The widespread use of plastics has brought huge environmental challenges to the world. According to the United Nations Environment Programme, of the 7 billion tons of plastic waste generated worldwide, less than 10% of it has been recycled. As the amount of plastic waste continues to increase, how to effectively recycle and dispose of these wastes has become a global focus. The following will compare the four commonly used plastic recycling methods in detail and analyze their respective advantages and disadvantages.
Landfill: Gradually Withdrawing from History Stage
Recycling Efficiency: Low
Landfill is a long-standing waste disposal method and one of the earliest large-scale plastic waste disposal technologies used in the world. Its basic principle is to bury waste plastic underground to avoid direct exposure to the environment. However, due to its high stability and low degradability, plastic materials can hardly be naturally degraded in landfills. This leads to the long-term existence of plastic waste in landfills, and in fact, no real “recycling” has been achieved.
Pollution Level: High
Although plastic waste is buried deep underground, it may still release harmful substances through long-term chemical reactions or physical processes. These harmful substances include heavy metals, volatile organic compounds and additives. They may penetrate into the groundwater layer and pollute the water source. What’s more serious is that once these pollutants enter the groundwater, they are almost difficult to remove. This will have a profound impact on the surrounding environment and human health.
Process Difficulty: Low
Early landfills required almost no complex facilities or technologies. Builders only needed to dig a piece of land and bury the waste. However, with the increase in the number of landfills and the increasing shortage of landfill space, the cost of building modern landfills has continued to rise. In addition, modern landfills must be equipped with complex pollution control facilities. This can reduce the impact on the environment to a certain extent.
Scope of Application: Wide
Since landfill is not restricted by the type of waste, it can handle almost all types of plastic waste. Therefore, it has been widely used in the past few decades. However, with the continuous strengthening of environmental protection policies, landfill has gradually withdrawn from the stage of history. In particular, in developed countries and regions, landfill is being replaced by more environmentally friendly and sustainable treatment methods.
Incineration: High Efficiency & Risks Coexist
Recycling Efficiency: Medium
Incineration is a treatment method that converts plastic waste into heat or electricity through high-temperature combustion. Unlike landfilling, incineration can quickly reduce the volume of plastic waste, usually to less than 10% of the original volume. However, plastics are converted into other forms of energy or substances during the incineration process and cannot be remade into plastic products. Therefore, incineration is more of a terminal treatment method for plastic waste.
Pollution Level: High
Incineration of plastic waste will produce a large amount of harmful gases, including carbon dioxide, carbon monoxide, hydrogen chloride, etc. These gases have a great destructive effect on the atmospheric environment, especially dioxins. As a persistent organic pollutant, it poses a serious threat to human health. Incomplete combustion during the incineration process may also produce particulate matter and smoke, which, if not effectively treated, will further aggravate air pollution.
Process Difficulty: High
Incineration technology is relatively complex and requires a variety of facilities such as high-temperature furnaces, waste gas treatment equipment and energy recovery systems. Since the incineration process requires strict temperature control and pollutant treatment, the construction and operation costs of the facilities are relatively high. Especially in developed countries, the construction of incineration plants must meet strict environmental protection standards, leading to further increases in facility investment.
Scope of Application: Wide
The energy consumption of high-temperature combustion in incineration is high. However, the heat energy released during the incineration process can be used for power generation or heating, forming a secondary utilization of energy. This partially offsets the negative impact of its high energy consumption. Incineration treatment is almost not limited by the type and scale of plastic waste, and can treat urban domestic waste and industrial waste on a large scale.
Pyrolysis: The Frontier of Future Plastic Recycling
Recycling Efficiency: High
Plastic pyrolysis technology decomposes waste plastics into fuel oil, syngas and other chemical raw materials through high temperature. Multiphase recycling achieves the maximum decomposition of waste resources. Therefore, it is an effective way of resource recycling. Its pyrolysis products not only contribute to the energy supply of various industrial facilities. In particular, plastic pyrolysis oil can also be used for plastic production. This realizes the real resource cycle.
Pollution Level: Low
The secondary pollutants generated inside the plastic pyrolysis machine mainly include a small amount of harmful gases (such as sulfides, nitrogen oxides) and pyrolysis residues. Compared with incineration technology, pyrolysis produces fewer types of secondary pollutants and lower concentrations. This makes pyrolysis have significant advantages in environmental protection. Not only that, pyrolysis equipment can be equipped with high-end exhaust gas treatment systems, which makes exhaust emissions meet EU standards.
Process Difficulty: Medium
In recent years, plastic pyrolysis technology has made significant progress, gradually moving from laboratory research to industrial application. Many countries and companies are already building and operating pyrolysis plants, especially in some developed regions, where pyrolysis technology has been widely used. Despite this, plastic pyrolysis technology continues to improve. Plastic catalytic pyrolysis and continuous pyrolysis technologies are gradually moving towards the mainstream market.
Scope of Application: Wide
Pyrolysis adopts the syngas recycling concept and has low energy consumption. In practical applications, pyrolysis technology has been used to treat a variety of plastic wastes such as industrial waste, packaging materials, and agricultural films. Particularly, pyrolysis is particularly effective in treating high-polymer plastics (such as PP, PE, PS). In addition, pyrolysis technology has the flexibility of processing scale, and can operate effectively whether it is a small-scale local processing facility or a large-scale industrial device.
Future Outlook of Plastic Recycling
In the future, with the continuous advancement of environmental protection technology, plastic recycling technology will develop in a cleaner and more efficient direction. In this process, the comprehensive utilization of multiple technologies may become a new trend in the field of plastic recycling. This will not only help reduce the harm of plastic waste to the environment, but also effectively utilize plastic waste. Thus, this realizes the recycling of resources. Ultimately, the development of plastic recycling technology will contribute to achieving the goal of “zero waste” and building a sustainable society.
