparative Example 1E

[0057] As a comparison, other treatment conditions are the same as those in Example 1, treating the same wastewater, except that the breakpoint chlorination process in Example 1 is deleted.

[0058] After detection, after denitrifying the wastewater by deleting the breakpoint chlorination process, the TOC is reduced to 7.9 mg / L, the ammonia nitrogen is reduced to 36.7 mg / L, and the total nitrogen is reduced to 37.1 mg / L. It does not meet the requirements for entering the ion-exchange membrane caustic soda production.

[0059] Comparative Example 1F

[0060] As a comparison, other treatment conditions are the same as those in Example 1, treating the same wastewater, except that the ammonia nitrogen membrane separation in the combined process is placed before the ultraviolet photocatalysis.

[0061] After detection, after treating the wastewater by placing the ammonia nitrogen membrane separation in the combined process before the ultraviolet photocatalysis, the TOC is reduced to 8.6 mg / L, the ammonia nitrogen is reduced to 25.4 mg / L, and the total nitrogen is reduced to 51.2 mg / L. It does not meet the requirements for entering the ion-exchange membrane caustic soda production.

[0062] Example 2

[0063] Combined with Figure 1 , this example provides a resource treatment method for high-salt, high-total nitrogen, and high-TOC dye wastewater. According to the difference of the influent C 氨氮 / C 总氮 , several processes among ozone oxidation, ultraviolet photocatalysis, ammonia nitrogen membrane separation, breakpoint chlorination, and electrocatalysis are selectively used for combined treatment of the wastewater, specifically including the following steps:

[0064] S1: Measure the TOC, total nitrogen, and ammonia nitrogen contents of the wastewater;

[0065] S2: Select the treatment method according to the following conditions

[0066] (i) When C 氨氮 / C 总氮When the value is between 0.8 and 1, an ozone oxidation, ultraviolet photocatalysis, ammonia nitrogen membrane separation, breakpoint chlorination combined process is used for treatment;

[0067] (ii) When C 氨氮 / C 总氮 When the value is between 0 and 0.8, an ozone oxidation, ultraviolet photocatalysis, ammonia nitrogen membrane separation, breakpoint chlorination, electrocatalysis combined process is used for treatment;

[0068] The sample was taken from the dye wastewater of an enterprise. This wastewater has problems of high salt, high total nitrogen, and high TOC dye wastewater. After testing, TOC = 1526.1 mg / L, ammonia nitrogen = 630.7 mg / L, total nitrogen = 1126.2 mg / L, C 氨氮 / C 总氮 = 0.56. Therefore, (ii) is adopted, that is, an ozone oxidation, ultraviolet photocatalysis, ammonia nitrogen membrane separation, breakpoint chlorination, electrocatalysis combined process is used for treatment. Specifically:

[0069] The ozone generation amount of the ozone oxidation unit is 1 g / L / h, the dosage of hydrogen peroxide is 0.2%, and the reaction time is 20 min. The wavelength of the ultraviolet photocatalysis unit is 254 nm, the oxidant is hydrogen peroxide, and the catalyst is SrFexTi1-xO rich in Lewis acid 3 / TiO 2 , the ultraviolet light intensity is controlled at 40 mw / cm throughout the process 2 , the dosage of the oxidant is controlled at 1.2% (mass ratio), and the advanced oxidation reaction time is 50 min. The absorption liquid of the ammonia nitrogen membrane separation unit is a sulfuric acid solution with a concentration of wt = 5%, the influent SS ≤ 10 ppm, the temperature is 35 - 45 °C, and the pH ≥ 10. The dosing agent in the breakpoint chlorination section is a sodium hypochlorite solution with wt = 10%, and the influent pH is 6 - 7. The current density of electrocatalysis is 20 mA / cm 2 , and the pH is 6 - 9. After treatment, the TOC is reduced to 7.8 mg / L, the ammonia nitrogen is reduced to 0.7 mg / L, and the total nitrogen is reduced to 1.7 mg / L. It meets the requirements for entering the ion-exchange membrane caustic soda production. Therefore, the treated brine enters the ion-exchange membrane caustic soda unit for resource utilization. It meets the requirements for resource utilization and realizes the resource treatment of high-salt, high-total nitrogen, and high-TOC dye wastewater.

[0070] Comparative Example 2A

[0071] As a comparison, other treatment conditions are the same as those in Example 2, and the same wastewater is treated. The difference is that: the stripping process is used instead of the ammonia nitrogen membrane separation, electrocatalysis, and breakpoint chlorination denitrification combined process in Example 1 for treatment. The specific steps and conditions are: adjusting the wastewater pH to 9, heating to 90 °C, and aerating for 90 min.

[0072] After detection, after the denitrification treatment of the wastewater by the stripping process in this comparative example, the TOC was reduced to 7.6 mg / L, the ammonia nitrogen was reduced to 219.4 mg / L, and the total nitrogen was reduced to 619.4 mg / L. It does not meet the requirements for entering the ion-exchange membrane caustic soda production.

[0073] Comparative Example 2B

[0074] For comparison, other treatment conditions were the same as those in Example 2, treating the same wastewater. The difference was that: the resin adsorption process was used instead of the ammonia nitrogen membrane separation, electrocatalysis, and breakpoint chlorination denitrification combined process in Example 1 for treatment. The specific steps and conditions were: adjusting the pH of the wastewater to 3, using GC-15 type resin, controlling the flow rate at 1 BV / h, and conducting an adsorption experiment.

[0075] After detection, after the denitrification treatment of the wastewater by the stripping process in this comparative example, the TOC was reduced to 8.7 mg / L, the ammonia nitrogen was reduced to 326.4 mg / L, and the total nitrogen was reduced to 526.4 mg / L. It does not meet the requirements for entering the ion-exchange membrane caustic soda production.

[0076] Comparative Example 2C

[0077] For comparison, other treatment conditions were the same as those in Example 2, treating the same wastewater. The difference was that the electrocatalysis process in Example 2 was deleted.

[0078] After detection, after removing the electrocatalysis process, the TOC was reduced to 7.1 mg / L, the ammonia nitrogen was reduced to 0.8 mg / L, and the total nitrogen was reduced to 386.5 mg / L. It does not meet the requirements for entering the ion-exchange membrane caustic soda production.

[0079] Comparative Example 2D

[0080] For comparison, other treatment conditions were the same as those in Example 2, treating the same wastewater. The difference was that the ammonia nitrogen membrane separation in Example 2 was deleted.

[0081] After detection, after the denitrification treatment of the wastewater by deleting the ammonia nitrogen membrane separation process, the TOC was reduced to 8.1 mg / L, the ammonia nitrogen was reduced to 532.4 mg / L, and the total nitrogen was reduced to 533.1 mg / L. It does not meet the requirements for entering the ion-exchange membrane caustic soda production.

[0082] Comparative Example 2E

[0083] For comparison, other treatment conditions were the same as those in Example 2, treating the same wastewater. The difference was that the breakpoint chlorination process in Example 2 was deleted.

[0084] After detection, after the denitrification treatment of the wastewater by deleting the breakpoint chlorination process, the TOC was reduced to 8.5 mg / L, the ammonia nitrogen was reduced to 24.8 mg / L, and the total nitrogen was reduced to 25.6 mg / L. It does not meet the requirements for entering the ion-exchange membrane caustic soda production.

[0085] Comparative Example 2F

[0086] As a comparison, other treatment conditions were the same as those in Example 2, treating the same wastewater, except that electrocatalysis in the combined process was placed before ammonia nitrogen membrane separation.

[0087] After testing, when treating the wastewater with ammonia nitrogen membrane separation in the combined process placed before ultraviolet photocatalysis, the TOC was reduced to 7.2 mg / L, the ammonia nitrogen was reduced to 0.8 mg / L, and the total nitrogen was reduced to 10.7 mg / L. It did not meet the requirements for entering the ion-exchange membrane caustic soda production.

[0088] Example 3

[0089] The sample was taken from the dye wastewater of an enterprise. This wastewater had problems of high salt, high total nitrogen, and high TOC dye wastewater. After testing, TOC = 1526.1 mg / L, ammonia nitrogen = 630.7 mg / L, total nitrogen = 1126.2 mg / L, C 氨氮 / C 总氮 = 0.56. Instead of using (ii), (i) was adopted, that is, an ozone oxidation, ultraviolet photocatalysis, ammonia nitrogen membrane separation, and breakpoint chlorination combined process was used for treatment. Specifically:

[0090] The ozone generation amount of the ozone oxidation unit was 1 g / L / h, the dosage of hydrogen peroxide was 0.2%, and the reaction time was 20 min. The wavelength of the ultraviolet photocatalysis unit was 254 nm, the oxidant was hydrogen peroxide, and the catalyst was SrFexTi1-xO rich in Lewis acid 3 / TiO 2 , and the ultraviolet light intensity was controlled at 40 mw / cm throughout the process 2 , the dosage of the oxidant was controlled at 1.5% (mass ratio), and the advanced oxidation reaction time was 60 min. The absorption liquid of the ammonia nitrogen membrane separation unit was a 10 wt% sulfuric acid solution, the influent SS ≤ 10 ppm, the temperature was 35 - 45 °C, and the pH ≥ 10. The dosing agent in the breakpoint chlorination section was a 10 wt% sodium hypochlorite solution, and the influent pH was 6 - 7. After treatment, the TOC was reduced to 6.8 mg / L, the ammonia nitrogen was reduced to 0.3 mg / L, and the total nitrogen was reduced to 321.5 mg / L. It could not meet the requirements for entering the ion-exchange membrane caustic soda production.

[0091] Example 4

[0092] The sample was taken from the dye wastewater of an enterprise. This wastewater was high-salt, high-total nitrogen, and high-TOC dye wastewater. After testing, TOC = 1796.3 mg / L, ammonia nitrogen = 1120.7 mg / L, total nitrogen = 1227.9 mg / L, C 氨氮 / C 总氮= 0.93. Instead of adopting (i), (ii) is adopted, that is, an ozone oxidation, ultraviolet photocatalysis, ammonia nitrogen membrane separation, electrocatalysis, breakpoint chlorination combined process is used for treatment. Specifically:

[0093] The ozone generation amount of the ozone oxidation unit is 1 g / L / h, the dosage of hydrogen peroxide is 0.2%, and the reaction time is 20 min. The wavelength of the ultraviolet photocatalysis unit is 254 nm, the oxidant is hydrogen peroxide, and the catalyst is SrFexTi1-xO rich in Lewis acid 3 / TiO 2 , and the ultraviolet light intensity is controlled at 40 mw / cm throughout the process 2 , the dosage of the oxidant is controlled at 1.5% (mass ratio), and the advanced oxidation reaction time is 60 min. The absorbent of the ammonia nitrogen membrane separation unit is a sulfuric acid solution with a concentration of wt = 5%, the influent SS ≤ 10 ppm, the temperature is 35 - 45 °C, and the pH ≥ 10. The dosing agent in the breakpoint chlorination section is a sodium hypochlorite solution with wt = 10%, and the influent pH is 6 - 7. The current density of the electrocatalysis is 20 mA / cm 2 , and the pH is 6 - 9. After treatment, the TOC is reduced to 8.3 mg / L, the ammonia nitrogen is reduced to 0.3 mg / L, and the total nitrogen is reduced to 1.5 mg / L. Although the effluent of this group can also meet the requirements for entering the ion-exchange membrane caustic soda production, due to the addition of the electrocatalysis process, the investment and operating costs are significantly increased, and such a situation does not conform to the economic principle of the enterprise.

[0094] The method of the present invention is directed to high-salt, high-total-nitrogen, and high-TOC wastewater generated in the dye industry. Since it is difficult to treat such wastewater by conventional processes and secondary pollution is likely to occur. To address this problem, according to the influent C 氨氮 / C 总氮 is different, an ozone oxidation, ultraviolet photocatalysis, ammonia nitrogen membrane separation, breakpoint chlorination, electrocatalysis combined process is selectively used to treat the wastewater. This process first realizes the efficient removal of TOC and partial nitrate nitrogen in the wastewater through ozone oxidation and ultraviolet photocatalytic oxidation, then realizes the removal of ammonia nitrogen in the wastewater through ammonia nitrogen membrane separation and breakpoint chlorination, and finally realizes the further removal of the remaining nitrate nitrogen in the wastewater through a special electrocatalytic electrode, converting it into nitrogen gas and reducing the total nitrogen content in the wastewater at the same time. After treating the high-salt, high-total-nitrogen, and high-TOC dye wastewater by the method of this application, the qualified brine can meet the ion-exchange membrane caustic soda brine standard. In addition, the ammonia nitrogen membrane separation process is used to recover the ammonia nitrogen in the wastewater during the wastewater treatment process, and the by-product ammonium sulfate produced can be sold externally to bring economic benefits. The entire process creates economic benefits for the enterprise while not generating secondary pollution, implementing the development concepts of cleaner production and circular economy.

[0095] The above embodiments are only the preferred embodiments of the present invention, but the implementation manners of the present invention are not limited by the above embodiments. For example, combinations of various forms of the solutions in Embodiments 1 to 4, and any other changes, modifications, substitutions, and combinations made without departing from the spirit and principle of the present invention shall be equivalent replacement manners and are all within the protection scope of the present invention.

Claims

1. A method for resource treatment of high-salt, high-total nitrogen, and high-TOC dye wastewater, characterized in that: The specific steps include: S1: Determine the TOC, total nitrogen content and ammonia nitrogen content of wastewater; S2: Select the treatment method according to the following conditions (i) When C 氨氮 / C 总氮 When the value is between 0.8 and 1, ozone oxidation, ultraviolet catalysis, ammonia nitrogen membrane separation, and breakpoint chlorination are used in sequence for treatment; (ii) When C 氨氮 / C 总氮 When the value is between 0 and 0.8, ozone oxidation, ultraviolet photocatalysis, ammonia nitrogen membrane separation, breakpoint chlorination, and electrocatalysis combined processes are used in sequence for treatment; The TOC, ammonia nitrogen and total nitrogen in the treated wastewater were controlled within 10mg / L, 1mg / L and 4mg / L respectively; The treated wastewater enters the ion membrane caustic soda unit for resource utilization; in, The ozone oxidation section uses ozone and hydrogen peroxide for synergistic oxidation treatment; In the UV photocatalytic process, the UV irradiation intensity is 20~100 mw / cm 2 , wavelength is 254 nm; the oxidant used is one or both of hydrogen peroxide and sodium hypochlorite solution; the catalyst for removing nitrate nitrogen is SrFe rich in Lewis acid x Ti 1-x O3 / TiO2; In the electrocatalytic process, the electrode is a Cu-Zn bimetallic electrode with a current density of 10~30 mA / cm 2 , pH value is 6-9, achieving the removal of high-concentration nitrate nitrogen.

2. The method according to claim 1, characterized in that The ozone oxidation section uses ozone and hydrogen peroxide for synergistic oxidation treatment. The ozone generation amount is 1-3g / L / h, the hydrogen peroxide dosage is 0.1-0.5%, and the treatment time is 10-30min.

3. The method according to claim 1, characterized in that In the ammonia nitrogen membrane separation section, the inlet water requirements are SS ≤ 10ppm, temperature 35-45℃, pH ≥ 10, and sulfuric acid is used as the absorption liquid for removing ammonia nitrogen, with a sulfuric acid concentration of 5~15wt%.

4. The method according to claim 1, characterized in that In the breakpoint chlorination section, the agent used is sodium hypochlorite with a pH value of 6~7 to achieve deep removal of ammonia nitrogen.

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