Comparison Of Discharge Standards For Dyeing And Finishing At Home And Abroad

The newly revised "environmental protection law" will be formally implemented in January 1, 2015, and now it has less than 3 months left.

Environmental protection department responsible person disclosed that the current "environmental protection law" related rules and regulations and other development work is being carried out in an orderly manner. Recently, 4 supporting rules have been basically completed, and public consultation has begun.

Specifically to the printing and dyeing industry, Wujiang "antimony incident" and other issues have been plaguing the enterprise is the standard. Therefore, this newspaper specially invited the Donghua University environmental science and Engineering Institute Ma Chunyan, Liu Guoxiu, Xi Dan Li three experts, to the domestic and foreign printing and dyeing discharge standards for detailed reading.

You asked me:

Q: is there any difference between domestic and foreign printing and dyeing enterprises in terms of water quality and domestic quality?

R: guests: because of the different production processes of printing and dyeing enterprises at home and abroad, the effluent quality is totally different.

China's printing and dyeing enterprises include all processes such as pre treatment (scouring, desizing, alkali decrement, etc.) to dyeing, printing, finishing and so on. The wastewater generated by this process has large amount of water, complex pollutants and high concentration of organic matter.

Printing and dyeing enterprises abroad are relatively simple in production technology. An enterprise usually only takes charge of the production of one process, such as dyeing enterprises only dyeing, excluding pre-processing and finishing.

Therefore, the waste water volume is small, the water quality is stable, and the pollutant concentration is low.

Turbidity, turbidity, shunt and separate treatment will be the trend, for example: nonylphenol event, antimony pollution event, etc., because it is mainly produced in a certain process, and the quality of separation is relatively easy, and the treatment of mixed wastewater is very difficult.

Where are the main differences of Q: emission standards?

R:, according to the discharge standards of dyeing and finishing wastewater at home and abroad, China's emission limits are obviously stricter than those of other countries. The reason is that China's population is densely, the environmental pollution problem is serious, the water self purification ability is poor, and the environmental capacity is far smaller than that of foreign countries.

What is the current standard of Q: implementation? What is the biggest feature of the standard compared with foreign countries?

R: domestic implementation is GB4287-2012.

There are 3 main points: first, the standard value requirement is obviously higher than that of the 92 year standard.

China's environmental protection situation is grim, the printing and dyeing industry is too intensive, and environmental capacity is scarce.

The environmental protection "12th Five-Year plan" lays emphasis on papermaking and printing and dyeing as the key point of industrial control, with a total reduction of 10% (8% of other industries).

The two is the indirect emission of COD to 200mg/L.

The indirect discharge means that the waste water is discharged into the centralized sewage treatment system into the pipe network, that is to say, the standard of the take over is COD200mg/L.

The limit is not formulated according to the characteristics of textile dyeing and finishing wastewater. It is a unified set of requirements issued by the Ministry of environmental protection in a series of industrial wastewater discharge standards. For example, the emission limits for indirect pollutants emitted from the "iron ore mining and industrial pollutant discharge standard" (GB28661-2012), the "wool textile industry water pollutant discharge standards" (GB28937-2012), and the standard for the discharge of ammonia pollutants in industrial water (GB13458-2013) are also 200mg/L.

Even the indirect emission COD limits of some industrial emission standards are 150mg/L, such as "emission standard for pollutants in coking chemical industry" (GB16171-2012) and "discharge standard for battery industry pollutants" (GB30484-2013).

The purpose is to reduce the handling pressure of the centralized sewage treatment system and ensure that the final effluent discharged into the water is up to the standard.

Three, six valent chromium and aniline are not to be detected.

No detection is not equal to zero, and the concentration should be lower than the standard detection limit.

For example, the concentration of six valent chromium should be lower than the lowest detection concentration of 0.004mg/L in the determination of six valent chromium in water, two benzoyl two hydrazine spectrophotometry (GB/T 7467-1987).

The concentration of aniline should be lower than the lowest detection concentration 0.03mg/L in the determination of aniline in water N- (1- naphthyl) ethylenediamine azo spectrophotometric method (GB/T11889-1989).

Emission standards for dyeing and finishing abroad

From the United States, Germany and the European Union, the best practical technology analysis shows that chemical oxygen demand (COD) is mostly controlled between 130 -160mg/ L, which is basically similar to that of China's textile dyeing and finishing industry water pollutant discharge standard (GB4287-92).

However, the definition and name of dyeing and finishing wastewater are not the same as those in China.

For example, most of them are represented by the highest and average values, and the average value is adopted in China.

According to the Federal Ministry for the Environment, Nature Conservation and Nuclear Safety, Germany, the requirements for wastewater discharge under several common conditions are shown in Table 1.

Table 1 wastewater requirements at discharge point

Among them, the requirements of ammonia nitrogen and total nitrogen are suitable for the biochemical reaction of sewage treatment plants, and the effluent temperature is above 12 C.

Wastewater discharge requirements before mixing are shown in Table 2.

The production of tainted wastewater requires that wastewater should not be contained:

(1) organic chlorine carrier (accelerated dyeing).

(2) chlorine bleaching, except for bleaching of synthetic fibers with sodium chlorite.

3. Use free chlorine after sodium chlorite.

Arsenic, mercury and their mixtures.

(5) alkylphenol (APEO) as a rinsing agent.

Compounds Cr6+ used in oxidizing agents for sulphur dyes and vat dyes.

EDTA, DTPA and phospholipid in the softeners used in water treatment.

Cumulate chemicals, dyes and textile auxiliaries.

Emission standards for dyeing and finishing in the United States

According to Part410-Textile Mills Point Source Category

(1) textile finishing wastewater

This part of the standard applies to the waste water generated in various processes of textile mills: fabric finishing, including all the following unit operations: bleaching, mercerizing, dyeing, resin processing, waterproofing, fire prevention, etc.

The BPT best practical control tech. used by the US Environmental Protection Agency (EPA) to meet the discharge requirements for textile finishing wastewater is shown in Table 3.

The BAT best available control technology used by the US Environmental Protection Agency (EPA) to meet the emission requirements for textile finishing wastewater is shown in Table 4.

(2) yarn finishing wastewater

This part of the standard applies to the waste water generated in the following processes of textile mills: yarn dyeing and finishing, including all the following unit operations: flushing, mercerizing, resin processing, dyeing and special finishing.

The BPT best practical control technology, which is published by the US Environmental Protection Agency (EPA), can meet the emission requirements for the treatment of yarn finishing wastewater, as shown in Table 5.

The BAT best available control technology, which is published by the US Environmental Protection Agency (EPA), can meet the emission requirements for the treatment of yarn finishing wastewater, as shown in Table 6.

The EU did not propose emission standards, but rather recommended textile dyeing and finishing wastewater treatment technologies.

According to the reference document "BAT Integrated Pollution Prevention and Control (IPPC) Reference Document on Best", "Integrated Pollution", "the comprehensive pollution control and control" issued by the European Commission, the textile technology and its produced wastewater come from pretreatment, dyeing, printing and dyeing, finishing and washing.

After biochemical treatment, the depth treatment (three grade treatment), for example, the recovery of activated carbon, etc.;

In combination with biochemical and chemical methods, powdered activated carbon and iron salt are used.

Ozone technology is preferred before the activated sludge system.

The European Union does not have a unified discharge standard for water pollutants in textile dyeing and finishing industry. Its BAT guide lists the emission status of organic fine chemical industry (including textile dyeing and finishing industry) in EU countries, and the COD emissions are generally 120 to 250mg/l.

Emission standards for dyeing and finishing in Japan

Japan's national emission standards are comprehensive emission standards, and COD limits for all industries are 120mg/l.

In order to control eutrophication in Biwa Ko, Japan has set strict local standards. The existing enterprises and newly established enterprises carry out the 30mg/l and 20mg/l limits respectively, but this is equivalent to the special control areas that need special protective measures.

Discharge standard of water pollutants in textile dyeing and finishing industry at home and abroad