Which of the following best explains why pyrolysis is considered a more sustainable method for managing plastic waste compared to traditional incineration or landfilling?
Show answer & explanation
Correct answer: B
Explanation
Solution: The correct answer is Pyrolysis transforms plastic waste into reusable gases, oils, and char without combustion, thereby reducing greenhouse gas emissions.
Explanation:
☛ Pyrolysis is the thermal decomposition of organic matter at elevated temperatures (usually between 300°C to 900°C) strictly in the absence of oxygen or an inert atmosphere.
☛ Unlike conventional incineration, which burns waste in the presence of oxygen and releases harmful greenhouse gases, dioxins, and toxic fly ash, pyrolysis operates without combustion.
☛ This process breaks down polymer chains into valuable products such as pyrolysis oil (liquid fuel), syngas (combustible gases), and char (solid carbon residue).
☛ These recovered products can be used as clean alternative fuels or chemical feedstocks to manufacture new plastics, drastically cutting reliance on fossil fuels and reducing landfill burden.
Extra Exam-Relevant Facts:
☛ Endothermic Nature: Pyrolysis is an endothermic reaction requiring external heat input, whereas incineration is an exothermic combustion reaction.
☛ Plastic in Landfills: Conventional landfilling of plastics leads to severe environmental hazards due to leaching of toxic additives (like phthalates and bisphenol A) and microplastic contamination.
☛ Syngas Utilization: The non-condensable gas mixture (containing methane, hydrogen, and carbon monoxide) generated during pyrolysis can be recycled to power the pyrolysis reactor itself.
☛ Circular Economy: Pyrolysis of plastics is classified under chemical (advanced) recycling, which helps maintain a closed-loop circular economy.
Important One-Liners for Upcoming Exams:
☛ The chemical decomposition of organic materials by heating in the absence of oxygen is known as? → Pyrolysis
☛ A fuel gas mixture consisting primarily of carbon monoxide and hydrogen is called? → Syngas (Synthesis Gas)
☛ The thermal waste treatment method involving complete combustion in excess oxygen is called? → Incineration
☛ The solid, carbon-rich residue left behind after pyrolysis is known as? → Char (Carbon Black)
☛ Which highly toxic persistent organic pollutants are released during improper incineration of PVC plastics? → Dioxins and Furans