Summary Reader Response (Draft 2)

 The Levy (2022) article that is posted on The University of Texas at Austin news site, titled “Plastic-eating Enzyme Could Eliminate Billions of Tons of Landfill Waste'', revealed to the readers that researchers at The University of Texas at Austin have developed an enzyme variant that can accelerate the degradation of environmentally harmful plastics in hours or days instead of centuries. The article also stated that the researchers mainly focused on polyethylene terephthalate (PET), a polymer most commonly found in consumer packaging and certain fibers and textiles. This enzyme variant is able to disintegrate the plastic into smaller parts (depolymerization) and then put it back together (repolymerization) which begins the upcycling process. Lavars (2022) mentioned that plastic-eating enzymes were first created in 2016, and among the factors that have hindered the application of this plastic-eating enzyme are its inability to function at low temperatures and different pH ranges, its failure to treat untreated plastic waste directly, and its slow reaction times. However, the Levy (2022) article claimed that this new and improved enzyme variant is proven to be superior in breaking down PET plastics more efficiently. Most of today’s plastic waste ends up in landfill. This enzyme has the potential to remove waste from landfills and green high-waste industries, which would be a significant contribution to the cleanup of landfills and greening of high-waste industries.

The recycling of plastic using plastic-eating enzymes could lead to a more sustainable approach compared to traditional recycling methods in terms of efficiency, fitting in circular economy and environment, and health benefits. Even so, this enzyme would not be the solution to plastic problems but only put a dent in them as it does not break down plastic as readily as many had hoped.

Today's environmentally conscious generation wonders what would happen to plastic once it reaches its end of life, or becomes worn out; the whereabouts of single-use plastic in the case that it cannot be recycled. Unfortunately, the waste is disposed of in landfills. According to the European Union (EU), up to 80% of ocean waste consists of plastic. As plastic can survive in landfills for hundreds of years due to its resistance to degradation, these versatile materials become environmental nightmares. Modifiers, such as pigments or fillers, may also be present in the plastic, which can cause problems during the decomposition process (BioLabTests, 2022).

Traditional plastic recycling methods can be generally classified into mechanical and chemical approaches. For years, mechanical recycling has been used to recycle plastic waste at large scale. The process involves a series of steps: sorting, washing, grinding, and extruding plastics into raw materials for reuse. It is also normally a downcycling process since the quality of the reprocessed plastic material will significantly degrade and the end product will be of lower value and eventually resulting in lower-quality plastic that is discarded in landfills (Mechanical Recycling, n.d.). In other words, mechanical recycling is fitting in a circular economy due to the incapability of upcycling plastics. In contrast, enzymatic conversion of plastic possesses the ability to not just fit in a circular economy, but also offers new opportunities for upcycling. According to the research (Zhu et al., 2021b), plastic substrates can be depolymerized by enzyme biocatalysis into oligomers and monomers, which can then be reprocessed into new plastic products by or refined into new value-added chemicals in a circular economy. In this case, plastics would be reused indefinitely and eliminate reliance on fossil fuels resources. 

According to Chemical Recycling: Distraction, Not Solution (2020), chemical plastic recycling, used plastic is broken down using some combination of heat, pressure, depleted oxygen, catalysts, and/or solvents to produce fuel or new plastic. With plastic containing a wide range of toxicants, heating causes more toxicants to be released. Products and by-products contain toxicants that are released into the environment through air emissions and toxic residues, especially when they are burned. Some of the toxicants include benzene, toluene, formaldehyde, vinyl chloride, hydrogen cyanide, PBDEs, PAHs, and high-temperature tars. While the plastic-eating enzyme recycling approach shows that the enzyme demonstrates superior degradation of PET plastic at a low temperature of 30 to 50 °C (86 to 122 °F), a variety of pH levels, and pressure. In some experiments, it was able to break down plastics in as little as 24 hours and almost entirely degrade 51 different untreated PET products within a week (Lavars, 2022). Since the enzyme can quickly break down post-consumer plastic waste at minimal heating, it is definitely more environmentally friendly, and time-saving. Enzymes also consume less energy, whereas chemical recycling is energy intensive and requires external energy. Chemical Recycling: Distraction, Not Solution (2020) also mentioned that chemical recycling emits greenhouse gasses directly, chemical recycling also perpetuates the extraction of fossil fuels for plastic manufacturing, further aggravating climate change. The outputs of chemical recycling are generally burned as fuel, and very little of the waste plastic actually become new plastic, even when technology is advanced. As such, chemical recycling does not have a place in a circular economy as compared.

Despite the plastic-eating enzyme being a more sustainable approach compared to traditional recycling methods. It would not be the solution to plastic problems but only put a dent in them as it does not break down plastic as readily as many had hoped. According to research (Cobongela, 2021), polyester, polyamides (PA), and polyurethanes (PU) are among the plastics that are hydrolyzable by most enzymes reported so far. There are only a limited number of reports on enzymes that degrade non-hydrolyzable plastics since they are extremely resistant to biological cleavage. This shows that many enzymes only work for specific kinds of plastic, and much of our trash may contain a bad mixture of several types and layers of plastic (Temming, 2021). Also, often enzymes only can work under specific conditions such as ambient temperature. Despite enzymatic plastic degradation being a more environmentally friendly method of recycling plastic waste, it has remained a topic to be explored further with a major improvement.  However, research has been done by scientists that using genetic engineering could create bacteria capable of producing more efficient plastic-degrading enzymes. These genetically modified bacteria may be able to thoroughly break down plastics as well as break down other types of plastic (Cooper, 2022). 

In conclusion, enzymatic plastic recycling is a more efficient and sustainable approach compared to traditional recycling methods. By continuing research into plastic-eating enzymes, it has the potential to be an excellent tool to combat the problem of plastic pollution in the near future scientists are finding more natural and efficient ways to solve our plastic problem Though these chemical machines can help us recycle plastic better, overall, reducing the amount of plastic used in the first place is a much easier and likely less expensive solution to our plague of plastic pollution. 

References

BioLabTests. (2022, July 22). Plastic-eating bacteria: a solution to plastic pollution? BioLabTests. https://biolabtests.com/plastic-eating-bacteria/

Chemical Recycling: Distraction, Not Solution (pp. 1–8). (2020). GAIA. https://www.no-burn.org/wp-content/uploads/2021/11/CR-Briefing_June-2020.pdf

Cobongela, S. Z. Z. (2021). Enzymes Involved in Plastic Degradation. Degradation of Plastics, 95–110. https://doi.org/10.21741/9781644901335-4

Lavars, N. (2022, April 28). Fast-acting enzyme breaks down plastics in as little as 24 hours. New Atlas. https://newatlas.com/environment/fast-acting-enzyme-plastics-24-hours/

Levy, N. (2022). Plastic-eating Enzyme Could Eliminate Billions of Tons of Landfill Waste. [online] UT News. Available at: https://news.utexas.edu/2022/04/27/plastic-eating-enzyme-could-eliminate-billions-of-tons-of-landfill-waste/.

Malewar, A. (2022, April 28). Plastic-eating enzymes can break down plastics in as little as 24 hours. Inceptive Mind. https://www.inceptivemind.com/plastic-eating-enzymes-break-down-plastics-24-hours/24446/

Mechanical Recycling. (n.d.). Circular Economy Asia. https://www.circulareconomyasia.org/mechanical-recycling/

Temming, M. (2021, March 16). Chemists are reimagining recycling to keep plastics out of landfills. Endplasticwaste.org. https://endplasticwaste.org/en/our-stories/chemists-are-reimagining-recycling

Zhu, B., Wang, D., & Wei, N. (2021b). Enzyme Discovery and Engineering for Sustainable Plastic Recycling. Trends in Biotechnology, 40(1). https://doi.org/10.1016/j.tibtech.2021.02.008