Abstract: Water reuse in printing and dyeing wastewater is an important starting point for total pollution control and energy saving and emission reduction. Summarizes the sources of waste water and the characteristics of water quality in the printing and dyeing industry; analyzes the influence of excessive reuse rate of water in the printing and dyeing wastewater on the economy, products and sewage treatment system of the enterprise, suggests that effective attention should be paid to the effective treatment of concentrated liquid and the prevention and control of membrane pollution during the operation of the membrane technology . Key words: printing and dyeing wastewater; deep treatment; reuse As one of China's traditional pillar industries with advantages, the printing and dyeing industry has enjoyed rapid growth since the 1990s and its water consumption and displacement have also risen sharply. National Bureau of Statistics data show that in 2010 the textile wastewater discharge amounted to 2,454,700,000 tons, ranking third in the country's industrial sector. In recent years, along with the rapid economic development in our country, the freshwater resources are increasingly scarce, and the deep treatment and reuse of printing and dyeing wastewater have drawn more and more attention. 1, the status of domestic printing and dyeing wastewater treatment and reuse China has more research on the reuse of printing and dyeing wastewater, from the current research and application of the situation mainly has the following characteristics: (1) Most of the reuse technologies are in the experimental stage, mostly small and pilot, with few practical applications and low reuse rates of water, generally less than 50%. They are mainly used for low water quality requirements Of the former procedures, the lack of conducive to improving the quality and reuse of water reuse and efficient technology to promote the use of. (2) Reuse The treatment is mainly to further process the printing and dyeing wastewater on the basis of the standard treatment to reach the standard of reuse water quality. The treatment process mainly adopts the techniques of coagulation, adsorption, filtration and oxidation, among which the key technologies for removing salinity and hardness are few. (3) Due to the limitations of the existing technologies, a large amount of reuse of printing and dyeing wastewater brings a series of problems to the production and wastewater treatment systems, including the accumulation of organic pollutants and inorganic salts. At present, there is not much research on the water quality of long-term wastewater reuse and its impact on water treatment system. In particular, the problem of accumulation of inorganic salts is basically not involved. 2, printing and dyeing wastewater treatment and reuse of advanced technology introduction Printing and dyeing wastewater treatment methods commonly used are: physical and chemical methods, chemical methods, biochemical methods, membrane technology and other combinations of technology. Rely on a single treatment process is difficult to achieve the purpose of deep processing and reuse, the existing process must be integrated, the use of a variety of joint processing methods in order to truly achieve the goal of reuse. 2.1 materialized method The physicochemical method is mainly adsorption method, and the most commonly used adsorbents in the advanced treatment and reuse of printing and dyeing wastewater are activated carbon, diatomaceous earth, activated alumina, fly ash, zeolite and bentonite. Dyeing wastewater treatment and reuse of advanced research and application of more activated carbon. Activated carbon has large specific surface area, strong hydrophilicity, good adsorption and decoloring effect, and is especially suitable for the adsorption and decoloration of small molecule water-soluble dyes. Activated carbon for secondary biological treatment of printing and dyeing wastewater residual contaminants (such as synthetic dyes, surfactants, etc.) has a good adsorption capacity, but the high cost of processing, renewable energy consumption, often with other combinations of textile printing and dyeing wastewater Deep processing. Zhang Jianli and so on. 2.2 Ozone decolorization and activated carbon adsorption combined system of textile enterprises in Zibo City, a printing and dyeing wastewater reuse treatment, influent COD value of 8O ~ 100mg / L, chroma 0.25 ~ 0.35, the effluent COD 6 ~ 10mg / L , The chroma is 0.01 ~ 0.03, the treated water can be used in the enterprise cooling circulation system, and the economic benefits and environmental benefits are obvious. Xie Danping and other [3] using a continuous membrane filtration system (CMF) - activated carbon adsorption process of a printing and dyeing plant wastewater treatment station drainage for reuse, the treated effluent Fe, Mn removal rate of 100%, the color of 4, turbidity 0.2 NTU, COD <10mg / L, to meet the printing and dyeing enterprises water quality requirements. 2.3 chemical method Dyeing wastewater treatment commonly used oxidants Fenton reagent and ozone. Fenton method has the advantages of simple, rapid, flocculation-producing, but there are still some drawbacks such as low utilization of oxidant, poor oxidation efficiency and high treatment cost. At present, Fenton method is often combined with electrochemical oxidation of textile printing and dyeing wastewater reuse deep treatment. Such as Jiang Hing-hua et al (1) the iron-carbon micro-electrolysis Fenton reagent combined oxidation technology for the A / O treatment of printing and dyeing wastewater effluent, under the best reaction conditions, COD removal rate of 90% or more, the color removal rate of 99 %, Reached the printing and dyeing wastewater reuse requirements. For printing and dyeing wastewater color characteristics, the strong oxidation of ozone can effectively remove the organic matter in the color and waste water, ozone also has bactericidal deodorant function. In practical engineering applications, ozone oxidation is rarely used alone to treat printing and dyeing wastewater. Instead, it is used in combination with other methods such as ozone-activated carbon and ozone-biological aerated filters. Lin et al. (2) Pass ozone in a fluidized bed or fixed bed packed with activated charcoal and combine ozone oxidation and activated carbon adsorption into a single process. The study found that ozone oxidation can prolong regeneration of activated carbon and reduce its cost of regeneration; activated carbon is not only an adsorbent, but also a catalyst for ozone oxidation. Both can make up for their inherent deficiencies. Has a good synergy. Gu Xiaoyang et al (3) the use of ozone - biological aerated filter process of a textile water treatment plant biochemical treatment of water reuse treatment, influent COD about 8Omg / L, 16 times the color, turbidity of about Under the condition of 8NTU, when the ozone dosage is 30 ~ 45mg / L, the biological residence time of the biological filter is 3 ~ 4h, the gas-water ratio is 5:1, the effluent COD <30mg / Times, turbidity <1NTU, to meet the production process of water quality requirements. 2.4 biochemical method Biochemical method is mainly the use of microbial metabolism to decompose pollutants, not only can be used for printing and dyeing wastewater discharge standards, but also can be used as advanced processing and reuse technology. Biochemical methods are mainly biological aerated filter, bio-activated carbon, biochemical methods are rarely used as a deep treatment of reuse process, the actual use of more biochemical methods combined with other processes. Biological Aerated Filter (BAF) is a new biofilm treatment technology integrating physical adsorption, filtration and biodegradation. It is suitable for the treatment of low suspended solids and low COD wastewater [7-8] . BAF used in the printing and dyeing wastewater treatment is mainly due to the wastewater treated by anaerobic hydrolysis + contact oxidation process, the B / C value is very small, poor biodegradability, refractory residual organic matter was first filter and filter on the biological Membrane adsorption, the residence time is equivalent to the biofilm mud age, so there is enough contact time, so that these organisms are degraded by microorganisms. Huang Ruimin [9] BAF treatment after coagulation treatment can make the COD index of knitted cotton dyeing wastewater below the national wastewater discharge standards, close to the requirements of production and reuse. BAF effluent and then through the fine filtration to remove small suspended solids and ion exchange to remove inorganic salts in the water, the water of the indicators can be reused. Biological activated carbon is a combination of biological treatment and activated carbon adsorption process, microbial oxidation and decomposition and biological adsorption and activated carbon physical adsorption coordination, so that the treatment effect is greatly enhanced. Gengshu lock [10] using biological contact oxidation - biological carbon fluidized bed tandem device for printing and dyeing wastewater depth treatment, influent COD of 113 ~ 263mg / L, color 20 ~ 200 times, SS 14 ~ 184mg / L premise , Respectively, the removal rate reached 70% ~ 89%, 73% ~ 90%, 78% ~ 79%. After treatment, the effluent quality meets the dyeing and printing process requirements. 3, membrane technology Membrane separation technology is one of the hot spots in R & D and engineering application in the field of reuse of printing and dyeing wastewater at home and abroad. Currently used in the printing and dyeing wastewater reuse membrane separation techniques are: reverse osmosis (RO), nanofiltration (NF), microfiltration (MF) and ultrafiltration (UF). These membrane separation processes are driven by the pressure difference. When the wastewater flows through the membrane surface, the pollutants in the wastewater are intercepted and the water permeates through the membrane to achieve the deep treatment of wastewater. Ultrafiltration can remove most of the turbidity and organic matter in the wastewater, which can reduce the pollution of the reverse osmosis membrane, prolong the service life of the membrane and reduce the operating cost of the membrane system. Reverse osmosis can not only effectively remove organic matter, reduce COD, but also has excellent desalination effect. Because COD removal, decolorization, desalination can be completed in one step, the quality of its effluent, can be directly used in the printing and dyeing sectors, while the concentrated water can be returned to the normal process, to achieve zero discharge of waste water and cleaner production. An increasing number of studies have shown that the combination of different membrane separation techniques (eg microfiltration, ultrafiltration, nanofiltration, reverse osmosis, etc.) or membrane separation techniques in combination with other technologies (eg membrane bioreactors) A research direction of advanced treatment of printing and dyeing wastewater. Membrane bioreactor is one of the new technologies for printing and dyeing wastewater treatment. Membrane bioreactor is combined with bioreactor to achieve the reuse of water quality. Xia Yan et al. The MBR-NF combined process was applied to treat the primary sedimentation tank effluent of Suzhou East Wastewater Treatment Plant. When influent COD 372 ~ 1121 mg / L, ammonia nitrogen 16.17 ~ 26.85 mg / L and total nitrogen 19.18 ~ 46.54 mg / L , The average removal rates of COD, ammonia nitrogen and total nitrogen in effluent were 87%, 95.8% and 70.2% respectively after HRT 30 h and 300% MBR. After the nanofiltration treatment, the water quality could meet the requirements of printing and dyeing process Reuse request. Schoeberl and other MBR secondary effluent using nanofiltration post-treatment, effluent treatment to meet the reuse standards, but at the same time pointed out that the method is still facing higher technical difficulty and economic costs. Fu Jiang Tao and other treatment using a double membrane process of a printing and dyeing plant wastewater and reuse, COD removal rate of 99%, turbidity and color removal rates were close to 100%, reverse osmosis salt removal rate of more than 98% to meet Back to the requirements of printing and dyeing production. Marcucci and other sand filtration - ultrafiltration - reverse osmosis and sand filtration - ultrafiltration - nanofiltration two kinds of deep treatment of secondary effluent wastewater treatment, reverse osmosis salt removal rate of 95% or more, Back to the printing and dyeing production processes, including the light-colored dyeing process with the highest water quality requirements. Amar et al. Used the technology to process the effluent of the printing and dyeing factory, and the effluent effect reached the requirement of production reuse. 3.1 Other combinations of processes Due to the membrane technology on the influent water quality requirements, therefore, generally need to be properly pre-treated wastewater can be treated membrane. He Yaozhong et al [16] adopted the integrated process of "integrated ozone BAF + up-flow BAF" to deeply process textile printing and dyeing wastewater, which can provide stable and reliable influent for membrane separation system. Integrated ozone BAF in the ozone dosage is 20 ~ 30mg / L, with the best operating performance. Combined with subsequent biological aerated filter, effluent COD <40mg / L, BOD <10mg / L, SS <10mg / L, chroma <4 times. Membrane separation system, the reverse osmosis water completely meet the dyeing and finishing process of water requirements, membrane filtration concentrate COD <100 mg / L, BOD <30mg / L, SS <50mg / L, chroma <32 times, up to standards. The combined process not only ensures membrane filtrate concentrate discharge standards, to solve the past engineering applications, membrane filtration concentrate follow-up treatment problems, and can bring significant economic benefits, for the textile printing and dyeing wastewater treatment and reuse facilities upgrade Retrofitting provides a new solution. Qilu Qing and other pretreatment system (ozone - biological aerated filter integrated device + biological aerated filter) and membrane system (ultrafiltration + reverse osmosis) combined process of deep processing of textile printing and dyeing wastewater. Experiments show that the ozone oxidation and BAF biological retention adsorption make the pretreatment system to ensure the quality of the membrane influent, after the membrane system processing, freshwater reuse, concentrated water can still be discharged. The optimal operating parameters of the pretreatment system are as follows: gas-water ratio of 5, organic load of about 2.1,1.0 kg (COD) / m3, dissolved oxygen concentration of 3.8 mg / L, water temperature of 35 ~ 40 ℃; Biological aerated filter, the formation of ozone - biological aerated filter unit, ozone dosage should be 20 ~ 30mg / L. When the pretreatment system influent COD mass concentration average of 101.3mg / L, turbidity 8.0NTU, SS mass concentration of 21.9mg / L, ammonia concentration of 3.4mg / L, color 21 times, after pretreatment system stability The average concentration of COD in treatment and effluent can be reduced to 7.4mg / L, the turbidity is 4.2 NTU, the concentration of SS is 3.0mg / L, the concentration of ammonia nitrogen is 0.7mg / L and the color is 2 times. Pretreatment system to remove contaminants efficiently, effectively ensure the membrane system inlet water quality. Determination of concentrated water pH 7.3 to 8.3, 32 times the color, COD mass concentration of 45.7 ~ 97.9mg / L, can be directly discharged. During the stable operation of membrane system, the pH value of RO produced was 7.4-7.9 and the conductivity was 50-200μs / cm. The average desalination rate was 98.2%. 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April 14, 2024