PLA: BIODEGRADABLE COMPOSTABLE BIOPLASTIC

Around 330 million tonnes of plastic are produced every year, and the numbers are anticipated to double in 20 years. The nuance of plastic pollution and increasing concerns about sustainability had scientists wrap their heads around the problem until bio-based polyethylene or bioplastic was developed in 1869.  It’s been around ever since and rules the packaging industry. It is widely used to manufacture shopping bags, bin bags, tableware, and packaging of vegetables, fruits, meat, drinks, and other products.

Unlike conventional plastics, bioplastic is made from renewable, organic biomass like corn, sugar cane, beet, etc. They are touted as biodegradable, compostable plastics that can replace the harmful fossil-derived toxic plastics in our food and around our homes.

Of 9 billion tons of petroleum-based plastic ever produced, only a tiny proportion of plastic is recycled. About 165 million tons of plastic have been circling deep in our oceans, with over 8 million tons joining the stream each year. Being a fossil product, it takes hundreds of years to degrade naturally in landfill sites. In contrast to traditional plastics, bioplastic is a significant improvement.

Photo by Jon Tyson on Unsplash

Bioplastic is often cited as the best alternative to plastic petrol-based plastic. As the name conveys, bioplastic is made from a family of different organic sources. Each has its unique properties and applications and can be reverted into its smallest constituents (e.g., carbon dioxide, oxygen, and ammonia).  They are naturally degradable, produced less carbon, and are less toxic; they don’t contain phthalates or bisphenol-A (BPA); endocrine hormone disrupters found in petroleum-derived plastic. The global market for bioplastic is projected to grow to over $40 billion in 2022.

Non-Biodegradable, Biodegradable, or Compostable Bioplastic; what’s the difference?

There is always some confusion when we’re talking about bioplastic being biodegradable or compostable, so let’s clarify these terms first.

1-Non-Biodegradable

All material things are degradable. Bioplastic made from sturdy biomass cannot be easily broken down by microorganisms, is termed as non-biodegradable. They’re either photodegradable (degrade in sunlight) or oxo-degradable (degrade in heat and light). However, degradability doesn’t mean that it is environmentally safe. Petroleum-based plastics break down into tiny microplastics, and that too, in decades! From here, these are funneled down the stream, thus entering our oceans and affecting marine life.

2-Partially biodegradable

Also dubbed as Durable plastics, these bioplastics aren’t compostable. Even microbial degradation under suitable conditions can take up to six months.

3-Biodegradable

Biodegradable plastic breaks down entirely into water and carbon dioxide or compost by microorganisms’ action under suitable conditions. Decomposition of biodegradable plastics can take weeks to months, depending on the material, moisture, and temperature. Although organic in its origin, biodegradable bioplastic don’t always break down completely into their natural elements. They often leave residues behind.

4-Compostable

Compostable bioplastic naturally degrades into its mineral constituents within 90 days in a compost pile or composting site. It returns the nutrients to the soil to be taken up by plants, leaving no toxic residue.

Photo by Nareeta Martin on Unsplash

Types of Bioplastic

Moving forward to the types of bioplastic, the most common types of bioplastic include;

Starch-based bioplastic:

It can be made from raw or modified (thermoplastic) starch or starch-based sugars like PLA through the bacterial fermentation process. Wheat, corn, maize, potato, tapioca, cassavas are common starch sources. First, ever bioplastic was made from maize starch.

Cellulose-based plastics:

It is made from the chemically-modified natural cellulose. Wood pulp, hemp, and cotton are predominant sources of cellulosic bioplastics.

Polylactic acid (PLA) bioplastic:

PLA bioplastic is the most important bioplastic today. These are made from lactic acid obtained through microbial fermentation of starch. The starch is derived from sources same as mentioned above.

4. PHA (polyhydroxyalkanoates):

PHA-based bioplastic is also made from microbial fermentation of plant-based starch. PHA granules are produced and stored (as much as 80%) intercellularly by microorganisms in nutrient-deficient conditions. This PHA polymer is harvested by breaking the cell wall and extracting it using aqueous organic solvents. PHA based bioplastics are truly biodegradable; it decomposes completely within one year, yielding carbon dioxide and water under aerobic conditions.

5. PBAT (polybutyrate adipate tetraphthalate)

PBAT is a petrochemical that is used for manufacturing bioplastics. These are also biodegradable. PBAT plastics are used in conjunction with starch-based bioplastics to improve their performance. For its unmatchable elasticity and flexibility, it is used in manufacturing shopping bags, bin bags, wraps, and other packaging materials. It is highly biodegradable.

6. Bio-based bioplastic

These bioplastics are made wholly or partially from bio-based material, usually used as blends, containing one bio-based and one biodegradable fossil ingredient. The common examples of bio-based bioplastics are bio-polyethylene (bio-PE), bio-polypropylene (bio-PP), and bio-polyethylene tetraphthalate (bio-PET). These are chemically identical to conventional plastics and thus can be used for the same purposes.

Among all, PLA is the most commonly used bioplastic. And here’s why.

What is PLA Bioplastic?

PLA or polylactic acid is a polyester product made from the fermentation of renewable resources like corn starch, beet, or sugar cane. To manufacture PLA bioplastic, corn kernels are immersed in sulfur dioxide and hot water, a wet milling process, where it splits into starch, fiber, and protein. It is then ground to separate the corn oil from the starch.

The starch contains long chains of carbon, like plastic, to which acids or enzymes are added. It breaks starch into dextrose (D-glucose), fermented to produce the long-chain polymer, i.e., L-lactic acid or lactide monomers. PLA is more like polyethylene, polystyrene, or polypropylene.

Since PLA bioplastic is derived from carbon-absorbing plants, it is a sustainable approach to reduce greenhouse gas emissions. PLA also doesn’t release toxic fumes into the atmosphere when incinerated.

Plastic made from PLA is the most popular, inexpensive, biodegradable bioplastic on the market. 33 percent of the consumers in the U.S. preferred reusable tableware, utensils, and silverware in 2019.

It’s incorporated in food packaging, tableware, home furnishings, clothing, and cosmetics. Following a ban on white or plastic pollution in countries like China, Turkey, Italy, Ireland, South Africa, Uganda, Thailand, San Francisco, there’s a growing market for carbon-neutral PLA as an eco-friendly alternative to conventional plastic.

The pros and cons of PLA bioplastic

The increasing environmental awareness among the masses and the spiking demand for renewable plastic alternatives have gained bioplastic polymers a reputation as an “eco-friendly product.” However, it is still far from a panacea for dealing with plastic pollution. Let’s have a meticulous look at the pros and cons of using PLA bioplastic in everyday life.

The pros of using PLA bioplastic

  1. It is made from renewable resources such as sugarcane, corn starch, or other agricultural waste. It can be classified as bio-based, biodegradable products.
  2. Since it is carbon-neutral, it reduces the number of toxic gas emissions. Its sources actually absorb carbon from the atmosphere.
  3. PLA bioplastic products like tableware or bottles are safe to use as per U.S Food and Drug Administration (FDA). It doesn’t produce phthalates, BPA, or other toxic chemicals.
  4. It is also safe to use as packaging material or in the production of biomedical or clinical equipment in bone fixation devices, such as screws, plates, and intravenous drug delivery systems.
  5. It exhibits thermoplasticity even at low temperatures. For this reason, PLA is the most desirable raw material for bioplastic.
  6. This has paved roads for genetically modified plants to breed high-yielding corn for industrial use. Notable brands like Cargill have been tampering with genes to produce higher yields.
  7. PLA biodegrades at a much faster rate than plastic. Under the right conditions, PLA decomposes within 180 days.
  8. The invention of PLA plastic is the base for the clean energy technology of this century. It can drastically reduce the carbon footprint of our industries.

The cons of using PLA bioplastic

Despite its multi-faceted benefits, it is fraught with drawbacks as an alternative to petroleum-derived plastic:

  1. First things first, though biodegradable, it is still Plastic. Bioplastic encourages reliance on plastic as an inexpensive commodity in everyday life and industries, particularly food packaging, tableware manufacturing, shopping bags/bin bags manufacturing, etc.
  2. The biodegradation process is too slow to be maintained in the backyard or landfill site. It could take hundreds to thousands of years to degrade naturally in a landfill facility.
  3. The biodegradation of bioplastic requires optimum heating to 140 degrees Fahrenheit with a constant supply of digestive microbes. Such conditions are only possible in the industrial composting site.
  4. When it has out-served its purpose, PLA bioplastic needs to be segregated from the recyclable waste and sent directly to the composting facility nearby. Being chemically different, it can contaminate the recycling process. Furthermore, there aren’t many composting facilities in most countries.
  5. With the growing market for PLA bioplastic, there’s an increasing demand for genetically modified corn, particularly in the U.S. this has raised moral concerns about utilizing the entire yield of corn for bioplastic manufacturing rather than feeding the poor.  Also, the future costs of genetic modification to the environment and human health is still unknown.
  • Until the means of disposal and recycling are worked out, PLA can’t be touted as better than conventional plastic.
  • PLA is not as durable and flexible as conventional plastic unless it is blended with one.

Is PLA bioplastic really environment-friendly?

Photo by Brian Yurasits on Unsplash

Any plastic that is degradable by microorganisms is referred to as bioplastic, even if it isn’t made from renewable sources. Likewise, bio-based plastics, which are wholly or partially produced from organic biomass, aren’t always biodegradable. Hence, when PLA bioplastic surfaced, it had many promises to be fulfilled. It has been the center of controversies regarding the use of GMO crops, relative environmental toxicity, and increased reliance on plastic.

Let’s have a detailed look if PLA bioplastic is really an environment-friendly product.

Renewable biomass

The prime feature that makes them superior to conventional plastics is using renewable biomass for its production. These plants sequester carbon dioxide from the atmosphere and regrow quickly. Production of bioplastic ensures this carbon is locked in the raw material, converted into glucose, and fermented to carbon-neutral bioplastic.

Also, it is biodegradable. This way, neither is it depleting non-renewable fossil resources nor polluting our environment like petroleum-based plastic does. Although PLA bioplastic is the best alternative to conventional plastic at the consumer level, the raw material still consumes a large amount of energy during production. Considering the carbon emissions associated with growing crops using fertilizer and pesticides and converting them into chemicals, one can say that bioplastic has a negative environmental impact.  

The increasing demand for bioplastic has resulted in the extensive harvesting of corn or sugarcane crops. The eco-friendly incentives offered by bioplastic are juxtaposed because this harvest can negatively impact soil and water bodies. In current times when potable water and fertile land are scarce, diverting these resources to the production of crops for biomass could be seen as morally and socially irresponsible. 

Genetically Modified Crops

The growing market of PLA plastic has encouraged the development of genetically engineered corn and other plants. NatureWorks, an initiative of Cargill, is the world’s largest producer of PLA from genetically modified corn. High-yielding, fast-growing corn is in the best interests of producers. Consequently, genetically modified corn presents certain environmental challenges. Pest-resistant GMO corn has adverse effects on the population of Monarch butterflies, for example.

Controversial Use of Crops 

Edible crops for inedible products like PLA plastic have always been a hot topic for debate as it cuts corn production for food. It is deemed irresponsible to use crops for anything other than feeding over 8 billion people. 

Inefficient waste management

The improper disposal of bioplastic waste is a persistent environmental nuisance. It frequently ends up mixed with petroleum-based plastics as consumers find it difficult to distinguish among different categories of bioplastics from conventional plastic. Once mixed, it can contaminate and wreck the whole recycling batch. 

Photo by Christian Wiediger on Unsplash

Bioplastic requires proper disposal under specific conditions. On top of this, the biodegradation of PLA bioplastic requires an appropriate industrial-grade composting facility for complete biodegradation, which isn’t commercially available. Often, they’re incinerated to avoid the long-due biodegradation process.

Hence, compostable plastic needs to be segregated into compostable bins and sent to the composting facility directly. Otherwise, PLA plastic waste would end up in landfills or our oceans with the rest of the plastic, resulting in the death of millions of marine animals.

Minimal Toxin Pollution

Although made from renewable resources, PLA bioplastic releases 10 times fewer VOCs than a conventional one. These small toxins are released into the atmosphere that can enter your lungs if you breathe them in. This imposes a risk of emphysema, asthma, and other pulmonary diseases.

Optimum conditions for biodegradability 

While fossil-derived plastic can take up to 1000 years to biodegrade, a PLA plastic bag biodegrades in 3 to 6 months under suitable conditions. Conditions as 60 degrees Celsius temperature and a constant supply of industrial digestive enzymes in a controlled setting are viable in an industrial composting facility. However, in a landfill setting, the PLA bioplastic can take from 100 to 1000 years to break down. Is this any better than conventional plastic?

Nonetheless, bioplastic is a worthwhile concept. The ultimate goal is to replace conventional plastics with bioplastic alternatives, and PLA bioplastic is renewable and biodegradable. There are prospects that bioplastic will be more eco-friendly in the future.

Production of PLA bioplastic also requires less energy than conventional plastics. That means PLA bioplastic produces less carbon dioxide during its production, locks carbon dioxide inside its raw material, and reduces the global carbon footprint. All in all, it is a carbon-neutral product. It is a lightweight, reusable alternative to conventional single-use disposables.

What should we do?

Plastic has become a necessary evil. We depend so much on plastic in our lives. Most of the overwhelming volume of plastic waste comprises single-use plastic such as straws, disposable cups, plates, and containers, packaging, and more. Since only a fraction of this waste is recycled, a major proportion of this waste ends in our oceans.

PLA Plastic

Photo by Dustan Woodhouse on Unsplash

A recent survey conducted by the International Coastal Ocean Cleanup, one of the world’s largest volunteer programs for healthy oceans, recorded that plastic packaging was the most commonly collected item (over 4.7 million pieces) in 2019. An earlier 2015 survey by country in Europe on annual consumption volume of single-use plastic straws shows that Germany was the biggest consumer of disposable plastic straws, with an estimated volume of 4.8 billion units, followed by France with 3.2 billion units.

These stats for small single-use commodities are enough to wreak havoc on marine life. When we take into account the billions of tonnes of plastic (in all forms) that is produced and dumped in our oceans every year, the effects are unimaginable. Every year, hundreds of marine animals get entangled in plastic shopping bags or six-pack rings. Many others are feeding on microplastics produced from the photochemical degradation of petroleum-based plastics.

While scientists are developing the most sustainable alternatives to fossil-exhaustive plastic, it is our responsibility to bring out behavioral changes at the individual level. We need to avoid single-use plastic as much as we can. We need to discontinue our throwaway habits on the next level, be it conventional or bio-based plastic. Bioplastic is a promising alternative to regular plastic, but it is challenging as waste itself.

Proper disposal and management of bioplastic waste would make it the best choice as an eco-friendly product. It’s efficient to replace the traditional plastic and help keep billions of tonnes of trash from ending up in landfill sites or our oceans. Stringent regulations can also play an important role in establishing eco-friendly, biodegradable plastic trends throughout the product’s life cycle. 

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