Treatment method of polymethacrylate production wastewater

Abstract

The invention relates to the field of wastewater treatment, and discloses a treatment method of polymethacrylate production wastewater. The treatment method comprises the following steps: contacting wastewater to be treated with a catalyst and an oxidizing agent I to perform Fenton catalytic oxidation reaction to obtain wastewater I; relative to 1L of the to-be-treated wastewater, the dosage of the oxidizing agent I is 15-25g; under the acidic condition, the wastewater I is in contact with an oxidizing agent II, a precipitator, 1, 6-diaminohexane and a coagulant aid for an oxidation precipitation reaction. According to the treatment method, the COD removal rate of the wastewater can be further improved under the acidic condition, the dosage of the catalyst and the oxidizing agent is small, the cost is low, the solid waste amount is small, the chroma of the wastewater can be effectively reduced under the preferable condition, the biodegradability of the obtained treated wastewater is good, anaerobic treatment and aerobic treatment which are sequentially carried out can be further combined, and the treatment effect is good. And effluent with lower CODcr concentration and chromaticity is obtained.

Description

Technical Field

[0001] The invention relates to the field of wastewater treatment, and in particular to a method for treating wastewater produced by polymethacrylate production. Background Art

[0002] Polymethacrylates are a class of high molecular weight copolymers with methacrylate as the core monomer. They show excellent pour point depression effect on a variety of oil products. The core monomer methacrylate can be polymerized with other unsaturated monomers and plays an important role in the pour point depression process of oil products, thus attracting widespread attention.

[0003] Polymethacrylates are mainly used in areas such as diesel viscosity reduction. At low temperatures, diesel will gradually precipitate wax crystals and cross-link with each other to form a three-dimensional network structure, which will wrap up the remaining liquid diesel, causing the diesel to lose its low-temperature fluidity, leading to blockage of fuel lines or filters in the diesel engine fuel system, seriously affecting the storage, transportation and use of oil products in cold areas.

[0004] At present, the methods to improve the low-temperature fluidity of diesel include the pour point depressant addition method, dewaxing method, diesel blending method, etc. Compared with other methods, pour point depressant has the advantages of small dosage, wide source of raw materials, low price, simple process, good pour point depressant effect, etc. A small amount of addition can significantly reduce the condensation point and cold filter point of diesel, thereby improving the low-temperature fluidity of diesel. Polymethacrylate is a high-quality lubricating oil pour point depressant, but polymethacrylate will produce raw water containing anthracene and quinone substances during the production process. The raw water has high organic matter content, high chroma, high salt content, and difficult biodegradation. Due to the characteristics of esterification wastewater, it is impossible to solve the treatment problem of esterification wastewater by simply relying on physical or biochemical process treatment.

[0005] Traditional methods for treating esterification wastewater mainly include physical methods (adsorption, extraction, membrane separation, etc.), chemical precipitation methods and chemical oxidation methods (photocatalytic oxidation, supercritical water oxidation, chlorine dioxide oxidation, ultrasonic degradation, electrochemical oxidation, etc.). These existing technologies have limited COD reduction levels and cannot effectively reduce the color of wastewater.

[0006] In addition, in the chemical precipitation method, calcium, magnesium and other ions in the wastewater usually need to be precipitated under alkaline conditions. In the prior art, even when the CODcr concentration is low, a large amount of catalysts and oxidants still need to be added, resulting in a large amount of solid waste, which ultimately leads to excessively high treatment costs. How to properly treat polymethacrylate wastewater is a key factor restricting the development of this production process.

[0007] CN104086040A discloses a water-washing epoxy resin wastewater treatment system and process, which includes advanced oxidation precipitation, hydrolysis anaerobic, two-stage aerobic CBR and other processes. The process needs to be diluted before entering the treatment system. After dilution, the concentration of wastewater pollutants is at a low level, and the actual treatment capacity of the process is not high.

[0008] CN111003848A discloses a method for treating wastewater containing phosphonate and / or phosphite, wherein the method is pre-oxidized by adding sodium hypochlorite, then ferrous sulfate and sodium hypochlorite are added to the obtained pre-oxidized wastewater for catalytic oxidation, then lanthanum cerium chloride is added to the obtained oxidized wastewater for flocculation, and finally the flocculation precipitation is removed. In order to flocculate better, the method further comprises adding alkali solution to adjust the pH value of the oxidized wastewater to 7-9 (i.e. neutral or alkaline) after adding lanthanum cerium chloride, and then flocculating. Although the method can reduce the initial chemical oxygen demand (COD) of the wastewater > 4000ppm and the total phosphorus (TP) > 1000ppm to COD < 20ppm and TP < 5ppm, the pollutant concentration of the wastewater is still at a relatively low level, and a large amount of iron salt (10000mg / L) and lanthanum cerium chloride solution need to be added, which results in a large amount of solid waste being generated even when the organic matter concentration of the wastewater is not high, and the method is not applicable to high COD wastewater.

[0009] CN101456648A discloses a method for treating polyester production wastewater, which first adds phosphate and ammonium salt, adjusts the pH value of the wastewater to 6.5-8.0, then performs anaerobic treatment, controls the anaerobic effluent to 300-500 mg / L, and then performs aerobic treatment on the treated wastewater. Although this method can make the treated wastewater meet the sewage discharge standard, the pollutant concentration of the wastewater is still at a low level. Although the wastewater contains biological inhibitory substances, it can still be directly treated by anaerobic plus aerobic methods, indicating that the B / C of the wastewater itself is not low, the biological toxicity of the biological inhibitory substances is not strong, and only phosphate and ammonium salts are added to perform biochemical treatment, which is not applicable to low B / C wastewater. Summary of the invention

[0010] The purpose of the present invention is to overcome the problems in the existing esterification wastewater treatment method, such as excessive use of catalysts and oxidants, high cost, large amount of solid waste, and low COD removal rate of wastewater. In the wastewater treatment process, if calcium and magnesium ions are used, precipitation reaction must be carried out under alkaline conditions, and then the pH value must be adjusted, which requires large acid consumption.

[0011] In order to achieve the above object, the present invention provides a method for treating polymethacrylate production wastewater, the method comprising the following steps:

[0012] (1) contacting the wastewater to be treated with a catalyst and an oxidant I to perform a Fenton catalytic oxidation reaction to obtain wastewater I;

[0013] Wherein, relative to 1L of the wastewater to be treated, the dosage of the oxidant I is 15-25g;

[0014] (2) Under acidic conditions, the wastewater I is contacted with an oxidant II, a precipitant, 1,6-diaminohexane and a coagulant aid to carry out an oxidation precipitation reaction.

[0015] In the existing traditional methods for treating esterification wastewater, calcium, magnesium and other ions in the wastewater usually need to be precipitated under alkaline conditions. In addition, even when the CODcr concentration of the wastewater is low, a large amount of catalysts and oxidants still need to be added, resulting in a large amount of solid waste and excessively high treatment costs. The inventors of the present invention found during the research process that the COD reduction level of the above-mentioned traditional precipitation method is limited. The inventors of the present invention also found that catalytic oxidation of the wastewater and then addition of aluminum salts and / or iron salts did not generate precipitation under different pH conditions, and the reduction of COD and chromaticity was not obvious.

[0016] In addition, even if wastewater with excessively high CODcr concentration is catalytically oxidized, the resulting wastewater still contains biologically toxic substances.

[0017] Furthermore, if calcium salts, magnesium salts, iron salts, and aluminum salts are directly used for flocculation reaction under different pH conditions, the wastewater still cannot produce precipitation and the COD does not decrease significantly.

[0018] The treatment method of the present invention first performs moderate catalytic oxidation on the wastewater and then performs secondary oxidation under acidic conditions. It can change the existence form of CODcr in the wastewater and its molecular structure through catalytic oxidation + secondary oxidation, and then combine with a precipitant, 1,6-diaminohexane and a coagulant to achieve its subsequent removal.

[0019] The inventors of the present invention discovered during the research process that organic matter containing color in wastewater cannot be effectively removed under a single flocculant condition before and after oxidation, and traditional iron salts, calcium salts, aluminum salts, and magnesium salts cannot effectively remove CODcr and color in wastewater under full pH conditions (1-13). However, when 1,6-diaminohexane is added, it can form a precipitate with the organic matter in the wastewater together with the precipitant and the coagulant aid under low pH (acidic) conditions, which is completely different from traditional precipitation conditions.

[0020] Through the above technical scheme, the treatment method provided by the present invention first subjects the wastewater to be treated to a Fenton catalytic oxidation reaction, and then, under acidic conditions, the obtained wastewater I is contacted with an oxidant II, a precipitant, 1,6-diaminohexane and a coagulant to an oxidation precipitation reaction, which can further improve the COD removal rate of the wastewater, and the amount of catalyst and oxidant used is small, the cost is low, and the amount of solid waste is small. Under preferred circumstances, the chromaticity of the wastewater can also be effectively reduced, and the biodegradability of the treated wastewater obtained is good, and it can be further combined with anaerobic treatment and aerobic treatment performed in sequence to obtain effluent with lower CODcr concentration and chromaticity. DETAILED DESCRIPTION

[0021] The endpoints and any values ​​of the ranges disclosed in this article are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.

[0022] Technical terms in the present invention shall be understood according to their general meanings in the art unless otherwise stated, if they are defined.

[0023] In the present invention, "at least one" means one or two or more.

[0024] As mentioned above, the present invention provides a method for treating wastewater from the production of polymethacrylate, the method comprising the following steps:

[0025] (1) contacting the wastewater to be treated with a catalyst and an oxidant I to perform a Fenton catalytic oxidation reaction to obtain wastewater I;

[0026] Wherein, relative to 1L of the wastewater to be treated, the dosage of the oxidant I is 15-25g;

[0027] (2) Under acidic conditions, the wastewater I is contacted with an oxidant II, a precipitant, 1,6-diaminohexane and a coagulant aid to carry out an oxidation precipitation reaction.

[0028] According to some embodiments of the present invention, in step (1), the wastewater to be treated is contacted with a catalyst and an oxidant I to carry out a Fenton catalytic oxidation reaction, and the CODcr concentration of the wastewater to be treated is reduced by Fenton catalytic oxidation, thereby changing the existence form of organic matter in the wastewater to be treated, thereby facilitating further removal of organic matter in the wastewater to be treated.

[0029] According to some embodiments of the present invention, in step (1), the CODcr concentration of the wastewater to be treated is >15000 mg / L; the chromaticity is ≥4000 times; the B / C is 0.015-0.025; the pH value is 12-13.5; and the conductivity is 40-50 mS / cm.

[0030] The treatment method provided by the present invention is particularly suitable for treating wastewater that meets the above requirements, and can obtain effluent with low CODcr concentration and low chroma.

[0031] According to some embodiments of the present invention, in step (1), the catalyst and the oxidant I may be catalysts and oxidants conventionally used in the art for performing Fenton catalytic oxidation reactions, and there are no particular limitations thereon, as long as Fenton catalytic oxidation reactions can be performed.

[0032] According to some embodiments of the present invention, preferably, the catalyst is ferrous sulfate.

[0033] According to some embodiments of the present invention, preferably, in step (1), the amount of the catalyst used is 3000-5000 mg, preferably 3500-4000 mg, relative to 1 L of the wastewater to be treated.

[0034] According to some embodiments of the present invention, in step (1), the amount of the oxidant I is 15-25 g, preferably 15-20 g, relative to 1 L of the wastewater to be treated. When the organic matter in the wastewater is initially oxidized, controlling the amount of the oxidant I within the above range is conducive to enabling the organic matter to be effectively removed by subsequent secondary oxidation and precipitation methods.

[0035] According to some embodiments of the present invention, preferably, the oxidant I is hydrogen peroxide.

[0036] More preferably, the hydrogen peroxide is provided in the form of hydrogen peroxide with a mass fraction of 28%-30%.

[0037] According to some embodiments of the present invention, preferably, in step (1), the amount of hydrogen peroxide used is 10-17 mL, preferably 11.7-13.3 mL, relative to 1 L of the wastewater to be treated.

[0038] Controlling the amount of the catalyst and the hydrogen peroxide within the above-mentioned preferred range is beneficial to further promote the subsequent oxidation precipitation reaction under acidic conditions, and is beneficial to further obtain treated wastewater with lower CODcr concentration, low chroma and high B / C.

[0039] According to some embodiments of the present invention, preferably, in step (1), the reaction time of the Fenton catalytic oxidation reaction is 60-240 min, preferably 90-150 min.

[0040] According to some embodiments of the present invention, preferably, before performing the Fenton catalytic oxidation reaction, step (1) further comprises: adjusting the pH value of the wastewater to be treated to 2-4, preferably 2.5-3.5. By adopting the above preferred embodiment, the wastewater is partially oxidized to change the existence form of CODcr in the wastewater, which is conducive to the subsequent removal of CODcr in the wastewater.

[0041] According to some embodiments of the present invention, in step (2), under acidic conditions, the wastewater I is contacted with an oxidant II, a precipitant, 1,6-diaminohexane and a coagulant to perform an oxidation precipitation reaction. In the above steps, under acidic conditions, the oxidizing property of hypochlorous acid of the oxidant II can be used to further change the form of organic matter in the wastewater I; the calcium ions, magnesium ions and barium ions of the precipitant are used to precipitate organic matter in the wastewater I; and the sulfonic acid substances in the wastewater I can be removed by combining the 1,6-diaminohexane and the coagulant. In the above steps, the raw materials cooperate with each other to form floccules with cations, cations and organic matter, thereby further reducing the CODcr concentration, and the chromaticity of the treated wastewater can also be reduced, and its biodegradability is also good.

[0042] According to some embodiments of the present invention, in step (2), the type of the oxidant II can be selected from a wide range and can be a hypochlorite commonly used in the art. Preferably, the oxidant II is calcium hypochlorite and / or sodium hypochlorite.

[0043] According to some embodiments of the present invention, in step (2), the type of the precipitant can be selected from a wide range and can be a salt containing at least one of calcium ions, magnesium ions and barium ions conventionally used in the art. Preferably, the precipitant is at least one of calcium chloride, magnesium chloride and barium chloride.

[0044] According to some embodiments of the present invention, preferably, in step (2), the coagulant aid is anionic polyacrylamide. More preferably, the weight average molecular weight of the anionic polyacrylamide is 4 million to 10 million g / mol, preferably 4 million to 8 million g / mol. By adopting the above preferred embodiment, the small particles produced by the precipitant and the organic matter generate large particles, which is conducive to further removing the CODcr of the wastewater and reducing the chromaticity.

[0045] According to some embodiments of the present invention, preferably, in step (2), the amount of the oxidant II is 2000-4000 mg, preferably 2000-3500 mg, relative to 1 L of the wastewater to be treated. The above preferred embodiment is conducive to further removal and reduction of organic matter and chromaticity in wastewater.

[0046] According to some embodiments of the present invention, preferably, in step (2), the amount of the precipitant used is 1000-3500 mg, preferably 1000-3000 mg, relative to 1 L of the wastewater to be treated. The above preferred embodiment is conducive to further removal and reduction of organic matter and chromaticity in wastewater.

[0047] According to some embodiments of the present invention, preferably, in step (2), the amount of 1,6-diaminohexane used is 30-100 mg, preferably 40-60 mg, relative to 1 L of the wastewater to be treated. The above preferred embodiment is conducive to further removal and reduction of organic matter and chromaticity in wastewater.

[0048] According to some embodiments of the present invention, preferably, in step (2), the amount of the coagulant aid is 40-80 mg, preferably 50-70 mg, relative to 1 L of the wastewater to be treated. The above preferred embodiment is conducive to further removal and reduction of organic matter and chromaticity in wastewater.

[0049] According to some embodiments of the present invention, preferably, in step (2), the pH value of the oxidation precipitation reaction is 2-6, preferably 2-3, and more preferably 2.5-3. The above preferred embodiment is conducive to further reducing the CODcr concentration and chromaticity of the effluent.

[0050] Preferably, the reaction time of the oxidation precipitation reaction is 30-120 min, preferably 45-90 min.

[0051] According to some embodiments of the present invention, preferably, step (2) further comprises: performing solid-liquid separation on the product obtained by the oxidation precipitation reaction to obtain wastewater II. There is no particular limitation on the method of solid-liquid separation, which can be performed with reference to the prior art.

[0052] Preferably, the solid-liquid separation method is centrifugal separation; the conditions of the centrifugal separation include: a centrifugal speed of 5000-8000 r / min, preferably 6000-7000 r / min; a centrifugal time of 10-30 min, preferably 15-25 min.

[0053] According to some embodiments of the present invention, preferably, step (2) further comprises: adjusting the pH value of the wastewater II to 6.5-7.5.

[0054] According to some embodiments of the present invention, the wastewater II has low CODcr concentration, low chroma, and good biodegradability.

[0055] According to some embodiments of the present invention, preferably, the treatment method further comprises: subjecting the wastewater II to anaerobic treatment and aerobic treatment in sequence. The above preferred embodiment is conducive to further reducing the CODcr concentration and chromaticity of the effluent.

[0056] According to some embodiments of the present invention, preferably, the conditions of the anaerobic treatment include: anaerobic temperature of 30-40°C, hydraulic retention time (HRT) of 36-60h. The above preferred embodiment is conducive to further reducing the CODcr concentration and chromaticity of the effluent.

[0057] According to some embodiments of the present invention, preferably, the aerobic treatment conditions include: aerobic temperature of 25-35°C, empty bed residence time (EBRT) of 6-12h. The above preferred embodiment is conducive to further reducing the CODcr concentration and chromaticity of the effluent.

[0058] The present invention will be described in detail below through examples.

[0059] In the following examples and comparative examples, unless otherwise specified, the methods used are conventional methods in the art.

[0060] COD analysis method: HJ 828-2017 Determination of chemical oxygen demand in water - dichromate method;

[0061] BOD5 analysis method: HJ 505-2009 Water quality five-day biochemical oxygen demand (BOD5) determination dilution and inoculation method;

[0062] pH analysis method: electrode method for determining pH value of water quality;

[0063] The conductivity was measured by a conductivity analyzer;

[0064] TOC analysis method: HJ 501-2009 Determination of total organic carbon in water quality - combustion oxidation-non-dispersive infrared absorption method;

[0065] SO4 2- Reference for analytical method: GB / T 14642-2009 Determination of fluoride, chlorine, phosphate, nitrite, nitrate and sulfate in industrial circulating cooling water and boiler water - ion chromatography;

[0066] Na + Reference for analysis method: GB / T 5750.6-2006 Standard test method for metal indicators of drinking water;

[0067] Cl - Reference for analytical method: GB / T 14642-2009 Determination of fluoride, chlorine, phosphate, nitrite, nitrate and sulfate in industrial circulating cooling water and boiler water - ion chromatography;

[0068] Chroma analysis method: HJ 1182-2021 Determination of water quality chroma - Dilution multiple method.

[0069] The wastewater is polymethacrylate production wastewater, and its basic properties are shown in Table 1. The wastewater has the characteristics of high pH value, high conductivity, high COD, high chroma and low B / C.

[0070] Table 1

[0071]

[0072] The following examples are used to illustrate the method for treating polymethacrylate production wastewater provided by the present invention.

[0073] Example 1

[0074] (S1) adjusting the pH value of the wastewater to be treated (200 mL) to 2 with sulfuric acid, and then contacting the adjusted wastewater with a catalyst and an oxidant I to perform a Fenton catalytic oxidation reaction to obtain wastewater I; wherein:

[0075] The catalyst is ferrous sulfate heptahydrate;

[0076] The amount of catalyst used is 4000 mg relative to 1 L of wastewater to be treated;

[0077] The oxidant I is hydrogen peroxide, which is provided in the form of 30% by mass hydrogen peroxide;

[0078] Relative to 1L of wastewater to be treated, the amount of hydrogen peroxide used is 10.6mL (i.e., the amount of hydrogen peroxide used is 15.5g);

[0079] The reaction time of Fenton catalytic oxidation reaction is 120min;

[0080] (S2) contacting the above wastewater I with an oxidant II, a precipitant, 1,6-diaminohexane and a coagulant aid to perform an oxidation precipitation reaction; wherein:

[0081] The oxidant II is sodium hypochlorite and calcium hypochlorite; the precipitant is magnesium chloride; the coagulant aid is anionic polyacrylamide; the weight average molecular weight of the anionic polyacrylamide is 4 million g / mol;

[0082] Relative to 1L of wastewater to be treated, the dosage of sodium hypochlorite is 1000mg, and the dosage of calcium hypochlorite is 1000mg;

[0083] Relative to 1L of wastewater to be treated, the amount of magnesium chloride used is 1000mg;

[0084] Relative to 1L of wastewater to be treated, the amount of 1,6-diaminohexane used is 40mg;

[0085] Relative to 1L of wastewater to be treated, the dosage of anionic polyacrylamide is 60mg;

[0086] The pH value of the reaction system was adjusted to 3 with sulfuric acid, and the reaction time of the oxidation precipitation reaction was 45 min;

[0087] (S3) subjecting the product obtained by the oxidation precipitation reaction to solid-liquid separation to obtain wastewater II; wherein:

[0088] The method of solid-liquid separation is centrifugal separation;

[0089] The conditions for centrifugal separation are: centrifugal speed is 7000r / min; centrifugal time is 20min;

[0090] The test showed that the CODcr concentration of wastewater II was 9160 mg / L and the chromaticity was 20 times;

[0091] (S4) adjusting the pH value of the wastewater II to 7 with sodium hydroxide, and then subjecting the adjusted wastewater (with a B / C of 0.32) to anaerobic treatment and aerobic treatment in sequence; wherein:

[0092] The conditions for anaerobic treatment were: anaerobic temperature was 35°C, hydraulic retention time HRT was 48h;

[0093] The conditions for aerobic treatment were: aerobic temperature of 30 °C and empty bed residence time EBRT of 8 h;

[0094] The CODcr concentration of the effluent obtained after treatment is 57.7 mg / L and the chromaticity is 5 times.

[0095] Example 2

[0096] (S1) adjusting the pH value of the wastewater to be treated (200 mL) to 3 with sulfuric acid, and then contacting the adjusted wastewater with a catalyst and an oxidant I to perform a Fenton catalytic oxidation reaction to obtain wastewater I; wherein:

[0097] The catalyst is ferrous sulfate heptahydrate;

[0098] The amount of catalyst used is 3500 mg relative to 1L of wastewater to be treated;

[0099] The oxidant I is hydrogen peroxide, which is provided in the form of 30% by mass hydrogen peroxide;

[0100] Relative to 1L of wastewater to be treated, the amount of hydrogen peroxide used is 11.7mL (i.e., the amount of hydrogen peroxide used is 17.1g);

[0101] The reaction time of Fenton catalytic oxidation reaction is 120min;

[0102] (S2) contacting the above wastewater I with an oxidant II, a precipitant, 1,6-diaminohexane and a coagulant aid to perform an oxidation precipitation reaction; wherein:

[0103] The oxidant II is sodium hypochlorite; the precipitants are calcium chloride and magnesium chloride; the coagulant aid is anionic polyacrylamide; the weight average molecular weight of the anionic polyacrylamide is 6 million g / mol;

[0104] Relative to 1L of wastewater to be treated, the dosage of sodium hypochlorite is 2000mg;

[0105] Relative to 1L of wastewater to be treated, the amount of calcium chloride used is 1000mg, and the amount of magnesium chloride used is 1500mg;

[0106] Relative to 1L of wastewater to be treated, the amount of 1,6-diaminohexane used is 50mg;

[0107] Relative to 1L of wastewater to be treated, the dosage of anionic polyacrylamide is 50mg;

[0108] The pH value of the reaction system was adjusted to 2.5 with sulfuric acid, and the reaction time of the oxidation precipitation reaction was 60 min;

[0109] (S3) subjecting the product obtained by the oxidation precipitation reaction to solid-liquid separation to obtain wastewater II; wherein:

[0110] The method of solid-liquid separation is centrifugal separation;

[0111] The conditions for centrifugal separation are: centrifugal speed is 7000r / min; centrifugal time is 30min;

[0112] The test showed that the CODcr concentration of wastewater II was 8680 mg / L and the chromaticity was 20 times;

[0113] (S4) adjusting the pH value of the wastewater II to 7 with sodium hydroxide, and then subjecting the adjusted wastewater (whose B / C is 0.38) to anaerobic treatment and aerobic treatment in sequence; wherein:

[0114] The conditions for anaerobic treatment were: anaerobic temperature was 35°C, hydraulic retention time HRT was 48h;

[0115] The conditions for aerobic treatment were: aerobic temperature of 30 °C and empty bed residence time EBRT of 8 h;

[0116] The CODcr concentration of the effluent obtained after treatment was 54.7 mg / L and the chromaticity was 5 times.

[0117] Example 3

[0118] (S1) adjusting the pH value of the wastewater to be treated (200 mL) to 2.5 with sulfuric acid, and then contacting the adjusted wastewater with a catalyst and an oxidant I to perform a Fenton catalytic oxidation reaction to obtain wastewater I; wherein:

[0119] The catalyst is ferrous sulfate heptahydrate;

[0120] The amount of catalyst used is 5000 mg relative to 1L of wastewater to be treated;

[0121] The oxidant I is hydrogen peroxide, which is provided in the form of 30% by mass hydrogen peroxide;

[0122] Relative to 1L of wastewater to be treated, the amount of hydrogen peroxide used is 13.3mL (i.e., the amount of hydrogen peroxide used is 19.5g);

[0123] The reaction time of Fenton catalytic oxidation reaction is 120min;

[0124] (S2) contacting the above wastewater I with an oxidant II, a precipitant, 1,6-diaminohexane and a coagulant aid to perform an oxidation precipitation reaction; wherein:

[0125] The oxidant II is sodium hypochlorite; the precipitant is magnesium chloride; the coagulant aid is anionic polyacrylamide;

[0126] The weight average molecular weight of anionic polyacrylamide is 8 million g / mol;

[0127] Relative to 1L of wastewater to be treated, the dosage of sodium hypochlorite is 2000mg; the dosage of magnesium chloride is 2000mg;

[0128] Relative to 1L of wastewater to be treated, the amount of 1,6-diaminohexane used is 60mg;

[0129] Relative to 1L of wastewater to be treated, the dosage of anionic polyacrylamide is 60mg;

[0130] The pH value of the reaction system was adjusted to 3 with sulfuric acid, and the reaction time of the oxidation precipitation reaction was 60 min;

[0131] (S3) subjecting the product obtained by the oxidation precipitation reaction to solid-liquid separation to obtain wastewater II; wherein:

[0132] The method of solid-liquid separation is centrifugal separation;

[0133] The conditions for centrifugal separation are: centrifugal speed is 8000r / min; centrifugal time is 30min;

[0134] The test showed that the CODcr concentration of wastewater II was 8600 mg / L and the chromaticity was 20 times;

[0135] (S4) adjusting the pH value of the wastewater II to 7 with sodium hydroxide, and then subjecting the adjusted wastewater (whose B / C is 0.39) to anaerobic treatment and aerobic treatment in sequence; wherein:

[0136] The conditions for anaerobic treatment were: anaerobic temperature was 35°C, hydraulic retention time HRT was 48h;

[0137] The conditions for aerobic treatment were: aerobic temperature of 30 °C and empty bed residence time EBRT of 8 h;

[0138] The CODcr concentration of the effluent obtained after treatment is 54.4 mg / L and the chromaticity is 5 times.

[0139] Comparative Example 1

[0140] The method of Example 1 is different from that of Example 1:

[0141] In step (S2), the pH value of the reaction system is adjusted to 11 with sodium hydroxide, and the rest are the same;

[0142] The same as step (S3), the test shows that the CODcr concentration of wastewater II is 99700 mg / L, the chromaticity is 2500 times; B / C is 0.03, and biochemical treatment is impossible.

[0143] By comparing Example 1 and Comparative Example 1, it can be seen that when the pH value of the reaction system of step (S2) is alkaline, although the wastewater I can undergo an oxidative precipitation reaction with the reaction raw materials in step (S2), the CODcr concentration and chromaticity of the obtained wastewater II are not significantly reduced, and the B / C of the wastewater II is too low to be biochemically treated.

[0144] Comparative Example 2

[0145] The method of Example 1 is different from that of Example 1:

[0146] In step (S2), the pH value of the reaction system is adjusted to 7 with sodium hydroxide, and the rest are the same;

[0147] The same as step (S3), no precipitation is produced after centrifugation;

[0148] The test shows that the CODcr concentration of the treated wastewater is 100,000 mg / L, the chromaticity is 5,000 times; the B / C is 0.02, and biochemical treatment is impossible.

[0149] By comparing Example 1 and Comparative Example 2, it can be seen that when the pH value of the reaction system in step (S2) is neutral, the wastewater I and the reaction raw materials in step (S2) cannot undergo an oxidative precipitation reaction, the organic matter in the wastewater I cannot be precipitated, and its CODcr concentration cannot be further reduced, so that the CODcr concentration of the treated wastewater is still too high, and its B / C is too low, and biochemical treatment cannot be carried out.

[0150] Comparative Example 3

[0151] The method of Example 1 is different from that of Example 1:

[0152] In step (S2), the oxidant II is not used, and the wastewater I is directly contacted with the precipitant, 1,6-diaminohexane and the coagulant aid, and the rest are the same;

[0153] The same as step (S3), no precipitation is produced after centrifugation;

[0154] The test shows that the CODcr concentration of the treated wastewater is 111000 mg / L, the chromaticity is 5000 times; the B / C is 0.02, and biochemical treatment is impossible.

[0155] By comparing Example 1 and Comparative Example 3, it can be seen that when the reaction raw materials in step (S2) lack oxidant II, the wastewater I and the reaction raw materials in step (S2) cannot undergo an oxidation precipitation reaction, and the organic matter in the wastewater I cannot be further removed, and its CODcr concentration cannot be further reduced, so that the CODcr concentration and chromaticity of the treated wastewater are still too high, and its B / C is too low, and biochemical treatment cannot be carried out.

[0156] Comparative Example 4

[0157] The method of Example 1 is different from that of Example 1:

[0158] In step (S2), no precipitant is used, and wastewater I is directly contacted with oxidant II, 1,6-diaminohexane and coagulant aid, and the rest are the same;

[0159] The same as step (S3), no precipitation is produced after centrifugation;

[0160] The test shows that the CODcr concentration of the treated wastewater is 108800 mg / L, the chromaticity is 5000 times; the B / C is 0.02, and biochemical treatment is impossible.

[0161] By comparing Example 1 and Comparative Example 4, it can be seen that when the reaction raw materials in step (S2) lack a precipitant, the wastewater I and the reaction raw materials in step (S2) cannot undergo an oxidative precipitation reaction, the organic matter in the wastewater I cannot be precipitated, and its CODcr concentration cannot be further reduced, so that the CODcr concentration and chromaticity of the treated wastewater are still too high, and its B / C is too low, and biochemical treatment cannot be carried out.

[0162] Comparative Example 5

[0163] The method of Example 1 is different from that of Example 1:

[0164] In step (S2), no coagulant is used, and wastewater I is directly contacted with oxidant II, precipitant and 1,6-diaminohexane, and the rest are the same;

[0165] The step (S3) is the same;

[0166] The test shows that the CODcr concentration of wastewater II is 58200 mg / L, the chromaticity is 1000 times; the B / C is 0.08, and biochemical treatment is impossible.

[0167] By comparing Example 1 and Comparative Example 5, it can be seen that when the reaction raw materials in step (S2) lack a coagulant aid, although the wastewater I can undergo an oxidation precipitation reaction with the reaction raw materials in step (S2), the CODcr concentration and chromaticity of the obtained wastewater II are not significantly reduced, and the B / C of the wastewater II is too low to be biochemically treated.

[0168] Comparative Example 6

[0169] The method of Example 1 is different from that of Example 1:

[0170] In step (S2), instead of using a precipitant or 1,6-diaminohexane, 2000 mg / L of PAC and 1000 mg / L of aluminum chloride were used, and the rest were the same;

[0171] The step (S3) is the same;

[0172] The test shows that the CODcr concentration of wastewater II is 110,000 mg / L, the chromaticity is 5,000 times; the B / C is 0.02, and biochemical treatment is impossible.

[0173] Comparative Example 7

[0174] The method of Example 1 is different from that of Example 1:

[0175] In step (S2), instead of using a precipitant or 1,6-diaminohexane, 2000 mg / L PFS and 1000 mg / L ferric chloride were used, and the rest were the same;

[0176] The step (S3) is the same;

[0177] The test shows that the CODcr concentration of wastewater II is 109000mg / L, the chromaticity is 5000 times; the B / C is 0.02, and biochemical treatment is impossible.

[0178] Comparative Example 8

[0179] The method of Example 1 is different from that of Example 1:

[0180] In step (S1), relative to 1L of wastewater to be treated, the amount of hydrogen peroxide used is 20mL (i.e., the amount of hydrogen peroxide used is 29.3g); the rest are the same;

[0181] The step (S2) is the same;

[0182] The same as step (S3), no precipitation is produced after centrifugation;

[0183] The test showed that the CODcr concentration of wastewater II was 97200 mg / L and the chromaticity was 5000 times;

[0184] In step (S4), the pH value of the wastewater II is adjusted to 7 with sodium hydroxide. The B / C of the wastewater after adjustment is 0.02, and biochemical treatment is not possible.

[0185] By comparing Example 1 and Comparative Example 8, it can be seen that when an excessive amount of oxidant is used, the organic matter in the wastewater cannot be removed by the subsequently added oxidant II, precipitant, 1,6-diaminohexane and coagulant, which results in the B / C of the wastewater being too low and unable to be biochemically treated.

[0186] It can be seen from the above results that the treatment method provided by the present invention can not only effectively improve the COD removal rate of wastewater, but also, under preferred circumstances, can reduce the chromaticity of wastewater, and the biodegradability of the treated wastewater is also good. Through sequential anaerobic treatment and aerobic treatment, the CODcr concentration and chromaticity of the effluent can be further reduced.

[0187] The preferred embodiments of the present invention are described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.

Claims

1. A method for treating wastewater from the production of polymethacrylate, characterized in that: The processing method comprises the following steps: (1) contacting the wastewater to be treated with a catalyst and an oxidant I to perform a Fenton catalytic oxidation reaction to obtain wastewater I; Wherein, relative to 1L of the wastewater to be treated, the dosage of the oxidant I is 15-25g; (2) Under acidic conditions, the wastewater I is contacted with an oxidant II, a precipitant, 1,6-diaminohexane and a coagulant aid to carry out an oxidation precipitation reaction.

2. The processing method according to claim 1, wherein: In step (1), the CODcr concentration of the wastewater to be treated is greater than 15000 mg / L; the chromaticity is greater than or equal to 4000 times; the B / C is 0.015-0.025; the pH value is 12-13.5; and the conductivity is 40-50 mS / cm.

3. The processing method according to claim 1 or 2, wherein: In step (1), the catalyst is ferrous sulfate; Preferably, in step (1), the amount of the catalyst used is 3000-5000 mg, preferably 3500-4000 mg, relative to 1 L of the wastewater to be treated; Preferably, in step (1), the oxidant I is hydrogen peroxide; relative to 1L of the wastewater to be treated, the amount of the oxidant I is 15-20g; Preferably, the hydrogen peroxide is provided in the form of hydrogen peroxide with a mass fraction of 28%-30%; Preferably, relative to 1L of the wastewater to be treated, the amount of the hydrogen peroxide used is 10-17mL, preferably 11.7-13.3mL.

4. The processing method according to any one of claims 1 to 3, wherein: In step (1), the reaction time of the Fenton catalytic oxidation reaction is 60-240 min, preferably 90-150 min; Preferably, before carrying out the Fenton catalytic oxidation reaction, step (1) further comprises: adjusting the pH value of the wastewater to be treated to 2-4, preferably 2.5-3.

5.

5. The processing method according to any one of claims 1 to 4, wherein: In step (2), the oxidant II is calcium hypochlorite and / or sodium hypochlorite; Preferably, the precipitant is at least one of calcium chloride, magnesium chloride and barium chloride; Preferably, the coagulant aid is anionic polyacrylamide; More preferably, the weight average molecular weight of the anionic polyacrylamide is 4 million to 10 million g / mol, preferably 4 million to 8 million g / mol.

6. The processing method according to any one of claims 1 to 5, wherein: In step (2), the amount of the oxidant II is 2000-4000 mg, preferably 2000-3500 mg, relative to 1 L of the wastewater to be treated; Preferably, relative to 1L of the wastewater to be treated, the amount of the precipitant is 1000-3500 mg, preferably 1000-3000 mg; Preferably, relative to 1L of the wastewater to be treated, the amount of 1,6-diaminohexane used is 30-100 mg, preferably 40-60 mg; Preferably, relative to 1L of the wastewater to be treated, the amount of the coagulant aid is 40-80 mg, preferably 50-70 mg.

7. The processing method according to any one of claims 1 to 6, wherein: In step (2), the pH value of the oxidation precipitation reaction is 2-6, preferably 2-3, more preferably 2.5-3; Preferably, the reaction time of the oxidation precipitation reaction is 30-120 min, preferably 45-90 min.

8. The processing method according to any one of claims 1 to 7, wherein: Step (2) further comprises: performing solid-liquid separation on the product obtained by the oxidation precipitation reaction to obtain wastewater II; Preferably, the solid-liquid separation method is centrifugal separation; the conditions of the centrifugal separation include: a centrifugal speed of 5000-8000 r / min, preferably 6000-7000 r / min; a centrifugal time of 10-30 min, preferably 15-25 min.

9. The processing method according to claim 8, wherein: Step (2) also includes: adjusting the pH value of the wastewater II to 6.5-7.

5.

10. The processing method according to claim 8 or 9, wherein: The treatment method further comprises: sequentially subjecting the wastewater II to anaerobic treatment and aerobic treatment; Preferably, the conditions of the anaerobic treatment include: anaerobic temperature of 30-40°C, hydraulic retention time of 36-60h; Preferably, the conditions of the aerobic treatment include: an aerobic temperature of 25-35° C. and an empty bed residence time of 6-12 h.

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