Team:Worldshaper-XSHS/Description
Description
Our hometown, Xiao Shan, is an industrial satellite city of Hangzhou. In the past, our country did not pay attention to environmental problems while developing industry, and many environmental damage problems caused by industrial pollution appeared. Now, we realize that "green mountains and clear water are actually mountains of gold and silver" said our president. At the same time of development, we also pay attention to environmental protection and find all kinds of new ways to solve the problems of industrial pollution. Our team in which to investigate, found that the textile industry in the world produced by the wastewater is a common and important pollution problem, printing and dyeing wastewater unreasonable discharge will lead to water color change and affect the life of aquatic organisms so this kind of industrial wastewater treatment should be paid attention to. Textile printing and dyeing wastewater pollution has been in the forefront of China's industrial industry, its wastewater emissions accounted for about 11% of the national wastewater emissions, every year 2-2.3 billion tons. The discharge of chemical oxygen demand (COD) is about 240-300,000 tons per year, accounting for about 9% of the total industrial industry. Printing and dyeing wastewater accounted for more than 70 percent of the textile industry wastewater. It is reported that the printing and dyeing factory will produce 3-5 tons of waste water for every 100 meters of fabric processed. According to the data, China's printing and dyeing industry water use efficiency is low, unit water consumption is 3-4 times than that of foreign countries, and the average content of pollutants in the wastewater as high as 2-3 times that of western countries. In the survey, we found that Xiao Shan also has a lot of printing and dyeing enterprises.
Our team was inspired to use our synthetic biology method to decolorize dyes in dyeing wastewater. In the process of searching information, we found that most of the modern printing and dyeing enterprises are using a compound called azo dye, this dye in various fields of printing and dyeing are widely used which means it is an ideal dyeing wastewater degradation experiment samples.
In the survey of the public, we see from the results of the questionnaire that most people do not understand printing and dyeing wastewater, do not understand the principles of printing and dyeing wastewater treatment, just know the harm it brings, but the understanding of it is not deep. At the same time, it can be seen that people do care about the printing and dyeing wastewater problems, and the government is also to pay attention to the harm of this issue. It makes us realize that what we are doing is helpful to society and it will bring benefits to human beings, even for a little.
Azo dyes are organic compounds bearing the functional group R−N=N−R′, in which R and R′ are usuallyaryl. They are a commercially important family of azo compounds, i.e. compounds containing the linkageC-N=N-C. Azo dyes are widely used to treat textiles, leather articles, and some foods. Chemically relatedto azo dyes are azo pigments, which are insoluble in water and other solvents.
When looking up the information about azo dyes, we found that modern enterprises have been using a variety of physical and chemical methods to decolorize wastewater containing azo fuel degradation, but the existing methods more or less have some difficulty solving the existence of hard damage.
Physical processing
The most widely used in the physical treatment method is the adsorption method, which is very effective for removing dissolved organic substances in water, and it has good adsorption performance only for water-soluble dyes such as cationic dyes, direct dyes, acid dyes, and reactive dyes. The disadvantage is that the amount of sludge generated is large and further processing is difficult.
Chemical treatment
The chemical treatment methods for printing and dyeing wastewater mainly include the coagulation method and the oxidation method, which have their respective effects in water treatment.
- Coagulation
There are mainly coagulation sedimentation methods and coagulation air flotation methods. The advantages of the coagulation method are simple process flow, convenient operation and control, low equipment investment, small floor space, high decolorization efficiency for hydrophobic dyes; disadvantages are high operating cost, large amount of sludge and difficulty in dehydration. Aqueous dyes have poor handling.
- Oxidation
There are several methods such as ozone oxidation and photooxidation. The ozone oxidation method can obtain good decolorization effect for most dyes, but the decolorization effect of water-insoluble dyes such as vulcanization, reduction and coating is poor, and equipment investment and power consumption need to be further reduced.
Electrolysis
Electrolysis has a good treatment effect on the treatment of printing and dyeing wastewater containing acid dyes, and the decolorization rate is 50%-70%, but the treatment effect on wastewater with deep color and high COD is poor.
After comparison, we found that using our technology in the field of synthetic biology to decolorize azo dyes is a very cost-effective and efficient method.
Therefore, we searched for enzymes related to the decolorization and degradation of azo dyes, and found that two enzymes were effective in decolorizing and degrading azo dyes, one called azo reductase and the other called laccase. Each enzyme identified two genes. Therefore, we hope to use these four genes to design a gene loop that can decolorize azo dyes efficiently and cheaply.