Process for purifying printing and dyeing wastewater by centrifugally inducing nano-magnetofluid to chemically net nano-micelles and micron disperse dyes in printing and dyeing wastewater

Abstract

The invention relates to the technical field of printing and dyeing wastewater treatment, and discloses a process for purifying printing and dyeing wastewater by centrifugally inducing nano-magnetofluid to chemically net nano-micelles and micron disperse dyes in the printing and dyeing wastewater, which comprises the following steps: conveying the printing and dyeing wastewater to an adjusting tank, and adjusting the water quality and the water quantity of the printing and dyeing wastewater; introducing the printing and dyeing wastewater adjusted by the adjusting tank into a dosing reaction tank, adjusting the pH value to 7-9, and adding a modified nano magnetic fluid; the modified nano magnetic fluid is prepared from ferroferric oxide magnetic nanoparticles and sodium dodecyl benzoate; introducing the printing and dyeing wastewater into a centrifugal machine, and performing centrifugal treatment at a certain rotating speed; and carrying out physicochemical treatment on the centrifugally treated supernatant liquid of the printing and dyeing wastewater to realize up-to-standard discharge. The COD (Chemical Oxygen Demand) and chroma removal rates of the printing and dyeing wastewater treated by the method disclosed by the invention both reach 85% or above, and an ultrahigh removal rate is realized. Compared with the traditional process, the method has the advantages of lower energy consumption, lower investment, favorable treatment effect, low cost and favorable industrial application prospect.

Description

Technical Field

[0001] The invention relates to the technical field of sewage treatment, and in particular to a process for purifying printing and dyeing wastewater by capturing nano micelles and micron disperse dyes in printing and dyeing wastewater through a centrifugal induced nano magnetic fluid chemical net. Background Art

[0002] Printing and dyeing, also known as dyeing and finishing, is a processing method that mainly involves pre-treatment, dyeing, printing, finishing, washing and other processes. It uses various types of fiber woven fabrics as raw materials, and produces fabrics with a single color or colored patterns through physical and chemical processing processes. According to the processed fabrics, printing and dyeing can be divided into printing and dyeing of pure cotton fabrics, cotton and chemical fiber blended fabrics, pure chemical fiber fabrics, silk fabrics, silk fabrics, linen fabrics, wool fabrics, etc. Among them, printing and dyeing of cotton fabrics and cotton and chemical fiber blended fabrics is the largest printing and dyeing processing category. In terms of product varieties, printing and dyeing products are generally divided into cotton, chemical fiber and their blended printing and dyeing products, wool woven dyeing and finishing products, silk printing and dyeing products, linen spinning printing and dyeing products and knitting printing and dyeing products. Printing and dyeing wastewater mainly includes desizing wastewater, scouring wastewater, mercerizing wastewater, dyeing wastewater, printing wastewater and washing wastewater. These wastewaters have the characteristics of large water volume, high content of organic pollutants, high alkalinity, and large changes in water quality. They are one of the more difficult industrial wastewaters to treat. Wastewater contains dyes, slurries, dispersants and other additives, oils, acids and alkalis, fiber impurities, sand substances, inorganic salts, etc. Some wastewater also contains unreacted dyes, pigments, strong colors, unreacted additives, reaction products and fabric shedding, etc. What's more serious is that some printing and dyeing wastewater may also contain carcinogenic and teratogenic organic compounds, as well as toxic heavy metals, etc. Therefore, it is very important to remove pollutants in printing and dyeing wastewater to meet the discharge standards.

[0003] Faced with the characteristics of large volume, high content of organic pollutants, high alkalinity, large water quality changes, and complex composition of printing and dyeing wastewater, it is necessary to treat the printing and dyeing wastewater to meet the discharge standards through systematic, professional, and efficient treatment processes. As the country's environmental protection requirements continue to increase, the standards for printing and dyeing wastewater in the textile dyeing and finishing industry are becoming increasingly stringent. How to make printing and dyeing wastewater meet the discharge standards under the new requirements has become a major problem that needs to be solved urgently.

[0004] The treatment methods for printing and dyeing wastewater mainly include physical methods, chemical methods, biological methods and combined methods. Physical methods can be divided into adsorption methods, coagulation and sedimentation methods and membrane separation methods. Coagulation treatment is a technology widely used in the treatment of printing and dyeing wastewater. By adding appropriate coagulants, suspended solids, colloids and some soluble pollutants in the wastewater are condensed into large particles or flocs, thereby achieving effective removal of pollutants. The removal rate of coagulation and sedimentation of printing and dyeing wastewater in existing coagulation treatment is generally around 30%, and the decolorization effect is not obvious. The coagulant used must also be improved polyaluminum silicate sulfate (PASS), polyaluminum silicate chloride iron (PSAFC), polyaluminum silicate sulfate iron (PSAFS) and polyaluminum silicate sulfate boron (PSBA). After the wastewater is treated with this coagulant, the color of the wastewater cannot meet the standard after anaerobic and aerobic physical and chemical treatment, and advanced oxidation treatment is required to meet the discharge standard. Although the membrane separation method is highly efficient, it has high operating costs due to the difficulty of membrane pollution and regeneration. The microorganisms are attached to the filter material or certain carriers to form a biofilm. When the wastewater contacts the biofilm, the organic matter is adsorbed and degraded by the microorganisms, thereby purifying the wastewater. Several traditional methods for decolorizing and reducing COD in printing and dyeing wastewater are not effective, or the treatment efficiency is very low. Centrifugal induced nanomagnetic fluid chemical net captures nanomicelles and micron dispersed dyes in printing and dyeing wastewater to purify printing and dyeing wastewater, with high decolorization rate, large COD reduction, and short treatment time. The supernatant pretreated by this method is subjected to physical and chemical treatment, and the drainage color is easy to meet the standard, the physical and chemical treatment co-flow time is greatly shortened, and the investment and operating costs of physical and chemical treatment are greatly reduced. In addition, most of the dyes can also be recovered and reused. This technology that treats wastewater and recycles dyes at low cost is rare. Faced with today's increasingly severe environmental pollution problems, traditional and single treatment methods have been difficult to meet the requirements. We should fully understand the advantages and disadvantages of various methods and their scope of application, and design a low-cost and efficient printing and dyeing wastewater treatment process in combination with economic benefits.

[0005] The existing coagulants used for coagulation treatment of printing and dyeing wastewater mainly interact with each other through electrochemical or chemical coagulation. Generally, when the coagulant is added to the water, it will adsorb on the surface of the dye solid particles and change the surface charge properties of the particles. In this way, the repulsive force between the particles is reduced, while the attractive force is increased, causing the solid particles to interact with each other and eventually forming a large precipitate or scum. However, since a large amount of dispersant is used in the dye dyeing liquid, the repulsive force between the dye particles in the entire system is increased. This force is much greater than the adsorption force of conventional coagulants on dye particles, and thus conventional coagulants can only remove about 30% of the dye and part of the COD (Li Zhe. Preparation and performance study of polyacrylamide-polyaluminum silicate composite flocculant [D]. Tianjin: Tianjin University of Science and Technology, 2016.). Unlike common sewage particles, where there is no dispersant, the dispersant in the dyeing liquid is an interfacial active substance that can improve the stability of the pigment dispersion system. The dispersant added to the liquid medium can be adsorbed on the surface of the pigment crushed into fine particles to form an adsorption layer, generating charge repulsion and steric hindrance effects, preventing the dispersed pigment particles from forming harmful flocculation again, and keeping the dispersion system in a stable suspended state. Dye wastewater contains a high concentration of dispersant, which forms a certain stable spatial network structure under its solubilization, dispersion and stabilization effects, allowing the dye particles to exist stably in the water. It is difficult to destroy this stable structure with general coagulants, and it is not suitable to aggregate fine particle dyes together. Summary of the invention

[0006] Based on this, the present invention provides a process for purifying printing and dyeing wastewater by capturing nano-micelles and micron disperse dyes in printing and dyeing wastewater by centrifugal induced nano-magnetic fluid chemical net, so as to solve the problem that it is difficult to achieve good technical effects by using conventional coagulants in the existing coagulation process for treating printing and dyeing wastewater.

[0007] To achieve the above object, the present invention provides a process for purifying printing and dyeing wastewater by capturing nano-micelles and micron disperse dyes in printing and dyeing wastewater by centrifugal induction nano-magnetic fluid chemical net, which comprises the following steps:

[0008] S1. Transport printing and dyeing wastewater to the regulating tank to adjust its water quality and water volume;

[0009] S2, passing the printing and dyeing wastewater regulated in the regulating tank in step S1 into the dosing reaction tank, adjusting the pH to 7-9, and adding modified nano magnetic fluid to capture and aggregate nano micelles and micron disperse dyes in the wastewater, and preliminarily removing the chroma and COD in the printing and dyeing wastewater;

[0010] The modified nano magnetic fluid is composed of ferroferric oxide magnetic nanoparticles and a modifier, and the modifier is sodium dodecyl benzoate;

[0011] S3, passing the printing and dyeing wastewater treated in step S2 into a centrifuge for centrifugal treatment at a certain speed;

[0012] S4, subjecting the supernatant liquid of the printing and dyeing wastewater treated in step S3 to physical and chemical treatment to achieve discharge standards.

[0013] As a further preferred technical solution of the present invention, in step S2, the concentration of the modified nano-magnetic fluid added to the dosing reaction tank is 10-100 mg / L.

[0014] As a further preferred technical solution of the present invention, in step S2, the concentration of the modifier added to the modified nano-magnetic fluid is 1 / 10,000 to 1 / 1,000 of the mass concentration of ferrosoferric oxide.

[0015] As a further preferred technical solution of the present invention, in step S3, the centrifugal speed of the centrifuge is 600-30000 r / min.

[0016] As a further preferred technical solution of the present invention, the steps of performing physicochemical treatment in step S4 specifically include:

[0017] S4-1, passing the supernatant liquid of the printing and dyeing wastewater treated in step S3 into a regulating water tank, and adjusting the pH to 7.

[0018] S4-2, passing the printing and dyeing wastewater after pH adjustment in step S4-1 into the electron supply type UASB reactor, the anoxic tank, and the aerobic tank in sequence;

[0019] S4-3, the printing and dyeing wastewater treated in the aerobic tank in step S4-2 is passed into the secondary sedimentation tank for mud and water separation, and the sludge is dehydrated and then transported for external treatment.

[0020] As a further preferred technical solution of the present invention, the following steps are also included after step S4-3:

[0021] The supernatant after precipitation in the secondary sedimentation tank in step S4-3 is sequentially passed into the electron supply type anoxic biological filter and the electron supply type aerated biological filter to further degrade the organic matter in the printing and dyeing wastewater; part of the nitrified liquid in the electron supply type aerated biological filter is returned to the electron supply type anoxic biological filter; the printing and dyeing wastewater treated by the electron supply type aerated biological filter is passed into the composite membrane MBR reactor to remove the suspended matter contained in the effluent of the biological filter.

[0022] As a further preferred technical solution of the present invention, before starting the physicochemical treatment in step S4-2, denitrifying bacteria and nutrient solution are added, both in an amount of 0.1-10 kg / t.

[0023] The present invention adopts the above technical solution to achieve the following beneficial effects:

[0024] In the dosing reaction tank, a certain proportion of nano magnetic fluid is added as a net capture agent, so that the nano magnetic fluid and the nano micelles and micron dispersed dyes in the printing and dyeing wastewater are polymerized and grown into large particles by van der Waals force, so as to cooperate with the centrifugal process to efficiently remove the chroma and COD in the printing and dyeing wastewater; the supernatant of the centrifugal treatment is physicochemically treated after adjusting the pH, so that the pollutants are further degraded, and the mud and water are separated in the subsequent secondary sedimentation tank, and the water-containing sludge enters the filter press for dehydration. The COD and chroma removal rates of the printing and dyeing wastewater treated as above are both above 85%, achieving an ultra-high removal rate. Compared with the traditional process, the present invention has lower energy consumption, less investment, good treatment effect, low cost, and good industrial application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0026] Figure 1 The research is about the mechanism of magnetic fluid (ferroferric oxide) modified by sodium dodecylbenzoate and applied to the printing and dyeing wastewater network to capture nano-micelles and micron disperse dyes in wastewater.

[0027] Figure 2 This is a comparison chart of the printing and dyeing wastewater before and after purification in Example 1.

[0028] The purpose, features and advantages of the present invention will be further described with reference to the accompanying drawings in conjunction with the embodiments. DETAILED DESCRIPTION

[0029] The specific implementation of the present invention is described in detail below in conjunction with the accompanying drawings. It should be understood that the specific implementation described here is only used to illustrate and explain the present invention, and is not used to limit the present invention.

[0030] Unless otherwise defined, the technical terms used in the following examples have the same meanings as those generally understood by those skilled in the art to which the present invention belongs. The test reagents used in the following examples, unless otherwise specified, are all conventional biochemical reagents; the experimental methods, unless otherwise specified, are all conventional methods.

[0031] The surface of the magnetic powder is negatively charged (ζ=-10.5mV), which leads to the same type of electrical action between the magnetic fluid particles in water. The magnetic fluid (ferroferric oxide) used in the present invention is evenly dispersed in water and modified by sodium dodecylbenzoate. The positive ions of the dye particles are gathered around the negatively charged magnetic powder particles due to adsorption and electrical neutralization. Then, due to the disappearance of electrostatic repulsion, the dye particles and the magnetic powder particles and themselves grow through van der Waals attraction. Finally, through the bridging effect, the agglomerates are further flocculated into large flocs and precipitated. The magnetic flocculation reaction involving magnetic powder involves electrical neutralization, van der Waals forces, and other aggregation and growth, and is separated from the dispersant and water under the action of magnetic force. The action mechanism is as follows: Figure 1 shown.

[0032] In the following examples and comparative examples, the physicochemical treatment equipment of Nanjing Luanxin Environmental Technology Co., Ltd. and salt-tolerant bacteria purchased on the market were selected.

[0033] Embodiment 1:

[0034] The printing and dyeing wastewater in Table 1 is purified, specifically comprising the following steps:

[0035] (1) The printing and dyeing wastewater in Table 1 is transported to the regulating tank to adjust its water quality and water volume.

[0036] (2) The wastewater after adjustment in the adjustment tank in step (1) is passed into the dosing reaction tank, and the pH is adjusted to 8, wherein 60 mg / L of a magnetic nanofluid composed of sodium dodecylbenzene sulfonate and ferrosoferric oxide is added (sodium dodecylbenzene sulfonate is used as a magnetic fluid modifier, and its addition concentration is one thousandth of the mass concentration of ferrosoferric oxide) to capture and aggregate nano-micelles and micron-dispersed dyes in the wastewater, thereby achieving preliminary removal of chroma and COD in the printing and dyeing wastewater.

[0037] (3) The printing and dyeing wastewater after preliminary treatment in step (2) is passed into a centrifuge and centrifuged at a centrifugal speed of 10000 r / min for 30 min.

[0038] (4) The supernatant liquid of the printing and dyeing wastewater obtained by centrifugation in step (3) is passed into a regulating water tank and the pH is adjusted to 7 for subsequent physical and chemical treatment.

[0039] (5) The printing and dyeing wastewater after pH adjustment in step (4) is sequentially introduced into an electron supply type UASB reactor and an anoxic tank to further degrade organic matter. At the same time, denitrifying bacteria and conventional nutrient solution purchased on the market are added at the initial stage of physicochemical treatment, and the dosage is 10 kg / t. The printing and dyeing wastewater treated in the anoxic tank is then introduced into a high-efficiency aerobic tank to carry out nitrification reaction, thereby significantly degrading COD and chromaticity.

[0040] (6) The printing and dyeing wastewater treated in the high-efficiency aerobic tank in step (5) is passed into a secondary sedimentation tank, and the water-containing sludge is separated from the sludge by a filter press, and the sludge is dehydrated and then transported for external treatment.

[0041] (7) The supernatant after precipitation in the secondary sedimentation tank in step (6) is sequentially passed into an electron supply type anoxic biological filter and an electron supply type aerated biological filter to further degrade organic matter in the printing and dyeing wastewater.

[0042] (8) Returning part of the nitrified liquid in the electron supply type aerated biological filter in step (7) to the electron supply type anoxic biological filter.

[0043] (9) The printing and dyeing wastewater treated by the electron supply aerated biological filter in step (8) is passed into the composite membrane MBR reactor to remove the suspended solids contained in the effluent of the biological filter. The macroscopic comparison picture of the final effluent and the initial influent is as follows: Figure 2 As shown, it can be seen that the final effluent is nearly transparent, and its chromaticity is significantly improved compared to the initial influent.

[0044] Comparative Example 1:

[0045] As a control experiment of Example 1, a process substantially the same as that of Example 1 was adopted, with the only difference being that no magnetic nanofluid was added to the dosing reaction pool in step (2).

[0046] Comparative Example 2:

[0047] As a control experiment of Example 1, a process substantially the same as that of Example 1 was adopted, with the only difference being that sodium dodecylbenzene sulfonate was not added to the dosing reaction tank in step (2), but only ferrosoferric oxide in an amount equivalent to that in Example 1 was added.

[0048] Comparative Example 3:

[0049] As a control experiment of Example 1, a process basically the same as that of Example 1 was adopted, with the only difference being that step (3) was omitted, i.e., the effluent from the dosing reaction tank was directly used in step (4).

[0050] Comparative Example 4:

[0051] As a control experiment of Example 1, steps (1)-(3) adopt the process basically the same as that of Example 1, except that steps (4)-(9) are omitted, that is, the upper clear liquid of the printing and dyeing wastewater after the preliminary treatment in step (3) of Example 1 is used as the final effluent.

[0052] Embodiment 2:

[0053] The process is basically the same as that in Example 1, except that the concentration of sodium dodecylbenzene sulfonate added to the dosing reaction tank in step (2) is one ten-thousandth of the mass concentration of ferrosoferric oxide.

[0054] The initial water inflow data for treating the printing and dyeing wastewater in the above-mentioned Examples 1 and 2 and Comparative Examples 1-4 are shown in Table 1, and the initial water inflow was adjusted to the same water quality and water volume before treatment.

[0055] Table 1 Water inlet related parameters

[0056]

[0057] The final effluent data of the printing and dyeing wastewater treated by Examples 1 and 2 and Comparative Examples 1-4 are shown in Table 2.

[0058] Table 2 Water-related parameters

[0059]

[0060] Comparing and analyzing the data in Table 1, by comparing Example 1 with Comparative Examples 1 and 2, it can be seen that after adding the magnetic nanofluid modified by sodium dodecylbenzene sulfonate with ferroferric oxide, the COD and chromaticity removal rates of Example 1 are significantly improved, reaching 95% and 90% respectively; compared with Comparative Example 3, the COD and chromaticity after centrifugal treatment are significantly reduced, which shows that centrifugal treatment before physicochemical treatment has a significant improvement effect on the reduction of COD and chromaticity; compared with Comparative Example 4, it can be seen that COD and chromaticity can still be further removed to a large extent after subsequent physicochemical treatment. Compared with Example 1, the amount of sodium dodecylbenzene sulfonate used as a magnetic fluid modifier in Example 2 is reduced, and the effluent results show that although it is worse than Example 1, sodium dodecylbenzene sulfonate can also cooperate with ferroferric oxide net to capture nano micelles and micron disperse dyes in wastewater at extremely low dosage, and better achieves the removal of chromaticity and COD in printing and dyeing wastewater, and the removal rate reaches more than 85%.

[0061] In summary, the process of the present invention has good treatment effect, simple operation and good industrial application prospect.

[0062] Although specific embodiments of the present invention are described above, those skilled in the art should understand that these are merely examples and that various changes or modifications may be made to the embodiments without departing from the principles and essence of the present invention. The scope of protection of the present invention is limited only by the appended claims.

Claims

1. A process for purifying printing and dyeing wastewater by capturing nano-micelles and micron disperse dyes in printing and dyeing wastewater by centrifugal induction nano-magnetic fluid chemical net, characterized in that: The following steps are involved: S1. Transport printing and dyeing wastewater to the regulating tank to adjust its water quality and water volume; S2, passing the printing and dyeing wastewater regulated in the regulating tank in step S1 into the dosing reaction tank, adjusting the pH to 7-9, and adding modified nano magnetic fluid to capture and aggregate nano micelles and micron disperse dyes in the wastewater, and preliminarily removing the chroma and COD in the printing and dyeing wastewater; The modified nano magnetic fluid is composed of ferroferric oxide magnetic nanoparticles and a modifier, and the modifier is sodium dodecyl benzoate; S3, passing the printing and dyeing wastewater treated in step S2 into a centrifuge for centrifugal treatment at a certain speed; S4, subjecting the supernatant liquid of the printing and dyeing wastewater treated in step S3 to physical and chemical treatment to achieve discharge standards.

2. The process for purifying printing and dyeing wastewater by capturing nano-micelles and micron disperse dyes in printing and dyeing wastewater by centrifugal induced nano-magnetic fluid chemical net according to claim 1 is characterized in that: In step S2, the concentration of the modified nano-magnetic fluid in the dosing reaction pool is 10-100 mg / L.

3. The process for purifying printing and dyeing wastewater by capturing nano-micelles and micron disperse dyes in printing and dyeing wastewater by centrifugal induced nano-magnetic fluid chemical net according to claim 2 is characterized in that: In step S2, the concentration of the modifier added to the modified nano-magnetic fluid is one ten-thousandth to one thousandth of the iron mass concentration of the ferroferric oxide magnetic nanoparticles.

4. The process for purifying printing and dyeing wastewater by capturing nano-micelles and micron disperse dyes in printing and dyeing wastewater by centrifugal induced nano-magnetic fluid chemical net according to claim 1, characterized in that: In step S3, the centrifugal speed of the centrifuge is 600-30000 r / min.

5. The process for purifying printing and dyeing wastewater by capturing nano-micelles and micron disperse dyes in printing and dyeing wastewater by centrifugal induced nano-magnetic fluid chemical net according to any one of claims 1 to 4, characterized in that: The steps of performing physical and chemical treatment in step S4 specifically include: S4-1. Pass the supernatant of the printing and dyeing wastewater treated in step S3 into a regulating water tank and adjust the pH to 7. S4-2, passing the printing and dyeing wastewater after pH adjustment in step S4-1 into the electron supply type UASB reactor, the anoxic tank, and the aerobic tank in sequence; S4-3, the printing and dyeing wastewater treated in the aerobic tank in step S4-2 is passed into the secondary sedimentation tank for mud and water separation, and the sludge is dehydrated and then transported for external treatment.

6. The process for purifying printing and dyeing wastewater by capturing nano-micelles and micron disperse dyes in printing and dyeing wastewater by centrifugal induced nano-magnetic fluid chemical net according to claim 5, characterized in that: The step S4-3 further includes the following steps: The supernatant after precipitation in the secondary sedimentation tank in step S4-3 is sequentially passed into the electron supply type anoxic biological filter and the electron supply type aerated biological filter to further degrade the organic matter in the printing and dyeing wastewater; part of the nitrified liquid in the electron supply type aerated biological filter is returned to the electron supply type anoxic biological filter; the printing and dyeing wastewater treated by the electron supply type aerated biological filter is passed into the composite membrane MBR reactor to remove the suspended matter contained in the effluent of the biological filter.

7. The process for purifying printing and dyeing wastewater by capturing nano-micelles and micron disperse dyes in printing and dyeing wastewater by centrifugal induced nano-magnetic fluid chemical net according to claim 5, characterized in that: Before starting the physicochemical treatment in step S4-2, denitrifying bacteria and nutrient solution are added, both in amounts of 0.1-10 kg / t.

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