Attention: How to solve the global plastic waste dilemma?
Canadian Prime Minister Justin Trudeau announced on the 10th that Canada will ban single-use plastic products from 2021. This statement makes the disposal and recycling of plastic waste once again become the focus of public attention in the context of strict control over the use of single-use plastic products in many countries and regions around the world. In the end, what are the ways to deal with plastic waste, and what problems do you face when dealing with it? Are there any mature alternatives to plastics, or is it only possible to minimize the use of single-use plastics?
Four modes of dealing with plastic waste
At present, the global disposal methods of waste plastics include landfill, incineration, recycling granulation and pyrolysis.
Landfilling is the traditional method that is widely used to dispose of waste plastic waste. This simple and direct physical treatment method has great hidden dangers and hazards, and increases the pressure on the use of land resources. The refractory plastics seriously hinder the infiltration of groundwater, and the additives in the plastics cause secondary pollution of the land. Plastic waste - whether in rivers, oceans or on land - can persist in the environment for centuries. It is almost impossible for plastic to decompose completely in nature. Most plastic items never completely disappear, they just keep getting smaller.
Incineration is also a widely used method of plastic waste disposal. According to the BBC, 'Incinerators' say plastics are extracted from oil and gas, mainly hydrocarbons, and when incinerated, generate a lot of heat, which is then used to generate electricity. Incinerating plastic waste in this way now replaces the burning of polluting fuels such as coal or oil in some places. However, burning plastic produces toxic and harmful gases, which can enter the environment if the incinerator is not efficient. Take Germany as an example. At present, the country has 200,000 tons of PVC waste every year, 30% of which is burned in incinerators. The German environment department has stipulated that all incinerators must comply with a limit of less than 0.1ng (nanogram) per cubic meter of exhaust gas. Although the air pollution standard of incinerators in Germany has been recognized as a high standard in the world, it still does not say that the incineration method will not release harmful substances due to mechanical failure.
Liu Jianguo, a professor at the School of Environment of Tsinghua University, said in an interview with a reporter from the Global Times that a relatively complete control system should be used to make the plastic waste burn more fully, and a complete flue gas purification system should be set up later to treat the flue gas in place. , so that pollution can be effectively controlled.
Recycled granulation is a method of physically recycling plastic waste. Most recyclable plastics are mechanically broken down into pellets, which are then remanufactured into new plastic products such as packaging, seating or clothing. However, the recycled granulation method also has limitations, the process is not suitable for plastic films, pouches and other laminated plastics, which are often sent to landfill or incinerated.
Pyrolysis of waste plastics. This chemical decomposition method refers to the process of using the thermal instability of organic matter in solid waste and placing it in a pyrolysis reactor for thermal decomposition. This technology can convert waste plastics into high value-added energy products such as fuel oil, natural gas, and solid fuel.
Why is the world still scratching its head in plastic disposal when there are multiple disposal modes?
First, there is too much plastic production. Plastic production has grown faster than any other material since the 1950s. The BBC reported that a 2018 report by the United Nations Environment Programme said that only 9% of the 9 billion tons of plastic products produced worldwide are recycled and about 12% are incinerated. The remaining 79% ends up in landfills or flows into the natural environment. At present, the world uses as many as 5 trillion plastic bags every year. If they are lined up one by one, they can cover two France.
Secondly, whether it is chemical method or physical method conversion and utilization, there is a difficulty, that is, the recycled waste plastics are mixed, and it is not easy to identify and classify. high. Sorting is an important factor in determining the economics of material reuse. At present, foreign sorting technology has developed rapidly, and many automatic sorting lines have been put into use, which can sort and process different types of materials very accurately. And this classification process must be a part completed by the whole society. For example, after the first classification of the family, the plastic waste is divided into three categories: 'combustible', 'non-combustible' and 'recyclable (resources)'; The second classification: the combustible garbage is collected separately, the non-burnable garbage is crushed and sorted, and the recyclable plastics are collected by category; then the waste treatment company will carry out the final treatment.
Thirdly, there is a problem of cost and benefit: whether the comprehensive treatment cost of plastic waste is lower than the comprehensive value created by the recycling of resources. This comprehensive value includes both economic value and social value. The comprehensive processing cost is an invisible threshold. Because the characteristics of this field are that it takes up a lot of labor and requires high technology (capital). For example, the environmental protection measures of incinerators are higher than those of coal power plants; the screening machine for waste plastics is a large-scale precision instrument, and the price of a photoelectric sorting machine is very high. At the same time, in the process of plastic waste recycling, there are collection, transportation, sorting and other processes, and a lot of labor is required, and developed countries are generally reluctant to provide so much labor in related fields.
Liu Jianguo, a professor at the School of Environment, Tsinghua University, said that plastic waste disposal is actually the result of the global allocation of resources by the market economy. It does not mean that there is no relevant processing technology in the world. Developed countries are more advanced in related technical fields, but because they feel that the cost is not cost-effective. , so it is necessary to find the cheapest and most efficient disposal method - sending a large amount of plastic waste abroad to developing countries.
Are there any feasible technical solutions to replace plastics?
Liu Jianguo said that in general, the conditions for replacing plastics in a large area are not yet available, because it has many superior functions, which other materials do not have. And cost is a big hindrance.
Japanese private and government research institutes have been working on plastic replacement technologies, such as a degradable shopping bag, whose composition is 70% resin and 30% starch, and its strength can be adjusted through food-grade additives. Although this technology has passed the test, its price is 2.5 times that of plastic, which is difficult to promote. In addition, Japanese paper companies are studying the replacement of plastic containers with paper. It is to spray the surface of the paper to make it have the characteristics of isolating air and moisture, so that it can be used as a soft drink packaging bag. This technology has been put into use, but after the waste is recycled as waste paper, it cannot be recycled, and it increases the difficulty of sorting waste paper, and finally only increases the amount of incineration. Therefore, from the perspective of materials, plastics are replaced, and from the perspective of renewable resources, the recyclability rate is reduced. How to solve this contradiction is a problem that requires the business community to constantly think about.
According to the BBC, bioplastics are made from renewable substances, often including vegetable oils, tapioca starch, wood chips or food waste. However, a start-up in Indonesia is replacing plastic with seaweed packaging. They use seaweed to make sandwich and hamburger wrappers, coffee bags and seasoning packets, and soap wrappers. Seasoning packets made from seaweed can be dissolved in hot water and eaten directly without throwing away the wrapping paper. Has the dual benefits of being sustainable and nutritious.
Strengthening recycling regulations is a common practice in the global governance of plastic waste. The EU currently provides a strategic framework for its member states to recycle 55% of plastic waste from 2030. In the United States, while there is no federal law requiring citizens to recycle, states have their own legislation. In Japan, local governments organize and encourage residents to sort garbage.
Some of South Korea's 'plastic restriction' programs are worth learning from. According to statistics from the Korea Statistics Office, in 2016, South Korea's per capita consumption of plastic products was 98.2 kg, ranking first in the world; the consumption of plastic bags was 21.6 billion, which was 6 times that of Germany and more than 100 times that of Finland. Taking disposable coffee cups as an example, the total annual consumption of disposable plastic coffee cups in South Korea is as high as 26 billion.
In order to reduce the use of plastic products, South Korea's Ministry of Environment banned the use of single-use plastic cups in coffee shops since August last year. With the arrival of the New Year, the scope of 'plastic restrictions' has expanded from coffee shops to supermarkets and bakeries. On January 1 this year, South Korea's amendment to the Law on Conserving Resources and Promoting Resource Recycling came into effect. It stipulates that 2,000 large supermarkets and 11,000 supermarkets with an area of more than 165 square meters in South Korea completely ban single-use plastic bags. According to the amendment, in addition to the use of plastic bags for meat, fish and other water-containing products, relevant supermarkets and large supermarkets can only provide customers with metered and charged garbage bags, environmentally friendly shopping bags and empty paper shells made from waste plastics. boxes, etc. for packing. The amendment also stipulates that more than 18,000 bakeries across the country will not be able to provide plastic bags for free starting this year.
The South Korean government has also increased penalties for violators. Law enforcement officers will visit coffee shops from time to time to conduct on-site inspections. If they violate the regulations, they will be fined up to 2 million won (1 million won is about 6,000 yuan) according to the size of the coffee shop and the number of violations. In addition, large supermarkets are found to be using single-use plastic bags, and merchants will be fined up to 3 million won. The South Korean government introduced incentive measures at the end of last year. For dry cleaners and transportation packaging plastics, umbrella plastic covers, disposable plastic gloves, food cling film and other five kinds of plastic products, if the manufacturer can recycle and reprocess, the government will recycle according to the recycling. Production provides financial support to producers.
Article link：http://bisenet.com/article/201906/189952.htm