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Zhijia Zhang

Dr.Deborah Salvo

ENGL 2304

July 11, 2024

Introduction

1. Purpose

An in-depth analysis of biodegradable and compostable plastics, including

studying the degradation of biodegradable plastic shopping bags in streams and

riparian areas, assessing their degradation rates in the natural environment, and

exploring their possible impact on ecosystems. It will also look at these plastics from

an economic perspective and the potential role of some countries in driving this

change, and make recommendations for the development of the global bioplastics

industry.

2. background

In modern times, the use of plastics has become ubiquitous, providing

convenience all over the world. However, the impact of plastic waste on the

environment has sparked global concern, leading to a shift towards sustainable

alternatives. The quest for environmentally friendly solutions is driving the

development and adoption of compostable and biodegradable plastics. Impacts of

plastics on aesthetics, biota and ecosystems are dependent on how long plastic items

last, and what degradation products are released, in recipient environments.[1]

Traditional plastics are derived from petroleum and have been the cornerstone of

packaging and single-use products due to their durability and cost effectiveness. [2]

However, they persist in the environment and pose a threat to wildlife and

ecosystems, fueling consumer demand for more environmentally friendly options.

Statistics from the database show that only a small fraction of the plastic waste

generated is recycled, and most end up in landfills or the natural environment, causing

long-term damage.

The scientific community and industry have been studying bioplastics, which are

synthesized from biomass-derived monomers. These materials, such as polylactic acid

(PLA)[2], starch, cellulose pulp,are designed to break down under certain conditions,

return to nature without leaving harmful residues, and do not fill the soil as compost.

Figure 1.Recycled, environmentally friendly plastics can be made into fertilizer

to help plants grow. At the same time, these plastics can also be converted into new

bioplastics in biorefineries for manufacturing products. The process is both

environmentally friendly and sustainable. This image is provided by the organization

"European Bioplastics.

The global adoption of biodegradable and compostable plastics is growing

stronger, especially in the packaging sector, which is a major contributor to plastic

consumption. This shift will have a impact on the global chemical industry, and China

and India will be key players in this transformation. These countries not only have a

vast market, but also have the manufacturing capacity and agricultural resources to

produce bioplastics on a large scale.

The transition to bioplastics is an important environmental trend driven by

society's heightened focus on environmental health and sustainable sex life. As the

public, especially the younger generation, deepen their understanding of

environmental issues, their demand for environmentally friendly products is also

growing, there are more products using bioplastics on the market, such as packaging

materials, disposable tableware, etc. These products not only meet the needs of

consumers for environmental protection, but also bring great development

opportunities for the bioplastics industry.

However, the process of acceptance and use of compostable and biodegradable

plastics is not without difficulties, and production costs, technological innovation, and

the establishment of supporting infrastructure for composting and recycling are key

factors that need to be addressed. In addition, developers and materials companies

should clarify guidelines and regulations, that is, ensure that these materials are

compostable and biodegradable, safe and low-risk.

3. Scope

The report will compare ordinary plastics and degradable/compostable plastics through

three criteria: carbon emissions,biodegradability,cost.

carbon emissions:

Based on the method of life cycle assessment (LCA)[5], this report makes a

comprehensive comparison of carbon emissions of conventional plastics (PE and PP)

and compostable plastics (PBAT-LA and PLA). In Figure 2,Starting from the

feedstock acquisition stage (T1), the feedstock for conventional plastics is primarily

derived from naphtha obtained through the secondary distillation of crude oil, a

process that results in higher carbon emissions if carbon capture is not considered.

Table 2 shows that the carbon content of PE and PP ranges from 85.60% to 93.02%

and 77.60% to 85.62%, respectively. This carbon is converted into carbon dioxide

emissions during the production process. In contrast, the feedstock for compostable

plastics, such as polylactic acid, uses biomass to absorb atmospheric carbon dioxide,

with a biological carbon content of 50.00% to 50.20%.

Moving on to the plastic production phase (T2), the steam cracking process for

traditional plastics generates CO2 and CH4 emissions, with CO2 emission factors of

2.250 t.t-1 for both PE and PP, and CH4 emission factors of 3.30 kg.t-1. The carbon

emissions for the production of compostable plastics PBAT-LA and PLA are 2.95-

3.22 kg CO2eq and 1.30-2.19 kg CO2eq per kilogram of product, respectively, which
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includes electricity consumption and the use of fossil fuels during the production

process.

The waste disposal phase (T4) further highlights the differences in environmental

impact between the two types of plastics. Traditional plastics, when landfilled and

incinerated, produce a significant amount of CO2 emissions. Compostable plastics, on

the other hand, significantly reduce carbon emissions through environmentally

friendly methods such as chemical recycling, industrial composting, and anaerobic

digestion. For instance, the chemical recovery rate, industrial composting rate, and

anaerobic digestion ratio, as reflected in Table 2, each affect the final carbon

emissions.

Table 2.The relevant parameters of different plastic products.Source:

https://doi.org/10.1016/j.eng.2023.10.002.
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Figure 2.The system boundary, BDO: 1,4-butanediol; APA: adipic acid; TPA:

terephthalic acid; LA: lactic acid. Source:https://doi.org/10.1016/j.eng.2023.10.002.

Data and charts show that compostable plastics have a lower environmental

impact at the raw material acquisition, product manufacturing and waste disposal

stages, although their production costs may currently be higher than conventional

plastics. With the global pursuit of sustainable development, compostable plastics will

be more widely used in the market because of their environmental performance.

Technological innovation, cost control, and policy and market support will be key

factors driving this transformation. Through this comprehensive comparison, it can be

seen that while the carbon footprint of compostable plastics may be comparable to

that of conventional plastics at some stages of production, over the entire product life

cycle, they offer a more environmentally friendly solution than conventional plastics.

Biodegradability：
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There are significant differences between conventional and compostable plastics

in terms of biodegradability. Conventional plastics, such as polyethylene (PE),

polypropylene (PP), polyethylene terephthalate (PET), polyvinyl chloride (PVC), and

polystyrene (PS), have a very long degradation time in the natural environment, often

taking hundreds of years. For example, PE and PP can take up to 600 years to

degrade, while PVC and PS take 450 and 300 years respectively. These materials are

difficult to break down by microorganisms in the natural environment due to the

stability of their chemical structure.

In contrast, compostable plastics are designed to degrade in a shorter period of

time. They often contain additives or are made from bio-based materials that can be

broken down by microorganisms and thus converted to water, carbon dioxide and

organic matter in the composting process. Compostable plastics typically degrade in a

few months to about a year, which greatly reduces their long-term environmental

impact. However, the effective degradation of compostable plastics requires specific

conditions, such as high temperatures and appropriate humidity, which are usually

achieved in industrial composting facilities. Although compostable plastics cannot be

a direct replacement for traditional plastics in the short term, they will gradually

become more widespread in the future.

Table 3.Source:www.explainthatstuff.com/bioplastics.html.
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Cost：

In exploring the economic costs of traditional versus compostable plastics, this report

takes a number of perspectives, including factors such as initial production costs,

market demand and consumer preferences, and global production distribution.

Conventional plastics have lower initial production costs due to their proven

production processes and large-scale production capabilities. In contrast, compostable

plastics, while currently more expensive to produce, are expected to decrease in cost

with technological advances and large-scale production, while reducing

environmental pollution and associated health costs, which has significant economic

benefits in the long term.

Figure 4. Socio-economic impact categories for biodegradable plastics and positive

or negative change of diferent indicators.

Source： https://doi.org/10.1002/cssc.202002044.

From Figure 4, it is clear that changes in consumer preferences have a significant

impact on the economics of bioplastics . As environmental awareness increases,

consumers are increasingly inclined to choose environmentally friendly products,

which provides an opportunity for compostable plastics to command a market

premium. Changes in policies and regulations, such as carbon taxes or bans on

conventional plastics, while providing tax incentives for compostable waste plastics,

reduce their relative costs.

As production costs are influenced by regional resource availability and labor

costs, data on the global distribution of plastics production shows that the Asian and

Oceania regions dominate. In Europe, the packaging industry is the main area of

plastics use, accounting for 40% of total plastics production. The application of

compostable plastics reduces the environmental impact of waste, thereby reducing

costs. In addition, the environmental impacts and economic losses of plastic waste,

such as the large amounts of plastic entering the oceans every day, highlight the

advantages of compostable waste plastics in reducing these losses.

Figure 5.Plastic production by country in 2019. NAFTA: North America free Trade

Agreement (Canada, Mexico, and United States); is: Commonweath ofIndependent

states (Armenia, Azerbaijan, Belarus, Georgia, Kazakhstan,Kyrgyzstan, Moldova,

Russia, Tajikistan, Turkmenistan, Ukraine, and Uzbekistan).

Source:https://doi.org/10.1002/cssc.202002044.

Figure 6. Plastic production by sector in Europe, Others include medical appliances,

furniture, and machine building.Source:https://doi.org/10.1002/cssc.202002044.

In conclusion, while conventional plastics may have a cost advantage in the short

term, compostable plastics have a promising economic outlook and are likely to

capture a larger share of the global plastics market, taking into account long-term

biodegradability and carbon emissions, consumer health, and changing market

demands and technological advances. As the global economy grows and consumer
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demand for sustainable products increases, market demand for biodegradable plastics

will also grow.

Reference

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Plastic Carrier Bags in a Stream and Its Riparian Area.” Annales de Limnologie, vol.

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https://doi-org.ezproxy.lib.uh.edu/10.1051/limn/2019017.

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[3] Cristóbal, Jorge, et al. “Management Practices for Compostable Plastic

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[4] Block, Dave, and Graham Chapman. “Certifying Biodegradability of

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