An industrial water-saving and sewage recycling method for a blanket printing and washing combined line

Abstract

The present application relates to the technical field of textile printing and dyeing wastewater treatment and recycling, and particularly discloses a method for recycling industrial water-saving wastewater in a blanket printing and dyeing washing combined line, wherein short pile is intercepted from the waste water containing pile and is conditioned into short pile slurry, the dry base short pile return quantity is determined according to the initial colority of the high-colority washing wastewater, the treatment flow or the treatment water quantity and the available dry base short pile mass, the short pile slurry is added into the high-colority washing wastewater to perform a color-loading enrichment reaction, and the color-loading short pile flocculation is separated according to the relative change of the colority decline slope and the turbidity change, and the regenerated water is obtained through filtration; meanwhile, the dry base short pile return quantity or the separation trigger condition of the next treatment cycle is feedback corrected according to the filtration pressure difference growth, the turbidity before filtration and the short pile residual quantity, and the regenerated water is recycled to the corresponding washing section according to the regenerated water quality grade. The present application can reduce the dependence on external medicaments by using the endogenous short pile in the washing line, reduce the risk of filtration blockage, and improve the stability of the quality and quantity recycling of the regenerated water.

Description

Technical Field

[0001] This invention relates to the field of textile dyeing and printing wastewater treatment and recycling technology, and in particular to a method for recycling industrial water-saving wastewater from a combined blanket dyeing and washing line. Background Technology

[0002] A combined line for printing and dyeing blankets typically includes processes such as pre-washing, soaping, rinsing, and post-finishing washing after printing or dyeing. During production, wastewater containing short fibers, residual dyes, surfactants, softeners, and colloidal contaminants is generated. Existing treatment methods usually involve first removing fibrous impurities through screens, sieves, or filtration equipment, and then using processes such as coagulation, flotation, sedimentation, precision filtration, or membrane treatment to reduce the color, turbidity, and organic matter content of the wastewater. The treated water is then reused in some washing processes according to the company's water needs, or mixed with other wastewater and sent to the plant's integrated wastewater treatment system.

[0003] However, the short fibers in blanket washing wastewater are relatively fine, making them prone to forming adhesive mixed pollutants with residual dyes, auxiliaries, and colloidal contaminants. If these pollutants directly enter subsequent filtration or membrane treatment units, they can easily cause an increase in filtration pressure differential and a decrease in operational stability. At the same time, existing treatment processes mostly treat high-color wastewater with fixed dosages, fixed residence times, or fixed filtration procedures. It is difficult to make adaptive adjustments based on changes in color load, fiber contaminant content, solid-liquid separation state, and filtration load of different batches of wastewater. This results in insufficient matching between the quality of the treated reclaimed water and the water requirements of different washing sections, which is not conducive to the stable water saving and graded reuse of the blanket printing and dyeing washing line. Summary of the Invention

[0004] The technical problem this invention aims to solve is that existing wastewater treatment processes for blanket dyeing and finishing mainly operate with fixed dosages, fixed residence times, or fixed filtration procedures. This makes it difficult to adapt to changes in color load, short fiber and colloidal pollutant content, solid-liquid separation state, and filtration load of different batches of wastewater. Consequently, the filtration operation is unstable, and the reclaimed water quality is not well matched with the water requirements of different washing sections, which is not conducive to stable water conservation and differentiated reuse. Therefore, we propose an industrial water-saving wastewater reuse method for combined blanket dyeing and finishing lines.

[0005] To achieve the above objectives, this application adopts the following technical solution: a method for the reuse of industrial water-saving wastewater from a combined line for printing and dyeing blankets, comprising the following steps:

[0006] Step 1: Short fibers are intercepted from the wastewater containing fibers discharged from the carpet printing and dyeing washing line. The short fibers are then screened, dewatered, and wet-conditioned to make short fiber slurry. At the same time, the usable dry basis short fiber quality of this treatment cycle is determined.

[0007] Step 2: Detect the initial color and treatment flow rate or treatment volume of the high-color washing wastewater to be treated. Based on the initial color, treatment flow rate or treatment volume and the available dry basis short fiber mass for this treatment cycle, determine the amount of dry basis short fiber to be recycled for this treatment cycle.

[0008] Step 3: Calculate the amount of short fiber slurry to be added based on the amount of dry-based short fiber recycled, and add the corresponding amount of short fiber slurry to the high-color washing wastewater for a color enrichment reaction, so that the residual dyes, auxiliaries and colloidal pollutants in the high-color washing wastewater are enriched in the short fibers and form color-loaded short fiber flocs.

[0009] Step 4: During the color enrichment reaction, the color and turbidity of the supernatant are detected. Based on the change in the slope of color decrease relative to the initial slope of color decrease and the change in the turbidity of the supernatant, the separation triggering conditions of the color-carrying short fibers are determined.

[0010] Step 5: After the separation triggering conditions are met, the colored short fibers are separated, and the decolorized water after separation is filtered to obtain reclaimed water.

[0011] Step 6: Based on the increase in filtration pressure difference, turbidity before filtration, and residual short fibers during the filtration process, the amount of dry short fibers to be reintroduced or the separation triggering conditions for the next treatment cycle are adjusted accordingly. The reclaimed water is then reused in the corresponding washing section of the blanket printing and dyeing washing line based on the quality of the reclaimed water.

[0012] Preferably, in step one, the down-containing wastewater comes from the pre-washing section, soaping section, or pre-washing section of the blanket printing and dyeing washing line, or the short down obtained is temporarily stored in the short down temporary storage tank.

[0013] Preferably, in step one, after the short fibers are screened and dewatered, they are replenished with low-color recycled water or intermediate rinsing water for wet conditioning, so that the solid content of the short fiber slurry is 1.5% to 4.0%.

[0014] Preferably, in step one, a conditioning agent is added to the short-fiber slurry during wet conditioning. The conditioning agent is cationic polyacrylamide or a compound system of polyaluminum chloride and cationic polyacrylamide. The amount of conditioning agent added is calculated based on the volume of the high-color washing wastewater to be treated entering the high-color reaction tank.

[0015] Preferably, in step two, when the initial color intensity is less than 250 times, the amount of dry-based short fibers recycled is 0.6 kg to 0.9 kg of dry-based short fibers per cubic meter of high-color washing wastewater; when the initial color intensity is 250 to 400 times, the amount of dry-based short fibers recycled is 0.9 kg to 1.2 kg of dry-based short fibers per cubic meter of high-color washing wastewater; and when the initial color intensity is greater than 400 times, the amount of dry-based short fibers recycled is 1.2 kg to 1.4 kg of dry-based short fibers per cubic meter of high-color washing wastewater.

[0016] Preferably, in step two, when the available dry-based short fiber mass of the current treatment cycle is insufficient to meet the minimum refill requirement of the current treatment cycle, conventional coagulation compensation treatment is performed on the high-color washing wastewater, or the treated reclaimed water is downgraded and reused in the pre-washing section, the pre-washing section of the dark batch, or equipment rinsing; when the available dry-based short fiber mass of the current treatment cycle is higher than the amount of dry-based short fiber required for the current treatment cycle, the amount of short fiber slurry added is calculated based on the determined amount of dry-based short fiber refill.

[0017] Preferably, in step three, after the short-fiber slurry is added to the high-color reaction tank, it is mixed and reacted with high-color washing wastewater under stirring conditions, so that residual dyes, surfactants and colloidal pollutants are enriched on the surface of the short fibers and in the gaps between fibers, forming separable color-carrying short-fiber flocs.

[0018] Preferably, in step four, the color and turbidity of the supernatant are detected according to the set detection cycle, and the color decrease slope of adjacent detection periods is calculated; when the color decrease slope in two consecutive detection cycles decreases to 10% to 25% of the color decrease slope in the initial stage of the reaction, and the turbidity of the supernatant decreases below the set range or shows an upward trend, it is determined that the separation trigger condition of the colored short fibers has been met.

[0019] Preferably, in step five, at least one of the following methods is used to separate the colored short fibers: air flotation, sieving, sedimentation, drum filtration, or microfiltration. The decolorized water after separation enters a precision filtration unit for filtration treatment.

[0020] Preferably, in step six, when the increase in filtration pressure difference reaches or exceeds the set pressure difference threshold, and the turbidity and short fiber residue before filtration reach or exceed the corresponding threshold, it is determined that the separation of colored short fiber flocs is insufficient or the amount of dry-based short fiber fed back is too high, and the amount of dry-based short fiber fed back is reduced in the next treatment cycle or the separation of colored short fiber flocs is started in advance; when the increase in filtration pressure difference reaches or exceeds the set pressure difference threshold, but the turbidity and short fiber residue before filtration do not reach the corresponding threshold at the same time, filter cartridge backwashing, replacement or conventional coagulation compensation is started, and the current amount of dry-based short fiber fed back is maintained; the water quality grade of the filtered reclaimed water is determined according to color, turbidity, COD, conductivity and pH, and it is reused in the corresponding washing section of the blanket printing and dyeing washing line.

[0021] The technical effects and advantages of this invention are as follows:

[0022] This invention intercepts and reuses short fibers that would otherwise clog filters on blanket washing lines for the treatment of high-chroma wastewater. The amount of dry-based short fibers to be added is determined based on the initial chroma of the wastewater, the volume of water to be treated, and the available dry-based short fiber mass. This allows the short fibers to participate in the color-enriching reaction after conditioning, transforming dispersed residual dyes, auxiliaries, and colloidal contaminants into more easily separable color-enriched short fiber flocs. Compared to direct precision filtration or simply adding external coagulants, this invention utilizes the short fibers generated by the production line itself, reducing reliance on external agents. It also reduces the clogging load on subsequent filtration units caused by dye colloids and short fibers, improving the decolorization stability and filtration stability of the high-chroma washing wastewater.

[0023] This invention further determines the separation timing of colored short-fiber flocs by the relative change in the slope of color decrease and the change in turbidity. It also combines the filtration pressure difference, the turbidity before filtration, and the amount of residual short fibers to provide feedback correction for the amount of dry-based short fibers reintroduced or the separation triggering conditions in the next treatment cycle. This establishes a continuous correspondence between short-fiber reintroduction, color enrichment, floc separation, and filtration load. The treated reclaimed water is then graded according to color, turbidity, COD, conductivity, and pH and reused in different washing stages. This avoids low-grade reclaimed water from being mistakenly used in the high-requirement washing stage and reduces the low-value use of high-quality water, thus better meeting the batch fluctuations and graded reuse needs of continuous production in blanket printing and dyeing enterprises. Attached Figure Description

[0024] The disclosure of this invention is illustrated with reference to the accompanying drawings. It should be understood that the drawings are for illustrative purposes only and are not intended to limit the scope of protection of this invention.

[0025] Figure 1 This is a schematic diagram illustrating the linkage control of the short fiber temporary storage amount, high-color wastewater load, and dry-based short fiber refeed amount in this invention.

[0026] Figure 2 This is a logic diagram for determining the triggering condition of the separation of colored short fiber fibers in this invention;

[0027] Figure 3 This is a graph showing the effect of the amount of dry-based short fibers reintroduced on the color removal rate, effluent turbidity, and filtration pressure difference of the present invention.

[0028] Figure 4 This is a graph showing the changes in color and turbidity of the supernatant over reaction time during the color enrichment process of this invention.

[0029] Figure 5 This is a comparison chart of color removal rate and filtration pressure difference increase under different processing methods of the present invention;

[0030] Figure 6 This is a feedback correction logic diagram for the filtration pressure difference, turbidity before filtration, and short fiber residue in this invention. Detailed Implementation

[0031] It is readily understood that, based on the technical solution of this invention, those skilled in the art can propose various interchangeable structural methods and implementations without altering the essential spirit of the invention. Therefore, the following detailed embodiments and accompanying drawings are merely illustrative examples of the technical solution of this invention and should not be considered as the entirety of the invention or as limitations or restrictions on the technical solution of this invention.

[0032] This embodiment provides a method for industrial water-saving wastewater recycling in a combined blanket printing and dyeing washing line. It is applicable to wastewater containing fluff and high-color wastewater generated during the blanket printing, dyeing, soaping, rinsing, and finishing washing processes. The combined blanket printing and dyeing washing line includes a pre-washing section, a soaping section, a middle rinsing section, and a final washing section arranged along the blanket conveying direction. The wastewater discharged from the pre-washing and soaping sections usually contains short fluff, residual dyes, surfactants, softeners, and colloidal contaminants. If this type of wastewater directly enters a precision filtration or membrane treatment unit, the short fluff can easily form adhesive contaminants with dye colloids and auxiliaries, causing an increase in filtration pressure differential. If only external decolorizing agents are added to treat the high-color wastewater, it is easy to increase the consumption of agents and the amount of sludge generated.

[0033] To implement this method, the wastewater treatment branch of the blanket printing and dyeing washing line can be equipped with a short fiber interception unit, a short fiber temporary storage tank, a conditioning tank, a high-chroma reaction tank, a colored short fiber separation unit, a precision filtration unit, and a reclaimed water temporary storage tank. It can also be equipped with a colorimeter, a turbidity detector, a flow meter, a pressure detection point, and a short fiber residue detection point to obtain the detection data needed for determining the amount of dry-basis short fiber to be added back, judging the timing of colored short fiber separation, and filtration feedback correction. Specifically, the short fiber interception unit is used to intercept water-containing short fibers from the fiber-containing wastewater; the short fiber temporary storage tank is used to temporarily store refillable short fibers; the conditioning tank is used to perform wet conditioning on the dehydrated short fibers; the high-chroma reaction tank is used for the color enrichment reaction of the short fibers; the colored short fiber separation unit is used to separate the colored short fiber flocs; the precision filtration unit is used to filter the decolorized water; and the reclaimed water temporary storage tank is used to temporarily store and distribute reclaimed water.

[0034] The specific steps are as follows:

[0035] Step S1: Short fibers are intercepted in the wastewater containing fibers discharged from the blanket printing and dyeing washing line, and the intercepted water-containing short fibers and the wastewater after primary filtration are exported separately.

[0036] Specifically, the down-containing wastewater preferably comes from the pre-washing section, soaping section, or the pre-washing section of the dark-colored blanket batch. The down-containing wastewater first enters the short-fiber interception unit, which can be an inclined screen, arc screen, rotary screen, or drum screen with a screen mesh of 80 to 160 mesh; in one specific embodiment, the screen mesh is 120 mesh. After short-fiber interception, water-containing short fibers and primary filtration wastewater are obtained. The water-containing short fibers enter the short-fiber temporary storage tank, and the primary filtration wastewater enters the high-color treatment branch or conventional equalization tank according to the online color and turbidity detection results. A low-speed stirrer is installed in the short-fiber temporary storage tank with a stirring speed of 15 r / min to 35 r / min to reduce short-fiber deposition and clumping.

[0037] Step S2 involves screening, dewatering, and wet conditioning the water-containing short fibers to obtain a short fiber slurry that can participate in the color enrichment of high-chroma wastewater.

[0038] Specifically, long fiber clumps, sand particles, impurities, and obviously agglomerated tufts are first removed from the water-containing short fibers. Then, the moisture content is controlled at 82%–92% through pressure filtration, screw extrusion, or centrifugal dewatering. In one specific embodiment, the moisture content is controlled at 86%–90%. The dewatered short fibers are then introduced into a conditioning tank in a wet state. Low-color recycled water or mid-stage rinsing water is added to the conditioning tank to control the solid content of the short fiber slurry at 1.5%–4.0%. Subsequently, depending on the type of conditioning agent selected and the wastewater quality, the pH of the short fiber slurry or the high-color wastewater to be treated is adjusted to 6.0–8.5. In one specific embodiment, when cationic polyacrylamide is used, the pH is controlled at 6.5–8.0; when polyaluminum chloride and cationic polyacrylamide are combined, the pH is controlled at 6.8–8.2.

[0039] The conditioning agent is added to the short fiber slurry in the form of an aqueous solution, and its final dosage is calculated based on the volume of the high-chroma wastewater to be treated entering the high-chroma reaction tank. Among them, the calculated dosage of cationic polyacrylamide is 0.4 mg / L to 1.2 mg / L, and the calculated dosage of polyaluminum chloride is 30 mg / L to 70 mg / L. In actual operation, the concentration of the conditioning agent mother liquor and the flow rate of the dosing pump are determined according to the flow rate of the short fiber slurry and the flow rate of the high-chroma wastewater. This wet conditioning is mainly used to improve the dispersion state of the short fibers in the high-chroma wastewater and the ability of color-carrying flocs to form.

[0040] Step S3: Detect the pollution load and short fiber temporary storage amount of high-chroma washing wastewater, and determine the amount of dry-based short fiber to be recycled accordingly.

[0041] Specifically, the high-chroma washing wastewater can be dark-colored blanket soap washing wastewater, pre-wash wastewater after printing, or rinsing wastewater before switching between light and dark color batches. The high-chroma treatment branch is equipped with an online colorimeter, a turbidity detector, a COD sampling and detection port, and a flow meter. At the beginning of a treatment cycle, the initial color C0, initial turbidity T0, COD value, and treatment flow rate Q of the high-chroma washing wastewater are detected, and the usable dry-based short-pile mass G of this treatment cycle is detected. The usable dry-based short-pile mass G is calculated based on the short-pile wet material mass and its moisture content, or based on the short-pile sizing material mass and its solid content. The dry-based short-pile refeed amount M is determined based on the initial color C0, the treatment flow rate Q, and the usable dry-based short-pile mass G.

[0042] In this embodiment, the dry basis short fiber refill amount M is the refill amount measured on a dry basis. When actually added, it is converted into the short fiber slurry addition amount based on the solid content or moisture content of the short fiber slurry.

[0043] like Figure 1 As shown, within a treatment cycle, based on the initial color C0, treatment flow rate Q or the treated water volume calculated according to the treatment cycle, and the available dry-based short fiber mass G, the dry-based short fiber refill amount M and the total demand for this batch are calculated. When G meets the total demand for this batch, the short fiber slurry is added normally according to the calculated value M, and the subsequent color enrichment reaction S4 begins. When G is insufficient, the conventional coagulation compensation mode is activated, or the treatment target is adjusted to downgrade and reuse before entering the high-color treatment branch. Wherein, when Q represents the treated water volume for this batch, the total demand for this batch can be determined by M×Q. When Q is obtained in real time by the flow meter, the total demand for this batch can be determined by accumulating or converting Q according to the treatment cycle.

[0044] In one specific embodiment, the amount of dry-based short fibers reintroduced, M, is determined based on 0.6 kg to 1.4 kg of dry-based short fibers per cubic meter of high-chroma wastewater; when the initial color C0 is less than 250 times, the amount of dry-based short fibers reintroduced is 0.6 kg / m³. 3 ~0.9kg / m 3 When the initial color intensity C0 is 250 to 400 times, the dry basis short fiber refeeding amount is 0.9 kg / m². 3 ~1.2kg / m 3 When the initial color intensity C0 is higher than 400 times, the dry basis short fiber refeeding amount is 1.2 kg / m². 3 ~1.4kg / m 3 The above-mentioned return-in volume range can be adjusted according to the type of blanket, wastewater color load, short fiber moisture content, and subsequent filtration status.

[0045] When the available dry-based short fiber mass G is insufficient to meet the minimum refill requirement of the current treatment cycle, the high-chroma wastewater enters the conventional coagulation compensation mode, or the treated reclaimed water is downgraded and reused in the prewashing section, the prewashing of dark batches, or equipment flushing; when the available dry-based short fiber mass G is higher than the amount of dry-based short fiber required for the current treatment cycle, the amount of short fiber slurry added is calculated based on the calculated dry-based short fiber refill amount M, and the corresponding amount of short fiber slurry is added to the high-chroma reaction tank; thus, the amount of dry-based short fiber refill is matched with the pollution load of the high-chroma washing wastewater and the temporary storage status of short fibers on site.

[0046] Step S4: A certain amount of short-pile sizing is added to high-color washing wastewater to carry out a color enrichment reaction, so that residual dyes, auxiliaries and colloidal pollutants are enriched on the surface of the short pile and form color-loaded short-pile flocs.

[0047] Specifically, the short-fiber slurry is added to a high-chroma reaction tank via a metering pump or screw conveyor. The high-chroma reaction tank is equipped with baffles and a low-shear agitator. The stirring speed is 60 r / min to 120 r / min, the reaction temperature is 25℃ to 45℃, and the reaction time is 10 min to 30 min. After the short fibers enter the high-chroma wastewater, some residual dyes, surfactants, and colloidal pollutants accumulate on the surface and between the fibers. Under the action of a small amount of conditioning agent, they form separable color-loaded short-fiber flocs. The purpose of this step is to transform the dispersed dye residues and colloidal pollutants in the high-chroma wastewater into color-loaded flocs that are easier to separate by air flotation, sieving, or precision filtration.

[0048] Step S5: During the color enrichment reaction, the color and turbidity of the supernatant are detected, and the separation timing of the color-carrying short fibers is determined based on the relative change in the slope of color decrease and the change in turbidity.

[0049] Specifically, the color C of the supernatant was measured every 3 to 5 minutes during the color enrichment reaction. t and turbidity T t The colorimetric decrease slope K is calculated for adjacent detection periods. Taking the colorimetric decrease slope K0 at the beginning of the reaction as a reference, when the colorimetric decrease slope K decreases to 10% to 25% of K0 in two consecutive detection cycles, and the turbidity of the supernatant decreases below the set range or shows an upward trend, it is determined that the color-enriched reaction has entered the plateau stage, and then the color-enriched short fiber separation unit is started. Under specific water sample conditions, the empirical slope range corresponding to the above plateau stage can also be determined by beaker test or on-site small test.

[0050] like Figure 2 As shown, after the color enrichment reaction begins, the initial color decrease slope K0 is recorded, and then the color C of the supernatant is obtained at a detection cycle of 3 min to 5 min. t and turbidity T tThe color reduction slope K and K / K0 for the current period are calculated. When K / K0 drops to the set range for two consecutive cycles and the turbidity of the supernatant no longer decreases or increases, the color enrichment reaction is determined to have entered the plateau stage, and the color short fiber separation unit is started. If any of the above conditions are not met, sampling and testing continue according to the detection cycle.

[0051] Step S6: Separate the colored short fiber flocs from the wastewater to obtain decolorized water and colored short fiber scum or filter residue.

[0052] Specifically, the colored short fiber separation unit can employ dissolved air flotation, inclined screen separation, rotary drum filtration, shallow air flotation, sedimentation scraping, or microfiltration separation. In one specific embodiment, the colored short fiber separation unit employs dissolved air flotation, with a dissolved air flotation pressure of 0.25 MPa to 0.38 MPa, a reflux ratio of 10% to 20%, and a flotation residence time of 8 min to 15 min. The colored short fiber scum generated by air flotation enters the sludge thickening and dewatering unit, and the separated decolorized water enters the precision filtration unit. The precision filtration unit can employ a bag filter, a cartridge filter, or a microfiltration membrane module, with a filtration accuracy of 5 μm to 20 μm. In one specific embodiment, a 10 μm cartridge filter is used.

[0053] Step S7: Filter the decolorized water and adjust the dry basis short fiber reintroduction amount or separation triggering conditions for the next treatment cycle based on the filtration pressure difference, turbidity before filtration, short fiber residue, and raw water load changes.

[0054] Specifically, pressure detection points are set at the inlet and outlet of the precision filter unit to detect the filtration pressure difference ΔP, and the turbidity T before filtration is detected at the inlet of the precision filter unit. f and short fiber residue F f The residual amount of short fibers F f The concentration of fine flocs and short fibers remaining in the water before filtration can be determined by an online suspended solids detector, laser particle size analyzer, fiber morphology image analysis device, or offline gravimetric method.

[0055] The increase in filtration pressure difference ΔP after 60 minutes of continuous operation 60 Increased, and the turbidity T before filtration f and short fiber residue F f When the temperature rises synchronously, it is determined that the separation of colored short fibers is insufficient or the amount of dry-based short fibers re-injected is too high. In the next treatment cycle, the amount of dry-based short fibers re-injected is reduced, or the separation of colored short fibers is initiated earlier. When ΔP 60 Increased but turbidity T before filtration f and short fiber residue F fIf there is no significant increase, the cause should be primarily determined to be the filter media fouling cycle, changes in dissolved pollutants in the raw water, or the filter cartridge backwashing status. Initiate filter cartridge backwashing, replacement, or routine coagulation compensation, while maintaining the current dry-basis short fiber refill rate. When ΔP 60 If the color removal rate is low but below the set requirement, the amount of dry-based short fibers re-injected in the next processing cycle should be appropriately increased or the color enrichment reaction time should be extended, but the adjusted amount of dry-based short fibers re-injected should not exceed the upper limit of the re-injection amount determined in step S3.

[0056] like Figure 6 As shown, when ΔP 60 If there is no abnormal increase, maintain the current parameters and continue operating; when ΔP 60 If the turbidity T is abnormally high, further readings should be taken of the turbidity before filtration. f and short fiber residue F f If T f and F f If the synchronous increase is significant, it is judged as insufficient separation or excessive dry-based short fiber refeeding amount, and the dry-based short fiber refeeding amount for the next cycle is reduced or the color-carrying short fiber separation is started earlier; if T f and F f If there is no significant increase in temperature, the primary cause is filter media contamination, changes in dissolved pollutants in the raw water, or abnormal filter cartridge backwashing status. Initiate filter cartridge backwashing, rinsing, replacement, or routine coagulation compensation. Through the above feedback correction, the adjusted parameters will be applied to the next treatment cycle.

[0057] Step S8: The filtered reclaimed water is reused in different washing sections of the blanket printing and dyeing washing line according to the water quality grade.

[0058] Specifically, the filtered reclaimed water enters a reclaimed water storage tank, which is equipped with sensors for color, turbidity, COD, conductivity, and pH. The reclaimed water reuse stage is determined based on these parameters. The increase in filtration pressure differential serves as a feedback parameter for the operational stability of the treatment system and is not used as an indicator of reclaimed water quality. In one specific implementation, the reclaimed water is reused when its color is not higher than 70 times, turbidity is not higher than 30 NTU, COD is not higher than 200 mg / L, and conductivity is not higher than 3500 μS. When the reclaimed water has a color intensity of 100 times, a turbidity of 40 NTU, a COD of 260 mg / L, a conductivity of 5000 μS / cm, and a pH of 6.0 to 9.0, it is reused in the pre-washing section, the pre-washing section for dark-colored batches, or for equipment rinsing. When the reclaimed water quality exceeds the above ranges, it is returned to the high-color treatment branch or enters the plant's integrated wastewater treatment system.

[0059] The above steps S3 to S7 form an interrelated control relationship: the pollution load of high-chroma wastewater and the amount of short fibers temporarily stored affect the amount of dry-based short fibers added back; the amount of dry-based short fibers added back affects the color enrichment reaction and the state of color-based short fiber floc formation; the relative change in the slope of chroma decrease and the change in turbidity affect the timing of color-based short fiber separation; and the subsequent filtration pressure difference, the turbidity before filtration, and the amount of residual short fibers jointly provide feedback on the amount of dry-based short fibers added back or the separation triggering conditions for the next treatment cycle. Through this control relationship, the color-carrying state of short fibers, the floc separation state, the filtration load change, and the stage of reclaimed water reuse in the wastewater of blanket dyeing and printing correspond to each other.

[0060] To verify the effects of the above-mentioned dry-based short fiber refeeding amount, color separation timing, filtration pressure feedback, and segmented reuse on the treatment effect of wastewater from blanket dyeing and finishing, the following experiments are conducted using specific water samples. The test water samples were taken from the mixed wastewater of the dark blanket pre-washing section and soaping section of the blanket dyeing and finishing combined line. The short fibers were taken from the retentate of the pre-washing section of the same washing combined line. The test indicators included color, COD, turbidity, conductivity, short fiber residue, and filtration pressure difference. Unless otherwise specified, each test was repeated 3 times. The data in the table are average values. The test results are used to illustrate the implementation effect of the method of the present invention in typical blanket washing wastewater.

[0061] Example 1

[0062] This embodiment illustrates the impact of the amount of dry-based short fibers reintroduced on the decolorization effect and subsequent filtration load of high-color blanket washing wastewater; the mixed wastewater from the soaping section and pre-washing section of dark blue blankets is taken as the high-color treatment target, with a treatment volume of 1.0 m³. 3 The batch had a raw water color of 336 times, COD of 812 mg / L, turbidity of 96.5 NTU, pH of 7.8, conductivity of 3260 μS / cm, and water temperature of 34℃. After short fibers were intercepted by a 120-mesh inclined sieve, squeezed for dewatering, and sieved, the moisture content was 88.6%, and the average length of the dry-based short fibers was mainly distributed between 0.4 mm and 2.8 mm. After the short fibers were dispersed in low-color rinsing water, the pH was adjusted to 7.2, and cationic polyacrylamide with a calculated dosage of 0.8 mg / L was added. Different dry-based short fibers were added to high-color wastewater and reacted for 20 min at a stirring speed of 90 r / min. Then, dissolved air flotation was used to separate the colored short fiber flocs, followed by 10 μm precision filtration. The treatment effect was tested, and the results are shown in Table 1. The 0 g / L group was the blank control group, which did not add short fiber slurry but maintained the same stirring time, pH conditions, and subsequent air flotation filtration conditions.

[0063] Table 1. Effects of different dry-based short fiber refeed amounts on the treatment effect of high-color washing wastewater

[0064] 0 194 42.3 22.0 19.5 0.052 0.5 132 60.7 32.6 22.8 0.041 0.8 92 72.6 40.8 25.9 0.034 1.1 74 78.0 44.5 31.7 0.037 1.4 63 81.3 47.2 38.6 0.050 1.8 56 83.3 48.0 47.5 0.068

[0065] As shown in Table 1, under the conditions of this embodiment, when the amount of dry-based short fiber added increased from 0 g / L to 0.8 g / L and 1.1 g / L, the color removal rate significantly improved, and the increase in filtration pressure difference over 60 minutes was lower than that of the 0 g / L blank control group. This may be because after the addition of an appropriate amount of short fiber, some dispersed dye residues and colloidal pollutants formed color-carrying flocs that were easier to separate by air flotation, thereby improving the subsequent filtration influent conditions. When the amount of dry-based short fiber added continued to increase to 1.4 g / L and 1.8 g / L, the color removal rate still improved, but the effluent turbidity and the increase in filtration pressure difference increased simultaneously, indicating that excessively high dry-based short fiber added amounts may increase the fine fiber residue and floc separation load. Under the conditions of this water sample, when the amount of dry-based short fiber added was controlled between 0.8 g / L and 1.1 g / L, the decolorization effect and filtration stability were relatively coordinated.

[0066] Figure 3 The trends of color removal rate, effluent turbidity, and 60-minute filtration pressure differential increase are shown under different dry-basis short fiber refeed amounts; combined with Table 1 and Figure 3 It can be seen that as the amount of dry-based short fiber added increases, the overall color removal rate increases, but the rate of increase gradually slows down; the effluent turbidity increases with the increase of the amount of dry-based short fiber added, indicating that when the amount of short fiber added is excessive, the separation unit needs to bear more residual load of fine short fibers and flocs; the increase in filtration pressure difference over 60 minutes shows a trend of first decreasing and then increasing, reaching a low level around 0.8 g / L, and then increasing significantly after 1.4 g / L; this trend further illustrates that in this embodiment, the range of 0.8 g / L to 1.1 g / L can balance decolorization efficiency and filtration stability, rather than the higher the amount of dry-based short fiber added, the more beneficial it is.

[0067] Example 2

[0068] This embodiment illustrates the color change pattern of the supernatant during the color enrichment reaction and the basis for judging the separation timing. The high-color washing wastewater from Example 1 was used, with a dry basis short fiber reintroduction amount of 1.0 g / L, a stirring speed of 90 r / min, a reaction temperature of 34℃, and samples were taken every 5 min. After sampling, the supernatant was allowed to stand for 2 min to detect the color and turbidity, and the color decrease slope of adjacent time periods was calculated. The results are shown in Table 2.

[0069] Table 2. Changes in color and turbidity of the supernatant during the short-fiber coloring process with reaction time.

[0070] 0 336 — 96.5 5 225 22.2 42.6 10 158 13.4 34.1 15 118 8.0 29.7 20 87 6.2 27.4 25 80 1.4 28.8 30 77 0.6 31.2

[0071] As shown in Table 2, the color of the supernatant decreased rapidly within the first 20 minutes after the addition of short fibers to the high-chroma wastewater, indicating that dye residues, auxiliaries, and colloidal contaminants may continue to accumulate in the short fibers and the flocs they form. After 20 minutes of reaction, the slope of the color decrease decreased significantly, and after 25 minutes, the slope of the color decrease was about 6.3% of the slope of the color decrease at the beginning of the reaction. At the same time, the turbidity of the supernatant increased from 27.4 NTU to 28.8 NTU, indicating that continuing to extend the reaction time has little contribution to the color decrease, while the fine flocs or short fiber residues tend to increase. Under the water sample conditions of this embodiment, when the slope of the color decrease decreases to less than about 10% of that at the beginning of the reaction within two consecutive detection cycles, accompanied by a rebound in turbidity, it can be used as a criterion for judging whether the colored short fiber flocs enter the separation process.

[0072] Figure 4 The trends of color and turbidity of the supernatant during the enrichment process are shown; combined with Table 2 and Figure 4 It can be seen that the color of the supernatant decreased from 336 times to 87 times in the 0-20 min range, with a relatively obvious downward trend. After 20 min, the rate of decrease slowed significantly, decreasing to only 80 times and 77 times at 25 min and 30 min, respectively. The turbidity of the supernatant decreased rapidly from 96.5 NTU to 27.4 NTU at 20 min, and then rebounded to 28.8 NTU and 31.2 NTU at 25 min and 30 min, respectively. Therefore, Figure 4 The 20-25 minute interval can be used as the recommended separation window under the water sample conditions in this embodiment, which is consistent with the logic of judging the separation timing based on K / K0 and turbidity changes in step S5.

[0073] Example 3

[0074] This embodiment compares the treatment effects of different treatment methods on high-chroma blanket washing wastewater. High-chroma washing wastewater from the same source was subjected to direct precision filtration, conventional coagulation filtration, filtration after short-fiber synergistic decolorization, and air flotation re-filtration after short-fiber synergistic decolorization. Direct precision filtration used a 10μm filter cartridge, conventional coagulation filtration used 120mg / L polyaluminum chloride and 1.0mg / L anionic polyacrylamide, and in the short-fiber synergistic decolorization method, the dry basis short fiber re-addition amount was 1.0g / L, and the cationic polyacrylamide equivalent addition amount was 0.8mg / L. The endpoint of the color enrichment reaction was determined based on the relative change in the slope of color decrease. The test results are shown in Table 3.

[0075] Table 3 Comparison of treatment effects of different treatment methods

[0076] Direct precision filtration 215 36.0 18.5 0 0.121 Conventional coagulation filtration 112 66.7 37.1 121.0 0.058 Short-fiber synergistic decolorization followed by filtration 78 76.8 42.9 0.8 0.049 Short fiber synergistic decolorization followed by air flotation and refiltration 62 81.5 48.4 0.8 0.034

[0077] As shown in Table 3, direct precision filtration has limited removal of color and COD, and the filtration pressure difference increases rapidly. This may be because some short fibers, dye colloids, and auxiliary pollutants directly enter the filter element surface and form a contamination layer. Conventional coagulation filtration has a certain decolorization effect, but the dosage of added chemicals is relatively high. Filtration after short fiber synergistic decolorization can improve the color removal rate and reduce the increase in filtration pressure difference. When an air flotation separation step is added after short fiber synergistic decolorization, the color removal rate increases to 81.5%, and the filtration pressure difference increase at 60 min decreases to 0.034 MPa, indicating that the separation of colored short fiber flocs before entering precision filtration helps to reduce the subsequent filtration load. The amount of conditioning agent added in the short fiber synergistic decolorization group is mainly used for short fiber dispersion and colored floc formation, and its dosage is lower than that in the conventional coagulation filtration group.

[0078] Figure 5 The comparison of color removal rate and 60-minute filtration pressure difference increase under different treatment methods is shown; combined with Table 3 and Figure 5 It can be seen that direct precision filtration has the lowest color removal rate and the highest 60-minute filtration pressure difference increase, indicating that relying solely on precision filtration is difficult to stably treat high-color washing wastewater containing short fibers and dye colloids. Conventional coagulation filtration can improve the color removal rate and reduce the pressure difference, but the dosage of added chemicals is relatively high. Filtration after short fiber synergistic decolorization and air flotation refiltration after short fiber synergistic decolorization both showed higher color removal rates and lower filtration pressure difference increases. Among them, air flotation refiltration after short fiber synergistic decolorization had the highest color removal rate and the lowest filtration pressure difference increase, indicating that separating the colored short fiber flocs before precision filtration is beneficial to simultaneously improve the decolorization effect and filtration stability.

[0079] Example 4

[0080] This embodiment illustrates the water quality stability and reuse stage determination method of the present invention in continuous treatment cycles; it processes high-chroma wastewater from a blanket dyeing and finishing line for five consecutive treatment cycles, with a treatment volume of 1.0 m³ per cycle. 3 The original water had a color of 318 to 374 times and a COD of 760 mg / L to 858 mg / L. The system controlled the amount of dry-based short fibers added back to 0.9 g / L to 1.2 g / L based on the original water color and the amount of short fibers temporarily stored. The system also triggered the separation of colored short fibers based on the relative change in the slope of the color decrease. The decolorized water after separation was filtered through a 10 μm precision filter and then entered the reclaimed water storage tank. The test results are shown in Table 4.

[0081] Table 4. Reclaimed water quality and reuse stages during continuous treatment cycles.

[0082] 1 336 1.0 62 26.4 176 3180 7.3 Mid-section washing 2 318 0.9 67 28.1 188 3260 7.4 Mid-section washing 3 374 1.2 82 36.5 245 3860 7.5 Pre-wash section hydration 4 342 1.0 69 27.0 190 3320 7.3 Mid-section washing 5 361 1.1 64 28.4 185 3410 7.4 Mid-section washing

[0083] As shown in Table 4, over five consecutive treatment cycles, the reclaimed water exhibited a color intensity of 62 to 82 times, a turbidity of 26.4 NTU to 36.5 NTU, a COD of 176 mg / L to 245 mg / L, and a conductivity of 3180 μS / cm to 3860 μS / cm. In the third cycle, the raw water had higher color intensity and COD, and the treated reclaimed water also showed corresponding increases in color intensity, turbidity, and COD. Therefore, it was reused for pre-washing replenishment rather than mid-washing. This result indicates that under the experimental conditions, segmented reuse based on color intensity, turbidity, COD, conductivity, and pH can allow the reclaimed water to be used in washing stages that are compatible with its water quality.

[0084] Example 5

[0085] This embodiment illustrates the impact of matching the short fiber storage capacity with the pollution load of high-chroma wastewater on the treatment strategy. Different batches of blanket washing wastewater were selected, and treatment conditions A, B, C, and D were set up respectively. Condition A represents the treatment state where the high-chroma wastewater load matches the available dry-basis short fiber quantity; Condition B represents the treatment state where the high-chroma wastewater load is high but the available dry-basis short fiber quantity is insufficient; Condition C represents the treatment state where the raw water color is low but the on-site short fiber storage capacity is large; and Condition D represents the treatment state where the raw water color is low. The treatment state is characterized by high viscosity and insufficient short fibers to reach the theoretical upper limit of demand. The raw water color, COD, and current available dry-based short fiber content are measured under each working condition, and the theoretical dry-based short fiber refill amount is determined according to step S3. When the available dry-based short fiber content is lower than the theoretical dry-based short fiber refill amount, the treatment is carried out by reducing the reuse stage or supplementing with conventional coagulation. When the available dry-based short fiber content is higher than the theoretical dry-based short fiber refill amount, the treatment is carried out according to the theoretical dry-based short fiber refill amount. The test results are shown in Table 5.

[0086] Table 5. Matching Test of Short Fiber Temporary Storage Capacity and High-Color Wastewater Load

[0087] Raw water color / time 320 365 238 428 <![CDATA[COD / mg·L -1 ]]> 785 842 602 910 <![CDATA[Theoretical dry basis short fiber return amount / g·L -1 > 1.0 1.2 0.7 1.4 <![CDATA[Available dry base short fiber amount / g·L -1 > 1.4 0.7 1.6 1.1 <![CDATA[Actual dry base short fiber return amount / g·L -1 > 1.0 0.7 0.7 1.1 Processing strategy Reinvestment as needed Supplement with PAC 40 mg / L and downgrade for reuse. Low-load reconnection Extend the residence time of air flotation and degrade for reuse Water color (in times) 68 96 74 104 Reuse destination Mid-section washing Pre-wash section hydration Pre-wash section hydration Equipment flushing

[0088] As shown in Table 5, when the available dry-based short fiber quantity matches the high-chroma wastewater load, such as in Condition A, the treated effluent can meet the conditions for mid-stage washing and reuse. When the high-chroma wastewater load is high and the available dry-based short fiber quantity is insufficient, such as in Conditions B and D, the effluent color is still high after only adding the available dry-based short fiber quantity. Therefore, it is more prudent to supplement with a small amount of coagulation or downgrade for reuse. When the raw water color is low but the available dry-based short fiber quantity is high, such as in Condition C, only the short fiber needs to be added according to the low load requirement, and there is no need to increase the short fiber dosage. This result indicates that the dry-based short fiber addition amount should not be a fixed value, but should be determined in combination with the wastewater load and the short fiber temporary storage status.

[0089] Example 6

[0090] This embodiment illustrates the role of filtration differential pressure feedback in correcting parameters for the next treatment cycle. A continuous operation test was conducted using high-chroma blanket washing wastewater from adjacent treatment cycles. The raw water chroma, dry-based short fiber refeeding amount, pre-filtration turbidity, short fiber residue, and 60-minute filtration differential pressure increase were measured for each cycle. When the filtration differential pressure increase increased in a certain cycle, accompanied by increases in pre-filtration turbidity and short fiber residue, the dry-based short fiber refeeding amount was reduced in the next cycle, and the colored short fiber separation was initiated earlier. The results are shown in Table 6.

[0091] Table 6 Filter Pressure Differential Feedback Correction Test

[0092] Raw water color / time 342 368 356 347 351 349 <![CDATA[Dry-based short fiber recycle dosage / g·L -1 > 1.1 1.2 1.0 1.0 1.0 1.0 Separation trigger condition <![CDATA[K≤20%K0]]> <![CDATA[K≤20%K0]]> <![CDATA[K≤25%K0]]> <![CDATA[K≤25%K0]]> <![CDATA[K≤25%K0]]> <![CDATA[K≤25%K0]]> Turbidity before filtration / NTU 33.4 48.6 36.2 32.7 31.9 32.5 <![CDATA[Residual short velvet content / mg·L -1 > 19.2 35.8 23.5 21.4 20.6 20.9 <![CDATA[ΔP 60 / MPa]]> 0.039 0.069 0.044 0.040 0.066 0.038 Water color (in times) 66 64 72 69 70 68 Operation adjustment maintain Triggering correction Run after correction maintain Backwash the filter cartridge and maintain the current dry-based short fiber refill rate. Recovery after backwashing

[0093] As shown in Table 6, the pressure difference increase in the second cycle reached 0.069 MPa, while the turbidity and short fiber residue before filtration increased to 48.6 NTU and 35.8 mg / L, respectively. This indicates that the pressure difference increase in this cycle may be related to insufficient separation of the colored short fiber or an excessive amount of dry-based short fiber refill. In the third cycle, the amount of dry-based short fiber refill was adjusted from 1.2 g / L to 1.0 g / L, and the separation trigger condition was adjusted from K≤20%K0 to K≤25%K0. The turbidity before filtration, the amount of short fiber residue, and the pressure difference increase all decreased, indicating that this feedback correction method is effective in reducing the subsequent filtration load. In the fifth cycle, the pressure difference increase reached 0.066 MPa, but the turbidity and short fiber residue before filtration did not increase significantly. After backwashing the filter cartridge, the pressure difference recovered in the sixth cycle, indicating that the increase in the pressure difference is not necessarily caused by the amount of dry-based short fiber refill; it needs to be judged in conjunction with the turbidity and short fiber residue before filtration.

[0094] Figure 6 The feedback correction logic for filtration differential pressure, pre-filtration turbidity, and short fiber residue is shown; combined with Table 6 and Figure 6 It can be seen that when ΔP 60 Abnormally high and T f F f When the temperature rises synchronously, the system prioritizes attributing the anomaly to insufficient separation of colored short fibers or excessive dry-based short fiber refeeding, and reduces the subsequent filtration load by lowering the dry-based short fiber refeeding amount in the next cycle, starting colored short fiber separation earlier, or adjusting the K / K0 threshold; when ΔP 60 Abnormally elevated but T f F f When the pressure is not increased synchronously, the system maintains the current dry-based short fiber return rate and prioritizes initiating filter backwashing, flushing, replacement, or routine coagulation compensation; thus, Figure 6 Together with Table 6, this method does not simply rely on the filtration pressure difference for adjustment, but rather uses ΔP 60 T f and F f The combined judgments enable feedback correction for the next processing cycle.

[0095] In the above embodiments, the high-color wastewater can be dark-colored blanket soaping wastewater, pre-wash wastewater after printing, or batch switching rinsing wastewater. The short fibers can originate from the pre-wash section, soaping section, or centralized fiber-containing wastewater interception unit of the same blanket printing and dyeing washing line. The method of separating the colored short fibers is not limited to dissolved air flotation, but can also use inclined screen, rotary drum filtration, shallow air flotation, sedimentation scraping, or a combination of microfiltration. The precision filtration unit is not limited to cartridge filters, but can also use bag filters or microfiltration membrane modules. The location of the reclaimed water reuse can be selected according to the actual layout of the enterprise's washing line, such as pre-wash section water replenishment, post-soaping rinsing water replenishment, pre-wash water replenishment for dark batches, or equipment rinsing water.

[0096] In this embodiment, the short fiber interception unit, short fiber temporary storage tank, conditioning tank, high colorimetric reaction tank, colored short fiber separation unit, precision filtration unit, and reclaimed water temporary storage tank can be linked and controlled by a PLC or field controller. The online colorimetric detector, turbidity detector, flow meter, pressure sensor, and short fiber residue detection point transmit detection data to the controller. The controller controls the short fiber metering pump, air flotation return pump, sludge discharge valve, and reclaimed water reuse valve according to the preset dry basis short fiber return amount range, colorimetric decrease slope relative threshold, filtration pressure difference threshold, pre-filtration turbidity threshold, and short fiber residue threshold. In the absence of an automatic control system, this method can also be implemented by manual sampling and manual adjustment.

[0097] Through the above steps, a closed-loop feedback control relationship is formed between the dry-based short fiber refeeding amount, the state of the color enrichment reaction, the state of the color-enriched short fiber separation, the filtration load change, and the reclaimed water reuse stage. During the treatment process, the pollution load of high-chroma wastewater and the short fiber temporary storage amount are used to determine the dry-based short fiber refeeding amount. The relative change in the chroma decrease slope and turbidity change in the color enrichment reaction are used to determine the separation timing. The subsequent filtration pressure difference, the turbidity before filtration, and the short fiber residue are used to correct the process parameters for the next treatment cycle. The treated reclaimed water enters the appropriate washing stage according to the chroma, turbidity, COD, conductivity, and pH, thereby realizing industrial water saving and wastewater reuse in the carpet printing and dyeing washing line.

[0098] The technical scope of this invention is not limited to the content described above. Those skilled in the art can make various modifications and variations to the above embodiments without departing from the technical concept of this invention, and all such modifications and variations should fall within the protection scope of this invention.

Claims

1. A method for the industrial water-saving recycling of wastewater from a combined blanket printing and dyeing washing line, characterized in that, Includes the following steps: Step 1: Short fibers are intercepted from the wastewater containing fibers discharged from the carpet printing and dyeing washing line. The short fibers are then screened, dewatered, and wet-conditioned to make short fiber slurry. At the same time, the usable dry basis short fiber quality of this treatment cycle is determined. Step 2: Detect the initial color and treatment flow rate or treatment volume of the high-color washing wastewater to be treated. Based on the initial color, treatment flow rate or treatment volume and the available dry basis short fiber mass for this treatment cycle, determine the amount of dry basis short fiber to be recycled for this treatment cycle. Step 3: Calculate the amount of short fiber slurry to be added based on the amount of dry-based short fiber recycled, and add the corresponding amount of short fiber slurry to the high-color washing wastewater for a color enrichment reaction, so that the residual dyes, auxiliaries and colloidal pollutants in the high-color washing wastewater are enriched in the short fibers and form color-loaded short fiber flocs. Step 4: During the color enrichment reaction, the color and turbidity of the supernatant are detected. Based on the change in the slope of color decrease relative to the initial slope of color decrease and the change in the turbidity of the supernatant, the separation triggering conditions of the color-carrying short fibers are determined. Step 5: After the separation triggering conditions are met, the colored short fibers are separated, and the decolorized water after separation is filtered to obtain reclaimed water. Step 6: Based on the increase in filtration pressure difference, turbidity before filtration, and residual short fibers during the filtration process, the amount of dry short fibers to be reintroduced or the separation triggering conditions for the next treatment cycle are adjusted accordingly. The reclaimed water is then reused in the corresponding washing section of the blanket printing and dyeing washing line based on the quality of the reclaimed water.

2. The method for industrial water-saving wastewater reuse in a combined blanket printing and dyeing washing line according to claim 1, characterized in that, In step one, the down-containing wastewater comes from the pre-washing section, soaping section, or pre-washing section of the blanket printing and dyeing washing line, or the short down obtained from the batch of dark blankets. The short down is temporarily stored in the short down storage tank.

3. The method for industrial water-saving wastewater reuse in a combined blanket printing and dyeing washing line according to claim 1, characterized in that, In step one, after the short fibers are screened and dewatered, they are wet-conditioned by adding low-color recycled water or intermediate rinsing water to make the solid content of the short fiber slurry 1.5% to 4.0%.

4. The method for industrial water-saving wastewater reuse in a combined blanket printing and dyeing washing line according to claim 3, characterized in that, In step one, a conditioning agent is added to the short-fiber slurry during wet conditioning. The conditioning agent is cationic polyacrylamide or a compound system of polyaluminum chloride and cationic polyacrylamide. The amount of conditioning agent added is calculated based on the volume of high-color washing wastewater to be treated entering the high-color reaction tank.

5. The method for industrial water-saving wastewater reuse in a combined blanket printing and dyeing washing line according to claim 1, characterized in that, In step two, when the initial color intensity is less than 250 times, the amount of dry-based short fibers recycled is 0.6 kg to 0.9 kg of dry-based short fibers per cubic meter of high-color washing wastewater; when the initial color intensity is 250 to 400 times, the amount of dry-based short fibers recycled is 0.9 kg to 1.2 kg of dry-based short fibers per cubic meter of high-color washing wastewater; when the initial color intensity is greater than 400 times, the amount of dry-based short fibers recycled is 1.2 kg to 1.4 kg of dry-based short fibers per cubic meter of high-color washing wastewater.

6. The method for industrial water-saving wastewater reuse in a combined blanket printing and dyeing washing line according to claim 5, characterized in that, In step two, when the available dry-based short fiber mass of this treatment cycle is insufficient to meet the minimum refill requirement of the current treatment cycle, conventional coagulation compensation treatment is performed on the high-color washing wastewater, or the treated reclaimed water is downgraded and reused in the pre-washing section, the pre-washing section of the dark batch, or equipment flushing; when the available dry-based short fiber mass of this treatment cycle is higher than the amount of dry-based short fiber required for the current treatment cycle, the amount of short fiber slurry added is calculated based on the determined amount of dry-based short fiber refill.

7. The method for industrial water-saving wastewater reuse in a combined blanket printing and dyeing washing line according to claim 1, characterized in that, In step three, after the short-fiber slurry is added to the high-color reaction tank, it is mixed and reacted with high-color washing wastewater under stirring conditions, so that residual dyes, surfactants and colloidal pollutants are enriched on the surface of the short fibers and in the gaps between fibers, forming separable color-carrying short-fiber flocs.

8. The method for industrial water-saving wastewater reuse in a combined blanket printing and dyeing washing line according to claim 1, characterized in that, In step four, the color and turbidity of the supernatant are detected according to the set detection cycle, and the color decrease slope of adjacent detection periods is calculated. When the color decrease slope in two consecutive detection cycles decreases to 10% to 25% of the color decrease slope in the initial stage of the reaction, and the turbidity of the supernatant decreases below the set range or shows an upward trend, it is determined that the separation trigger condition of the colored short fibers has been met.

9. The method for industrial water-saving wastewater reuse in a combined blanket printing and dyeing washing line according to claim 1, characterized in that, In step five, at least one of the following methods is used to separate the colored short fibers: air flotation, sieving, sedimentation, drum filtration, or microfiltration. The decolorized water after separation enters a precision filtration unit for filtration treatment.

10. The method for industrial water-saving wastewater reuse in a combined blanket printing and dyeing washing line according to claim 1, characterized in that, In step six, when the increase in filtration pressure difference reaches or exceeds the set pressure difference threshold, and the turbidity and short fiber residue before filtration reach or exceed the corresponding threshold, it is determined that the separation of colored short fiber flocs is insufficient or the amount of dry-based short fiber fed back is too high. In the next treatment cycle, the amount of dry-based short fiber fed back is reduced or the separation of colored short fiber flocs is started in advance. When the increase in filtration pressure difference reaches or exceeds the set pressure difference threshold, but the turbidity and short fiber residue before filtration do not reach the corresponding threshold at the same time, filter cartridge backwashing, replacement, or conventional coagulation compensation is started, and the current amount of dry-based short fiber fed back is maintained. The water quality grade of the filtered reclaimed water is determined according to color, turbidity, COD, conductivity, and pH, and it is reused in the corresponding washing section of the blanket printing and dyeing washing line.

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