A quaternary ammonium salt wastewater treatment process

Abstract

The invention provides a quaternary ammonium salt wastewater treatment process, and relates to the field of sewage treatment. The invention uses fluorinated iron and zirconium iron complexes as iron-based composite catalysts. In the micro-electrolytic oxidation process, hydrogen peroxide can be quickly decomposed to generate more hydroxyl radicals under neutral conditions, which has a good chain breaking effect on macromolecular organic matter. At the same time, tetramethylammonium bromide is selected to modify POSS in a coagulation and precipitation process, which has a large number of silanol groups and hydrogen bonds distributed in its pores and on its surface, has a strong adsorption capacity, and realizes efficient treatment of quaternary ammonium salt wastewater.

Description

Technical Field

[0001] The invention relates to the field of sewage treatment, and in particular to a quaternary ammonium salt wastewater treatment process. Background Art

[0002] Quaternary ammonium compounds (QACs) are an important class of chemical products that can be used as softeners, bactericides, surfactants, antistatic agents and phase transfer catalysts. A large number of raw and auxiliary materials containing heterocyclic, long-chain, organophosphorus and halogenated hydrocarbons are used in the production process of quaternary ammonium salts. Therefore, the wastewater generated in the production process of quaternary ammonium salts has the following characteristics: (1) It contains a certain amount of difficult biodegradable substances, such as halogenated hydrocarbons, tetraethylammonium hydroxide, crown ethers, tetrabutylammonium fluoride, tetraethylammonium fluoroborate and triethylamine hydrochloride; (2) It contains a certain amount of microbial toxic substances, such as acetonitrile, triethylamine, tripropylamine, tributylamine, tetrahydrofuran, crown ethers, tetraethylammonium fluoroborate and tetrabutylammonium fluoride. Biochemical treatment is often used in sewage treatment, but because the wastewater from quaternary ammonium salt production has the above characteristics, it will have a negative impact on the microorganisms in the biological treatment system, so the wastewater cannot be directly treated biochemically.

[0003] The "method for treating quaternary ammonium salt production wastewater" disclosed in Chinese patent literature has a publication number of CN113816561A, which includes pretreatment, iron-carbon micro-electrolysis oxidation treatment, primary coagulation and sedimentation treatment, oxidation treatment, biochemical treatment, secondary coagulation and sedimentation treatment and other steps; this method requires the addition of sulfuric acid to adjust the pH to acidic to promote the reaction during the iron-carbon micro-electrolysis oxidation treatment, and then uses alkaline solution to adjust the pH. At the same time, the introduced sulfate ions also need to be removed later, which cannot achieve efficient treatment of quaternary ammonium salt wastewater.

[0004] Therefore, how to reduce the pH adjustment process in micro-electrolytic oxidation and primary coagulation sedimentation treatment while maintaining the quaternary ammonium salt wastewater treatment effect and achieving efficient wastewater treatment has become a technical problem that needs to be solved. Summary of the invention

[0005] In view of the deficiencies in the prior art, the object of the present invention is to provide a quaternary ammonium salt wastewater treatment process, aiming to solve the problem that the existing treatment process needs to add sulfuric acid to adjust the pH to acidic to promote the reaction during iron-carbon micro-electrolysis oxidation treatment, and then use alkaline solution to adjust the pH. At the same time, the introduced sulfate ions also need to be removed later, and the quaternary ammonium salt wastewater cannot be treated efficiently.

[0006] The present invention uses fluorinated iron and zirconium iron composites as iron-based composite catalysts. In the process of micro-electrolytic oxidation treatment, hydrogen peroxide can be quickly decomposed to generate more hydroxyl radicals under nearly neutral conditions, which has a good chain breaking effect on macromolecular organic matter. At the same time, tetramethylammonium bromide is selected to modify POSS in a coagulation and precipitation treatment. POSS has a large number of silanol groups and hydrogen bonds distributed in its pores and on its surface, has a strong adsorption capacity, and comprehensively realizes the efficient treatment of quaternary ammonium salt wastewater.

[0007] The technical solution of the present invention is as follows:

[0008] The present invention provides a quaternary ammonium salt wastewater treatment process, characterized in that it comprises the following steps:

[0009] Step S1: pre-treating quaternary ammonium salt wastewater;

[0010] Step S2: adjusting the pH of the pretreated wastewater to 7.2, and then adding an iron-based composite catalyst and hydrogen peroxide for micro-electrolytic oxidation treatment;

[0011] Step S3: mixing the wastewater after micro-electrolysis oxidation treatment with tetramethylammonium bromide-modified POSS for reaction and performing a coagulation and sedimentation treatment;

[0012] Step S4: mixing the supernatant after the primary coagulation and sedimentation treatment with ozone for oxidation treatment;

[0013] Step S5: biochemically treating the wastewater after oxidation treatment;

[0014] Step S6: The supernatant after the biochemical treatment is mixed with a coagulant and a coagulant aid for secondary coagulation and sedimentation treatment, and the treated supernatant can be discharged.

[0015] The following are preferred technical solutions of the present invention, but are not intended to limit the technical solutions provided by the present invention. Through the following preferred technical solutions, the objectives and beneficial effects of the present invention can be better achieved and realized.

[0016] Preferably, the pretreatment in step S1 is a multiple-effect evaporation treatment.

[0017] Preferably, in step S2, the amount of the iron-based composite catalyst added is 900 mg / L, and the amount of hydrogen peroxide added is 2000 mg / L.

[0018] As a preferred technical solution of the present invention, the iron-based composite catalyst in step S2 includes iron oxyfluoride and ferrozirconium composite; the mass ratio of the iron oxyfluoride and ferrozirconium composite is 1:(1-1.5).

[0019] As a preferred technical solution of the present invention, the preparation method of the fluorine oxide is as follows: in parts by weight, 5 parts of iron powder are added to 350 parts of silicic acid, stirred at 50°C for 24 hours, and dried to obtain crystals; 6 parts of the crystals are added to 300 parts of n-propanol, mixed evenly to obtain a precursor solution; the precursor solution is transferred to a reactor, reacted at 200°C for 24 hours, and after the reaction is completed, solid-liquid separation is performed, and the obtained solid is vacuum dried at 100°C for 12 hours to obtain fluorine oxide.

[0020] The strong electron-withdrawing ability of the coordinated F atoms of fluorinated iron can greatly reduce the local electron density of the Fe site, thereby reducing the energy barrier for hydrogen peroxide adsorption and subsequent OO bond cleavage in the rate-limiting step, significantly promoting the activation of hydrogen peroxide. 3+ The enhanced interaction between ions and hydrogen peroxide makes ferric fluoride have strong pH adaptability, thus breaking the limitation of operation under harsh pH conditions, achieving rapid decomposition of hydrogen peroxide under near-neutral conditions to produce more hydroxyl radicals, reducing and oxidizing most of the organic matter in the wastewater, having a good chain-breaking effect on macromolecular organic matter, and having a good ring-opening effect on aromatic hydrocarbons and heterocyclic organic matter, which can greatly reduce the concentration and toxicity of pollutants and achieve efficient treatment of quaternary ammonium salt wastewater.

[0021] As a preferred technical solution of the present invention, the preparation method of the zirconium-iron composite is as follows: by weight, 1 part of zirconium sulfate and 10 parts of ferric chloride are added to 100 parts of acetonitrile aqueous solution (mass fraction 30%), and then 10 parts of 1 mol / L sodium hydroxide solution are added dropwise, and ultrasonic mixing is performed for 0.5 hours to obtain a suspension; the suspension is mechanically stirred at 80°C for 1 hour, and after stirring, it is allowed to stand for 2 hours, and centrifuged to obtain a precipitate; 50 parts of deionized water are added to 10 parts of the precipitate for resuspending to obtain a resuspension and performing programmed temperature crystallization, and the obtained crystals are washed with deionized water, centrifuged, and vacuum dried at 80°C for 12 hours to obtain a zirconium-iron composite.

[0022] Preferably, the process of programmed temperature crystallization is: firstly heating the resuspension from room temperature to 60°C and then keeping it warm for 0.5h, then heating it to 120°C and then keeping it warm for 1.5h, then heating it to 140°C and then keeping it warm for 10h, and finally cooling it to room temperature.

[0023] Amorphous zirconium dioxide in the zirconium-iron composite can associate and dissociate through its surface hydroxyl groups and hydrogen peroxide. The intermediate products of the association and dissociation process can increase the Fe 3+ The activity of FeO2 is increased, thereby promoting the generation of hydroxyl radicals; the doping of zirconium in the zirconium-iron complex increases the charge density around the iron site, which helps Fe 2+The electron loss process strengthens the activation of hydrogen peroxide; at the same time, the high-valent iron of the zirconium-iron complex under neutral conditions has a high redox potential and strong oxidizing ability, which can achieve selective removal of wastewater under near-neutral pH conditions.

[0024] As a preferred technical solution of the present invention, the preparation method of tetramethylammonium bromide modified POSS described in step S3 is: in parts by weight, 20 parts of hydroxy POSS are added to 150 parts of 2mol / L sulfuric acid solution, stirred for reaction at 55°C for 3h, cooled to room temperature after the reaction is completed, filtered, washed, and dried to obtain acidified solids; 3 parts of tetramethylammonium bromide and 40 parts of ethanol are added to 60 parts of deionized water, stirred at 60°C for 0.5h, and then 20 parts of acidified solids are added, stirred for reaction at 35°C for 2h, cooled to room temperature after the reaction is completed, centrifuged, washed, dried, and ground to obtain tetramethylammonium bromide modified POSS.

[0025] As a preferred technical solution of the present invention, the preparation method of the hydroxy POSS is as follows: by weight, 20 parts of tetrapropoxysilane are added to 100 parts of methanol, mixed evenly, 3 parts of tetramethylammonium hydroxide are added, and the mixture is reacted at 40° C. for 24 hours to obtain a mixed solution, and the mixed solution is concentrated, washed with water, and dried to obtain hydroxy POSS.

[0026] POSS material has the characteristics of many pores, low density, and large specific surface area. It is mainly adsorbed by surface complexation and ion exchange. Since a large number of silanol groups (Si-OH) and hydrogen bonds are distributed in its pores and on its surface, it has a strong adsorption capacity. At the same time, POSS material modified with tetramethylammonium bromide is used, and organic functional groups are covered on the surface of the POSS material, thereby effectively adsorbing the fluorine oxide and zirconium iron complex introduced in the previous steps to form larger precipitated particles, achieving the effect of solid-liquid separation and avoiding the generation of new polluting elements due to micro-electrolytic oxidation.

[0027] Preferably, the ozone used in the oxidation treatment in step S4 is an oxidant; ozone can further completely decompose small organic molecules into carbon dioxide and water, thereby improving the biodegradability of the wastewater.

[0028] Preferably, the biochemical treatment described in step S5 can be carried out with reference to the method disclosed in patent "CN113816561A", specifically as follows: the wastewater after oxidation treatment is passed into an anaerobic hydrolysis acidification tank for reaction, and then precipitated in an anaerobic sedimentation tank, part of the sludge precipitate is transported to the anaerobic hydrolysis acidification tank, and the remaining precipitate is transported to a sludge storage tank, the supernatant obtained by the reaction is passed into a primary anoxic tank and a primary aerobic tank in sequence for reaction, part of the supernatant after the reaction in the primary aerobic tank is returned to the primary anoxic tank for circulation, and the remaining supernatant is passed into a secondary anoxic tank and a secondary aerobic tank in sequence for reaction, part of the sludge precipitate in the secondary anoxic tank is transported to the primary anoxic tank, part of the supernatant after the reaction in the secondary aerobic tank is returned to the secondary anoxic tank for circulation, and the remaining supernatant enters a secondary sedimentation tank for precipitation, part of the sludge precipitate is transferred to the secondary anoxic tank, and the remaining sludge precipitate is transferred to a sludge storage tank for storage.

[0029] Preferably, in step S6, the coagulant is aluminum chloride, and the coagulant aid is acrylamide.

[0030] Compared with the prior art, the present invention has the following beneficial effects:

[0031] (1) The present invention adopts the synergistic effect of ferric fluoride and zirconium iron complex in the process of micro-electrolytic oxidation treatment to treat wastewater without adding acid to lower the pH; ferric fluoride has strong pH adaptability and can promote the rapid decomposition of hydrogen peroxide under near-neutral conditions, thereby greatly reducing the concentration and toxicity of pollutants; the zirconium iron complex has a high redox potential of high-valent iron under neutral conditions and strong oxidation ability, and can achieve selective removal of wastewater under near-neutral pH conditions;

[0032] (2) The present invention uses tetramethylammonium bromide to modify POSS for a coagulation and precipitation treatment, and realizes efficient adsorption through surface complexation and ion exchange of POSS material. At the same time, the modified organic functional groups cover the surface of POSS material, which can effectively adsorb fluorine oxide and zirconium iron complex, avoiding the generation of new polluting elements due to micro-electrolytic oxidation. DETAILED DESCRIPTION

[0033] For the convenience of understanding the present invention, the present invention lists the following embodiments. It should be understood by those skilled in the art that the embodiments are only to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0034] The sources of some components in the examples and comparative examples are as follows: hydrogen peroxide CAS No. 7722-84-1; ozone CAS No. 10028-15-6; aluminum chloride CAS No. 7446-70-0; acrylamide CAS No. 79-06-1.

[0035] Preparation of ferric fluoride oxide: In parts by weight, 5 parts of iron powder (CAS No. 7439-89-6) are added to 350 parts of silicic acid (CAS No. 16961-83-4), stirred at 50°C for 24 hours, and dried to obtain crystals; 6 parts of the crystals are added to 300 parts of n-propanol (CAS No. 71-23-8), mixed evenly to obtain a precursor solution; the precursor solution is transferred to a reactor, reacted at 200°C for 24 hours, and after the reaction is completed, solid-liquid separation is performed, and the obtained solid is vacuum dried at 100°C for 12 hours to obtain ferric fluoride oxide.

[0036] Preparation of zirconium-iron complex: by weight, 1 part of zirconium sulfate (CAS No. 34806-73-0) and 10 parts of ferric chloride (CAS No. 7705-08-0) were added to 100 parts of acetonitrile (CAS No. 75-05-8) aqueous solution (mass fraction 30%), and then 10 parts of 1 mol / L sodium hydroxide solution were added dropwise, and ultrasonic mixing was performed for 0.5 h to obtain a suspension; the suspension was mechanically stirred at 80°C for 1 h, and after stirring, it was allowed to stand for 2 h, and centrifuged to obtain a precipitate; 50 parts of deionized water were added to 10 parts of the precipitate for resuspending to obtain a resuspension and programmed temperature crystallization was performed, first the resuspension was heated from room temperature to 60°C and then kept warm for 0.5 h, then heated to 120°C and then kept warm for 1.5 h, then heated to 140°C and then kept warm for 10 h, and finally cooled to room temperature; the obtained crystals were washed with deionized water, centrifuged, and vacuum dried at 80°C for 12 h to obtain a zirconium-iron complex.

[0037] Preparation of tetramethylammonium bromide modified POSS: In parts by weight, 20 parts of tetrapropoxysilane (CAS No. 682-01-9) are added to 100 parts of methanol (CAS No. 67-56-1), mixed evenly, 3 parts of tetramethylammonium hydroxide (CAS No. 10424-65-4) are added, and the mixture is reacted at 40°C for 24 hours to obtain a mixed solution, and the mixed solution is concentrated, washed with water, and dried to obtain hydroxy POSS. Add 20 parts of hydroxy POSS to 150 parts of 2 mol / L sulfuric acid solution, stir and react at 55°C for 3 hours, cool to room temperature after the reaction is completed, filter, wash, and dry to obtain acidified solid; add 3 parts of tetramethylammonium bromide (CAS No. 64-20-0) and 40 parts of ethanol (CAS No. 64-17-5) to 60 parts of deionized water, stir at 60°C for 0.5h, then add 20 parts of acidified solid, stir and react at 35°C for 2h, cool to room temperature after the reaction is completed, centrifuge, wash, dry, and grind to obtain tetramethylammonium bromide modified POSS.

[0038] Embodiment 1 This embodiment provides a quaternary ammonium salt wastewater treatment process, comprising the following steps:

[0039] Step S1: pre-treating the quaternary ammonium salt wastewater by multi-effect evaporation;

[0040] Step S2: adjusting the pH of the pretreated wastewater to 7.2, and then adding an iron-based composite catalyst (the mass ratio of iron oxyfluoride and zirconium iron composite is 1:1) and hydrogen peroxide for micro-electrolytic oxidation treatment, wherein the amount of the iron-based composite catalyst added is 900 mg / L, and the amount of hydrogen peroxide added is 2000 mg / L;

[0041] Step S3: mixing the wastewater after micro-electrolysis oxidation treatment with tetramethylammonium bromide-modified POSS for a coagulation and precipitation treatment, wherein the dosage of tetramethylammonium bromide-modified POSS is 100 mg / L;

[0042] Step S4: mixing the supernatant after the primary coagulation and sedimentation treatment with ozone for oxidation treatment;

[0043] Step S5: biochemically treating the wastewater after oxidation treatment, specifically: passing the wastewater after oxidation treatment into an anaerobic hydrolysis acidification tank for reaction, and then precipitating in an anaerobic sedimentation tank, transporting part of the sludge precipitate to the anaerobic hydrolysis acidification tank, and transporting the remaining precipitate to a sludge storage tank, passing the supernatant obtained by the reaction into a primary anoxic tank and a primary aerobic tank in turn for reaction, returning part of the supernatant in the primary aerobic tank after reaction to the primary anoxic tank for circulation, and the remaining supernatant flowing into a secondary anoxic tank and a secondary aerobic tank in turn for reaction, transporting part of the sludge precipitate in the secondary anoxic tank to the primary anoxic tank, returning part of the supernatant in the secondary aerobic tank after reaction to the secondary anoxic tank for circulation, and the remaining supernatant entering a secondary sedimentation tank for precipitation, transferring part of the sludge precipitate to the secondary anoxic tank, and transferring the remaining sludge precipitate to a sludge storage tank for storage;

[0044] Step S6: The supernatant after the biochemical treatment is mixed with aluminum chloride and acrylamide for secondary coagulation and sedimentation treatment, wherein the amount of aluminum chloride added is 150 mg / L and the amount of acrylamide added is 10 mg / L, and the treated supernatant can be discharged.

[0045] Embodiment 2 This embodiment provides a quaternary ammonium salt wastewater treatment process, comprising the following steps:

[0046] Step S1: pre-treating the quaternary ammonium salt wastewater by multi-effect evaporation;

[0047] Step S2: adjusting the pH of the pretreated wastewater to 7.2, and then adding an iron-based composite catalyst (the mass ratio of iron oxyfluoride and zirconium iron composite is 1:1.5) and hydrogen peroxide for micro-electrolytic oxidation treatment, wherein the amount of the iron-based composite catalyst added is 900 mg / L, and the amount of hydrogen peroxide added is 2000 mg / L;

[0048] Step S3: mixing the wastewater after micro-electrolysis oxidation treatment with tetramethylammonium bromide-modified POSS for a coagulation and precipitation treatment, wherein the dosage of tetramethylammonium bromide-modified POSS is 100 mg / L;

[0049] Step S4: mixing the supernatant after the primary coagulation and sedimentation treatment with ozone for oxidation treatment;

[0050] Step S5: biochemically treating the wastewater after oxidation treatment, specifically: passing the wastewater after oxidation treatment into an anaerobic hydrolysis acidification tank for reaction, and then precipitating in an anaerobic sedimentation tank, transporting part of the sludge precipitate to the anaerobic hydrolysis acidification tank, and transporting the remaining precipitate to a sludge storage tank, passing the supernatant obtained by the reaction into a primary anoxic tank and a primary aerobic tank in turn for reaction, returning part of the supernatant in the primary aerobic tank after reaction to the primary anoxic tank for circulation, and the remaining supernatant flowing into a secondary anoxic tank and a secondary aerobic tank in turn for reaction, transporting part of the sludge precipitate in the secondary anoxic tank to the primary anoxic tank, returning part of the supernatant in the secondary aerobic tank after reaction to the secondary anoxic tank for circulation, and the remaining supernatant entering a secondary sedimentation tank for precipitation, transferring part of the sludge precipitate to the secondary anoxic tank, and transferring the remaining sludge precipitate to a sludge storage tank for storage;

[0051] Step S6: The supernatant after the biochemical treatment is mixed with aluminum chloride and acrylamide for secondary coagulation and sedimentation treatment, wherein the amount of aluminum chloride added is 150 mg / L and the amount of acrylamide added is 10 mg / L, and the treated supernatant can be discharged.

[0052] Embodiment 3 This embodiment provides a quaternary ammonium salt wastewater treatment process, comprising the following steps:

[0053] Step S1: pre-treating the quaternary ammonium salt wastewater by multi-effect evaporation;

[0054] Step S2: adjusting the pH of the pretreated wastewater to 7.2, and then adding an iron-based composite catalyst (the mass ratio of iron oxyfluoride and zirconium iron composite is 1:1.2) and hydrogen peroxide for micro-electrolytic oxidation treatment, wherein the amount of the iron-based composite catalyst added is 900 mg / L, and the amount of hydrogen peroxide added is 2000 mg / L;

[0055] Step S3: mixing the wastewater after micro-electrolysis oxidation treatment with tetramethylammonium bromide-modified POSS for a coagulation and precipitation treatment, wherein the dosage of tetramethylammonium bromide-modified POSS is 100 mg / L;

[0056] Step S4: mixing the supernatant after the primary coagulation and sedimentation treatment with ozone for oxidation treatment;

[0057] Step S5: biochemically treating the wastewater after oxidation treatment, specifically: passing the wastewater after oxidation treatment into an anaerobic hydrolysis acidification tank for reaction, and then precipitating in an anaerobic sedimentation tank, transporting part of the sludge precipitate to the anaerobic hydrolysis acidification tank, and transporting the remaining precipitate to a sludge storage tank, passing the supernatant obtained by the reaction into a primary anoxic tank and a primary aerobic tank in turn for reaction, returning part of the supernatant in the primary aerobic tank after reaction to the primary anoxic tank for circulation, and the remaining supernatant flowing into a secondary anoxic tank and a secondary aerobic tank in turn for reaction, transporting part of the sludge precipitate in the secondary anoxic tank to the primary anoxic tank, returning part of the supernatant in the secondary aerobic tank after reaction to the secondary anoxic tank for circulation, and the remaining supernatant entering a secondary sedimentation tank for precipitation, transferring part of the sludge precipitate to the secondary anoxic tank, and transferring the remaining sludge precipitate to a sludge storage tank for storage;

[0058] Step S6: The supernatant after the biochemical treatment is mixed with aluminum chloride and acrylamide for secondary coagulation and sedimentation treatment, wherein the amount of aluminum chloride added is 150 mg / L and the amount of acrylamide added is 10 mg / L, and the treated supernatant can be discharged.

[0059] Comparative Example 1

[0060] This comparative example provides a quaternary ammonium salt wastewater treatment process, comprising the following steps:

[0061] Step S1: pre-treating the quaternary ammonium salt wastewater by multi-effect evaporation;

[0062] Step S2: adding sulfuric acid to the wastewater until the pH is 3.5, then adding hydrogen peroxide at a dosage of 2000 mg / L and adding ferrous sulfate at a dosage of 1000 mg / L to the wastewater for reaction, in parts by weight, the iron-carbon filler used in the iron-carbon micro-electrolysis cell contains 70 parts of iron, 15 parts of carbon, 5 parts of palladium and 3 parts of titanium;

[0063] Step S3: firstly adjust the pH value of the wastewater after the iron-carbon micro-electrolysis oxidation treatment to 7.5 with sodium hydroxide, then add polyaluminium chloride at a dosage of 150 mg / L and stir to react, and then add polyacrylamide at a dosage of 10 mg / L to the supernatant and stir to react;

[0064] Step S4: mixing the supernatant after the primary coagulation and sedimentation treatment with ozone for oxidation treatment;

[0065] Step S5: biochemically treating the wastewater after oxidation treatment, specifically: passing the wastewater after oxidation treatment into an anaerobic hydrolysis acidification tank for reaction, and then precipitating in an anaerobic sedimentation tank, transporting part of the sludge precipitate to the anaerobic hydrolysis acidification tank, and transporting the remaining precipitate to a sludge storage tank, passing the supernatant obtained by the reaction into a primary anoxic tank and a primary aerobic tank in turn for reaction, returning part of the supernatant in the primary aerobic tank after reaction to the primary anoxic tank for circulation, and the remaining supernatant flowing into a secondary anoxic tank and a secondary aerobic tank in turn for reaction, transporting part of the sludge precipitate in the secondary anoxic tank to the primary anoxic tank, returning part of the supernatant in the secondary aerobic tank after reaction to the secondary anoxic tank for circulation, and the remaining supernatant entering a secondary sedimentation tank for precipitation, transferring part of the sludge precipitate to the secondary anoxic tank, and transferring the remaining sludge precipitate to a sludge storage tank for storage;

[0066] Step S6: The supernatant after the biochemical treatment is mixed with aluminum chloride and acrylamide for secondary coagulation and sedimentation treatment, wherein the amount of aluminum chloride added is 150 mg / L and the amount of acrylamide added is 10 mg / L, and the treated supernatant can be discharged.

[0067] Comparative Example 2

[0068] This comparative example provides a quaternary ammonium salt wastewater treatment process, which is different from Comparative Example 1 only in that this comparative example uses an iron-based composite catalyst (the mass ratio of iron oxyfluoride and ferrozirconium composite is 1:1) instead of ferrous sulfate and iron-carbon filler in the micro-electrolytic oxidation reaction, and the rest is the same as Comparative Example 1.

[0069] Comparative Example 3

[0070] This comparative example provides a quaternary ammonium salt wastewater treatment process, which is different from Comparative Example 1 only in that tetramethylammonium bromide-modified POSS is used in the first coagulation and sedimentation to replace aluminum chloride and polyacrylamide, and the rest is the same as Comparative Example 1.

[0071] The method disclosed in the reference patent "CN113816561A" was used to test the wastewater after micro-electrolysis oxidation reaction and primary coagulation and sedimentation. The test results are shown in the following table:

[0072]

[0073] The applicant declares that the present invention uses the above embodiments to illustrate the detailed process flow of the present invention, but the present invention is not limited to the above detailed process flow, that is, it does not mean that the present invention must rely on the above detailed process flow to be implemented. Those skilled in the art should understand that any improvement of the present invention falls within the protection scope and disclosure scope of the present invention.

Claims

1. A quaternary ammonium salt wastewater treatment process, It is characterized in that The steps include: Step S1: pre-treating quaternary ammonium salt wastewater; Step S2: adjusting the pH of the pretreated wastewater to 7.2, and then adding an iron-based composite catalyst and hydrogen peroxide for micro-electrolytic oxidation treatment; Step S3: mixing the wastewater after micro-electrolysis oxidation treatment with tetramethylammonium bromide-modified POSS for reaction and performing a coagulation and sedimentation treatment; Step S4: mixing the supernatant after the primary coagulation and sedimentation treatment with ozone for oxidation treatment; Step S5: biochemically treating the wastewater after oxidation treatment; Step S6: mixing the supernatant after the biochemical treatment with a coagulant and a coagulant aid for secondary coagulation and sedimentation treatment, and the treated supernatant can be discharged; The pretreatment in step S1 is a multiple-effect evaporation treatment; The iron-based composite catalyst in step S2 includes iron oxyfluoride and a zirconium-iron composite; the mass ratio of the iron oxyfluoride to the zirconium-iron composite is 1:(1-1.5); the preparation method of the iron oxyfluoride is as follows: by weight, 5 parts of iron powder are added to 350 parts of silicic acid, stirred at 50° C. for 24 hours, and dried to obtain crystals; 6 parts of the crystals are added to 300 parts of n-propanol, and mixed evenly to obtain a precursor solution; The precursor solution was transferred to a reactor and reacted at 200°C for 24 hours. After the reaction was completed, solid-liquid separation was performed, and the obtained solid was vacuum dried at 100°C for 12 hours to obtain iron fluoride oxide; The preparation method of the zirconium-iron composite is as follows: by weight, 1 part of zirconium sulfate and 10 parts of ferric chloride are added to 100 parts of acetonitrile aqueous solution, and then 10 parts of 1 mol / L sodium hydroxide solution are added dropwise, and ultrasonic mixing is performed for 0.5 hours to obtain a suspension; the suspension is mechanically stirred at 80° C. for 1 hour, and after stirring, the suspension is allowed to stand for 2 hours, and a precipitate is obtained by centrifugation; 50 parts of deionized water are added to 10 parts of the precipitate for resuspending to obtain a resuspension, and programmed temperature crystallization is performed, and the obtained crystals are washed with deionized water, centrifuged, and vacuum dried at 80° C. for 12 hours to obtain the zirconium-iron composite; The preparation method of tetramethylammonium bromide modified POSS is as follows: by weight, 20 parts of hydroxy POSS are added to 150 parts of 2 mol / L sulfuric acid solution, stirred at 55° C. for reaction for 3 hours, cooled to room temperature after the reaction is completed, filtered, washed, and dried to obtain an acidified solid; 3 parts of tetramethylammonium bromide and 40 parts of ethanol are added to 60 parts of deionized water, stirred at 60° C. for 0.5 hours, and then 20 parts of the acidified solid are added, stirred at 35° C. for reaction for 2 hours, cooled to room temperature after the reaction is completed, centrifuged, washed, dried, and ground to obtain tetramethylammonium bromide modified POSS; The preparation method of the hydroxy POSS is as follows: by weight, 20 parts of tetrapropoxysilane are added to 100 parts of methanol, mixed evenly, 3 parts of tetramethylammonium hydroxide are added, reacted at 40° C. for 24 hours to obtain a mixed solution, and the mixed solution is concentrated, washed with water, and dried to obtain the hydroxy POSS; The process of the programmed temperature crystallization is as follows: firstly, the resuspension is heated from room temperature to 60°C and then kept at this temperature for 0.5h, then heated to 120°C and then kept at this temperature for 1.5h, then heated to 140°C and then kept at this temperature for 10h, and finally cooled to room temperature; In step S6, the coagulant is aluminum chloride, and the coagulant aid is acrylamide.

2. A quaternary ammonium salt wastewater treatment process according to claim 1, It is characterized in that In step S2, the amount of the iron-based composite catalyst added is 900 mg / L, and the amount of hydrogen peroxide added is 2000 mg / L.

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