La rapid decomposition of bioplastics It has become one of the major obsessions of materials science and waste management. And with good reason: as we speak, millions of tons of plastics and microplastics are accumulating in seas, soils, and rivers, crippling ecosystems and infiltrating our food chain. Faced with this situation, the new accelerated degradation bioplastics They appear as a way to reduce the impact without giving up certain conveniences of plastic.
In recent years, the number of projects seeking truly sustainable bioplasticsPackaging that fragments and is completely consumed by microorganisms, foams that disappear into the ocean faster than paper, recycled plastics that become biodegradable thanks to copolymers, or composting processes reinforced with specific microorganisms and viruses that accelerate degradation. All of this in parallel with a profound reflection on What does it mean for a plastic to be biodegradable?, compostable and what actual conditions it needs to disappear without a trace.
The problem of plastics and microplastics
The amount of plastic waste in oceans and ecosystems It continues to grow. Recent scientific estimates calculate that around 2,3 million tons of plastic float on the surface of the seas, a colossal figure that only reflects the tip of the iceberg, since a significant portion sinks or breaks down into smaller particles.
What worries the scientific community most are the microplastics less than 5 millimetersTiny fragments that are dispersed everywhere: in water, air, sediment, and even snow in remote areas. These particles come from both the fragmentation of larger objects and primary sources, such as tire abrasion, the washing of synthetic clothing, or the microgranules present in some cosmetic and personal hygiene products.
These microplastics end up altering marine ecosystemsThey enter the food chain of fish, birds, and marine mammals, and eventually end up in the food we humans eat. Evidence points to potential harmful effects on health and biodiversity, ranging from inflammatory problems to hormonal disruptions and the bioaccumulation of toxic substances associated with plastic.
Furthermore, these floating particles tend to clump together, forming what are known as “plastic islands”Enormous accumulations occur in areas where ocean currents converge. It is estimated that there are between 15,000 and 51,000 trillion microplastics in the planet's surface waters, a virtually unimaginable figure that illustrates the extent to which plastic pollution has spiraled out of control.
Why does conventional plastic take so long to degrade?
Traditional synthetic plastics, such as the polyethylene in bags or the PET in bottles, are made up of very strong and inert polymersTheir long molecular chains are not easily attacked by microorganisms present in the environment, and they barely react chemically under normal conditions of pH, temperature and pressure.
This enormous chemical stability allows the plastic to take centuries to decomposeTo give you an idea, a conventional plastic bottle can take around 450 years to fully decompose, while a non-biodegradable plastic bag might take about two decades. Along the way, it breaks down into increasingly smaller pieces, which become persistent microplastics.
In contrast, materials such as organic waste or natural fibers (For example, cellulose) decompose relatively quickly thanks to the activity of fungi, bacteria, and other soil organisms. The key is that their structures are recognizable and metabolizable by biota, while many synthetic plastics are practically “invisible” to these biological processes.
This almost indelible nature, coupled with the massive use of single-use plastics, has generated a problem that the UN already considers one of the the most urgent environmental challenges of our timeEvery minute, around one million plastic bottles are purchased, and approximately five trillion bags are consumed annually; many of these products are designed to be used only once and end up in the trash immediately.
What exactly is a bioplastic?
The term bioplastic The term is used widely and sometimes confusingly. A material can be called a bioplastic if it meets at least one of these conditions: it is produced wholly or partly from raw materials of biological origin (such as corn, sugar cane or cellulose), is biodegradable, or has both characteristics at the same time.
In theory, usable bioplastics could be obtained from almost anything agricultural or food wasteFruit and vegetable scraps, food industry byproducts, forestry waste, etc. In practice, the most widespread today are derived from crops such as corn, sugarcane, or wood pulp, in addition to other renewable resources, and there are specific developments such as milk-based bioplastics.
It is worth emphasizing that Bioplastic is not automatically synonymous with biodegradableThere are bioplastics made from renewable resources that behave very similarly to traditional plastics in terms of their environmental impact, and others that only degrade under very specific conditions (usually those found in industrial composting). That's why it's so important to pay attention to the certifications and standards that accompany the product.
In Europe, the compostability of a material is assessed following standards such as EN 13432 and EN 14995A compostable plastic must not only disintegrate within a certain time in composting facilities, but also leave no toxic residues and generate compost that can be used as a soil nutrient.
Advantages and limitations of current bioplastics
The main virtue of well-designed bioplastics is their lower potential environmental impactBecause they are made from renewable sources or have biodegradable structures, they can reduce the use of fossil fuels and, in certain cases, shorten the time that the waste remains in the environment.
The rate of degradation of a bioplastic depends on its internal and environmental propertiesIn humid environments with a good presence of microorganisms, decomposition is usually faster than in dry or cold environments. However, degradation times are not always much shorter than those of synthetic plastics if conditions are not suitable.
Many bioplastics are designed to industrial compostingIn these environments, high temperatures, controlled humidity, and optimal aeration are achieved, along with a highly active microbial community. Under these conditions, materials like polylactic acid (PLA) can degrade in just 2 to 6 months. In a typical landfill, lacking oxygen and with lower temperatures, the same material can take years to decompose.
Another advantage is that bioplastics production can be supported by renewable energies and circular processesreducing greenhouse gas emissions. However, currently its manufacturing costs remain higher than those of conventional plastic, which limits its widespread adoption, although trends point to improvement as production scales up.
In any case, neither synthetic plastics nor bioplastics should end up discarded in nature. Bioplastics are designed to degrade better if managed properly, for example, depositing them in the organic fraction When they are compostable and the collection system allows it. If they end up in seas or rivers, they can continue to generate plastic or microplastic waste, although in some designs these are more easily consumed by microorganisms.
Bioplastics that degrade rapidly in compost and in the environment
One of the most striking advances comes from a Brazilian research group that has developed a bioplastic with encapsulated bioactive particles These particles, derived from functional foods such as carrots or chia seeds, are incorporated into the polymer matrix, creating "weak points" that promote the attack of microorganisms.
According to results published in an international polymer science journal, this material loses around 90% of its mass in about 180 days under optimal composting conditions. Interestingly, even if the packaging is left in the environment, degradation remains relatively rapid thanks to the combined action of humidity, temperature, and local biota.
Like all polymeric materials, this bioplastic also generates microplastics during its decomposition. The major difference from traditional synthetic packaging is that the The generated fragments are completely consumed by microorganisms, so no particles remain persistent in the long term. In synthetic plastics, however, these microplastics accumulate and remain in the environment for decades or centuries.
This bioplastic is primarily intended for single-use applicationsContainers, bags, trays, and other products that, after brief use, end up in the waste stream. It's not recyclable like a classic synthetic polymer, but the project's philosophy is to cover the disposable plastics segment with materials that don't generate lasting environmental liabilities.
The lead researcher on the project emphasizes that Synthetic polymers will continue to be necessary In critical applications requiring high durability and specific performance, such as automotive parts, aerospace components, or protective equipment, the key is to reserve conventional plastics for these long-life uses and replace the rest with biodegradable polymers and advanced bioplastics.
Accelerating biodegradation in waste treatment plants
Although compostable bioplastics are designed to disappear under controlled conditions, in practice many composting and anaerobic digestion plants They do not fully decompose within the usual processing times. This results in plastic residue in the final compost and complicates its use as fertilizer.
To tackle this challenge, a consortium led by a plastics technology institute is coordinating a project that proposes a rather ingenious solution: using a combination of specialized microorganisms and bacteriophages (phages) viruses to accelerate the degradation of compostable bioplastics in organic waste treatment processes.
The approach consists of two complementary lines of action. On the one hand, phages are used that They attack the bacteria that hinder Or they compete with biodegrading microorganisms, leaving the way clear for the species that are capable of breaking down the plastic. On the other hand, microorganisms with a high capacity to attack compostable polymers are introduced or enhanced, reinforcing their presence to levels that make the process much more efficient.
The researchers emphasize that the key is to identify which microorganisms are most active for each type of bioplastic and to ensure that they are present in sufficient quantities throughout the treatment process. To validate these approaches, laboratory, pilot, and industrial-scale trials are planned, following current standards on biodegradation and fragmentation, to ensure both efficacy and environmental safety.
One of the great advantages of this strategy is that It does not require modifying existing facilities.Waste management plants could integrate these microbial and phage consortia into their existing processes without significant investments in new equipment. For companies in the sector, this represents an opportunity to improve bioplastics processing and reduce rejects without overhauling their entire infrastructure.
The ultimate goal is to develop a innovative accelerated biodegradation process of compostable bioplastics that are environmentally safe and fit within the principles of the circular economy. In this way, the aim is to increase the valorization of the organic fraction both in the form of raw materials (high-quality compost) and energy, and to reduce the presence of plastics in the environment to the absolute minimum.
Ultrafast bioplastics in the ocean: the case of foamed cellulose diacetate
Another area of innovation focuses on the single-use plastic foam products, such as trays, packaging, or insulation materials, which often end up in the sea and barely degrade. Polystyrene foam is a good example: lightweight, cheap, and very persistent in the marine environment.
Researchers at a US oceanographic institution have worked for years to understand how different types of plastic degrade in the oceanwhich products contribute most to pollution and how to design truly biodegradable alternatives in marine environments. Based on this knowledge, they have developed a foam based on cellulose diacetate (CDA), a polymer derived from wood pulp.
The novelty of this development is that, by introducing into the material small pores through a foaming processThis process allows CDA foam to degrade up to 15 times faster than the equivalent solid CDA. In laboratory tests simulating real marine conditions, CDA foams lost between 65% and 70% of their mass over a period of 36 weeks.
The scientists also compared straws made from different materials: conventional plastic, paper, solid CDA, and foamed CDA. They observed that the Foamed CDA straws degraded 190% faster than solid CDA straws, achieving an even shorter lifespan in the environment than paper straws. Careful control of variables such as temperature, light, and water renewal allowed for a fairly accurate reproduction of the ocean's microbiological dynamics.
From a materials engineering perspective, the use of biodegradable foams is particularly interesting because they are materially efficientThey provide the same functionality with less material, reducing costs and associated impacts. Furthermore, if they are formulated with polymers capable of biodegrading in the marine environment, their persistence is significantly reduced compared to traditional plastics.
The most urgent application of these CDA foams is the polystyrene foam replacement in food packaging and other single-use products that frequently end up in the ocean. In fact, lightweight, compostable trays made of foamed CDA are already being introduced to the market, designed to replace plastic trays in industrial food packaging without requiring changes to existing production lines.
This development has been made possible thanks to close collaboration between academia and the bioplastics industry, which has allowed not only a thorough understanding of the CDA biodegradation in the oceanbut also to ensure that the new material is scalable and used in real-world applications. The companies involved point out that the use of biodegradable materials in consumer goods is a fundamental step in reducing plastic pollution and moving towards more sustainable production and consumption models.
Recycled biodegradable plastics that disappear in soil in 45 days
In addition to developing entirely new bioplastics, another promising line of research involves transform existing plastics in biodegradable materials through advanced recycling chemical reactions. A striking example is that of a biodegradable plastic created by Brazilian and French researchers from post-consumer PET packaging, the polymer typically used in beverage bottles.
PET is a highly resistant aromatic polymerPET, with benzene rings in its structure, is practically non-biodegradable under normal environmental conditions. It can take a century or more to disappear from a landfill or natural environment. To change this, the scientific team combined recycled PET with an aliphatic polyester, a type of open-chain polymer that is easily consumed by soil microorganisms.
By mixing both components and synthesizing a PET-aliphatic polyester copolymerThey succeeded in obtaining a material that biodegrades in soil in just 45 days. The proportion of each component and the catalyst used during polymerization are crucial: in the tests, samples with 20% aliphatic polyester began to degrade after 45 days, while those with 40% showed much more intense deterioration in the same period.
Prior to this breakthrough with poly(trimethylene sebacate) (PTS), the team had already synthesized PET copolymers with another aliphatic polyester, poly(ethylene adipate) (PEA), which began to biodegrade in soil after about seven months—a huge improvement compared to the one hundred years it can take for isolated PET. The increase in PTS content proved to be a key factor for drastically accelerate biodegradation.
The synthesis process itself is relatively simple: post-consumer PET bottles are washed, shredded, and placed in a glass reactor along with the selected aliphatic polyester fraction. Under an inert nitrogen atmosphere, high temperature, and mechanical stirring, a catalyst is added, and the polymerization reaction takes place, resulting in a new plastic with different mechanical, thermal and biodegradation properties to the original PET.
Possible applications of this material include products of quick discard such as seedling pots, toothbrush handles, phone cards (in countries where they are still used), or cosmetic containers. Since they are made from recycled PET, the properties are not as high as those of virgin PET, but for items with a short lifespan, this is not a problem. The essential thing is that, once discarded, these products do not remain in the environment for decades.
To test the behavior of the new plastic, biodegradation tests were carried out by burying the samples in containers with aged soil and high humidity (between 85% and 95%). At regular intervals, pieces were extracted for analysis using electron microscopy and other advanced thermal and chemical characterization techniques, thus verifying the degree of degradation reached.
Interestingly, the team decided not to patent the process, intending to to demonstrate that real solutions exist The research addresses the problem of PET container accumulation in landfills and dumps and promotes the training of specialists in chemical recycling and biodegradable copolymers. The research has led to several master's and doctoral theses, delving into how the copolymer's composition influences its properties and its behavior in the presence of soil microorganisms.
How long does it take for different biodegradable plastics to degrade?
Beyond specific cases, it is helpful to have a general idea of the degradation time ranges of some common biodegradable plastics and the factors that most influence these processes. This allows us to calibrate what exactly “biodegradable” means in each context.
Among the environmental factors, the temperature, humidity and oxygen availability These factors are crucial. In an industrial composting environment, where high temperatures, adequate aeration, and optimal humidity are maintained, microorganisms work at full capacity and biodegradable plastic breaks down within weeks or a few months. In a landfill, with oxygen scarcity and lower temperatures, the same material degrades much more slowly.
Another crucial factor is the type of biodegradable polymerPolylactic acid (PLA), for example, which is produced from resources such as corn, typically degrades in 2 to 6 months in an industrial composting facility. In contrast, it can take several years in a landfill. Polyhydroxyalkanoates (PHAs), synthesized by certain bacteria, can degrade in less than 6 months under ideal conditions, while starch-based plastics (such as many biodegradable bags) require 3 to 6 months in industrial composting and 1 to 2 years under less favorable natural conditions.
El thickness and formulation of the material Other factors also play a role. Thin films and products with additives designed to accelerate decomposition degrade faster than thick pieces or formulations without these reinforcements. Therefore, two objects made with the same type of polymer can have very different degradation times depending on their design and end use.
Compared to conventional plastics, such as the low-density polyethylene used in many bags, which can take between 500 and 1000 years to decompose, biodegradable plastics theoretically represent a improvement of several orders of magnitudeHowever, this advantage only materializes if the waste is managed correctly and subjected to the conditions for which it was designed.
Finally, it's important to note that not all bioplastics fully degrade in the natural environment. Some, like PLA, urgently need to be processed. specific composting infrastructure to fulfill the promises made on their labels. Otherwise, their behavior may be closer to that of a conventional, long-lasting plastic, albeit with some differences.
All of this leads us to a key idea: bioplastics and new rapidly degradable materials—whether in compost, soil, or the ocean—are powerful tools for reducing the footprint of plastic pollution, but they only truly work when integrated into well-designed collection and treatment systemsThey are applied in appropriate uses (especially in single-use plastics) and combined with an overall reduction in the consumption of unnecessary packaging.