Aniline pollution in the hottest printing and dyei

Aniline pollution in the printing and dyeing industry is in urgent need of control

this year is the year of the implementation of the new environmental protection law and the year of the implementation of the new standard for aniline pollutants in the discharge standard of water pollutants for textile dyeing and finishing industry (GB). From January 1, 2015, the discharge of aniline pollutants in the sewage discharged from the printing and dyeing industry shall not exceed the detection limit, that is, less than 0.03mg/l. On March 27, 2015, the Ministry of environmental protection issued the announcement on the amendment of the national pollutant discharge standard (GB) (announcement 2015 No. 19). The announcement clearly stipulates that the sewage from printing and dyeing enterprises entering urban sewage treatment plants or discharged through urban sewage pipelines should reach the direct discharge limit. In the first half of this year, the East China Environmental Protection Supervision Center of the Ministry of environmental protection investigated more than 50 printing and dyeing enterprises in major printing and dyeing provinces such as Zhejiang, Jiangsu, Fujian and Shandong. It was found that at present, the aniline content in the wastewater discharged by most printing and dyeing enterprises is between 0.3 mg/l and 0.5mg/l after traditional process treatment, which does not meet the discharge requirements of the new standard

why is it so difficult to implement the new standard of aniline emission limits? The author believes that there are mainly the following reasons. First, 70% of the dyes used in China's printing and dyeing industry are benzidine azo dyes, which is the main source of aniline pollutants in printing and dyeing wastewater. Second, at present, China's alternative dyes are still unable to compete with benzidine type azo dyes in terms of performance and cheapness. Therefore, most printing and dyeing enterprises still choose to use benzidine type azo dyes instead of alternative dyes, resulting in a high level of aniline in wastewater. Third, the source manufacturers are unwilling to produce and develop alternative dyes because of the market for benzidine azo dyes and continue to produce in large quantities. Fourth, aniline substances have high stability in water, are difficult to degrade, can remain for a long time, and are toxic to organisms. Therefore, traditional treatment methods are difficult to work, and there is no treatment technology that can meet the requirements of the new standard. Fifth, in the past daily supervision, the local environmental protection departments neither monitored the aniline pollutants discharged from the printing and dyeing wastewater, nor punished the enterprises that discharged aniline exceeding the standard, which objectively led to the difficulty in the research and development, production and promotion of alternative dyes, and the slow progress of aniline wastewater treatment technology

in response to this situation, the Ministry of environmental protection issued the announcement on the implementation requirements of some indicators of the "adjustment of the discharge standard of water pollutants for textile dyeing and finishing industry" (GB) (Announcement No. 41, 2015) on June 17. The announcement clearly pointed out that the discharge standard of aniline pollutants in the new standard and the discharge standard of printing and dyeing enterprise wastewater entering urban sewage treatment plants in Announcement No. 19 of the Ministry of environmental protection in 2015 were suspended. This means that the old standard (GB) has been replaced by the new standard, and the implementation of the new standard has been suspended. In fact, a vacuum situation in which a large number of excellent talents in China's printing and dyeing industry are unwilling to engage in engineering and technical work without aniline pollutant emission limits has been formed as a result of the current results of China's printing and dyeing industry

aniline itself is a highly toxic substance with carcinogenic, teratogenic and mutagenic effects. It is an amino compound of benzene, and long-term contact with such substances will cause poisoning. Aniline is listed in the "blacklist of 14 priority environmental pollutants in China". According to statistics, China discharged 4.3 billion tons of printing and dyeing wastewater in 2012, and the output of printing and dyeing fabrics in East China accounted for about 85% of China's total output. For example, according to the current discharge level of aniline pollutants in the printing and dyeing industry in East China, the annual discharge of aniline pollutants to the water environment by the printing and dyeing industry alone (excluding the dye chemical manufacturing industry) in China is as high as more than 2200 tons. Among them, more than 1800 tons are discharged into the water environment of major printing and dyeing provinces such as Zhejiang, Jiangsu, Shandong and Fujian. If it is not controlled, it will bring huge pressure to the water environment of these places

aniline pollution control is urgent, and the emission of such pollutants cannot be in a vacuum without limits. New DuPont will take over Dow's businesses in water treatment, electronic materials and food nutrition. It is suggested that relevant departments should take practical and effective measures as soon as possible to curb the emission of aniline pollutants from the source. The discharge standard of aniline pollutants should be determined as soon as possible. The new standard, which is suspended now, can be implemented in three stages in five years. In the first stage, the emission limit of 0.3 mg/l can be implemented according to the current actual emission situation of printing and dyeing enterprises, which is more than three times higher than the original standard (GB). In the second stage, it can be considered to be derived from the current water quality standards of surface drinking water sources, and the limit of 0.1 mg/l can be implemented. In the third stage, the current new standard will be implemented according to the limit value of 0.03 mg/l. We should further strengthen environmental supervision. Take aniline as the main pollutant monitoring factor of printing and dyeing wastewater, and resolutely stop illegal production and excessive sewage discharge

new and established printing and dyeing enterprises should be prohibited from taking advantage of the relatively loose favorable conditions of the aniline pollutant discharge standard of 0.5 mg/l in the pollutant discharge standard for urban sewage treatment plants (GB) to newly pipe printing and dyeing wastewater into urban domestic sewage treatment plants. For those that have been put into the pipe, the current discharge at the plant boundary is subject to the limit of 0.3m g/l, except that it affects the misalignment of the jaws

the discharge standard of aniline pollutants in the discharge standard of pollutants for urban sewage treatment plants (GB) should be revised as soon as possible. Dye chemical manufacturing enterprises, pesticide production enterprises and other wastewater containing high concentrations of aniline are prohibited from entering urban sewage treatment plants, so as to prevent dilution and discharge up to standard

it is necessary to increase support for the research and development, promotion and use of 411.9 and production of alternative dyes, gradually replace benzidine azo dyes, and control the emission of aniline pollutants from the source. Relevant departments should give appropriate preference to policies and funds. At the same time, relevant scientific research institutions and industry departments should be organized to tackle key problems in aniline wastewater treatment technology in the printing and dyeing industry, so as to thoroughly solve the current difficulties faced by the industry

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