¡¾Environmental Protection Talk¡¿

As a basic material, plastic plays an important role in our production and life. However, the irregular and environmentally unfriendly production, use of plastics and recycling of plastic waste have made plastic pollution a global problem, and "plastic restriction" has accordingly become a common choice for the global prevention and control of plastic pollution.

There are two common misunderstandings about "plastic restriction":

One is to label plastics as "gray" without distinction, thinking that plastics are "bad things that pollute the environment." In fact, whether it is a substitute for steel and wood, or a packaging material to replace paper, glass and metal, plastics are relatively more energy-efficient and environmentally friendly. Plastic pollution is mainly caused by plastics that are easy to wear, difficult to recycle and easy to leak, especially disposable plastic products and plastic packaging. Therefore, when choosing plastic substitutes, it is necessary to comprehensively weigh the environmental impact of the product throughout its life cycle, and not to replace for the sake of replacement or against environmental impact.

Another misunderstanding is to label biodegradable plastics as "green" without distinction, believing that biodegradable plastics are made from renewable resources, have relatively low environmental impact, and are pollution-free after use.

First, in the field of plastics, biodegradable does not mean renewable. Biodegradable plastics include photodegradable, thermo-oxidative degradable, and biodegradable. They may be made from biomass raw materials, or they may be synthesized from fossil energy such as petroleum and coal like traditional plastics. In 2019, of the 617,000 tons of biodegradable plastic production capacity in China, bio-based plastic production capacity accounted for only 56%; of the new production capacity of biodegradable plastic projects currently under construction or planned (4.405 million tons), bio-based new production capacity accounted for only 36.3%, all of which were polylactic acid (PLA) plastics, and fossil-based thermoplastic biodegradable plastic PBAT (a polyester, full name: polybutylene adipate terephthalate copolyester) new production capacity accounted for 51.6%.

Second, the environmental impact of biodegradable plastics is not necessarily lower than that of traditional plastics. For example, the carbon footprint of thermoplastic biodegradable plastics of the same weight is 2.6 times that of traditional polyethylene (PE) plastics, and the former generally requires more materials when the functions are the same. Taking a supermarket's 15 kg plastic bag as an example, the degradable plastic bags (raw materials PBAT + PLA) currently used are 2.5 times heavier than the original PE plastic bags and are easily damaged.

Finally, the environmental impact of degradable plastics after use depends on the methods and conditions of terminal treatment. Used PBAT plastic bags belong to other garbage. Sending them to incineration plants not only violates the original intention of using degradable plastics, but also fails to reduce the environmental impact of the entire life cycle of plastic use through substitution - on the contrary, the environmental impact increases. If degradable plastics are landfilled in arid natural environments, their degradation ability will be greatly reduced. In 2019, China's production of degradable plastics was only 198,000 tons. We need to use limited degradable plastics on the "cutting edge" and formulate a list of priority areas and fields for the use of degradable plastics.

In China, there are still several difficulties and hot spots in "plastic restriction" that deserve attention:

Film plastic bags are a long-term difficult area for "plastic restriction". China consumes about 5.5 million tons of portable plastic bags every year, and there is huge potential for reduction. At present, there are two key places for reducing plastic bags-small-scale retail places in cities and rural areas. Our survey results on rural areas at the beginning of the year showed that the average annual use of plastic bags by rural residents was 394, and 73.2% of households had purchased plastic bags separately last year. Charging can significantly reduce the use of plastic bags, but there is a problem of "declining" effect. The "Consumer-side Research Report on the New Regulations on Plastic Ban and Restriction in the Yangtze River Delta" released by the Yangtze River Delta Consumer Protection Committee Alliance shows that only 32.5% of consumers will bring their own shopping bags when shopping in supermarkets. There are two problems with charging-who is responsible for the plastic bag charges, and how to organically connect the charges with the extended producer responsibility system. In addition, the online business of large supermarkets tends to provide plastic bags for free to attract and stick to customers. Obviously, to resolve the above problems, further breakthroughs in management mechanisms are needed.

Disposable plastic tableware is an emerging hot spot for China's "plastic restriction". In 2019, China's takeaway orders totaled 16.3 billion, consuming about 1.71 million tons of plastic. From the perspective of tableware use, the catering industry is naturally a sharing economy. Therefore, in the built-up areas and scenic spots designated by the "plastic restriction order", it is advisable to try the "shared tableware" takeaway service model, and convert the cost of disposable tableware into errand fees for recycling "shared tableware" - in this way, you can eat healthily and have a sense of ritual, while saving resources, increasing the income of takeaway brothers, and effectively transforming green production and consumption from concepts to practical actions.

Express packaging is another emerging hot spot for China's "plastic restriction". According to relevant surveys, China's express delivery industry uses 850,000 tons of plastic annually, among which film bags, internal buffers (bubble columns, bubble bags), and tapes are the plastic express packaging products with the largest consumption and the fastest growth in quantity. For these packages, some can be reduced and some can be replaced.

In the field of life, the other two major application areas of plastic packaging are food and daily chemicals, which consume 5.5 million tons and 1.15 million tons of plastics annually respectively. Here, food packaging does not include beverage packaging (beverage bottles) because the recycling rate and resource utilization rate of plastic bottles are very high. Food packaging becomes other garbage after use. It is recommended to take a two-pronged approach to reduce the amount of plastic used and discarded, and encourage the use of edible inner packaging. Daily chemicals and beverage packaging are priority areas for the implementation of the extended producer responsibility system, which can be used in conjunction with the deposit system to achieve better reduction effects.

In the field of agricultural production, China produces about 4.2 million tons of plastic waste each year, including 2.46 million tons of agricultural film (1.04 million tons of waste ground film), 280,000 tons of fertilizer packaging, and 130,000 tons of pesticide plastic packaging. It is imperative to innovatively establish a garbage classification and management system suitable for rural areas, which requires comprehensive consideration based on the responsibility of rural land in the main functional areas and the future path of urbanization. For villages with limited transportation capacity but with garbage incineration facilities nearby, non-recyclable plastic waste will be piled up separately and transported to incineration plants for disposal; for villages very far away from garbage incineration facilities, plastic waste will be sorted and piled up and landfilled separately, and priority will be given to cleaning and incineration of this part of the garbage when conditions permit.

The plastic waste we leave in nature today will be the source of microplastic pollution in soil and water bodies decades or hundreds of years later. Therefore, "plastic restriction" must be effectively reduced at the source, including innovative reduction in product and service design and packaging substitution; a clear "zero plastic waste" goal should be established at the end chain, including zero discharge of newly generated plastic waste into the natural environment and zeroing out old plastic waste left in the natural environment. "Zero plastic waste" requires innovation in the garbage classification mechanism, and at the same time, a supporting "ban on burning, limit on burning, and substitution" mechanism for plastics after use should be established. Among them, "ban on burning" refers to prohibiting the classification of packaging that can be recycled after washing (such as disposable tableware and yogurt boxes) as other garbage, and "substitution" refers to replacing energy-based recycling with resource-based recycling, thereby promoting the closed-loop development of the plastic economy.

In short, strengthening the prevention and control of the entire chain of plastic pollution through the "quartet" of design innovation, packaging substitution, waste plastic emission and incineration will have a gratifying effect - it is estimated that during the "14th Five-Year Plan" period, China can reduce the consumption of traditional plastics by 11.8 million tons and avoid the incineration of 6.2 million tons of plastics, thereby saving 25 million tons of raw materials and reducing carbon dioxide emissions by 110 million tons.

(Author: Cao Shuyan, Associate Professor of Beijing University of Petrochemical Technology)

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