Environmental Impacts of Recycling
The use of plastic is anticipated to triple by 2060 compared to 2019, driven by the expanding global economy; however, the recycling rate may double during this period, creating a significant unintended environmental leakage.
Until now, the environment has been housing multiple layers of first-generation nonbiodegradable plastics that have transgressed different compartments, which may unfold as a catastrophic environmental challenge.
It is estimated that 19–23 Mt of plastic waste generated globally in 2016 entered aquatic ecosystems, but could reach up to 53 Mt annually by 2030. Legacy plastic pollution is not just limited to marine and aquatic ecosystems. Due to the widespread use of plastics in agriculture and their limited recyclability, an estimated 12.5 Mt of plastics accumulate in agricultural soils annually. Additionally, recycling alone cannot reverse the damage incurred due to the leakage of plastics already in the environment.
Plastic recycling encompasses both positive and negative aspects, warranting a comprehensive evaluation to balance environmental benefits and burdens. Recycling plastic waste significantly reduces fossil fuel utilization, power consumption, and landfilling. The ripple effect is a decline in the emission of greenhouse gases, thus lowering the carbon footprints while contributing to the global economy and direct jobs. In fact, it is emphasized that reprocessing 1 ton of plastic can save up to approximately 130 million kilojoules of energy. A life cycle assessment (LCA) conducted on the environmental impact of 1) recycling plastic waste compared to alternative approaches and 2) application of secondary products instead of virgin materials marks a positive step toward climate control. Similarly, several other LCA studies have confirmed the superiority of plastics as material over their alternative option such as aluminium bottles, paper, and cotton bags. However, a notable limitation in several standard LCA methodologies lies in omitting a crucial factor—the long-term fate of chemicals and particulates released during EoL plastic The disadvantage of existing short-term LCAs in disregarding the consequences of chemical and particulate releases raises concerns about the overall efficacy of plastics and recycling as a solution to plastic pollution. This gap in evaluating the true ecological footprint of virgin and recyclate plastics (i.e., raw materials transported to a waste recycling facility for processing into a new materials or products) may result in unintended environmental and health costs.
Recycling facilities have been identified as potential hotspots and contributors of toxic and hazardous waste, however, there is limited attention to chemical or particle release from plastic recycling facilities. Despite the current and emerging technologies to recycle plastic waste, non-recoverable tiny plastic particles (microplastics) cannot be addressed with existing collection methods due to their exceptionally small size. Further, the size reduction and washing during mechanical recycling facilities tend to release significant microplastics into the environment. About 13% of plastics infiltrate water or air as microplastics from recycling facilities in the UK. A study on PET recycling facilities reveals microplastic releases range from approximately 23–1836 mg/L in wastewater that is distributed in the effluent (8–83 mg/L) and the sludge (52,166–68,866 mg/L) as it leaves the facility. Microplastics generated during the recycling process are governed by the properties of plastics (polymer type or hardness) and environmental exposure. Ideally, plastic recycling facilities are equipped with filters to prevent and mitigate environmental contamination, but it partially mitigates microplastic release and is not a comprehensive solution. Additionally, the leaching of harmful plastic chemicals during and after recycling also poses a significant threat. Recycled plastics exhibit higher levels of hazardous chemicals such as brominated flame retardants as legacy contaminants. The contamination not only hinders the wide application, it also poses health risks for workers and end-users. With this, it is imperative to produce toxic chemical-free material through controls over what is being recycled and standards for recycled plastics and their usability in different sectors.
While chemical recycling can produce food-grade plastics and has been heralded to fix plastics recycling, it is financially risky and can have far-reaching environmental implications compared to virgin plastics production. The damage to the environment through chemical recycling in terms of emissions, energy consumption, and water utilization surpasses those used in other technologies. Meanwhile, mechanical recycling is believed to exhibit a lower overall impact on climate change than chemical recycling and energy recovery, which contributes to greenhouse gas emissions and photochemical ozone formation. To address these concerns effectively, the transport and sorting of waste should be confined within closed spaces, filters should be installed and wastewater should be treated to prohibit the release of plastics and associated chemicals into the environment. Despite an apparent increase in the plastic recycling rate, lower-grade polymers with a limited lifespan are eventually disposed of as waste, thus challenging the circular economy of plastics and environmental sustainability.
Inefficient waste collection, coupled with the necessity for sorting before recycling, requires transportation to dedicated waste handling facilities leading to inadvertent loss and an escalation in carbon footprints. However, the global plastic waste trade is built on the premise of exporting for recycling, often to lower-income countries. Countries are also fraught with widespread environmental impacts and incredibly low recycling rates if accurately reported. Further, regional policies have far-reaching effects on global plastics recycling dynamics. Until 2018, China had been the reprocessing house for more than 50% of PET bottles, but the recent ban on foreign waste imports, including plastics, has left world recycling facilities scrambling. High-income countries began exporting plastic waste to other low-income countries, particularly those in the global south. Many of these low-income countries have become disproportionally impacted by plastic pollution due to overwhelming imports of plastic waste (for so-called “recycling”), as part of the global plastic waste trade. These countries lack adequate recycling facilities, which has led to excessive open-dumping or burning of plastic waste, including waste-to-energy incineration. Imported plastic, often of low quality, contaminated, or mislabelled, is diverted to landfilling and incineration, each contributing to negative environmental impacts. The other example of change in plastic waste dynamics includes the largest exporter of plastics (i.e., Japan), which saw a surge in reprocessing, while the use of virgin plastics increased in China which further increased the carbon footprint following the import ban
