Why Choose Pyrolysis Over Traditional Methods to Treat Waste Plastics

As an essential material in modern life and production, plastic is closely linked to energy, the economy, and the environment in its preparation, use, and end-of-life disposal. Particularly, the disposal and utilization of waste plastic are intimately connected with the construction of ecological civilization and the development of a circular economy, making it a key factor in future sustainable development.

The production and application of plastics have developed rapidly since the early 20th century. Currently, the main types of plastics include polyethylene (PE), polypropylene (PP), polyvinyl chloride (PVC), polystyrene (PS), polyethylene terephthalate (PET), acrylonitrile-butadiene-styrene (ABS), nylon (PA), polylactic acid (PLA), and others. With technological advancements, the variety and use of plastics continue to expand, leading to a corresponding increase in plastic waste generated each year.

Due to the inherent chemical inertness of plastics, they require several hundred years, at least, to fully degrade under natural conditions. This characteristic results in the continuous accumulation of discarded plastics in the natural environment, posing a threat to human health and the ecological environment.

The traditional methods of plastic waste disposal, including landfilling and incineration, have various drawbacks and are no longer able to meet the current requirements for plastic waste management. Plastic pyrolysis technology, on the other hand, provides a new avenue for the clean and efficient recovery, disposal, and utilization of waste plastics. This article will provide a brief summary of both traditional waste disposal methods and plastic pyrolysis, aiming to clearly illustrate the advantages brought about by plastic pyrolysis technology through a comparative analysis.

Traditional Plastic Waste Disposal Techniques

Landfilling

Landfill disposal involves mixing waste plastics with other garbage and depositing them in a landfill, where the waste naturally decomposes with the help of microorganisms in the soil. This method has been a primary means of waste disposal. However, the natural degradation of waste plastics in the soil takes hundreds of years and occupies significant land resources, making recycling impractical. Through natural degradation, the organic components of waste plastics produce gaseous byproducts such as CH4, CO2, NH3, as well as compounds like sulfides and chlorides. The high content of harmful components in these byproducts, when released into the atmosphere, poses environmental pollution risks such as acid rain, greenhouse gases, and ozone layer depletion.

waste plastic disposal landfill

Waste plastics, due to their corrosion resistance, aging resistance, and slow degradation, leave behind residues that, after exposure to wind and sun, form microplastics or nanoplastics through physical settling. These small-sized microplastics, with a large surface area relative to their size, can migrate through surface water or underground percolation, posing a greater hazard to the environment and living organisms than regular waste plastics. Although research on microplastics is still in its early stages, studies have indicated that the adsorption capacity of microplastics can alter the distribution of organic and inorganic compounds in the soil. This not only leads to a decline in the quality of surrounding soil but also affects soil physicochemical properties, resulting in soil environmental degradation. The migration of microplastics causes water pollution, severely impacting ecological health. Microplastics’ surfaces can adsorb bacteria and pathogens, causing damage to the intestinal mucosa and even leading to diseases after accumulation in the digestive system.

Considering the persistent ecological impacts, landfilling is not an ideal technique for plastic waste disposal and is inconsistent with the principles of green sustainable development.

Incineration

The resin content in most plastic products exceeds 65%. When burned in excess air at temperatures ranging from 800 to 1200 ℃, over 80% of the material oxidizes and decomposes into small molecular compounds. The heat generated during this process can be utilized as a source of energy for power generation or heating. Incineration, to a large extent, achieves the harmless, volume-reducing, and energy-producing disposal of waste plastics. Incineration is suitable for treating multi-component waste plastics and is characterized by low cost and high efficiency.

plastic incineration plant

However, research indicates that the ash produced during incineration contains microplastics, with a significant portion originating from the incineration of polypropylene (PP). These microplastics can be released into the environment during the disposal and utilization of the ash. Additionally, the incineration process generates heavy metals (such as chromium, lead, and mercury) and toxic organic pollutants (such as CO, polycyclic aromatic hydrocarbons (PAHs), and dioxins). These pollutants possess acute or chronic toxicity. The incineration of polyvinyl chloride (PVC) produces toxic gases like hydrogen chloride and sulfides, contributing to the formation of acid rain in the atmosphere, leading to secondary environmental pollution.

Marine Disposal Method

The ocean dumping method involves the disposal of waste generated on land or within ships into deep-sea areas using vessels, aircraft, or other means. It relies on the self-purification capacity and vast capacity of the ocean to manage waste. This method of waste disposal dates back to the 1860s and coastal nations are the primary users of this approach.

plastic polluted ocean waster

With the development of society, the quantity of industrial and domestic plastic waste discarded has gradually increased. Marine plastic waste has become a significant component of ocean garbage, constituting 60% to 80% (in some areas, even reaching 90% to 95%) of marine debris. The harm caused by marine plastic waste has become increasingly apparent. The global accumulation of plastic waste in the oceans has reached 1.5 × 10^8 tons and continues to grow at a rate of 1.2 × 10^7 tons per year. This has adverse effects on marine biodiversity and results in severe environmental pollution. For instance, plastic waste in the ocean is prone to being mistakenly ingested by marine livings, leading to respiratory and feeding problems. Entanglement with plastic can hinder the movement of sea animals, and the heavy metals present in plastic can harm marine life. As industrialization accelerates and international trade expands, the self-purification capacity of the ocean is no longer able to cope with the rate of plastic dumping. Consequently, the issuance of regulations regarding marine disposal to curb this detrimental trend has become a global initiative.

Plastic Pyrolysis Technology

Plastic pyrolysis technology involves the high-temperature heating of plastics in a pyrolysis reactor isolated from external air. This process converts polymers into smaller molecules, including their component monomers, smaller hydrocarbon substances, and petrochemical raw materials.

Currently, the most widely circulated types of plastics in the market are PE, PP, PVC, PS, and PET, with PE, PP, and PS accounting for approximately 70% of the total usage. Due to their rich carbon and hydrogen elements, these plastics are the main focus of research in the field of waste plastic pyrolysis. At a temperature of 730 ℃, the pyrolysis of PE, PP, and PS generates 35 wt% gas, 48.4 wt% oil, 14.3 wt% residue, and 2.2 wt% tar. The high-calorific-value gas (50 MJ/kg) produced can serve as an alternative fuel to coal. Using a conical fluidized bed reactor for the pyrolysis of polyolefins, the resulting product contains 69 wt% of high-quality commercial gasoline (without desulfurization requirements). The hydrocarbon compounds in the liquid products from polyolefin pyrolysis can be used to produce basic chemicals. Utilizing HZSM-5 zeolite catalyst for the pyrolysis of waste plastics, PE, PP, and PS can be reformed via catalysis to produce H2. Catalytic pyrolysis of waste plastics can reduce energy consumption, employing catalysts to simultaneously lower reaction temperatures and improve product quality.

Compared to traditional methods of plastic waste disposal, plastic pyrolysis has significant advantages. From the perspective of resource recovery and utilization, the catalytic pyrolysis of waste plastics can yield hydrocarbon products such as gasoline and paraffin. In terms of environmental benefits, the catalytic pyrolysis and gasification process for waste plastics is conducted in an oxygen-deficient atmosphere, which suppresses the generation of dioxins and reduces the emission of most heavy metals by allowing them to dissolve into the ash residue during the pyrolysis process.

As a provider of pyrolysis solutions, GEMCO Energy has been committed to the research and innovation of plastic pyrolysis technology. The company continuously optimizes and improves the existing plastic pyrolysis process, striving to provide customers with high-quality, efficient, and economical plastic pyrolysis solutions. The company’s current plastic pyrolysis facilities can handle single or mixed plastic waste, including PP, PE, PS, etc., with a service life of over ten years and high energy utilization efficiency. Our vision is to make our planet a better place through scientific, environmentally friendly, and sustainable waste management!

Get In Touch

Get in touch with us for a free consultation or request a customized quote, our expert engineering team is always ready to help. Together, we can build a clean, efficient, and sustainable future.

Customized EPC Projects

Reply Within 24 hours

After Sales Services