Immortal Plastic
How Plastic is made:
Everything starts from petroleum. What is Petroleum: Millions years ago, algae and plants lived in shallow seas. When they died, their remains sank to the seafloor, mixed with other stuff, and got buried. Over millions of years, with lots of pressure and heat, these leftovers turned into fossil fuels like coal, natural gas, and petroleum. People collect petroleum and then throw heating separate it into different fractions like gasoline, diesel, gas oil, kerosine etc and also naphtha which used a lot in plastic making.
Naphtha is essential for making a significant amount of plastic. This process can also involve using gas as an alternative. In this case gases like ethylene and propylene (monomers) from gasoline are connected into larger hydrocarbons (polymers). These long chains of polymers are then processed and shaped into the plastic products we use, like bottles, bags, and containers, through methods like melting and molding.
Biodegradation
How everything degrades?
In biodegradation microorganisms such as bacteria, fungi and enzymes break down organic material.
Enzymes act as catalysts, speeding up chemical reactions which break down larger molecules into smaller one.
Bacteria are vital decomposers in ecosystems. They break bonds between molecules, essentially "eat it".
Between plastic monomers are carbon-carbon bonds as in nature:
Why then it is such a problem for bacteria to break it down?
Plastics come from refining petroleum, an organic material, yes. But! The process of making plastic changes its structure a lot. In nature, microorganisms have to be familiar with the structure of organic compound they gonna break.
Plastic is not found in nature, and natural organisms don't recognize its unique structure even if base is carbon-carbon bonds. Also they don't know how to break them apart well. These materials which microorganism can't recognize are called "xenobiotic."
All Difficulties bacteria gonna meet:
Complex Structure: Plastics have intricate and artificial chemical structures not found naturally. Microorganisms and enzymes evolved to break down natural compounds struggle with these complex plastic structures.
Strong Bonds: The covalent bonds in plastics are tough, resisting the usual enzymatic attacks bacteria use to break down organic matter. Plastics often have more stable bonds than naturally occurring compounds.
Missing Functional Groups: Plastics may lack the specific chemical features enzymes look for during biodegradation. Natural compounds have features like hydroxyl or amine groups that make them easier for microbes to break down, which plastics might not have.
Low Water Absorption: Bacteria and enzymes need water for effective biodegradation, but many plastics, especially hydrophobic ones, resist water absorption. This limits the access of enzymes and microorganisms to the plastic, slowing down the biodegradation process.
Additives and Stabilizers: Plastics often include extra substances to improve performance. These additives can complicate biodegradation, being toxic or inhibiting microorganism growth.
Our Options
Can we work on bacteria which Could break down the plastic?
Some bacteria have been discovered with the ability to degrade certain types of plastic.
The process is often slow, and the range of plastics that can be efficiently broken down by natural microorganisms is limited.
Researchers are actively exploring the identification and development of enzymes or microorganisms that can more effectively break down plastics to address the environmental challenges associated with plastic pollution.
Can UV-light break down the plastic?
Yes, sunlight, especially the ultraviolet (UV) light in it, can break down certain types of plastics. This process is called photodegradation. When UV light interacts with the chemical bonds in plastics, it can break those bonds.
Not all plastics are affected the same way. Some plastics are made to resist UV damage by including special substances. Others, especially those used outdoors, might be more prone to UV damage.
Using UV light to decompose plastics may break them into smaller fragments, but it doesn't necessarily eliminate the environmental impact. Microplastics and nanoplastics can still contribute to pollution, harming ecosystems and potentially entering the food chain.
Industrial Decomposition and why all the plastic waste is not yet there?
Here are two ways in industrial decomposition:
Biological Decomposition: This involves using microorganisms (bacteria or enzymes) to break down plastics into simpler compounds through biological processes.
Chemical Decomposition: This includes processes like pyrolysis or hydrolysis, which use heat, chemicals, or catalysts to break down plastics into simpler chemical compounds. The resulting products can be used as feedstocks for the production of new materials or as fuels.
Challenges of Industrial Decomposition: Serious
In case on biological decomposition, even there are examples of bacteria that can degrade certain plastics, large-scale industrial applications are still under development.
In case of chemical decomposition - it is a recycling process and it meets next challenges:
Complex Plastic Waste: Plastic waste varies in types, additives, and contaminants, making sorting expensive and complex for industrial use.
Economic: Recycling costs may be way higher the value of recycled materials. Also demand for recycled plastics is often lower than new plastics.
Lack of Standardization: Global lack of recycling standards make it not so smooth to approach plastic recycling.
Also recycling can have negative environmental impacts like it needs high energy consumption, recycling processes contribute to greenhouse gas emissions, and also processes may have the potential use of toxic substances.
Plastic is very not easy to decompose. Us people are actively working on recycling methods, promoting decomposition with the help of bacteria, and developing bioplastics. These efforts are steps toward a future where plastic is less of a burden on the planet, showcasing a commitment to sustainability and a cleaner environment.
December 2023 Theme: Plastic