High-efficiency decolorizing industrial wastewater pretreatment coagulation device

Abstract

The invention relates to the field of wastewater treatment devices, in particular to an efficient decoloration industrial wastewater pretreatment coagulation device which comprises a primary coagulation area, a primary settling area, a deoxidizing area, a secondary coagulation area and a secondary settling area which are connected in sequence, wherein the primary coagulation zone is provided with a first coagulant adding device and a first pH regulator adding device; the deoxidizing area is provided with a deoxidant adding device; the second-stage coagulation zone is provided with a second coagulant adding device and a second pH regulator adding device, the first-stage coagulation zone mainly aims at suspended solids and part of dissolved organic matters, and charge neutralization and bridging effects are realized by utilizing a polynuclear complex formed by hydrolyzing Fe < 3 + > ions. And the second-stage coagulation focuses on solving the problems of refractory organic matters and chromaticity, and deep treatment is realized through formation of green rust. The strategy of step-by-step treatment not only improves the overall treatment efficiency, but also optimizes the reaction conditions of each stage by regulating and controlling the pH value.

Description

Technical Field

[0001] The invention relates to the field of wastewater treatment devices, and in particular to an industrial wastewater pretreatment coagulation device with high efficiency decolorization. Background Art

[0002] Industrial wastewater treatment has always been one of the major challenges in the field of environmental protection. Industrial wastewater usually has high chroma, high organic content and complex pollutant composition. These characteristics make it difficult for traditional treatment methods to meet increasingly stringent emission standards. In the prior art, coagulation, as a commonly used pretreatment method, has the advantages of simple operation and low cost, but it still has many limitations in treating complex industrial wastewater.

[0003] First, the traditional single coagulation treatment is not effective in removing difficult-to-degrade organic matter and certain special dyes. This is mainly because the action mechanism of conventional coagulants such as aluminum salts or iron salts mainly relies on charge neutralization and adsorption, and it is difficult to achieve effective degradation of some structurally stable organic pollutants. Secondly, coagulation treatment under single pH conditions is difficult to simultaneously take into account the needs of suspended matter removal and soluble organic matter degradation, which limits the treatment efficiency. Furthermore, coagulation treatment in the prior art often ignores the importance of improving the biodegradability of wastewater, which is not conducive to the subsequent biological treatment process.

[0004] In addition, when treating high-chroma wastewater, traditional coagulation often requires the addition of a large amount of coagulant to achieve the desired decolorization effect, which not only increases the treatment cost, but also may bring the risk of secondary pollution. At the same time, the coagulation treatment in the existing technology also has certain difficulties in forming stable and easy-to-sediment flocs, which affects the efficiency of solid-liquid separation and the stability of effluent water quality.

[0005] In view of the above problems, it is urgent to develop a new pretreatment coagulation device that can effectively decolorize and improve the organic matter removal rate and wastewater biodegradability. The ideal solution should be able to comprehensively consider the removal needs of different types of pollutants and achieve the coordinated optimization of multiple treatment objectives. Summary of the invention

[0006] The present invention is an innovative solution to the deficiencies of the prior art. Through a cleverly designed two-stage coagulation treatment, a precisely controlled pH environment, an innovative deoxygenation step, and a green rust formation mechanism, the present invention achieves efficient decolorization and deep treatment of industrial wastewater.

[0007] To achieve the above object, the present invention provides the following technical solution: an industrial wastewater pretreatment coagulation device with high efficiency decolorization, characterized in that the device comprises a primary coagulation zone, a primary sedimentation zone, a deoxygenation zone, a secondary coagulation zone and a secondary sedimentation zone connected in sequence;

[0008] Wherein, the primary coagulation zone is provided with a first coagulant dosing device and a first pH regulator dosing device;

[0009] The deoxidation zone is provided with a deoxidizer dosing device;

[0010] The secondary coagulation zone is provided with a second coagulant dosing device and a second pH regulator dosing device.

[0011] Preferably, the first coagulant is ferric chloride, and the addition amount thereof is 200-400 mg / L;

[0012] The first pH regulator is sodium hydroxide, and the addition amount thereof is 100-200 mg / L;

[0013] The deoxidizer is carbon dioxide or sodium pyrosulfite, the addition amount of sodium pyrosulfite is 200-300 mg / L; the addition amount of carbon dioxide is 10-100 mL / L;

[0014] The second coagulant is ferrous chloride, and the addition amount is 300-500 mg / L;

[0015] The second pH regulator is sodium hydroxide, and the addition amount thereof is 50-150 mg / L.

[0016] Preferably, both the primary coagulation zone and the secondary coagulation zone are provided with stirring devices.

[0017] Preferably, the invention also includes a coagulant aid dosing device arranged in the primary coagulation zone and the secondary coagulation zone.

[0018] Preferably, the coagulant aid is polyacrylamide, and the addition amount thereof is 0.5-2 mg / L.

[0019] A method for treating industrial wastewater using the pretreatment coagulation device comprises the following steps:

[0020] (1) introducing the wastewater to be treated into the primary coagulation zone, adding ferric chloride solution and sodium hydroxide solution, and performing the first coagulation treatment;

[0021] (2) introducing the wastewater treated in step (1) into a primary sedimentation area for sedimentation;

[0022] (3) introducing the supernatant of step (2) into a deoxygenation zone and adding a sodium pyrosulfite solution for deoxygenation treatment;

[0023] (4) introducing the wastewater treated in step (3) into a secondary coagulation zone, adding ferrous chloride solution and sodium hydroxide solution, and performing a second coagulation treatment, and controlling the pH value to be 9.0-9.5;

[0024] (5) introducing the wastewater treated in step (4) into a secondary sedimentation area for sedimentation to obtain treated effluent.

[0025] 7. The method for treating industrial wastewater according to claim 6, characterized in that in step (1) and step (4), it also includes adding a polyacrylamide solution as a coagulant aid.

[0026] Preferably, the method further comprises the following steps:

[0027] Before step (1), ferric chloride is dissolved in deionized water to prepare a 10-30 wt % solution, with a stirring speed of 300-500 rpm, a temperature of 20-25° C., and a stirring time of 5-10 minutes;

[0028] Before step (4), under nitrogen protection, ferrous chloride is dissolved in deoxygenated water to prepare a 20-40 wt% solution, with a stirring speed of 200-400 rpm, a temperature of 15-20° C., and a stirring time of 5-10 minutes.

[0029] Preferably, the method further comprises the following steps:

[0030] Before step (1), sodium hydroxide is dissolved in deionized water to prepare a 30-50 wt% solution, with a stirring speed of 200-300 rpm, a temperature of 25-30° C., and a stirring time of 5-10 minutes.

[0031] Preferably, the method further comprises the following steps:

[0032] Before step (3), sodium metabisulfite is dissolved in deionized water to prepare a 5-10 wt% solution, with a stirring speed of 200-300 rpm, a temperature of 15-20° C., and a stirring time of 15-30 minutes.

[0033] From the perspective of chemical mechanism, the core innovation of the present invention is to utilize the green rust formed under high pH and anaerobic conditions [Fe Ⅱ 3Fe Ⅲ (OH)7Cl】. As a compound with mixed valence and mainly ferrous iron, green rust has a unique layered structure and strong reducing properties. The special arrangement of its d-orbital electrons enables it to undergo electron transfer reactions with a variety of organic pollutants, promoting the reduction and degradation of macromolecular organic matter. At the same time, the layered structure of green rust provides a large number of active adsorption sites, achieving efficient adsorption of various pollutants through van der Waals forces and electrostatic effects.

[0034] In addition, the two-stage coagulation design of the present invention fully considers the characteristics of different pollutants. The first stage coagulation is mainly for suspended solids and some dissolved organic matter, using Fe 3+The multi-nuclear complex formed by ion hydrolysis achieves charge neutralization and bridging. The second stage of coagulation focuses on solving the problem of difficult-to-degrade organic matter and color, and achieves deep treatment through the formation of green rust. This step-by-step treatment strategy not only improves the overall treatment efficiency, but also optimizes the reaction conditions of each stage by adjusting the pH value.

[0035] Another innovative point of the present invention is the introduction of a deoxygenation step. By removing dissolved oxygen, not only favorable conditions are created for the formation of green rust, but also interference from certain oxidative pollutants is suppressed, further improving the treatment effect. At the same time, the reducing agent used in the deoxygenation process may have a pretreatment effect on certain organic pollutants, preparing for the subsequent degradation process.

[0036] In summary, the present invention achieves the following significant beneficial effects through the synergistic effect of multiple innovative mechanisms:

[0037] 1. Ultra-high chroma and COD removal rate effectively solves the problem of high chroma and high organic matter content in industrial wastewater.

[0038] 2. Significantly improve the biodegradability of wastewater, create favorable conditions for subsequent biological treatment, and reduce the overall treatment cost.

[0039] 3. Form stable and easy-to-sediment flocs, improve the solid-liquid separation efficiency and ensure the stability of effluent water quality.

[0040] 4. Through the formation of green rust, efficient removal of difficult-to-degrade organic matter is achieved, expanding the application scope of the coagulation method.

[0041] 5. The two-stage coagulation design enables the device to have the potential to treat a variety of complex industrial wastewaters, enhancing the applicability and promotion value of the technology.

[0042] These innovative solutions and remarkable technical effects make the present invention have important practical value and broad application prospects in the field of industrial wastewater pretreatment. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 This is a schematic diagram of a highly efficient decolorization industrial wastewater pretreatment coagulation device. DETAILED DESCRIPTION

[0044] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention. Therefore, the following detailed description of the embodiments of the present invention provided in the drawings is not intended to limit the scope of the invention claimed for protection, but merely represents the selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0045] Example 1: An efficient decolorization industrial wastewater pretreatment coagulation device

[0046] This embodiment provides a highly efficient decolorized industrial wastewater pretreatment coagulation device, which includes a primary coagulation zone, a primary sedimentation zone, a deoxygenation zone, a secondary coagulation zone, and a secondary sedimentation zone connected in sequence. The primary coagulation zone is provided with a first coagulant dosing device and a first pH regulator dosing device; the deoxygenation zone is provided with a deoxygenator dosing device; and the secondary coagulation zone is provided with a second coagulant dosing device and a second pH regulator dosing device.

[0047] The industrial wastewater treatment method of this embodiment comprises the following steps:

[0048] (1) First, the wastewater to be treated is introduced into the primary coagulation zone. In this zone, 200 mg / L ferric chloride solution is added as the first coagulant, and 100 mg / L sodium hydroxide solution is added as the first pH regulator to carry out the first coagulation treatment. Ferric chloride hydrolyzes in water to form a positively charged multinuclear complex, which can effectively neutralize the negative charge of suspended particles and promote coagulation.

[0049] (2) Secondly, the wastewater treated in step (1) is introduced into a primary sedimentation zone for sedimentation. During this process, flocs are gradually formed and settled, and most of the suspended matter is removed.

[0050] (3) Then, the supernatant of step (2) is introduced into the deoxygenation zone, and 200 mg / L sodium pyrosulfite solution is added for deoxygenation treatment. Sodium pyrosulfite can not only effectively remove dissolved oxygen, but also reduce some organic pollutants, creating favorable conditions for subsequent treatment. The deoxygenator can also be carbon dioxide; the amount of carbon dioxide added is 10-100 mL / L;

[0051] (4) Then, the wastewater treated in step (3) is introduced into the secondary coagulation zone. In this zone, 300 mg / L of ferrous chloride solution is added as the second coagulant, and 50 mg / L of sodium hydroxide solution is added as the second pH regulator, and the second coagulation treatment is carried out, and the pH value is controlled to be 9.0. Under this high pH and anaerobic condition, ferrous chloride will form green rust (Fe(OH)2), which has strong reducing properties and high adsorption properties, and can effectively degrade and adsorb organic pollutants in water, especially some difficult-to-degrade dye molecules.

[0052] (5) Finally, the wastewater treated in step (4) is introduced into a secondary sedimentation area for sedimentation to obtain treated effluent.

[0053] In step (1) and step (4), 0.5 mg / L polyacrylamide solution is added as a coagulant to enhance the strength of the flocs and improve the sedimentation efficiency.

[0054] Preferably, in an embodiment of the present invention, the preparation method of each solution is as follows:

[0055] a) before step (1), ferric chloride was dissolved in deionized water to prepare a 10 wt% solution, with a stirring speed of 300 rpm, a temperature of 20° C., and a stirring time of 5 minutes;

[0056] b) before step (4), under nitrogen protection, ferrous chloride was dissolved in deoxygenated water to prepare a 20 wt% solution, with a stirring speed of 200 rpm, a temperature of 15° C., and a stirring time of 5 minutes;

[0057] c) Before step (1), sodium hydroxide was dissolved in deionized water to prepare a 30 wt % solution, with a stirring speed of 200 rpm, a temperature of 25° C., and a stirring time of 5 minutes.

[0058] Example 2: An efficient decolorization industrial wastewater pretreatment coagulation device

[0059] The industrial wastewater pretreatment coagulation device provided in this embodiment has the same structure as that of embodiment 1, but differs in the treatment method and the addition amount of each component. The specific treatment method includes the following steps:

[0060] (1) First, the wastewater to be treated is introduced into the primary coagulation zone, and 300 mg / L ferric chloride solution and 150 mg / L sodium hydroxide solution are added to carry out the first coagulation treatment.

[0061] (2) Secondly, the wastewater treated in step (1) is introduced into a primary sedimentation area for sedimentation.

[0062] (3) Then, the supernatant of step (2) is introduced into the deoxygenation zone and 250 mg / L sodium pyrosulfite solution is added for deoxygenation treatment.

[0063] (4) Then, the wastewater treated in step (3) was introduced into the secondary coagulation zone, 400 mg / L of ferrous chloride solution and 100 mg / L of sodium hydroxide solution were added, and a second coagulation treatment was performed, and the pH value was controlled to be 9.25.

[0064] (5) Finally, the wastewater treated in step (4) is introduced into a secondary sedimentation area for sedimentation to obtain treated effluent.

[0065] In step (1) and step (4), 1.25 mg / L polyacrylamide solution is also added as a coagulant.

[0066] The preparation method of each solution is as follows:

[0067] a) ferric chloride solution: 20wt%, stirring speed 400rpm, temperature 22.5°C, stirring time 7.5 minutes; b) ferrous chloride solution: 30wt%, stirring speed 300rpm, temperature 17.5°C, stirring time 7.5 minutes; c) sodium hydroxide solution: 40wt%, stirring speed 250rpm, temperature 27.5°C, stirring time 7.5 minutes.

[0068] Example 3: An efficient decolorization industrial wastewater pretreatment coagulation device

[0069] The structure of the industrial wastewater pretreatment coagulation device in this embodiment is the same as that in embodiment 1, and the treatment method comprises the following steps:

[0070] (1) First, the wastewater to be treated is introduced into the primary coagulation zone, and 400 mg / L ferric chloride solution and 200 mg / L sodium hydroxide solution are added to carry out the first coagulation treatment.

[0071] (2) Secondly, the wastewater treated in step (1) is introduced into a primary sedimentation area for sedimentation.

[0072] (3) Then, the supernatant of step (2) was introduced into the deoxygenation zone and 300 mg / L sodium pyrosulfite solution was added for deoxygenation treatment.

[0073] (4) Then, the wastewater treated in step (3) was introduced into the secondary coagulation zone, 500 mg / L of ferrous chloride solution and 150 mg / L of sodium hydroxide solution were added, and a second coagulation treatment was performed, and the pH value was controlled to 9.5.

[0074] (5) Finally, the wastewater treated in step (4) is introduced into a secondary sedimentation area for sedimentation to obtain treated effluent.

[0075] In step (1) and step (4), 2 mg / L polyacrylamide solution is also added as a coagulant.

[0076] The preparation method of each solution is as follows:

[0077] a) ferric chloride solution: 30wt%, stirring speed 500rpm, temperature 25°C, stirring time 10 minutes; b) ferrous chloride solution: 40wt%, stirring speed 400rpm, temperature 20°C, stirring time 10 minutes; c) sodium hydroxide solution: 50wt%, stirring speed 300rpm, temperature 30°C, stirring time 10 minutes.

[0078] Example 4: An efficient decolorization industrial wastewater pretreatment coagulation device

[0079] The structure of the industrial wastewater pretreatment coagulation device in this embodiment is the same as that in embodiment 1, and the treatment method comprises the following steps:

[0080] (1) First, the wastewater to be treated is introduced into the primary coagulation zone, and 250 mg / L of ferric chloride solution and 125 mg / L of sodium hydroxide solution are added to carry out the first coagulation treatment.

[0081] (2) Secondly, the wastewater treated in step (1) is introduced into a primary sedimentation area for sedimentation.

[0082] (3) Then, the supernatant of step (2) was introduced into the deoxygenation zone and 225 mg / L sodium pyrosulfite solution was added for deoxygenation treatment.

[0083] (4) Then, the wastewater treated in step (3) was introduced into the secondary coagulation zone, 350 mg / L of ferrous chloride solution and 75 mg / L of sodium hydroxide solution were added, and a second coagulation treatment was performed, and the pH value was controlled to be 9.125.

[0084] (5) Finally, the wastewater treated in step (4) is introduced into a secondary sedimentation area for sedimentation to obtain treated effluent.

[0085] In step (1) and step (4), 0.875 mg / L polyacrylamide solution is also added as a coagulant.

[0086] The preparation method of each solution is as follows:

[0087] a) ferric chloride solution: 15wt%, stirring speed 350rpm, temperature 21.25°C, stirring time 6.25 minutes; b) ferrous chloride solution: 25wt%, stirring speed 250rpm, temperature 16.25°C, stirring time 6.25 minutes; c) sodium hydroxide solution: 35wt%, stirring speed 225rpm, temperature 26.25°C, stirring time 6.25 minutes.

[0088] Comparative Example 1: Single coagulation treatment

[0089] This comparative example adopts the traditional single coagulation treatment method, which is compared with Example 1. The specific steps are as follows:

[0090] (1) First, the wastewater to be treated is introduced into the coagulation zone, 200 mg / L of ferric chloride solution is added as a coagulant, and 100 mg / L of sodium hydroxide solution is added to adjust the pH value to 7.0.

[0091] (2) Secondly, the coagulated wastewater is introduced into the sedimentation area for sedimentation.

[0092] (3) Finally, collect the supernatant as the treated effluent.

[0093] In this comparative example, the preparation method of the ferric chloride solution is as follows: ferric chloride is dissolved in deionized water to prepare a 10 wt % solution, the stirring speed is 300 rpm, the temperature is 20° C., and the stirring time is 5 minutes.

[0094] Comparative Example 2: Two-stage coagulation treatment without deoxygenation step

[0095] This comparative example omits the deoxygenation step and is compared with Example 2. The specific steps are as follows:

[0096] (1) First, the wastewater to be treated is introduced into the primary coagulation zone, and 300 mg / L ferric chloride solution and 150 mg / L sodium hydroxide solution are added to carry out the first coagulation treatment.

[0097] (2) Secondly, the wastewater treated in step (1) is introduced into a primary sedimentation area for sedimentation.

[0098] (3) Then, the supernatant was directly introduced into the secondary coagulation zone, and 400 mg / L ferrous chloride solution and 100 mg / L sodium hydroxide solution were added for the second coagulation treatment, and the pH value was controlled at 9.25.

[0099] (4) Finally, the treated wastewater is introduced into the secondary sedimentation area for sedimentation to obtain treated effluent.

[0100] In this comparative example, the preparation method of each solution is the same as that of Example 2.

[0101] Comparative Example 3: Two-stage coagulation treatment at low pH

[0102] This comparative example uses a lower pH value for secondary coagulation treatment, and is compared with Example 3. The specific steps are as follows:

[0103] (1) First, the wastewater to be treated is introduced into the primary coagulation zone, and 400 mg / L ferric chloride solution and 200 mg / L sodium hydroxide solution are added to carry out the first coagulation treatment.

[0104] (2) Secondly, the wastewater treated in step (1) is introduced into a primary sedimentation area for sedimentation.

[0105] (3) Then, the supernatant was introduced into the deoxygenation zone and 300 mg / L sodium metabisulfite solution was added for deoxygenation treatment.

[0106] (4) Next, the treated wastewater was introduced into the secondary coagulation zone, and 500 mg / L ferrous chloride solution was added, but no sodium hydroxide solution was added, and the pH value was controlled to 7.0.

[0107] (5) Finally, the treated wastewater is introduced into the secondary sedimentation area for sedimentation to obtain treated effluent.

[0108] In this comparative example, the preparation method of each solution is the same as that of Example 3.

[0109] Comparative Example 4: Two-stage coagulation treatment without coagulant

[0110] This comparative example does not add polyacrylamide as a coagulant aid, and is compared with Example 4. The specific steps are as follows:

[0111] (1) First, the wastewater to be treated is introduced into the primary coagulation zone, and 250 mg / L of ferric chloride solution and 125 mg / L of sodium hydroxide solution are added to carry out the first coagulation treatment.

[0112] (2) Secondly, the wastewater treated in step (1) is introduced into a primary sedimentation area for sedimentation.

[0113] (3) Then, the supernatant was introduced into the deoxygenation zone and 225 mg / L sodium metabisulfite solution was added for deoxygenation treatment.

[0114] (4) Then, the treated wastewater was introduced into the secondary coagulation zone, and 350 mg / L of ferrous chloride solution and 75 mg / L of sodium hydroxide solution were added for the second coagulation treatment, and the pH value was controlled at 9.125.

[0115] (5) Finally, the treated wastewater is introduced into the secondary sedimentation area for sedimentation to obtain treated effluent.

[0116] In this comparative example, the preparation method of each solution is the same as that of Example 4.

[0117] Comparative Example 5: Two-stage coagulation treatment in reverse order

[0118] This comparative example changes the order of adding coagulants, using ferrous chloride first and then ferric chloride, and is compared with Example 1. The specific steps are as follows:

[0119] (1) First, the wastewater to be treated is introduced into the primary coagulation zone, 300 mg / L of ferrous chloride solution and 50 mg / L of sodium hydroxide solution are added, and the first coagulation treatment is carried out, and the pH value is controlled to be 9.0.

[0120] (2) Secondly, the wastewater treated in step (1) is introduced into a primary sedimentation area for sedimentation.

[0121] (3) Then, the supernatant was introduced into the deoxygenation zone and 200 mg / L sodium metabisulfite solution was added for deoxygenation treatment.

[0122] (4) Next, the treated wastewater is introduced into the secondary coagulation zone, and 200 mg / L ferric chloride solution and 100 mg / L sodium hydroxide solution are added for a second coagulation treatment.

[0123] (5) Finally, the treated wastewater is introduced into the secondary sedimentation area for sedimentation to obtain treated effluent.

[0124] In step (1) and step (4), 0.5 mg / L polyacrylamide solution was added as a coagulant. In this comparative example, the preparation method of each solution was the same as that of Example 1.

[0125] Comparative Example 6: High Concentration Single Coagulant Treatment

[0126] This comparative example uses a single coagulant at a high concentration for treatment, and is compared with Example 2. The specific steps are as follows:

[0127] (1) First, the wastewater to be treated is introduced into the coagulation zone, 500 mg / L of ferric chloride solution is added as a coagulant, and 200 mg / L of sodium hydroxide solution is added to adjust the pH value to 8.0.

[0128] (2) Secondly, the coagulated wastewater is introduced into the sedimentation area for sedimentation.

[0129] (3) Finally, collect the supernatant as the treated effluent.

[0130] In step (1), 1.25 mg / L polyacrylamide solution is added as a coagulant. In this comparative example, the preparation method of the ferric chloride solution is as follows: ferric chloride is dissolved in deionized water to prepare a 30 wt% solution, the stirring speed is 400 rpm, the temperature is 22.5° C., and the stirring time is 7.5 minutes. The preparation methods of other solutions are the same as those in Example 2.

[0131] Through these six comparative examples, the core innovations of the present invention can be fully verified, including the necessity of two-stage coagulation treatment, the importance of the deoxygenation step, the influence of high pH environment on the formation of green rust, the role of coagulant aids, the rationality of the order of coagulant addition and the superiority of step-by-step treatment.

[0132] Next, several test experiments will be designed to evaluate the effectiveness of the scheme.

[0133] Experimental design and methods:

[0134] In order to comprehensively evaluate the performance of the high-efficiency decolorization industrial wastewater pretreatment coagulation device of the present invention, the following experiments were designed:

[0135] 1. Chroma removal rate test

[0136] First, the standard platinum-cobalt colorimetric method was used to determine the chromaticity of the wastewater before and after treatment. The water samples before and after treatment were compared with the standard solution of known chromaticity to determine their chromaticity values. The chromaticity removal rate was calculated as follows:

[0137] Chroma removal rate (%) = (chroma before treatment - chroma after treatment) / chroma before treatment × 100%

[0138] 2.COD removal rate test

[0139] Secondly, the chemical oxygen demand (COD) was determined using the potassium dichromate method. The water sample was mixed with potassium dichromate and silver sulfate catalyst, heated at 150°C for 2 hours, and then titrated with ammonium ferrous sulfate. The COD removal rate was calculated as:

[0140] COD removal rate (%) = (COD before treatment - COD after treatment) / COD before treatment × 100%

[0141] 3. BOD5 / COD ratio determination

[0142] Then, the 5-day biochemical oxygen demand (BOD5) was determined. The water samples were incubated at 20°C for 5 days and the reduction in dissolved oxygen was measured. The BOD5 / COD ratio was calculated and used to evaluate the biodegradability of the wastewater.

[0143] 4. Determination of green rust formation

[0144] Next, the green rust content in the precipitate in the secondary coagulation zone was analyzed by X-ray diffraction (XRD). The dried precipitate was subjected to XRD analysis, and the relative content of green rust was compared by the intensity of characteristic peaks.

[0145] 5. Floc settling performance test

[0146] Finally, the sedimentation column test was used to evaluate the sedimentation performance of the flocs. The treated water sample was poured into a 1000 mL measuring cylinder and the sludge interface height was recorded after 30 minutes. The sedimentation rate was calculated as:

[0147] Sedimentation rate (%) = (initial height - height after 30 minutes) / initial height × 100%

[0148] Experimental results:

[0149] Table 1. Performance test results of Examples 1-4 and Comparative Examples 1-6

[0150]

[0151]

[0152] According to the experimental results, Example 3 performs best and can be regarded as the best embodiment of the present invention.

[0153] Results and discussion:

[0154] 1. Chroma removal rate: The examples of the present invention all showed excellent decolorization effects, especially Example 3, which achieved a chroma removal rate of 97.8%. This is mainly due to the two-stage coagulation treatment and the formation of green rust under high pH conditions. Green rust has strong reducing and adsorption properties and can effectively degrade and adsorb dye molecules. In contrast, Comparative Examples 1 and Comparative Examples 6 used a single coagulation treatment, and the chroma removal rate was significantly lower.

[0155] 2. COD removal rate: The COD removal rate of Example 3 is as high as 91.2%, far exceeding all comparative examples. This shows that the present invention can not only remove chromaticity, but also effectively degrade organic pollutants. The synergistic effect of the two-stage coagulation treatment, coupled with the formation of green rust, greatly improves the removal efficiency of organic matter.

[0156] 3. BOD5 / COD ratio: The BOD5 / COD ratios of all examples are significantly higher than those of the comparative examples, indicating that the present invention can effectively improve the biodegradability of wastewater. This is an unexpected technical effect, which may be due to the reduction effect of green rust, which converts the difficult-to-degrade macromolecular organic matter into more biodegradable small molecular substances.

[0157] 4. Relative content of green rust: The relative content of green rust in Example 3 is the highest, reaching 0.98. This is directly related to its excellent treatment effect. The green rust content of Comparative Examples 2 and 3 is relatively low, indicating the importance of the deoxygenation step and the high pH environment to the formation of green rust. No green rust was detected in Comparative Examples 1 and 6, verifying the innovation of the present invention.

[0158] 5. Sedimentation rate: The sedimentation rates of the examples are generally higher than those of the comparative examples, especially Example 3, which reaches 97.8%. This is attributed to the two-stage coagulation treatment and the use of coagulants, which form more dense and stable flocs. Comparative Example 4 does not use coagulants, and its sedimentation rate is significantly lower than that of Example 4, which proves the importance of coagulants.

[0159] In summary, the high-efficiency decolorization industrial wastewater pretreatment coagulation device of the present invention exhibits a number of unexpected technical effects:

[0160] 1. Ultra-high chroma and COD removal rate: Through the synergistic effect of two-stage coagulation and green rust formation, nearly complete decolorization and organic matter removal are achieved.

[0161] 2. Significantly improve the biodegradability of wastewater: This creates favorable conditions for subsequent biological treatment and reduces the overall treatment cost.

[0162] 3. Efficient floc sedimentation performance: not only improves water quality, but also significantly reduces the load of subsequent treatment.

[0163] 4. Broad-spectrum treatment capability: Comparing different embodiments, the present invention performs well under various conditions, indicating that it has the potential to treat a variety of complex industrial wastewaters.

[0164] The realization of these technical effects is due to the core innovation of the present invention: two-stage coagulation treatment, deoxygenation step, formation of green rust in high pH environment and use of coagulant. The synergistic effect of these factors creates a unique treatment environment that can simultaneously deal with multiple pollutants such as suspended solids, dissolved organic matter and difficult-to-degrade dyes, showing significant technical advantages and application prospects.

[0165] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device.

Claims

1. An industrial wastewater pretreatment coagulation device with high efficiency decolorization, characterized in that: The device comprises a primary coagulation zone, a primary sedimentation zone, a deoxygenation zone, a secondary coagulation zone and a secondary sedimentation zone connected in sequence; Wherein, the primary coagulation zone is provided with a first coagulant dosing device and a first pH regulator dosing device; The deoxidation zone is provided with a deoxidizer dosing device; The secondary coagulation zone is provided with a second coagulant dosing device and a second pH regulator dosing device.

2. The pretreatment coagulation device according to claim 1, characterized in that: The first coagulant is ferric chloride, and the addition amount thereof is 200-400 mg / L; The first pH regulator is sodium hydroxide, and the addition amount thereof is 100-200 mg / L; The deoxidizer is carbon dioxide or sodium pyrosulfite, the addition amount of sodium pyrosulfite is 200-300 mg / L; the addition amount of carbon dioxide is 10-100 mL / L; The second coagulant is ferrous chloride, and the addition amount thereof is 300-500 mg / L; The second pH regulator is sodium hydroxide, and the addition amount thereof is 50-150 mg / L.

3. The pretreatment coagulation device according to claim 1, characterized in that: The primary coagulation zone and the secondary coagulation zone are both provided with stirring devices.

4. The pretreatment coagulation device according to claim 1, characterized in that: It also includes a coagulant aid dosing device arranged in the primary coagulation zone and the secondary coagulation zone.

5. The pretreatment coagulation device according to claim 4, characterized in that: The coagulant aid is polyacrylamide, and the addition amount thereof is 0.5-2 mg / L.

6. A method for treating industrial wastewater using the pretreatment coagulation device according to any one of claims 1 to 5, characterized in that: The following steps are involved: (1) introducing the wastewater to be treated into the primary coagulation zone, adding ferric chloride solution and sodium hydroxide solution, and performing the first coagulation treatment; (2) introducing the wastewater treated in step (1) into a primary sedimentation area for sedimentation; (3) introducing the supernatant of step (2) into a deoxygenation zone and adding a sodium pyrosulfite solution for deoxygenation treatment; (4) introducing the wastewater treated in step (3) into a secondary coagulation zone, adding ferrous chloride solution and sodium hydroxide solution, and performing a second coagulation treatment, and controlling the pH value to be 9.0-9.5; (5) introducing the wastewater treated in step (4) into a secondary sedimentation area for sedimentation to obtain treated effluent.

7. The industrial wastewater treatment method according to claim 6, characterized in that: In step (1) and step (4), a polyacrylamide solution is also added as a coagulant.

8. The method for treating industrial wastewater according to claim 6, characterized in that: The method further comprises the following steps: Before step (1), ferric chloride is dissolved in deionized water to prepare a 10-30 wt % solution, with a stirring speed of 300-500 rpm, a temperature of 20-25° C., and a stirring time of 5-10 minutes; Before step (4), under nitrogen protection, ferrous chloride is dissolved in deoxygenated water to prepare a 20-40 wt% solution, with a stirring speed of 200-400 rpm, a temperature of 15-20° C., and a stirring time of 5-10 minutes.

9. The method for treating industrial wastewater according to claim 6, characterized in that: The method further comprises the following steps: Before step (1), sodium hydroxide is dissolved in deionized water to prepare a 30-50 wt% solution, with a stirring speed of 200-300 rpm, a temperature of 25-30° C., and a stirring time of 5-10 minutes.

10. The industrial wastewater treatment method according to claim 6, characterized in that: The method further comprises the following steps: Before step (3), sodium metabisulfite is dissolved in deionized water to prepare a 5-10 wt% solution, with a stirring speed of 200-300 rpm, a temperature of 15-20° C., and a stirring time of 15-30 minutes.

Images