How biodegradable plastics break down?



Plastic is a crucial material utilized in various applications in our daily lives. However, traditional plastics do not biodegrade in the natural environment; instead, they accumulate in landfills, oceans, and other ecosystems, contributing to environmental pollution. The development and utilization of bio-based plastics represent a solution to reduce plastic waste and safeguard the environment. This article aims to provide insights into the biodegradation process of bio-based plastics, serving as an eco-friendly alternative to traditional plastics.

1. Definition of biodegradable plastics

Biodegradable plastics have the ability to break down into organic compounds under the influence of microorganisms such as bacteria, fungi, and earthworms. These organic compounds can be reused by other organisms in nature or dissolve into the soil and water without causing environmental pollution.

Bio-based plastics can be produced from renewable raw materials, such as corn starch, potatoes, cassava, cellulose, or from fossil-based materials, such as polyethylene and polypropylene. The use of traditional plastics has had negative impacts on the environment. Traditional plastics do not biodegrade in the natural environment, instead accumulating in landfills, oceans, and other ecosystems. This can lead to natural degradation, including soil, water, and air pollution, as well as the risk of contaminating food and drinking water.

Due to these effects, the demand for environmentally friendly plastic alternatives is increasing. Biodegradable plastics are one such alternative, helping to reduce plastic waste, protect the environment, and promote sustainable development.

The biodegradation process of bio-based plastics begins when microorganisms come into contact with the plastic. Microorganisms secrete enzymes that break down the chemical bonds in the plastic into smaller molecules. These smaller molecules are then used by microorganisms as a source of energy. Specifically, the process is divided into three main stages:

Stage 1: Biological breakdown

The surface of biodegradable plastics is disrupted by environmental factors such as sunlight, temperature, and humidity. This breakdown creates conditions for microorganisms to access and degrade the plastic.

Stage 2: Biological reaction

Microorganisms use enzymes to break down the plastic molecules into smaller ones. These smaller molecules are then absorbed and used by microorganisms as food.

Stage 3: Homogenization

Microorganisms use the small molecules of the plastic to create new organic compounds, such as CO2, water, biomass, etc. These compounds can be reused by other organisms in nature or dissolve into the soil and water without causing environmental pollution.

Typically, biodegradable plastics can fully decompose within 6 months to 2 years. However, some types of biodegradable plastics can decompose completely within a few weeks.

Definition of biodegradable plastics

2. Biodegradation Mechanisms

This polymer breakdown process occurs in two main stages. In the initial stage, microorganisms secrete enzymes to hydrolyze plastic molecules into smaller ones. Subsequently, in the later stage, these smaller molecules are further degraded by microorganisms into CO2, water, and biomass.

Microbial action in natural environments

Microorganisms are single-celled organisms, extremely small and visible only under a microscope. They exist everywhere in the natural environment, from soil, water, and air to inside living organisms. Microorganisms play a crucial role in decomposing organic matter, contributing to environmental cleanliness.

Microorganisms break down organic matter by using enzymes to cleave organic molecules into smaller, more easily absorbable molecules. These smaller molecules are then utilized by microorganisms as food and a source of energy.

Soil biodegradation

Biodegradable plastics can undergo decomposition in soil through microbial activity. The biological decomposition process in soil involves specific stages.

In the biological reaction stage, microorganisms release enzymes to cleave plastic molecules into smaller molecules. These smaller molecules may be oligomers or monomers.

In the homogenization stage, microorganisms utilize the smaller molecules of the plastic as food and energy. Microorganisms break down these smaller molecules into final products, including CO2, H2O, and biomass.

Marine environments

Biodegradable plastics can also decompose in the marine environment through microbial action. The process of marine biological decomposition of biodegradable plastics is similar to the process in soil.

The time for marine biological decomposition of biodegradable plastics depends on factors similar to those affecting soil biological decomposition time. However, the marine environment generally has a higher pH than the soil environment, resulting in a longer time for marine biological decomposition of biodegradable plastics compared to soil biological decomposition time.

Biodegradation mechanisms

3. Factors Influencing Biodegradation

The biodegradation process of biodegradable plastics occurs in the natural environment, including soil, water, and air. The rate and extent of the biological degradation of these plastics depend on various factors.

3.1. Type of biodegradable plastic

Common types of biodegradable plastics today include:

PLA (Polylactic Acid)

PLA is produced from bio-based sources such as corn starch and potato starch. It shares properties with PET plastic, exhibiting high mechanical strength and good heat resistance. However, PLA has a lower biological degradation capability compared to other types of biodegradable plastics.

PHA (Polyhydroxyalkanoates)

PHA is produced by microorganisms during their growth and development. Similar to PE plastic, PHA possesses high mechanical strength, good heat resistance, and a high biological degradation capacity.

The biological degradation rate of biodegradable plastics depends on the chemical structure of the plastic. Plastics with branched structures and more hydroxyl bonds tend to biodegrade more easily than plastics with linear structures and fewer hydroxyl bonds.

3.2. Environmental conditions

Environmental conditions influence the biological degradation process of biodegradable plastics and include:

  • Temperature: Temperature is a crucial factor affecting the biological degradation rate of biodegradable plastics. Higher temperatures result in faster biological degradation.
  • Humidity: Humidity is another significant factor affecting the biological degradation rate. Higher moisture levels lead to faster biological degradation.
  • Presence of microorganisms: Microorganisms play a key role in the biological degradation process of biodegradable plastics. The more microorganisms present, the faster the biological degradation.
  • Sunlight: Sunlight can promote the biological degradation process, especially for biodegradable plastics containing colorants.
  • Oxygen: Oxygen is essential for the respiration process of microorganisms, thus promoting the biological degradation process.

The ideal environmental conditions for the biological degradation process of biodegradable plastics are a temperature range of 50 to 60 degrees Celsius and a moisture level of 60 to 70%. Under these conditions, the biological degradation of biodegradable plastics can occur entirely within a few months.

Factors Influencing Biodegradation

4. Biodegradable Plastics vs. Traditional Plastics

Plastic is a ubiquitous material in modern life, utilized in various sectors ranging from food packaging to household item manufacturing. However, traditional plastic is also a major contributor to environmental pollution. In contrast, biodegradable plastics present a potential alternative to traditional plastics, with the capability to mitigate the environmental impact of plastic.

Contrasting environmental impact

Traditional plastics are derived from non-renewable resources such as petroleum, contributing to substantial energy consumption and greenhouse gas emissions during their production. Moreover, traditional plastics cannot naturally biodegrade in the environment, taking hundreds or even thousands of years to decompose completely. During this time, plastic can contaminate soil, water, and air, adversely affecting human and animal health.

Biodegradable plastics, on the other hand, are made from renewable resources like corn starch, sugarcane, or plant-based oils. The production process of biodegradable plastics involves lower energy consumption and emits fewer greenhouse gasses compared to traditional plastics. Additionally, biodegradable plastics can naturally decompose in the environment within a few months or years, minimizing pollution.

Comparison of degradation rates

The degradation rate of plastic depends on various factors, including the chemical composition of the plastic, environmental conditions, and the presence of microorganisms. Traditional plastics may take hundreds or thousands of years to fully polymer breakdown in the environment, breaking down into small fragments known as microplastics that can infiltrate the food chain and pose health risks to humans and animals.

Biodegradable plastics exhibit a faster degradation rate. Some types of these plastics can decompose entirely within a few months or years. However, the degradation rate of biodegradable plastics is also influenced by environmental conditions. For example, these plastics may decompose more rapidly in moist conditions with a higher presence of microorganisms.

Biodegradable Plastics vs. Traditional Plastics

5. Challenges and Future Directions

Biodegradable plastics is a potential alternative to traditional plastic, simultaneously aiding in reducing environmental pollution. However, it still faces certain challenges, including:

Addressing misconceptions about biodegradable plastics

Many individuals believe that biodegradable plastics are entirely environmentally friendly and can naturally decompose. However, this is not the case. Biodegradable plastics still require processing in specialized bio waste treatment facilities, where conditions are suitable for microorganisms to break down the plastic. If biodegradable plastics are improperly disposed of in the environment, it may partially degrade but can still contribute to environmental pollution.

To address these misconceptions, there is a need for communication activities and educational efforts to enhance public awareness of biodegradable plastics. Regulatory agencies should also establish strict regulations regarding the sorting and treatment of biodegradable plastics waste.

Advancements in research and innovation

In recent years, scientists and businesses have been striving to develop biodegradable plastics with lower production costs and physical and chemical properties similar to traditional plastics. Progress in this research can make biodegradable plastics more competitive with traditional plastics, thereby promoting its usage.

Noteworthy advancements in research and development include:

  • Production from inexpensive renewable resources, such as wood, bamboo, or even agricultural waste.
  • Endurance under high temperatures and harsh environmental conditions, expanding the applications of biodegradable plastics.
  • Recyclability, helping minimize the amount of plastic waste.

Challenges and Future Directions

6. Conclusion

Biodegradable plastics emerge as a potential alternative to traditional plastics, serving as a practical measure to reduce environmental pollution. The biodegradation process of Biodegradable plastics relies on microorganisms in the natural environment.

This degradation process is influenced by the chemical structure of the plastic and environmental conditions such as temperature, humidity, microorganisms, sunlight, and oxygen. To enhance the biodegradation of biodegradable plastics, favorable environmental conditions must be created to facilitate the activity of biodegrading microorganisms.

EuroPlas, a leading plastic manufacturing company in Vietnam, aligns its mission with "Elevating plastic materials, contributing to environmental protection." Committed to ongoing research and development, EuroPlas focuses on producing environmentally friendly bio-based plastic products.

EuroPlas specializes in supplying the bio-based plastic compound BiONext

The flagship product of EuroPlas is the BiONext line of bio-based plastic compounds, suitable for various applications, including BiONext 102, BiONext 152, BiONext 400, BiONext 500, BiONext 600, and BiONext 700. In addition to the BiONext bio-based plastic compounds, EuroPlas also provides products for applications in biotechnical plastics, including supermarket bags, dental floss, and drinking straws.

EuroPlas pledges to deliver high-quality bioplastic compound products that are environmentally friendly, contributing to environmental protection and enhancing the quality of life.

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