Printing and dyeing enterprises are typical processing enterprises, which need to consume a large amount of dyes, auxiliaries, basic chemical raw materials and coal, water and electricity. In the production process, waste is inevitably produced, especially in the production of wastewater, which is the main pollutant in the printing and dyeing industry.
In today's world, water resources and energy are scarce. A large number of basic chemical raw materials required for printing and dyeing enterprises also consume a large amount of energy in the process of their own production, and cause pollution to the environment. Therefore, the treatment of waste is an indispensable production link for printing and dyeing enterprises. How to save resources and reduce the amount of dyes and chemical raw materials is related to the economic benefits of enterprises and the environmental benefits.
The high-efficiency and materialized combination technology was breakthrough. At the end of October 2005, Wuhan University of Science and Technology and Wuhan Fangyuan Environmental Technology Co., Ltd. jointly developed and researched new technologies and core technologies that can effectively solve the treatment and recycling of textile printing and dyeing wastewater. The high temperature printing and dyeing wastewater treatment project built in Shanghai has just been completed. The pre-design of the second type of project they built in Fujian was successfully launched.
A large amount of high-temperature printing and dyeing wastewater discharged every year in the country pollutes the environment, wastes a lot of water, and also loses huge heat energy. It is understood that this breakthrough, the only domestic process and core technology "infinite ultraviolet light catalytic oxidation" technology, is the latest research results from the national 863 major special new high-efficiency materialized combination technology. Professor Zeng Qingfu, deputy dean of Wuhan Institute of Science and Technology and Dr. Hai Qing, has started research on this subject since the 1990s. He has presided over the completion of the national “Ninth Five-Year Plan†key research projects on printing and dyeing wastewater photochemical decolorization technology and equipment research, as well as key research projects. Intermittent dyeing wastewater photocatalytic decolorization and reuse technology and equipment pilot and so on.
In this study, they used microwave-excited plasma and its synergistic oxidation, co-precipitation and co-precipitation integration technology, with microwave induction and adaptive adsorption catalyst as the core, and formed a synergistic process for classification treatment for different water quality. The working time of the electrodeless ultraviolet light source is more than 15000 hours, and the catalyst life is more than 6 months. When the new technology system is applied to treat the knitting and printing and dyeing wastewater, the COD removal rate is greater than 90%, the TOC removal rate is greater than 80%, and the chroma removal rate is greater than 95%, SS removal rate is greater than 97%; the treatment of knitted wastewater effluent can be directly used for washing and reuse; the treatment of printing and dyeing wastewater effluent reaches the first-class discharge standard; the treatment cost is less than 2.0 yuan / ton.
This technology achieves the goal of saving water while conserving textile wastewater pollution, while also saving a lot of heat. It is estimated that if 100,000 flat washing machines and overflow dyeing machines in the country are treated with this technology, it can save water costs by 6 billion yuan. According to calculations, the counter-washing water temperature of the flat washing machine is often higher than 85 °C, which contains considerable value of heat energy. The treatment of recycling 1 ton of this water can increase the income by about 10 yuan, and a flat washing machine can increase the heat energy value by more than 2,000 yuan a day. The process and core technology have obtained 2 invention patents and 1 practical new technology patent.
Dyeing and dyeing wastewater treatment is difficult. China's printing and dyeing industry consumes a lot of clean water every year. According to the discharge of 1 ton of printing and dyeing wastewater, 20 tons of clean water will be polluted. The annual discharge of wastewater that has not reached the standard will destroy hundreds of millions of tons of clean water. The number is amazing. Therefore, how to improve and improve printing and dyeing wastewater treatment technology, and adopt a scientific and rational combination of process technology and route to effectively solve the problem of printing and dyeing wastewater treatment, not only affecting a company or a region, but also affecting the development of the entire industry and even the national economy.
Printing and dyeing wastewater has many problems and difficulties in the treatment process technology, mainly in two aspects: First, COD (chemical oxygen demand) is difficult to degrade, and second, high chroma wastewater is difficult to decolorize. At present, the printing and dyeing wastewater treatment process commonly used in China generally adopts physicochemical, biochemical (or flocculation-biochemical-adsorption) process technology routes, including biological activated sludge pool treatment, physical chemical treatment and membrane treatment. The primary treatment is mainly flocculation, and the secondary treatment mainly uses biochemical technology, such as surface exposure, air exposure, contact oxidation, and biological turntable.
Although local governments have increased their efforts in recent years, some places have even introduced stricter sewage discharge standards than their superiors. However, in general, the printing and dyeing industry, especially in the dyeing and finishing industry, is seriously polluted. Analysis of the reasons, mainly the following points: First, after the accession to the WTO, the textile printing and dyeing industry has grown rapidly, but the processing facilities are difficult to synchronize, the total amount of pollutants discharged is still increasing; the second is the new process, raw materials, dyes, additives Continuous development and application make the pollutants discharged during the production process more complicated and difficult to handle. Third, most printing and dyeing products are medium and low-grade products with low profit, which is difficult to ensure the normal operation of wastewater treatment facilities. In particular, scattered factories often steal and discharge super-discharged water. Fourth, many private enterprises are pursuing low prices and unregulated competition, which makes sewage treatment technology and construction quality inferior and the treatment effect is not satisfactory.
High-water consumption industry will be restricted According to the data: At present, China's textile printing and dyeing industry has a total of 100,000 flat washing machines or overflow dyeing machines, and nearly 1 billion tons of high-temperature polluted wastewater is discharged every year. It is a difficult industrial industry. One of the wastewater. Each ton of printing and dyeing wastewater can pollute 20 tons of water. After joining the WTO, textile printing and dyeing has increased by double digits in recent years, but the pollutant treatment facilities are difficult to synchronize, and the total amount of pollutants has increased.
China's printing and dyeing industry is concentrated in the eastern coastal areas. By the end of 2003, the output of Zhejiang, Jiangsu, Guangdong, Shandong and Fujian provinces had accounted for 86.5% of the total output of national printing and dyeing fabrics, and these provinces were mostly the key river basins of the Huaihe River and Taihu Lake. The situation of pollution prevention and control work is grim. At present, the treatment of printing and dyeing wastewater is mainly concentrated, and some large printing and dyeing enterprises have separate sewage treatment facilities. Most of the printing and dyeing wastewater is discharged after treatment. However, due to different emission standards of different localities, the functional requirements of the water environment are different. The printing and dyeing water discharged after treatment has different effects on the local environment. At the same time, small printing and dyeing enterprises in some underdeveloped areas in China have repeatedly banned, resulting in greater water environmental hazards.
At present, China's water resources are relatively extensive, water use efficiency is not high, and water is wasted. Especially in the industrial sector, the reuse rate of industrial water is less than 60%, which is 15~25% lower than that of developed countries; the utilization of seawater and brackish water in industrial water is only 21.3% of Japan and 12.8% of the United States; At the same time, industrial wastewater discharges have increased sharply and flowed directly into rivers and lakes reservoirs without treatment, polluting existing water resources, resulting in further reductions in available water resources.
The national standards for water withdrawal quotas of seven industrial sectors with large water consumption, such as printing and dyeing, approved by the General Administration of Quality Supervision, Inspection and Quarantine and the National Standardization Administration, have been officially implemented since January 1, 2005, and have exceeded the quota standards. High water prices are implemented for water consumption; for enterprises that fail to meet the standards, they are ordered to rectify within a time limit, and those who refuse to rectify will reduce their water use plans, refuse water supply or refuse water.
At the end of 2004, the State Environmental Protection Administration also stated that by 2010, all printing and dyeing enterprises should adopt clean raw materials with environmentally friendly raw materials. The state will support the upgrading of production equipment in the printing and dyeing industry and the transformation of sewage treatment technology.
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