CN201864630U - Zero-discharge device for treating printing and dyeing wastewater - Google Patents

Abstract

A zero-discharge device for printing and dyeing wastewater treatment. The treatment object is high-concentration and high-salt printing and dyeing wastewater discharged by quality. The system includes three parts: physical and chemical pretreatment, RO desalination system and concentrated water treatment. Physical and chemical pretreatment includes three parts: coagulation sedimentation, sedimentation tank and UF; the RO system is divided into two stages of low pressure and high pressure. The fresh water of the first-stage and second-stage reverse osmosis is mixed as the final effluent of the system, which can be reused in some sections; the concentrated water of the second-stage reverse osmosis enters the membrane distillation system, and the concentrated water is distilled by using the waste heat of the low-concentration water discharged by separation to obtain a saturated solution. Finally, distilled water and solid salt are obtained through condensation and crystallization. The system is an energy-saving, environmentally friendly, low-carbon new printing and dyeing wastewater treatment process, which can achieve zero discharge and provide a new solution for the treatment of high-concentration and high-salt printing and dyeing wastewater.

Description

A zero discharge device for printing and dyeing wastewater treatment

Technical field:

The utility model belongs to the field of environmental protection and waste water treatment, in particular to a zero-discharge device for treating high-concentration and high-salt printing and dyeing waste water. the

Background technique:

The printing and dyeing industry not only consumes a lot of water but also is a major player in the drainage industry, accounting for about 35% of the total industrial drainage. Dyeing wastewater has the highest salt content in printing and dyeing wastewater. High-salt dyeing wastewater accounts for about 20% of the total water volume, and the salt content accounts for 70% to 80% of the total salt content. Printing and dyeing wastewater has a large amount of discharge, complex components, high concentration of pollutants, and high salt content. 10,000 tons of wastewater usually contains 40t-50t of salt, and contains both monovalent and divalent salts. the

The common treatment methods of printing and dyeing wastewater can be divided into three categories: physical method, chemical method and biological method. Physical methods mainly include grids and screens, regulation, precipitation, air flotation, filtration, membrane technology, etc. Chemical methods include neutralization, coagulation, electrolysis, oxidation, adsorption, disinfection, etc. Biological methods include anaerobic biological methods, good Oxybiological method, facultative biological method. At present, domestic printing and dyeing wastewater treatment methods are mainly biological methods, supplemented by physical and chemical methods. Due to the development of chemical fiber fabrics and the progress of printing and dyeing finishing technology in recent years, a large number of refractory organic substances such as new dyes, PVA sizing, and new additives have entered the printing and dyeing wastewater, making the treatment more difficult. The COD removal rate of the original biological treatment system mostly dropped from the original 70% to about 50%, or even lower. The removal of chroma is a major problem in the treatment of printing and dyeing wastewater, and the old biochemical methods have not been satisfactory in terms of decolorization. In addition, the COD caused by chemical slurry such as PVA accounts for a considerable proportion of the total COD of printing and dyeing wastewater, but because they are difficult to be utilized by common microorganisms, the removal rate is only 20% to 30%. Aiming at the above problems, some research work has been carried out at home and abroad. the

Cotton printing and dyeing wastewater has two basic characteristics: it contains high chroma, high chemical oxygen demand, low biochemical oxygen demand, and high pH; second, it has high salt content, which is characterized by high conductivity. Treatment of high chroma, high chemical oxygen demand, low biochemical oxygen demand sewage eliminates the common biological oxidation scheme. the

Utility model content:

The utility model is suitable for treating difficult-to-treat printing and dyeing wastewater with high COD content and high salt content, can make up for the defect that conventional biological treatment is difficult to deal with high-concentration and high-salt printing and dyeing wastewater, and can concentrate the salt in the printing and dyeing wastewater into solid salt to realize printing and dyeing The waste water is zero-discharged, and the effluent water quality is good. Not only can it be reused in some sections of the printing and dyeing process, saving water, but it also solves the problem of difficult treatment of concentrated water in conventional membrane separation systems. The utility model device includes three parts: physical and chemical pretreatment, RO desalination system and concentrated water treatment. The physical and chemical pretreatment includes three parts: coagulation and sedimentation 11, sedimentation tank 12 and UF13. The corrosion-resistant self-priming pump M1 is used to directly take the raw water from the printing and dyeing workshop assembly line to the adjustment tank 1 for cooling and cooling, and the PAM dosing pump M3, the PAC dosing pump M4, the decolorant dosing pump M5, and the pH regulator dosing pump M6 sequentially adds pH regulator, decolorizer, PAC, PAM before pump M2, and the liquid medicine mixture enters the coagulation settling tank 11, and the supernatant enters the inclined plate sedimentation tank 12 through the overflow weir 18. The feed liquid is further separated and settled in the inclined plate sedimentation tank 12, and the supernatant liquid is collected through a perforated water collection pipe and enters the ultrafiltration intermediate water tank 6 by gravity. The ultrafiltration membrane adopts the domestic large-flux anti-pollution tubular ultrafiltration membrane module 13, adopts the form of cross-flow filtration, 10% concentrated water is returned to the adjustment tank 1, and the remaining concentrated water is circulated externally, and the effluent accounting for 50% of the treatment requirements enters the first stage RO circulation barrel 8. the

The RO system is divided into first and second stages. The raw water in the first-stage RO circulation tank enters the first-stage reverse osmosis device 14 through the security filter 20, and the first-stage reverse osmosis concentrated water accounting for 50% of the treatment capacity enters the second-stage high-pressure reverse osmosis circulation tank 9 , as the water intake of the secondary RO system 15, the primary and secondary reverse osmosis fresh water are mixed into the clean water tank 10 as the final system outlet water, which can be reused in some sections; the secondary reverse osmosis high concentration water accounting for 25% of the treatment capacity enters Membrane distillation system 16. the

Membrane distillation system 16 adopts the internationally advanced porous hydrophobic hollow fiber distillation membrane, and utilizes the low-concentration water waste heat discharged from the mass separation to distill the concentrated water to obtain a saturated solution. Finally, distilled water and solid salt are obtained through condensation and crystallization. the

The theoretical basis of the utility model:

The utility model adopts the chemical coagulation method to solve the problems of high chroma, low biodegradability sewage, color reduction and CODcr, and the high salinity water adopts the reverse osmosis membrane method to desalinate, which improves the recovery rate of waste water. In order to meet the requirement of restricting particles in the water when the RO membrane enters the water, an ultrafiltration unit is added before entering the RO. the

Now the research and application of RO is increasingly known by the water treatment industry. The construction and long-term practical operation of many successful seawater desalination plants have proved that this is an increasingly mature technology, so it is the preferred process technology for treating high-salinity water. . It is still a thorny problem to use RO technology for high-salinity wastewater carrying a large amount of chromaticity and chemical oxygen demand components. The service life is shortened and the cost is increased. Therefore, the pre-treatment of this system minimizes the concentration of pollutants entering the RO membrane, and the subsequent process mainly relies on hydraulic cleaning, chemical cleaning and adding antiscalants to alleviate the attenuation of the membrane flux. the

In order to reduce the organic pollution of subsequent RO membranes, COD, chroma, and turbidity should be removed as much as possible in the pretreatment, and a reasonable process condition for staged treatment should be created to ensure the normal operation of the equipment. In the printing and dyeing industry, reactive dyes and shihlin dyes are commonly used now. After the dyes are dissolved in water, they exist in the form of colloids and ions in large quantities. These colloid particles are small and negatively charged. Many printing and dyeing factories use dyes according to orders. Production batches, it is important for wastewater treatment relations. The removal of these organic substances in water is related to the pH value of the water. The types, dosage, combination and proportion of the flocculant and polymer decolorizer are related to the effect of removing chroma and removing COD. Therefore, we have designed a coagulation sedimentation reactor and inclined plate reactor, the hydraulic conditions were calculated to verify the results. the

Some research results believe that the removal of residual dyes is related to the pH of the water, and the optimal ratio composition of high-efficiency decolorization and decontamination polymer flocculants (coagulation aids) and inorganic polymer coagulants can remove most of the chroma and COD. the

This system uses tubular ultrafiltration membranes. Although the membrane price is higher than that of hollow fiber membranes, hollow fiber membranes have high requirements for pretreatment, especially in the pretreatment of high-salt and high-concentration wastewater. The characteristics are unmatched by hollow membranes, and the use of tubular membranes can ensure long-term, stable and reliable operation of the entire wastewater treatment system! Greatly reduces membrane replacement costs and cleaning costs. From the comprehensive benefit analysis of equipment investment and operating costs, tubular membranes are cost-effective in the treatment of high-concentration wastewater. The application of large-flux ultrafiltration membrane can also help to remove residual turbidity and colloids, so that the pre-treatment can not only meet the SDI index of RO influent, but also reduce the subsequent organic pollution carried by RO, so that the whole system tends to Reasonable, the distribution of decolorization and decontamination shares is more conducive to operation and the functions of each unit are more prominent. the

The treatment effect of the utility model:

When the average conductivity of the influent water is 17581μs·cm-1, the average CODcr is 829mg/L, and the average chromaticity is 1709cu, the average conductivity of the water outlet through the system of the utility model is 642μs.cm-1, the average CODcr of the effluent is 44mg/L, and the effluent is turbid The average chromaticity of the effluent is 0.1NTU, the average chromaticity of the effluent is 2.5cu, and the removal rates are 96.35%, 95.3%, 99.7%, and 99.5%, which meet the water quality requirements for farmland irrigation in country A. Under certain conditions, it can be considered as industrial water recycling use. the

The utility model system has the characteristics of low investment, low operating cost, small floor space, safety, stability, reliability, low personnel operating costs and equipment maintenance costs, and can also recover energy from the concentrated solution to further reduce operating costs . the

The utility model system is suitable for the treatment of high-concentration and high-salt printing and dyeing wastewater in the cotton dyeing industry, and is of great significance to saving water resources. It can use its own rich cotton resources and relatively cheap power resources for plateau saline-alkali areas (such as Xinjiang, etc.) where water resources are relatively tight. , The introduction of printing and dyeing enterprises with large water demand has opened up a new way out. the

Description of drawings:

Fig. 1 is a processing schematic diagram of the processing system of the present invention. the

Parts, parts and numbers in the figure: water intake pump M1, lift pump M2, PAM dosing pump M3, PAC dosing pump M4, decolorizer dosing pump M5, pH regulator dosing pump M6, ultrafiltration circulation pump M7, Primary RO booster pump M8, secondary RO booster pump M9, regulating tank 1, PAM medicine tank 2, PAC medicine tank 3, decolorizer tank 4, pH regulator tank 5, ultrafiltration circulation pool 6, cleaning circulation pool 7. Primary RO circulation pool 7, secondary RO circulation pool 9, clear water pool 10, coagulation settling tank 11, inclined plate sedimentation tank 12, ultrafiltration equipment 13, primary RO equipment 14, secondary RO equipment 15, membrane Distillation equipment 16, coagulation settling tank side square area 17, overflow weir 18, inclined plate 19, security filter 20

Fig. 2 is a schematic diagram of the operation of the inner membrane distillation system of the treatment system of the present invention. the

Detailed ways:

The operation of the system of the present utility model will be further described below through specific embodiments in conjunction with the accompanying drawings. the

Example: This system is used to treat high-concentration and high-salt printing and dyeing wastewater from cotton dyeing. The corrosion-resistant self-priming pump M1 is used to directly take raw water from the printing and dyeing workshop assembly line. When taking water, record the type of dye used, and at the same time test the conductivity on site and pay attention to adjusting the water intake valve. Size, try to ensure the conductivity of the raw water taken to ensure the concentration multiple. the

Raw water enters the coagulation settling tank 11 through the lifting pump M2, before the lifting pump M2 passes through the PAM dosing pump M3, the PAC dosing pump M4, the decolorant dosing pump M5, and the pH regulator dosing pump M6 before the pump M2. Add pH regulator, decolorizer, PAC, PAM. The industrial hydrochloric acid with a mass fraction of 33% and water are prepared at a volume ratio of 1:2. According to the pH value of the influent, the dosing amount is 6-23L/h, and the dosing amount is 1.98-7.59kg/t; PAC is formulated The solution with 20% concentration is added according to the amount of 3.75L/h, and the dosage is 650g/t; the solution made of PAM with a concentration of 5‰ is added according to the amount of 10L/h, and the dosage is 0.5g/t. It should not be too large, otherwise it will cause membrane pollution and affect the service life of the membrane. The liquid medicine mixture enters the coagulation settling tank 11 and stays for 1.5 hours, and then the supernatant enters the inclined plate sedimentation tank 12 through the overflow weir 18 . The feed liquid is further separated and settled in the inclined plate sedimentation tank 12, and after staying for 2.4 hours, the supernatant is collected through a perforated water collection pipe and enters the ultrafiltration intermediate water tank 6. the

The ultrafiltration membrane system 13 uses a domestic 19-channel hydrophilic PVDF organic tubular membrane. The support layer is ultra-thin. Generally, it will not form blockage in the support layer and can handle high-solid-content substances and high-concentration liquids. It can effectively control the concentration polarization and fouling, and can adjust the flow rate of the feed liquid in a wide range; the feed liquid passes through the inner membrane surface of the lumen at a high flow rate to generate cross flow, and the material is not easy to accumulate on the membrane surface to form scaling, prolonging the membrane cleaning cycle. Cross-flow filtration is adopted, 10% concentrated water is returned to the adjustment tank 1, and the remaining concentrated water is circulated externally, the operating pressure is 0.045-0.18Mpa, and the treated water enters the first-level RO circulation pool 8, and a security filter 20 is installed in front of the first-level RO system . the

The primary RO system 14 is made of aromatic polyamide composite membrane material, the operating pressure is 1.4-1.8Mpa, the recovery rate is 50%, and 96% of salt substances can be retained, and the concentrated water accounting for 50% of the total treatment capacity enters the The secondary reverse osmosis 15 is further desalinated and concentrated; the membrane material of the secondary reverse osmosis system 15 is aromatic polyamide composite material, the operating pressure is 2.2-4.4Mpa, the recovery rate is 50%, and more than 98% of salt substances can be retained. The highly concentrated water, which accounts for 25% of the total treatment capacity and is more than three times concentrated, enters the evaporation system 16 . the

After pretreatment + reverse osmosis, the high concentrated water enters the evaporation membrane 1 after being heated by the heat exchanger, and the steam passing through the membrane is blown to the condenser to condense into pure water. After being heated by the heat exchanger, the remaining concentrated water enters the next stage of evaporation membrane 2 to continue to evaporate and concentrate, and the steam passing through the membrane is blown to the condenser to condense into pure water. The RO concentrated water is evaporated and concentrated by the n-stage evaporation membrane to obtain a 35% (crystallization concentration) concentrated liquid that enters the crystallizer, and finally obtains solid salt as solid waste for treatment or comprehensive utilization. The steam that passes through the evaporation membranes of each level passes through the condenser Purified water is obtained after condensation. the

When the distillation membrane can make full use of low-temperature waste heat, its operating cost will be significantly reduced. The total volume of printing and dyeing wastewater in Xinjiang is 20,000 tons/day, of which 18,000 tons/day is low-pollution wastewater, with an average water temperature of 45 degrees. After cooling to 25 degrees, the biological treatment method Danong irrigation standard is used for reuse. If the waste heat that needs to be cooled by the cooling tower in the biochemical wastewater treatment can be utilized, not only the cost of cooling 18,000 tons of waste water can be greatly reduced, but also the waste heat can be used to distill and treat 600 tons of concentrated waste water, (low temperature boiling heat utilization rate reaches 70% Around) 531 tons of pure water and 69 tons of compound salt are recovered. the

When membrane distillation fully utilizes waste heat to treat concentrated wastewater, the reverse osmosis membrane and other equipment in the pretreatment process do not need to reach the maximum operating state, and only need to recover 70% of fresh water to achieve the system treatment target. A recovery rate of 70% means that the entire pretreatment system is in a medium-load operating state, which can make the system more stable, safe and long-term. Extend the service life of the equipment and further reduce the engineering cost. the

The problem of recovery rate was noticed in the design of this system. The muddy water discharged from the coagulation settling tank 11 and the sedimentation tank 12 enters the biochemical pool in the plant for recovery, and the UF and RO hydraulic cleaning water returns to the adjustment tank 1 for further treatment without leakage. rate remains high. the

Claims (8)

1. treatment of dyeing wastewater Zero emission device is characterized in that: this device comprises that materialization pre-treatment, RO desalting system and dense water treatment three parts form; The materialization pre-treatment partly comprises equalizing tank (1), coagulant precipitation jar (11), settling tank (12), tubular ultra-filtration membrane (13) four parts composition; The RO desalting system comprises one-level RO system (14), secondary RO system (15), and the dense water of one-level RO is intake as secondary RO; Dense water treatment portion is meant membrane distillation system (16).

2. treatment of dyeing wastewater Zero emission device according to claim 1, it is characterized in that: equalizing tank (1) is directly fetched water from shop production line by vacuum primingpump (M1), be connected with lift pump (M2) between equalizing tank (1) and the coagulant precipitation jar (11), and by PAM dosing pump (M3), PAC dosing pump (M4), discoloring agent dosing pump (M5), pH regulator agent dosing pump (M6) successively at the agent of the preceding adding pH regulator of lift pump (M2), discoloring agent, PAC, PAM.

3. treatment of dyeing wastewater Zero emission device according to claim 1 is characterized in that: the design of coagulant precipitation jar (11) side has a square region (17), and in order to carry out the thorough mixing of liquid medicine behind pump, overflow weir (18) is arranged at top.

4. treatment of dyeing wastewater Zero emission device according to claim 1, it is characterized in that: place swash plate (19) in the settling tank (12), coagulant precipitation jar (11) supernatant liquor enters settling tank (12) by overflow weir (18) through pipeline self, the perforation header is established in the settling tank top, and supernatant liquor enters ultrafiltration circulatory pool (6) through pipeline self.

5. treatment of dyeing wastewater Zero emission device according to claim 1 is characterized in that: ultrafiltration system membrane module (13) is selected certain homemade antipollution tubular ultra-filtration membrane for use, adopts the cross flow filter form, and treat effluent enters the RO system and carries out desalting treatment.

6. treatment of dyeing wastewater Zero emission device according to claim 1 is characterized in that: one-level RO fresh water is discharged into the part of filtered water tank (10) as system's water outlet, and secondary RO fresh water is discharged into filtered water tank (10) also as the part of system's water outlet.

7. treatment of dyeing wastewater Zero emission device according to claim 1 is characterized in that: this technology of installing dense water treatment portion employing is a film distillation technology.

8. treatment of dyeing wastewater Zero emission device according to claim 1 is characterized in that: the membrane distillation equipment (16) of dense water treatment portion is made up of heat exchanger, evaporating film, crystallizer, condenser.

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