Mixed acid nitration organic wastewater treatment method and system

Abstract

The invention discloses a mixed acid nitration organic wastewater treatment method and system, and belongs to the technical field of organic chemical wastewater treatment.The mixed acid nitration organic wastewater treatment method comprises the steps that a set amount of zero-valent iron is added into wastewater containing acetic acid, sulfuric acid, nitric acid, nitropyrazole compounds and mesitylene under the strong acid condition; mixing and carrying out oxidation reaction; adjusting the pH value of the oxidized wastewater to be neutral, regulating and controlling COD / NO3 <->-N, and enabling the wastewater to enter an aerobic reactor and an anaerobic reactor for biochemical treatment. According to the method disclosed by the invention, the degradation of nitrogen heterocyclic nitro compounds, mesitylene and various micromolecular organic matters can be effectively realized through active free radicals generated by reaction of acetic acid in the wastewater and additional zero-valent iron, and further biochemical treatment is carried out by adopting an immobilized microorganism technology. According to the method, toxic and harmful pollutants in the wastewater can be effectively degraded, subsequent biochemical treatment requirements are met, and a practical value is provided for effective treatment of the wastewater in the production process of nitropyrazole compounds.

Description

Technical Field

[0001] The invention relates to the technical field of organic chemical wastewater treatment, and in particular to a mixed acid nitration organic wastewater treatment method and system. Background Art

[0002] With the rapid development of my country's industry, various chemical agents are widely used in various industries, especially in the fields of pesticides, medicine, textiles, papermaking, printing and dyeing, and chemicals. The production and use of explosives also bring about the problem of industrial wastewater with difficult-to-degrade organic matter. The treatment of organic wastewater has long been a major problem in water environment protection and a research hotspot for scientists at home and abroad. Therefore, in-depth research is carried out on the wastewater generated in the synthesis process of nitropyrazole, aiming to find an effective treatment method to alleviate environmental pressure.

[0003] Traditional industrial treatment methods generally use a combination of stripping, thermal decomposition and ammonia distillation to improve the biodegradability of wastewater. However, during the treatment process, the wastewater contains a large amount of DNP (3,4-dinitropyrazole), and high-temperature heating will have certain safety hazards. In addition, this method requires the equipment to be resistant to high temperatures and corrosion, which greatly increases the treatment cost.

[0004] Studies have shown that the use of Fenton, Fenton-like and photo-Fenton oxidation technologies can effectively treat nitrobenzene wastewater. However, during the application process, high-dose oxidants (such as hydrogen peroxide) or persistent ultraviolet irradiation are required to effectively degrade nitro compounds in the water. The use of external additives will further increase operating costs. At the same time, common oxides (hydrogen peroxide, sodium hypochlorite, chlorine dioxide, etc.) also have certain storage hazards. In addition, studies have shown that Fenton-like advanced oxidation technologies will produce more toxic secondary pollutants when treating nitro compounds. After the wastewater is oxidized, the biodegradability is only slightly improved, and it still brings considerable toxicity to microorganisms, which seriously increases the burden and harm of subsequent biochemical systems. Summary of the invention

[0005] In order to solve the deficiencies in the prior art, the present invention provides a method for treating mixed acid nitration organic wastewater, which uses acetic acid produced in the production process and added zero-valent iron as raw materials to produce active free radicals to achieve the oxidative degradation of nitropyrazole pollutants and difficult-to-degrade pollutants such as mesitylene in strong acid wastewater. Finally, combined with biochemical treatment, the wastewater is effectively discharged in compliance with the standards.

[0006] The present invention adopts the following technical solution.

[0007] The first aspect of the present invention discloses a method for treating mixed acid nitration organic wastewater, comprising the following steps:

[0008] Zero-valent iron advanced oxidation: A set amount of zero-valent iron is added to the wastewater and mixed to carry out oxidation reaction;

[0009] Biochemical treatment: The above oxidized wastewater is subjected to pH adjustment and COD / NO3 - -N regulation, and enters the aerobic and anaerobic reactors for biochemical treatment to obtain dischargeable wastewater.

[0010] Preferably, the wastewater is wastewater containing acetic acid, sulfuric acid, nitric acid, nitropyrazole compounds and mesitylene under strong acid conditions, wherein the content of acetic acid is not less than 0.28%, and the content of nitric acid is not less than 3%.

[0011] Preferably, the dosage of zero-valent iron is not less than 0.2 g / L.

[0012] Preferably, the pH is adjusted by using any one of NaOH, Na2CO3 or NaHCO3, COD / NO3 - -N adjustment uses sodium acetate or sodium nitrate.

[0013] Preferably, the pH is adjusted to neutral, the COD / NO3 - -N is regulated to 6-12.

[0014] Preferably, the reactor is an anaerobic-aerobic series reactor, the water temperature of which is controlled at 25-30°C, nitrogen is introduced into the anaerobic reactor to maintain anaerobic conditions, oxygen is introduced into the aerobic reactor to maintain aerobic conditions, and a peristaltic pump is used to circulate in the two reactors.

[0015] Preferably, the initial domestication bacterial agent in the anaerobic-aerobic series reactor is the composite microbial preparation B350, and the composite microbial preparation and water distribution components are added into a container to obtain a domestication medium, which is used for domestication to obtain a biofilm.

[0016] Preferably, the water distribution components include: KNO3, CH3COONa, ferric chloride, KH2PO4, MgCl2·6H2O, CaCl2 and trace element mother liquor.

[0017] Preferably, the composition of the acclimation medium is the same as that of the wastewater COD / NO3 - -N ratio.

[0018] The second aspect of the present invention provides a mixed acid nitration organic wastewater treatment system, which implements the mixed acid nitration organic wastewater treatment method, including: an oxidation module and a biochemical module;

[0019] The oxidation module includes a reaction container for adding zero-valent iron into wastewater to perform an oxidation reaction;

[0020] The biochemical module includes an anaerobic-aerobic series reactor, which is used to perform biochemical treatment on wastewater to achieve standard discharge of wastewater.

[0021] Compared with the prior art, the beneficial effects of the present invention include at least:

[0022] In view of the safety hazards and high processing costs of high-temperature heating in the combined process of stripping, thermal decomposition and ammonia distillation in the traditional process, as well as the poor biodegradability of difficult-to-degrade organic compounds, the present invention proposes a zero-valent iron advanced oxidation technology + biochemical treatment technology process to achieve effective treatment of strong acid organic wastewater generated in the production process of nitropyrazole compounds. Compared with traditional Fenton oxidation, the present invention uses acetic acid in the production process as an oxidant to effectively achieve the efficient degradation of 1-nitropyrazole, 3-nitropyrazole, 3,4-dinitropyrazole and mesitylene, and significantly reduce the toxicity of the oxidized water. In addition, combined with the biochemical treatment process, small molecular organic pollutants in the wastewater are further degraded to achieve standard discharge of wastewater. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is the change of pollutants when 0.05g of zero-valent iron is added to the wastewater obtained from N-nitrification reaction and C-nitrification reaction;

[0024] Figure 2 It is the change of pollutants when 0.1g of zero-valent iron is added to the wastewater obtained from N-nitrification reaction and C-nitrification reaction;

[0025] Figure 3 It is the change of pollutants when 0.2g of zero-valent iron is added to the wastewater obtained from N-nitrification reaction and C-nitrification reaction;

[0026] Figure 4 It is a schematic diagram of an anaerobic-aerobic tandem reactor;

[0027] Figure 5 Biochemical treatment of COD and NO3 - -N content changes with reaction time. DETAILED DESCRIPTION

[0028] In order to make the purpose, technical scheme and advantages of the present invention clearer, the technical scheme of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. The embodiments described in this application are only embodiments of a part of the present invention, rather than all embodiments. Based on the spirit of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work belong to the protection scope of the present invention.

[0029] The present invention provides a method for treating mixed acid nitration organic wastewater, comprising the following steps:

[0030] Step 1, zero-valent iron advanced oxidation technology: adding a set amount of zero-valent iron to the nitrified organic wastewater under strong acid conditions, and fully mixing to carry out oxidation reaction;

[0031] Advanced oxidation technology utilizes the active free radicals generated in the water. With its strong oxidizing properties, it can effectively oxidize organic pollutants in the water and improve the biodegradability of the water.

[0032] The wastewater in step 1 contains acetic acid, sulfuric acid, nitric acid, nitropyrazole compounds and mesitylene, wherein the content of acetic acid is not less than 0.28%, the content of nitric acid is not less than 3%, and the dosage of zero-valent iron is set to be not less than 0.2 g / L.

[0033] Step 2, biochemical treatment technology: adjust the pH of the oxidized wastewater to neutral and regulate COD / NO3 - -N is 6-12, with an optimal value of 10. The wastewater enters the aerobic and anaerobic reactors for biochemical treatment to achieve standard discharge.

[0034] In step 2, the pH value can be adjusted by using NaOH, Na2CO3, or NaHCO3, wherein NaHCO3 is the best. - -N adjustment uses sodium acetate or sodium nitrate.

[0035] In step 2, an anaerobic-aerobic series reactor is used, such as Figure 4 As shown, in the anaerobic-aerobic series reactor, the initial domesticated bacterial agent is the composite microbial preparation B350 (containing 28 functional microorganisms and rich catalytic enzymes).

[0036] Take 1 mL of the above bacterial agent and domesticate it in four 250 mL shake flasks to obtain biofilm.

[0037] The water composition is as follows: KNO3, CH3COONa, ferric chloride, KH2PO4, MgCl2·6H2O, CaCl2 and trace element mother solution.

[0038] In a preferred but non-limiting embodiment of the present invention, the water distribution components are specifically: KNO3 (0.72 g / L, NO3 - -N equivalent 100mg / L), CH3COONa (0.64g / L, COD equivalent 500mg / L), 750mg / L ferric chloride, KH2PO4 (21.9mg / L, phosphorus equivalent 5mg / L), 20mg / L MgCl2·6H2O, 1mg / LCaCl2, 1ml / L trace element mother solution.

[0039] The composition of the acclimatization medium is the same as that of the wastewater COD / NO3 --N ratio, two shake flasks were selected to maintain anaerobic state, and the other two shake flasks were continuously aerated to maintain aerobic state and ensure that the microorganisms could grow evenly on the polyurethane foam carrier (Polyurethane Foam, PUF, 1cm×1cm×1cm).

[0040] All shake flasks were incubated in a constant temperature water bath shaker (90 rpm) at 30°C in the dark. When the acclimated biofilm on the carrier was clearly visible and the water quality reached stability after a period of cultivation, a functionally stable biofilm was obtained.

[0041] The anaerobic-aerobic series reactor consists of two 500 mL containers connected in series. The water temperature is controlled at 25-30°C. 20 mL / min of nitrogen is introduced into one of the containers to maintain anaerobic conditions, and 20 mL / min of oxygen is introduced into the other container to maintain aerobic conditions. A peristaltic pump is used to circulate the gas in the two reactors at a flow rate of 5-20 mL / min. Figure 5 As shown, after biochemical treatment in the anaerobic-aerobic series reactor, COD and NO3 - The -N content decreases with the increase of reaction time.

[0042] It is worth noting that the above 500 mL container is only a choice of reaction container for experimental environment. In engineering practice, technicians in this field can use any reaction container with anaerobic-aerobic function to implement the present invention, which falls within the scope of the present invention.

[0043] Embodiment 1:

[0044] The wastewater solution obtained by N-nitration and C-nitration in the production process of 3,4-dinitropyrazole (DNP) was diluted 100 times, and 50 mL of the solution was taken into a 250 mL conical flask, and 0.05 g of iron filings were quickly added to each conical flask. Subsequently, the conical flask was placed in a water bath constant temperature oscillator at 25 ° C and 200 rpm for 300 minutes. Figure 1 As shown, the degradation rates of N-nitropyrazole, 3-nitropyrazole, mesitylene, and DNP were 85% after biochemical treatment.

[0045] Before hydration treatment, adjust the pH of the tail water with sodium bicarbonate solution to about 6-7. Add sodium nitrate solution to control the COD / NO3 in the tail water. - -N is about 10.

[0046] The wastewater is introduced into the anaerobic-aerobic series reactor, and circulates continuously in the anaerobic and aerobic reactors.

[0047] Embodiment 2:

[0048] The wastewater solution obtained by N-nitration and C-nitration in the production process of 3,4-dinitropyrazole (DNP) was diluted 100 times, and 50 mL of the solution was taken into a 250 mL conical flask, and 0.1 g of iron filings were quickly added to each conical flask. Subsequently, the conical flask was placed in a water bath constant temperature oscillator at 25°C and 200 rpm for 300 minutes. Figure 2 As shown, the degradation rates of N-nitropyrazole, 3-nitropyrazole, mesitylene, and DNP were 97.1%, 93.5%, 51%, and 98.9% respectively, after biochemical treatment.

[0049] Before hydration treatment, adjust the pH of the tail water with sodium bicarbonate solution to about 6-7. Add sodium nitrate solution to control the COD / NO3 in the tail water. - -N is about 10.

[0050] The wastewater is introduced into the anaerobic-aerobic series reactor, and circulates continuously in the anaerobic and aerobic reactors.

[0051] Embodiment 3:

[0052] The wastewater solution obtained by N-nitration and C-nitration in the production process of 3,4-dinitropyrazole (DNP) was diluted 100 times, and 50 mL of the solution was taken into a 250 mL conical flask, and 0.2 g of iron filings were quickly added to each conical flask. Subsequently, the conical flask was placed in a water bath constant temperature oscillator at 25°C and 200 rpm for 300 minutes. Figure 3 As shown, the degradation rates of N-nitropyrazole, 3-nitropyrazole, mesitylene, and DNP were 99% and 99% respectively after biochemical treatment.

[0053] Before hydration treatment, adjust the pH of the tail water with sodium bicarbonate solution to about 6-7. Add sodium nitrate solution to control the COD / NO3 in the tail water. - -N is about 10.

[0054] The wastewater is introduced into the anaerobic-aerobic series reactor, and circulates continuously in the anaerobic and aerobic reactors.

[0055] Compared with the prior art, the beneficial effects of the present invention include at least:

[0056] In view of the potential safety hazards and high processing costs of high-temperature heating in the combined process of stripping, thermal decomposition and ammonia distillation in the traditional process, as well as the poor biodegradability of difficult-to-degrade organic compounds, the present invention proposes a zero-valent iron advanced oxidation technology + biochemical treatment technology process to achieve effective treatment of strong acid organic wastewater generated in the production process of nitropyrazole compounds. Compared with traditional Fenton oxidation, the present invention uses acetic acid in the production process as an oxidant to effectively achieve the efficient degradation of 1-nitropyrazole, 3-nitropyrazole, 3,4-dinitropyrazole and mesitylene, and significantly reduce the toxicity of the oxidized water. In addition, combined with the biochemical treatment process, small molecular organic pollutants in the wastewater are further degraded to achieve standard discharge of wastewater.

[0057] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the relevant field should understand that the specific implementation methods of the present invention can still be modified or replaced by equivalents, and any modifications or equivalent replacements that do not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A mixed acid nitration organic wastewater treatment method, characterized in that: The steps include: Zero-valent iron advanced oxidation: A set amount of zero-valent iron is added to the wastewater and mixed to carry out oxidation reaction; Biochemical treatment: adjust the pH and COD / NO3 of the above oxidized wastewater - -N regulation, and enters the aerobic and anaerobic reactors for biochemical treatment to obtain dischargeable wastewater.

2. The method for treating mixed acid nitration organic wastewater according to claim 1, characterized in that: The wastewater contains acetic acid, sulfuric acid, nitric acid, nitropyrazole compounds and mesitylene under strong acid conditions, wherein the content of acetic acid is not less than 0.28%, and the content of nitric acid is not less than 3%.

3. The method for treating mixed acid nitration organic wastewater according to claim 1, characterized in that: The dosage of zero-valent iron is not less than 0.2 g / L.

4. The method for treating mixed acid nitration organic wastewater according to claim 1, characterized in that: The pH is adjusted by using any one of NaOH, Na2CO3 or NaHCO3, COD / NO3 - -N adjustment uses sodium acetate or sodium nitrate.

5. The method for treating mixed acid nitration organic wastewater according to claim 4, characterized in that: The pH is adjusted to neutral, the COD / NO3 - -N is regulated to 6-12.

6. The method for treating mixed acid nitration organic wastewater according to claim 1, characterized in that: The reactor is an anaerobic-aerobic series reactor, the water temperature of which is controlled at 25-30°C, nitrogen is introduced into the anaerobic reactor to maintain anaerobic conditions, oxygen is introduced into the aerobic reactor to maintain aerobic conditions, and a peristaltic pump is used to circulate in the two reactors.

7. The method for treating mixed acid nitration organic wastewater according to claim 6, characterized in that: The initial domestication bacterial agent in the anaerobic-aerobic series reactor is the composite microbial preparation B350. The composite microbial preparation and water distribution components are added into a container to obtain a domestication medium, which is used for domestication to obtain a biofilm.

8. The method for treating mixed acid nitration organic wastewater according to claim 7, characterized in that: The water distribution components include: KNO3, CH3COONa, ferric chloride, KH2PO4, MgCl2·6H2O, CaCl2 and trace element mother liquor.

9. The method for treating mixed acid nitration organic wastewater according to claim 6, characterized in that: The composition of the acclimation medium is the same as that of the wastewater COD / NO3 - -N ratio.

10. A mixed acid nitration organic wastewater treatment system, which implements a mixed acid nitration organic wastewater treatment method according to any one of claims 1 to 9, Features: Includes: oxidation module and biochemical module; The oxidation module includes a reaction container for adding zero-valent iron into wastewater to perform an oxidation reaction; The biochemical module includes an anaerobic-aerobic series reactor, which is used to perform biochemical treatment on wastewater to achieve standard discharge of wastewater.

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