As one of the three major synthetic materials, synthetic resin (i.e. plastic) is a synthetic material with large output and consumption. At the China synthetic resin industry development conference and 2018 new material development trend forum held in Xi'an in early November, recycling of waste plastics became a hot topic among experts and scholars attending the conference.







Waste plastics have threatened the living environment





Du Huanzheng, President of plastic cycle branch of China synthetic resin supply and Marketing Association and professor of Tongji University, said that in the past 50 years, the global plastic use has increased 20 times, and will double again in the next 20 years. It is estimated that the global plastic output will reach 1124 million tons by 2050. At present, China's plastic production and consumption are ranked first in the world, among which, the production accounts for 28% of the total global production.





"But plastic is also a double-edged sword. The waste plastics caused by mass production and consumption make the contradiction between human economic activities and ecological environment increasingly prominent. The waste plastics have seriously threatened the living environment of human beings. " Du said anxiously that more than 8 million tons of plastic waste enter the ocean every year, which has a serious impact on marine organisms, fisheries, tourism and even human beings, with economic losses of up to 8 billion US dollars. Millions of seabirds and hundreds of thousands of marine mammals die each year.





For example, the sea area between California and Hawaii in the United States has formed a "Pacific garbage island", a giant "plastic vortex" garbage dump area equivalent to two Texas plus four France. These plastic wastes will produce a lot of toxins after being swallowed by marine animals such as fish and turtles, which will enter into the human food chain from the bodies of marine organisms and birds.





Du Huanzheng also proposed the concept of "marine PM2.5". "'marine PM2.5 'mainly comes from primary and secondary microplastics. The industrial products of plastic particles enter the ocean through rivers or sewage, and decompose into smaller particles under the natural action, or the plastic garbage is broken and decomposed under the action of wind, wave, ultraviolet and biology. " Du told reporters.





The mainstream approach is not scientific





In terms of waste plastics recycling, the average recycling rates of waste plastics in Germany, the United States and Europe are 60%, 50% and 45% respectively; in China, only 25%, about 14 million tons of waste plastics are not recycled every year, and the direct waste of resources amounts to 28 billion yuan.





"Waste plastics are resources misplaced and have recycling value. Therefore, it should be sparse rather than blocked. It should be recycled rather than prohibited. " Wang Qi, academician of the Chinese Academy of engineering and professor of Sichuan University, said that if 15 million tons of waste plastics can be recovered every year, it would be equivalent to using 30 to 40 million tons of crude oil less, reducing carbon dioxide and sulfur dioxide emissions and saving 70% of energy consumption.





"At present, the commonly used recycling methods include chemical and physical methods, through collection, rough classification and selection, simple cleaning and crushing, granulation recycling." Wang Qi said frankly, but some materials are difficult to recycle, such as complex components of blending composite polymer materials, which are difficult to classify and separate; crosslinked waste plastics are insoluble and insoluble, which can not be reheated for processing, which is difficult to reuse. At present, 6.3 billion tons of waste plastics are accumulated in the world, only 9% of them are recycled, 12% are burned, 79% are buried or accumulated in the natural environment, which not only pollutes the environment seriously, but also wastes resources.





Du Huanzheng said that at present, the main methods of waste plastic landfill and incineration are unscientific, wasting resources and damaging the environment. The recycling of waste plastics in China is faced with many problems, such as serious lag of classification and recycling, confusion of recycling channels, etc. the legislation of recycling of plastic wastes needs to be strengthened and improved, and the systematic recycling system needs to be established.





According to the introduction, the new technology and equipment of solid-phase shearing and grinding developed by the polymer materials Engineering Laboratory of Sichuan university can recycle the waste plastic rubber, turn the waste into treasure, and realize the full utilization of resources, which is currently being industrialized and promoted.





Technological business models need innovation





Wang Qi told reporters that it is necessary to take measures such as policy guidance, enhancing citizens' awareness of environmental protection and establishing an effective recycling mechanism to control waste plastic pollution in the whole chain in the links of synthesis, processing, application and waste disposal.





Du Huanzheng also believes that the recycling of waste plastics needs to innovate policies, technologies and business models, and realize zero waste of plastics by reducing use, recycling resources and replacing biomass. He suggested that the EPR system should be established, that is, the producer should bear the responsibility of resources and environment for its products, extending from the production link to the whole life cycle of product design, circulation consumption, recycling and waste disposal. Through EPR, enterprises, governments, consumers and other relevant stakeholders can be connected, and the rights and responsibilities between them can be clarified, which plays a positive role in promoting the development of waste classification and resource recycling industry.





It is reported that China has listed the recycling of waste polymer materials as a strategic emerging industry, and has issued the medium and long term plan for the construction of recycling system (2015-2020), the law on the prevention and control of solid waste pollution (2018), etc. According to the industrial standard conditions for comprehensive utilization of waste plastics issued by the Ministry of industry and information technology, three types of enterprises are required to enter the market. Among them, the annual waste plastic treatment capacity of PET recycling bottle and chip type new enterprises is no less than 30000 tons; the annual waste plastic treatment capacity of waste plastic crushing, cleaning and sorting type new enterprises is no less than 30000 tons; the annual waste plastic treatment capacity of plastic recycling granulation type new enterprises is no less than 5000 tons. In terms of resource utilization, it is required that the comprehensive power consumption of plastic recycling related production links is less than 500 kwh / ton of waste plastic, PET recycling bottle chip enterprises and waste plastic crushing