High-salt printing and dyeing wastewater recycling method based on dual-mode system

Abstract

The invention belongs to the technical field of multi-stage treatment of printing and dyeing wastewater, and mainly relates to a high-salt printing and dyeing wastewater recycling method based on a dual-mode system. The invention aims to solve the problem that high-salt printing and dyeing wastewater is difficult to efficiently classify and treat in the prior art. Carrying out preliminary precipitation treatment on the high-salt printing and dyeing wastewater to obtain to-be-recycled wastewater; carrying out inorganic salt recovery treatment on the wastewater to be recovered to obtain desalted wastewater and an inorganic salt recovery product; after being detected by a fiber quantity detection unit, the desalted wastewater is classified and sent to a mode A or a mode B according to the fiber content to obtain dye-enriched wastewater; and carrying out dye recovery treatment and reverse osmosis separation treatment on the dye-enriched wastewater to obtain a dye recovery product and reclaimed water. According to the recycling method for the high-salinity printing and dyeing wastewater, different types of printing and dyeing wastewater can be subjected to classified treatment, the operation efficiency of each working section is effectively improved, a water body is effectively purified, and high-value components such as inorganic salt and dye in the printing and dyeing wastewater can be fully recycled.

Description

Technical Field

[0001] The invention belongs to the technical field of multi-stage treatment of printing and dyeing wastewater, and mainly relates to a high-salt printing and dyeing wastewater recycling method based on a dual-mode system. Background Art

[0002] As an important part of the textile industry, the printing and dyeing industry plays an important role in social production. After thousands of years of development, the modern printing and dyeing industry has long entered an automated and intensive production mode. Various types of textiles can be formed into rich colors and patterns through complex printing and dyeing processes, becoming an important necessity for people's lives. The complex process of the printing and dyeing industry usually includes multi-stage chemical treatment, accompanied by the use of a large amount of production water and production electricity. During the pretreatment, dyeing, printing and other processes, a large amount of residual dyes, auxiliaries and inorganic salts will be discharged together with the production water to form printing and dyeing wastewater. Printing and dyeing wastewater has a large amount of water, complex water quality, many difficult-to-decompose components, and great harm to the environment. Therefore, the rapid development of the printing and dyeing industry has also put forward new requirements for wastewater treatment technology.

[0003] The existing printing and dyeing wastewater treatment process is usually based on traditional physical and chemical methods such as coagulation, sedimentation, and adsorption, supplemented by aerobic biological treatment technologies such as activated sludge method and biofilm method, which can effectively treat specific wastewater. However, there are many types of pollutants in printing and dyeing wastewater, which are cumbersome to handle in multi-stage treatment processes, and it is difficult to classify and recover valuable components and harmlessly treat other components. In order to solve these key problems, the industry has conducted a lot of research and exploration in the field of printing and dyeing wastewater treatment in recent years, and has made certain progress.

[0004] For example, Chinese patent CN110156249B proposes an integrated method for pretreatment of high-concentration printing and dyeing wastewater based on tubular membranes. The invention combines a pretreatment unit, a biochemical treatment unit, a deep reuse treatment unit and a sludge treatment unit. The tubular membrane is used as the core structure of the reactor to effectively remove the difficult-to-degrade highly polluted organic matter in the raw water, reduce the COD of the wastewater, and recycle inorganic salts such as sodium sulfate while significantly reducing the process cost. However, the invention cannot classify the wastewater generated by different production lines, and cannot recycle other high-value products. Chinese patent CN114538576B proposes a printing and dyeing wastewater treatment system and a printing and dyeing wastewater treatment method. The invention designs a capacitor deionization module, which uses physical electrical adsorption and electrode material oxidation in the process of printing and dyeing wastewater treatment to efficiently remove organic pollutants in printing and dyeing wastewater. The invention has a high removal efficiency for organic pollutants, but does not have the function of recycling high-value components in printing and dyeing wastewater. Chinese patent CN117228906B proposes a printing and dyeing wastewater treatment process, which achieves a higher COD removal rate and zero wastewater discharge after pretreatment, salt separation and concentration of wastewater, and the treatment process is efficient and simple. The problem with this invention is that the treatment process does not take into account the various fiber components unique to printing and dyeing wastewater, and cannot efficiently classify and treat different types of printing and dyeing wastewater.

[0005] At present, the difficulty in efficiently classifying and treating high-salt printing and dyeing wastewater remains a major challenge facing the industry.

[0006] Therefore, a method for recycling high-salt printing and dyeing wastewater based on a dual-mode system was proposed. Summary of the invention

[0007] The purpose of the present invention is to provide a method for recycling high-salt printing and dyeing wastewater based on a dual-mode system. The high-salt printing and dyeing wastewater is subjected to preliminary precipitation treatment to obtain wastewater to be recycled; the wastewater to be recycled is subjected to inorganic salt recovery treatment to obtain desalted wastewater and inorganic salt recovery products; the desalted wastewater is detected by a fiber amount detection unit and sent to mode A or mode B according to the fiber content, and dye-enriched wastewater is obtained after treatment; the dye-enriched wastewater is subjected to dye recovery treatment and reverse osmosis separation treatment to obtain dye recovery products and reclaimed water. The high-salt printing and dyeing wastewater recycling method proposed in the present invention can classify and treat different types of printing and dyeing wastewater, can effectively improve the operating efficiency of each section, has a high water purification effect, and can fully recycle high-value components such as inorganic salts and dyes in the printing and dyeing wastewater.

[0008] To achieve the above object, the present invention provides the following technical solutions: The high-salt printing and dyeing wastewater is initially precipitated through a primary sedimentation tank, a filtration tank and a sedimentation-flotation combined treatment unit; the aeration intensity of the primary sedimentation tank is 10:1-12:1, and the aeration time is 3-4 hours; the filtration tank is a fast sand filter tank with a filtration speed of 15-20m 3 / h; the average particle size of the quartz sand in the rapid sand filter is 0.8-1.2mm; the high-salt printing and dyeing wastewater after the filter is passed into the sedimentation tank, the pH is adjusted to 6-8, the high-salt printing and dyeing wastewater stays in the sedimentation tank for 2 hours to obtain the wastewater after sedimentation; the wastewater after sedimentation is passed into the flotation tank, 200mg / L of ferrous sulfate is added, the wastewater after sedimentation stays in the flotation tank for 1 hour to obtain the pre-flotation wastewater; 3-7mg / L of polyacrylamide is added to the pre-flotation wastewater; dissolved air water is passed into the pre-flotation wastewater, and the scum and precipitate are removed after 1 hour to obtain the wastewater to be recycled; The wastewater to be recycled is passed through an electrodialysis unit, a sodium sulfate mechanical vapor recompression evaporation (MVR, the same below) unit, a high-pressure reverse osmosis unit and a sodium chloride MVR unit for inorganic salt recovery treatment; the wastewater to be recycled is passed through the electrodialysis unit to obtain sodium sulfate concentrate and desulfurized sodium wastewater; the desulfurized sodium wastewater is passed through a high-pressure reverse osmosis unit to obtain sodium chloride concentrate and desalinated wastewater; the sodium sulfate concentrate is passed through a sodium sulfate MVR unit to obtain industrial sodium sulfate; the sodium chloride concentrate is passed through the sodium chloride MVR unit to obtain industrial sodium chloride; wherein the inorganic salt recovery products include: industrial sodium sulfate and industrial sodium chloride; The desalinated wastewater is passed into a fiber content detection unit to detect whether the fiber content in the desalinated wastewater is higher than a threshold value; if the fiber content is lower than the threshold value, the desalinated wastewater is output as low-fiber wastewater for A-mode treatment to obtain A-mode pretreated wastewater; A-mode includes aerobic biological treatment; if the fiber content is higher than the threshold value, the desalinated wastewater is output as high-fiber wastewater for B-mode treatment to obtain B-mode pretreated wastewater; B-mode includes COD chemical treatment and COD biological treatment; The A-mode pretreated wastewater and the B-mode pretreated wastewater are passed through a sedimentation aeration unit to obtain dye-enriched wastewater; the dye-enriched wastewater is subjected to dye recovery treatment to obtain an intermediate product; the intermediate product is subjected to reverse osmosis separation treatment to obtain a dye recovery product and reclaimed water.

[0009] Preferably, the fiber quantity detection unit includes: a feed pipe, a control valve, a discharge pipe A, a discharge pipe B and a laser particle size analyzer; the fiber content is the total content of chemical fibers and natural fibers; chemical fibers include polyester fibers and nylon fibers; natural fibers include cotton fibers, linen fibers and silk fibers; the fiber content threshold is 1000 mg / L.

[0010] Preferably, desalinated wastewater is introduced through a feed pipe, and the fiber particle size and distribution in the desalinated wastewater are tested by a laser particle size analyzer to calculate the fiber content in the desalinated wastewater; if the fiber content is lower than 1000 mg / L, the desalinated wastewater is output as low-fiber wastewater, which is controlled by a control valve and transported to a discharge pipe A; if the fiber content is higher than 1000 mg / L, the desalinated wastewater is output as high-fiber wastewater, which is controlled by a control valve and transported to a discharge pipe B.

[0011] Preferably, the aerobic biological treatment includes: an activated sludge unit and a biological contact oxidation unit; after the low-fiber wastewater is treated in the activated sludge unit for 2 hours, it is treated in the biological contact oxidation unit for 1-2 hours to obtain A-mode pretreated wastewater.

[0012] Preferably, the COD chemical treatment includes: an adsorption-coagulation unit and a redox unit; the COD biological treatment includes: an upflow anaerobic sludge unit; after the high-fiber wastewater is passed through the adsorption-coagulation unit for 2 hours, it is passed through the redox unit for 3 hours, and then passed through the upflow anaerobic sludge unit for 1-2 hours to obtain B-mode pretreated wastewater; the adsorbent added to the adsorption-coagulation unit is activated carbon, the input concentration is 50 mg / L, and the adsorption time is 100 min; the coagulant added is polyaluminium chloride, the input amount is 50 mg / L, and the coagulation time is 30 min; the redox unit uses an electrochemical oxidation method, and the current density is 80 mA / cm 2 The electrodes used were graphite electrodes, the electrolysis time was 50 minutes, the hydraulic retention time of the upflow anaerobic sludge unit was 8 hours, and the organic loading rate was 5 kg COD / m 3 ·d, the rising flow rate is 1m / h, and the reaction temperature is 35℃.

[0013] Preferably, the dye recovery treatment comprises: an adsorption precipitation separation unit and a coagulation unit; the dye-enriched wastewater is passed through the adsorption precipitation separation unit for 1-3 hours, and then passed through the coagulation unit for 1 hour to obtain an intermediate product.

[0014] Preferably, the reverse osmosis separation treatment comprises: a reverse osmosis separation unit; passing the intermediate product into the reverse osmosis separation unit, and obtaining the reclaimed water and the dye recovery product after 3-5 hours of treatment; the water flux of the reverse osmosis separation unit is 30-50L / (m 2 h), the temperature is 35-40°C.

[0015] Compared with the prior art, the present invention has the following beneficial effects: 1. An inorganic salt recovery process is set up in the front section of the high-salt printing and dyeing wastewater recovery process, which effectively reduces the concentration of inorganic salts in the wastewater, facilitates subsequent biochemical treatment, and greatly reduces the technical difficulty of recovering other high-value components. At the same time, the MVR process can obtain high-purity industrial sodium chloride and industrial sodium sulfate, so that the present invention has a higher inorganic salt recovery rate.

[0016] 2. Before treating the desalination wastewater, a fiber quantity detection unit is introduced to classify and treat different types of printing and dyeing wastewater, which significantly improves the wastewater treatment range of the recovery system. A variety of wastewaters can be efficiently classified and treated, effectively solving the problem that the prior art can only treat wastewater from a single production line. At the same time, there is no need to design multiple recovery systems, and parallel processing of multiple wastewaters can be completed in the dual-mode system designed by the present invention.

[0017] 3. Direct aerobic biological treatment is performed on low-fiber wastewater, which has a simple process and can achieve a good effect of reducing COD; redox treatment and upflow anaerobic sludge treatment are performed on high-fiber wastewater to effectively decompose the high-concentration fiber in the wastewater, reduce COD, and reduce the difficulty of subsequent dye recovery treatment.

[0018] 4. Recover azo dyes, anthraquinone dyes, cationic dyes, etc. in dye-enriched wastewater. While recovering a portion of high-value products, the COD of the wastewater is significantly reduced, solving the problem that the existing technology is not comprehensive enough in recovering high-value components in printing and dyeing wastewater.

[0019] 5. Through multi-stage wastewater treatment, high-value components in the wastewater are fully recovered, and difficult-to-recover and low-value pollutants are treated more thoroughly, achieving harmless discharge of wastewater. The recycled water discharged by the recycling process proposed by the present invention meets the Class V water quality standard specified in GB3838-2002, achieving green treatment of printing and dyeing wastewater. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a schematic diagram of the principle of the method for recycling high-salt printing and dyeing wastewater based on the dual-mode system in the present invention.

[0021] Figure 2 The present invention is a process flow chart of the method for recycling high-salt printing and dyeing wastewater based on a dual-mode system.

[0022] Figure 3 It is a structural schematic diagram of the fiber quantity detection unit in the present invention.

[0023] In the figure: 1. Feed pipe; 2. Control valve; 21. Discharge pipe A; 22. Discharge pipe B; 3. Laser particle size analyzer. DETAILED DESCRIPTION

[0024] The technical solution of the present invention will be clearly and completely described below through some embodiments. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present invention.

[0025] Reference Figure 1 The principle schematic diagram shown in the figure shows that the present invention provides a method for recycling high-salt printing and dyeing wastewater based on a dual-mode system, and the technical scheme is as follows: The substance information involved in the present invention is as follows: Ferrous sulfate: CAS: 7720-78-7; Polyacrylamide: CAS: 9003-05-8; Polyaluminium chloride: CAS: 1327-41-9; Acid Red G: CAS: 3734-67-6; Disperse Blue 2BLN: CAS: 12217-79-7; Brilliant Red 5GN: CAS: 235-399-2; Reactive Brilliant Blue KN-R: CAS: 2580-78-1; Direct Lake Blue 5B: CAS: 2429-74-5; Disperse Yellow RGFL: CAS: 6250-23-3; Disperse Blue 2BLN: CAS: 12217-79-7; Hematoxylin: CAS: 517-28-2; Direct Fast Yellow RS: CAS: 25738-24-3; Vat Blue RSN: CAS: 81-77-6.

[0026] Example 1 Source A of high-salt printing and dyeing wastewater: nylon fabric printing and dyeing section, with a salt content of 4.25 g / L and a fiber content of 354.2 mg / L.

[0027] References Figure 2 The process flow chart shown in the figure is to treat the high-salt printing and dyeing wastewater through the primary sedimentation tank, the filtration tank and the sedimentation-flotation combined treatment unit for preliminary sedimentation treatment; the aeration intensity of the primary sedimentation tank is 10:1, and the aeration time is 4 hours; the filtration tank is a fast sand filter tank with a filtration speed of 20m 3 / h; the average particle size of the quartz sand in the rapid sand filter is 0.8mm; the high-salt printing and dyeing wastewater passing through the filter tank is passed into the sedimentation tank, and the pH is adjusted to 6. The high-salt printing and dyeing wastewater stays in the sedimentation tank for 2 hours to obtain the wastewater after sedimentation; the wastewater after sedimentation is passed into the flotation tank, 200mg / L of ferrous sulfate is added, and the wastewater after sedimentation stays in the flotation tank for 1 hour to obtain the pre-flotation wastewater; 7mg / L of polyacrylamide is added to the pre-flotation wastewater, and then dissolved air water is passed into it. After 1 hour, the scum and precipitate are removed to obtain the wastewater to be recycled.

[0028] The wastewater to be recycled is treated by electrodialysis unit, sodium sulfate MVR unit, high pressure reverse osmosis unit and sodium chloride MVR unit for inorganic salt recovery. The wastewater to be recycled is passed into the electrodialysis unit with a current density of 2.5 mA / cm 2 , the operating voltage is 120V, the wastewater flow rate is 3cm / s, and sodium sulfate concentrate and desulfurized sodium wastewater are obtained; the desulfurized sodium wastewater is passed into a high-pressure reverse osmosis unit, the operating pressure is 7.5MPa, and a sodium chloride concentrate and desalination wastewater are obtained; the sodium sulfate concentrate is passed into a sodium sulfate MVR unit, the evaporation temperature is 80°C, the evaporation pressure is 100kPa, and industrial sodium sulfate is obtained after evaporation; the sodium chloride concentrate is passed into the sodium chloride MVR unit, the evaporation temperature is 80°C, the evaporation pressure is 100kPa, and industrial sodium chloride is obtained after evaporation.

[0029] The desalinated wastewater is passed through Figure 3 The fiber quantity detection unit shown in the figure is fed into the feed pipe 1, and the fiber particle size and distribution in the desalination wastewater are detected by the laser particle size analyzer 3 to judge that the wastewater is low-fiber quantity wastewater; the low-fiber quantity wastewater is controlled by the control valve 2 and transported to the discharge pipe A21 and sent to the A mode for treatment.

[0030] The low-fiber wastewater was passed through the activated sludge unit for 2 hours, and then passed through the biological contact oxidation unit for 1 hour to obtain the A-mode pretreated wastewater. The A-mode pretreated wastewater was treated in the sedimentation aeration unit for 1 hour to obtain dye-enriched wastewater. The dye-enriched wastewater was passed through the adsorption sedimentation separation unit for 3 hours, and then passed through the coagulation unit for 1 hour to obtain an intermediate product. The intermediate product was passed through the reverse osmosis separation unit, and at a water flux of 30L / (m 2 h), and after treatment at 35°C for 3 hours, reclaimed water and dye recovery products were obtained.

[0031] Comparative Example 1 Different from Example 1, the inorganic salt recovery process is not carried out, and the high-salt printing and dyeing wastewater is directly sent to the fiber quantity detection unit for subsequent treatment after preliminary sedimentation treatment, and other process parameters remain unchanged.

[0032] Comparative Example 2 Different from Example 1, the high-salt printing and dyeing wastewater is directly sent to the fiber amount detection unit for subsequent treatment after preliminary sedimentation treatment, the obtained dye-enriched wastewater is then subjected to inorganic salt recovery treatment, and the obtained desalinated wastewater is subjected to reverse osmosis separation treatment to obtain reclaimed water, and other process parameters remain unchanged.

[0033] Experimental Example 1 According to GB3838-2002 standard, the reclaimed water obtained from Example 1 and Comparative Example 1 and Comparative Example 2 was tested, and the test data were pH value, dissolved oxygen, permanganate index, COD and the contents of sulfate, chloride, nitrate, iron and manganese. The relevant results are summarized in Table 1.

[0034] Table 1 Effects of different treatment processes on reclaimed water quality

[0035] As shown in the water quality data of Table 1, when the inorganic salt recovery and treatment section is missing or placed after other treatments, the quality of the resulting reclaimed water will deteriorate significantly. Example 1 Because the main inorganic salts are separated and recovered in the front section of the recovery process, the water treatment process in the subsequent section is not easily affected by high concentrations of inorganic salts, and the overall process has a good effect on wastewater treatment. The resulting reclaimed water meets the Class V water quality standard specified in GB3838-2002, and can achieve harmless discharge of wastewater. For Comparative Example 1, the lack of an inorganic salt recovery and treatment section not only makes the sulfate and chloride content of the reclaimed water produced by its process far higher than the normal standard, but also causes other sections to have poor treatment effects on wastewater, resulting in overall water quality deterioration. For Comparative Example 2, the post-placed inorganic salt recovery and treatment section can greatly reduce the content of sulfate and chloride in the reclaimed water, but the effect is worse than that of Example 1, and the impact of high concentrations of inorganic salts on other sections is still very serious, causing the quality of the reclaimed water to fail to meet the discharge standards. High concentrations of inorganic salts have significant negative effects on biological treatment units and membrane treatment units in multi-stage wastewater treatment processes. The high osmotic pressure of the living environment caused by high salt content will lead to reduced microbial activity in activated sludge tanks and other sections. Pre-removal of inorganic salts can maintain the osmotic pressure balance of the microbial living environment, which is beneficial to improving the removal efficiency of organic pollutants in the biological treatment stage. At the same time, high concentrations of inorganic salts can cause membrane pollution, reduce membrane flux and separation efficiency, and pre-removal of inorganic salts can help improve the efficiency of membrane separation methods such as reverse osmosis.

[0036] Example 2 Source A of high-salt printing and dyeing wastewater: nylon fabric printing and dyeing section, with a salt content of 4.25 g / L and a fiber content of 354.2 mg / L.

[0037] References Figure 2 The process flow chart shown in the figure is to treat the high-salt printing and dyeing wastewater through the primary sedimentation tank, the filtration tank and the sedimentation-flotation combined treatment unit for preliminary sedimentation treatment; the aeration intensity of the primary sedimentation tank is 12:1, and the aeration time is 3 hours; the filtration tank is a fast sand filter tank with a filtration speed of 17m / s. 3 / h; the average particle size of the quartz sand in the rapid sand filter is 1.2mm; the high-salt printing and dyeing wastewater passing through the filter tank is passed into the sedimentation tank, and the pH is adjusted to 8. The high-salt printing and dyeing wastewater stays in the sedimentation tank for 2 hours to obtain the wastewater after sedimentation; the wastewater after sedimentation is passed into the flotation tank, 200mg / L of ferrous sulfate is added, and the wastewater after sedimentation stays in the flotation tank for 1 hour to obtain the pre-flotation wastewater; 3mg / L of polyacrylamide is added to the pre-flotation wastewater, and then dissolved air water is passed into it. After 1 hour, the scum and precipitate are removed to obtain the wastewater to be recycled.

[0038] The wastewater to be recycled is treated by electrodialysis unit, sodium sulfate MVR unit, high pressure reverse osmosis unit and sodium chloride MVR unit for inorganic salt recovery. The wastewater to be recycled is passed into the electrodialysis unit with a current density of 2.5 mA / cm 2 , the operating voltage is 120V, the wastewater flow rate is 3cm / s, and sodium sulfate concentrate and desulfurized sodium wastewater are obtained; the desulfurized sodium wastewater is passed into a high-pressure reverse osmosis unit, the operating pressure is 7.5MPa, and a sodium chloride concentrate and desalination wastewater are obtained; the sodium sulfate concentrate is passed into a sodium sulfate MVR unit, the evaporation temperature is 80°C, the evaporation pressure is 100kPa, and industrial sodium sulfate is obtained after evaporation; the sodium chloride concentrate is passed into the sodium chloride MVR unit, the evaporation temperature is 80°C, the evaporation pressure is 100kPa, and industrial sodium chloride is obtained after evaporation.

[0039] The desalinated wastewater is passed through Figure 3 The fiber quantity detection unit shown in the figure is fed into the feed pipe 1, and the fiber particle size and distribution in the desalination wastewater are detected by the laser particle size analyzer 3 to judge that the wastewater is low-fiber quantity wastewater; the low-fiber quantity wastewater is controlled by the control valve 2 and transported to the discharge pipe A21 and sent to the A mode for treatment.

[0040] The low-fiber wastewater was passed through an activated sludge unit for 2 hours, and then passed through a biological contact oxidation unit for 1 hour to obtain A-mode pretreated wastewater. The A-mode pretreated wastewater was treated in a sedimentation aeration unit for 1 hour to obtain dye-enriched wastewater. The dye-enriched wastewater was passed through an adsorption sedimentation separation unit for 1 hour, and then passed through a coagulation unit for 1 hour to obtain an intermediate product. The intermediate product was passed through a reverse osmosis separation unit, and at a water flux of 50L / (m 2 h), and after treatment at 40°C for 5 hours, reclaimed water and dye recovery products were obtained.

[0041] Example 3 The difference from Example 2 is that a different source of high-salt printing and dyeing wastewater is used, and the other process parameters are the same except for the mode switching.

[0042] Source B of high-salt printing and dyeing wastewater: acrylic-cotton blended fabric printing and dyeing section, with a salt content of 6.88 g / L and a fiber content of 1534.7 mg / L.

[0043] Desalination wastewater is Figure 3 The fiber content detection unit shown in the figure is fed into the feed pipe 1, and the fiber particle size and distribution in the desalination wastewater are detected by the laser particle size analyzer 3, and the wastewater is judged to be high-fiber wastewater. The high-fiber wastewater is controlled by the control valve 2 and transported to the discharge pipe B22 and sent to the B mode for treatment.

[0044] After the high-fiber wastewater was passed through the adsorption-coagulation unit for 2 hours, it was passed through the redox unit for 3 hours, and then passed through the upflow anaerobic sludge unit for 1 hour to obtain the B-mode pretreated wastewater; wherein, the adsorbent added to the adsorption-coagulation unit was activated carbon, the input concentration was 50 mg / L, and the adsorption time was 100 min; the coagulant added was polyaluminium chloride, the input amount was 50 mg / L, and the coagulation time was 30 min; the redox unit used electrochemical oxidation method, and the current density was 80 mA / cm 2 The electrodes used were graphite electrodes, the electrolysis time was 50 minutes, the hydraulic retention time of the upflow anaerobic sludge unit was 8 hours, and the organic loading rate was 5 kg COD / m 3 ·d, the rising flow rate is 1m / h, and the reaction temperature is 35℃.

[0045] Comparative Example 3 The difference from Example 2 is that the fiber amount detection unit is removed, and the wastewater from the high-salt printing and dyeing wastewater source B is treated with the same process, and other process parameters are the same.

[0046] Comparative Example 4 The difference from Example 3 is that the fiber amount detection unit is removed, and the wastewater from the high-salt printing and dyeing wastewater source A is treated with the same process, and other process parameters are the same.

[0047] Experimental Example 2 The reclaimed water obtained in Example 2-3 and Comparative Example 3-4 of GB3838-2002 was tested for pH value, dissolved oxygen, permanganate index, COD, and the treatment of 15m3 in each process was statistically analyzed. 3 The time required for wastewater treatment is summarized in Table 2.

[0048] Table 2 Improvement of wastewater treatment efficiency by dual-mode system

[0049] As can be seen from Table 2, mode A can effectively complete the recovery and purification of low-fiber wastewater, and it takes less time, while mode B can effectively complete the recovery and purification of low-fiber wastewater and high-fiber wastewater, but it takes a long time. Mode B has a higher treatment effect than mode A, but the process is longer and more time-consuming. Therefore, it is of great significance to set up a fiber amount detection unit to classify and treat wastewater. In the presence of a fiber amount detection unit, both Example 2 and Example 3 can automatically select a suitable treatment mode according to the type of wastewater, and can complete the harmless discharge of wastewater. If the fiber amount detection unit is not used, and a single mode A or mode B is used as a section in the multi-stage wastewater treatment process, there will be problems such as poor treatment effect of high-fiber wastewater in Example 3 or too long treatment time for low-fiber wastewater in Example 4. The fiber quantity detection unit and the dual-mode treatment system can effectively solve the problem of parallel treatment of multiple wastewaters. The A mode treatment of low-fiber wastewater has a simple process and good effect; the B mode treatment of high-fiber wastewater can effectively decompose the high-concentration fiber in the wastewater and achieve a good wastewater treatment effect. Therefore, the design of the fiber quantity detection unit and the dual-mode design of the A mode and the B mode of the present invention effectively strike a balance between the treatment effect and the treatment cost, and have significant application value.

[0050] Example 4 Source A of high-salt printing and dyeing wastewater: nylon fabric printing and dyeing section, in which the salt content is 4.25g / L, the fiber content is 354.2mg / L, and the main components of the dye are acid red G and disperse blue 2BLN.

[0051] References Figure 2 The process flow chart shown in the figure is to treat the high-salt printing and dyeing wastewater through the primary sedimentation tank, the filtration tank and the sedimentation-flotation combined treatment unit for preliminary sedimentation treatment; the aeration intensity of the primary sedimentation tank is 11:1, and the aeration time is 4 hours; the filtration tank is a fast sand filter tank with a filtration speed of 15m 3 / h; the average particle size of the quartz sand in the rapid sand filter is 0.8mm; the high-salt printing and dyeing wastewater passing through the filter tank is passed into the sedimentation tank, and the pH is adjusted to 7. The high-salt printing and dyeing wastewater stays in the sedimentation tank for 2 hours to obtain the wastewater after sedimentation; the wastewater after sedimentation is passed into the flotation tank, 200mg / L of ferrous sulfate is added, and the wastewater after sedimentation stays in the flotation tank for 1 hour to obtain the pre-flotation wastewater; 5mg / L of polyacrylamide is added to the pre-flotation wastewater, and then dissolved air water is passed into it. After 1 hour, the scum and precipitate are removed to obtain the wastewater to be recycled.

[0052] The wastewater to be recycled is treated by electrodialysis unit, sodium sulfate MVR unit, high pressure reverse osmosis unit and sodium chloride MVR unit for inorganic salt recovery. The wastewater to be recycled is passed into the electrodialysis unit with a current density of 2.5 mA / cm 2, the operating voltage is 120V, the wastewater flow rate is 3cm / s, and sodium sulfate concentrate and desulfurized sodium wastewater are obtained; the desulfurized sodium wastewater is passed into a high-pressure reverse osmosis unit, the operating pressure is 7.5MPa, and a sodium chloride concentrate and desalination wastewater are obtained; the sodium sulfate concentrate is passed into a sodium sulfate MVR unit, the evaporation temperature is 80°C, the evaporation pressure is 100kPa, and industrial sodium sulfate is obtained after evaporation; the sodium chloride concentrate is passed into the sodium chloride MVR unit, the evaporation temperature is 80°C, the evaporation pressure is 100kPa, and industrial sodium chloride is obtained after evaporation.

[0053] The desalinated wastewater is passed through Figure 3 The fiber quantity detection unit shown in the figure is fed into the feed pipe 1, and the fiber particle size and distribution in the desalination wastewater are detected by the laser particle size analyzer 3 to judge that the wastewater is low-fiber quantity wastewater; the low-fiber quantity wastewater is controlled by the control valve 2 and transported to the discharge pipe A21 and sent to the A mode for treatment.

[0054] The low-fiber wastewater was passed through the activated sludge unit for 2 hours, and then passed through the biological contact oxidation unit for 1 hour to obtain the A-mode pretreated wastewater. The A-mode pretreated wastewater was treated in the sedimentation aeration unit for 1 hour to obtain dye-enriched wastewater. The dye-enriched wastewater was passed through the adsorption sedimentation separation unit for 2 hours, and then passed through the coagulation unit for 1 hour to obtain an intermediate product. The intermediate product was passed through the reverse osmosis separation unit, and at a water flux of 40L / (m 2 h), and after treatment at 37° C. for 4 hours, reclaimed water and dye recovery products were obtained.

[0055] Example 5 The difference from Example 4 is that a different source of high-salt printing and dyeing wastewater is used, and the other process parameters are the same except for the mode switching.

[0056] Source B of high-salt printing and dyeing wastewater: acrylic-cotton blended fabric printing and dyeing section, in which the salt content is 6.88g / L, the fiber content is 1534.7mg / L, and the main components of the dye are brilliant red 5GN and reactive brilliant blue KN-R.

[0057] Among them, the B mode process parameters are the same as those in Example 3.

[0058] Example 6 The difference from Example 4 is that a different source of high-salt printing and dyeing wastewater is used, and the other process parameters are the same except for the mode switching.

[0059] Source C of high-salt printing and dyeing wastewater: silk fabric printing and dyeing section, in which the salt content is 3.75g / L, the fiber content is 769.2mg / L, and the main components of the dye are brilliant red 5GN and direct lake blue 5B.

[0060] Example 7 The difference from Example 4 is that a different source of high-salt printing and dyeing wastewater is used, and the other process parameters are the same except for the mode switching.

[0061] Source D of high-salt printing and dyeing wastewater: polyester textile printing and dyeing section, in which the salt content is 5.24g / L, the fiber content is 783.4mg / L, and the main components of the dye are disperse yellow RGFL and disperse blue 2BLN.

[0062] Example 8 The difference from Example 4 is that a different source of high-salt printing and dyeing wastewater is used, and the other process parameters are the same except for the mode switching.

[0063] Source E of high-salt printing and dyeing wastewater: linen textile printing and dyeing section, in which the salt content is 5.24g / L, the fiber content is 2139.5mg / L, and the main components of the dye are hematoxylin, direct fast yellow RS, and vat blue RSN.

[0064] Among them, the B mode process parameters are the same as those in Example 3.

[0065] Experimental Example 3 The reclaimed water obtained in Examples 4-8 was tested according to GB3838-2002 standard. The test data included pH value, dissolved oxygen, permanganate index, COD, and the contents of sulfate, chloride, nitrate, iron, and manganese. The relevant results are summarized in Table 3.

[0066] The dye molecule content in AE, a high-salt printing and dyeing wastewater source, was analyzed by spectrophotometry and 15m 3 The molecular weight of dye contained in the wastewater is compared with that of 15 m 3 The quality of the recovered dyes obtained after wastewater treatment was compared, and the relevant results are summarized in Table 4.

[0067] Table 3 Treatment effects of different types of wastewater

[0068] Table 4 Dye recovery from different types of wastewater

[0069] As shown in the wastewater treatment results in Table 3, the recycling processes corresponding to Examples 4-8 have good treatment effects on different types of printing and dyeing wastewater, and no additional treatment sections are required. The classification treatment of different types of wastewater can be completed through the automatic switching of the dual-mode system. For five different types of high-salt printing and dyeing wastewater, the treated reclaimed water meets the Class V water quality standard and can be recycled as industrial water or discharged harmlessly. Therefore, the recycling method designed by the present invention has excellent wastewater treatment effects and can be applied to various types of printing and dyeing wastewater.

[0070] As shown in the dye recovery data in Table 4, the recovery process corresponding to Examples 4-8 has a good dye recovery effect on the basis of efficiently treating different types of printing and dyeing wastewater. The dyes involved in the wastewater AE mainly include azo dyes: acid red G, direct lake blue 5B, direct fast yellow RS, disperse yellow RGFL; anthraquinone dyes: disperse blue 2BLN, reactive brilliant blue KN-R, vat blue RSN; cationic dyes: three types of hematoxylin and brilliant red 5GN. Therefore, the recovery process of the present invention has a certain recovery capacity for different types of dyes such as azo dyes, anthraquinone dyes, and cationic dyes. While completing the efficient and harmless treatment of sewage, it can also carry out a more comprehensive recovery treatment of the high-value components therein.

[0071] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for recycling high-salt printing and dyeing wastewater based on a dual-mode system, characterized in that: The recycling method is as follows: The recycling method includes: preliminary precipitation treatment, inorganic salt recovery treatment, fiber quantity detection unit, A mode, B mode, dye recovery treatment and reverse osmosis separation treatment; The high-salt printing and dyeing wastewater is subjected to the preliminary precipitation treatment to obtain wastewater to be recycled; The wastewater to be recycled is subjected to the inorganic salt recovery treatment to obtain desalinated wastewater and inorganic salt recovery products; The desalinated wastewater is passed into the fiber content detection unit to detect whether the fiber content in the desalinated wastewater is higher than a threshold value; if the fiber content is lower than the threshold value, the desalinated wastewater is output as low-fiber wastewater for A-mode treatment to obtain A-mode pretreated wastewater; the A-mode includes aerobic biological treatment; if the fiber content is higher than the threshold value, the desalinated wastewater is output as high-fiber wastewater for B-mode treatment to obtain B-mode pretreated wastewater; the B-mode includes COD chemical treatment and COD biological treatment; The A-mode pretreated wastewater and the B-mode pretreated wastewater are passed through a sedimentation aeration unit to obtain dye-enriched wastewater; the dye-enriched wastewater is subjected to the dye recovery treatment to obtain an intermediate product; the intermediate product is subjected to reverse osmosis separation treatment to obtain a dye recovery product and reclaimed water.

2. The method for recycling high-salt printing and dyeing wastewater based on a dual-mode system according to claim 1, characterized in that: The preliminary sedimentation treatment includes: a primary sedimentation tank, a filtration tank and a sedimentation-flotation combined treatment unit; the aeration intensity of the primary sedimentation tank is 10:1-12:1, and the aeration time is 3-4 hours; the filtration tank is a fast sand filter tank, wherein the filtration speed is 15-20m 3 / h; the average particle size of the quartz sand in the rapid sand filter is 0.8-1.2mm.

3. The method for recycling high-salt printing and dyeing wastewater based on a dual-mode system according to claim 2, characterized in that: The sedimentation-flotation combined treatment unit is as follows: the high-salt printing and dyeing wastewater passing through the filtration tank is passed into a sedimentation tank, the pH value is adjusted to 6-8, the high-salt printing and dyeing wastewater stays in the sedimentation tank for 2 hours to obtain post-settlement wastewater; the post-settlement wastewater is passed into a flotation tank, ferrous sulfate is added, and the addition amount of ferrous sulfate is 200 mg / L; the post-settlement wastewater stays in the flotation tank for 1 hour to obtain pre-flotation wastewater; polyacrylamide is added to the pre-flotation wastewater, wherein the addition amount of polyacrylamide is 3-7 mg / L; dissolved air water is passed into the pre-flotation wastewater, and scum and precipitate are removed after 1 hour to obtain the wastewater to be recycled.

4. The method for recycling high-salt printing and dyeing wastewater based on a dual-mode system according to claim 1, characterized in that: The inorganic salt recovery treatment comprises: an electrodialysis unit, a sodium sulfate mechanical vapor recompression evaporation unit, a high-pressure reverse osmosis unit and a sodium chloride mechanical vapor recompression evaporation unit; the wastewater to be recovered is passed through the electrodialysis unit to obtain a sodium sulfate concentrate and desulfurized sodium wastewater; the desulfurized sodium wastewater is passed through the high-pressure reverse osmosis unit to obtain a sodium chloride concentrate and the desalinated wastewater; the sodium sulfate concentrate is passed through the sodium sulfate mechanical vapor recompression evaporation unit to obtain industrial sodium sulfate; the sodium chloride concentrate is passed through the sodium chloride mechanical vapor recompression evaporation unit to obtain industrial sodium chloride; the desalinated wastewater is passed through the fiber amount detection unit for further treatment; the inorganic salt recovery products comprise: the industrial sodium sulfate and the industrial sodium chloride.

5. The method for recycling high-salt printing and dyeing wastewater based on a dual-mode system according to claim 1, characterized in that: The fiber quantity detection unit comprises: a feed pipe (1), a control valve (2), a discharge pipe A (21), a discharge pipe B (22) and a laser particle size analyzer (3); the fiber content is the total content of chemical fibers and natural fibers; the chemical fibers include polyester fibers and nylon fibers; the natural fibers include cotton fibers, hemp fibers and silk fibers; the fiber content threshold is 1000 mg / L.

6. The method for recycling high-salt printing and dyeing wastewater based on a dual-mode system according to claim 5, characterized in that: The working process of the fiber quantity detection unit is as follows: The desalinated wastewater is introduced through a feed pipe (1), and the fiber particle size and distribution in the desalinated wastewater are tested by a laser particle size analyzer (3), and the fiber content in the desalinated wastewater is calculated; If the fiber content is lower than 1000 mg / L, the desalinated wastewater is output as the low-fiber wastewater and is controlled by the control valve (2) to be transported to the discharge pipe A (21); If the fiber content is higher than 1000 mg / L, the desalinated wastewater is output as the high-fiber wastewater, which is controlled by the control valve (2) and transported to the discharge pipe B (22); The discharge pipe A (21) leads to the A mode; the discharge pipe B (22) leads to the B mode.

7. The method for recycling high-salt printing and dyeing wastewater based on a dual-mode system according to claim 1, characterized in that: The aerobic biological treatment comprises: an activated sludge unit and a biological contact oxidation unit; after the low-fiber wastewater is treated in the activated sludge unit for 2 hours, it is treated in the biological contact oxidation unit for 1-2 hours to obtain the A-mode pretreated wastewater.

8. The method for recycling high-salt printing and dyeing wastewater based on a dual-mode system according to claim 1, characterized in that: The COD chemical treatment includes: an adsorption-coagulation unit and a redox unit; the COD biological treatment includes: an upflow anaerobic sludge unit; the high-fiber wastewater is passed through the adsorption-coagulation unit for 2 hours, then through the redox unit for 3 hours, and then through the upflow anaerobic sludge unit for 1-2 hours to obtain B-mode pretreated wastewater.

9. The method for recycling high-salt printing and dyeing wastewater based on a dual-mode system according to claim 1, characterized in that: The dye recovery process comprises: an adsorption precipitation separation unit and a coagulation unit; the dye-enriched wastewater is passed through the adsorption precipitation separation unit for 1-3 hours, and then passed through the coagulation unit for 1 hour to obtain the intermediate product.

10. The method for recycling high-salt printing and dyeing wastewater based on a dual-mode system according to claim 1, characterized in that: The reverse osmosis separation treatment comprises: a reverse osmosis separation unit; passing the intermediate product into the reverse osmosis separation unit, and obtaining the reclaimed water and the dye recovery product after 3-5 hours of treatment; the water flux of the reverse osmosis separation unit is 30-50L / (m 2 h), the temperature is 35-40°C.

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