Life Cycle Assessment Of Polyethylene Terephthalate Bottle

Amos Ncube, Yuri Borodin Department of Ecology and Basic Safety, Institute of Non-Destructive Testing,

Tomsk Polytechnic University, Tomsk Russia amocube@rocketmail.com

Abstract—With increasing concerns over waste and the need for ‘greener’ products, it is necessary to carry out LCAs of products and this will help manufacturers take the first steps towards greener designs by assessing their product’s carbon output. Life Cycle Assessment (LCA) is a process to evaluate the environmental burdens associated with a product, process or activity by identifying and quantifying energy and materials used and wastes released to the environment, and to assess the impact of those energy and material used and released to the environment. This assessment includes the entire life cycle of the polyethylene terephthalate (PET) bottle, processes encompassing materials and energy acquisition, manufacturing, use and waste management. The following four major components of an LCA study as described in the International Organization for Standardization (ISO) 14040/44 were used: Goal definition and scoping; Life-cycle inventory (LCI), Life-cycle impact assessment (LCIA), and Interpretation of results. Developing and providing sound environmental data using a life-cycle assessment approach will assist those and the targeted audience to pursue environmentally preferable alternatives.

Keywords- LCA, Environment, PET, Waste

I. INTRODUCTION

A. Overview Nowadays, world population has been increasing rapidly.

The rapid growth of a population in a country can contribute to high production of waste. Municipal waste and industrial waste can bring unhealthy and unpleasant environment or even diseases to human beings if the wastes are not managed properly.

As a government, it is unreasonable to limit the number of children for a family just in order to control the high production of waste. Therefore, one of the methods to reduce the production of waste is by understanding the Life Cycle Assessment of the product itself. Basically, Life Cycle Assessment is not a tool to reduce the production of waste. Instead, by conducting a Life Cycle Assessment, the researcher can comprehend the environmental attributes of a product from raw materials to landfill disposal or recycle as a new product, across its entire life.

Life Cycle Assessment (LCA) is a process to evaluate the environmental burdens associated with a product, process or activity by identifying and quantifying energy and materials used and wastes released to the environment, and to assess the impact of those energy and material used and released to the

environment [7]. The assessment should include the entire life cycle of the product, process or activity encompassing materials and energy acquisition, manufacturing, use and waste management.

In this case, bottles from PET will be thoroughly investigated because bottle waste is one of the major problem components in municipal solid waste management in Tomsk. There has been least past research that discusses on the subject of Life Cycle Assessment (LCA) of PET bottles in Tomsk, Siberia. In addition, PET bottles are predominantly employed in packaging of beverages such as beer and water. Plastic products like PET bottles are durable, although having functional benefits, can cause problems at the end of their products’ lives. As PET bottles have found more markets worldwide, the amount of PET bottles produced increases as well. This phenomenal growth was caused by the desirable properties of PET bottles and their adaptability to low-cost manufacturing techniques. The life cycle of PET includes production, transportation, use and disposal which have contributed to the release of waste emissions. This results in toxins exiting in the water, air and food chain, bringing the people around the polluted area severe health problems. Recently, environmental groups are voicing serious concern about the possible damaging impacts of PET on the environment. PET bottles end products and materials eventually contribute to the solid waste stream.

B. Objective of the Study The general aim of the study was to evaluate the

environmental performance of polyethylene terephthalate (PET) bottle,

The specific objectives are: a) To evaluate environmental burdens associated with PET

bottle product, process or activity by quantifying energy and wastes released to the environment.

b) To determine the main environmental burdens of PET. c) To expand the analysis on the improvement areas of the

PET bottle “end of life” for the purpose of lowering the environmental burdens focusing on recycling and disposal.

C. Scope of the Study Scope of the study should cover the entire life cycle of the

PET bottle encompassing raw material processing, manufacturing, transportation, use, recycling and disposal. This study will concentrate only on air emissions released within the

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life cycle of PET bottle which contributes to the impact of global warming. Therefore, this paper will focus on the bottle from the LCA perspective. PET bottle was chosen because of lack of scientific data on the life cycle flow of the PET bottle in the Tomsk region of Siberia, Russia. Life Cycle Assessment (LCA) is going to be used as a tool to evaluate the impacts associated with all stages of a product’s life cycle from cradle to grave both downstream and upstream. The basis of an LCA study is an inventory of all the inputs and outputs of industrial processes that occur during the life cycle of a product. This includes the production phase and the life cycle processes including the distribution, use and final disposal of PET bottle product. In each phase the LCA inventories the inputs and outputs and assesses their impacts. Once the inventory has been completed, a LCA considers the impacts. This phase of the LCA is called the impact assessment: LCAs can be very large scale studies quantifying the level of inputs and outputs but due to limited funding and financing this study will aim to focus on a small scale case study of the Tomsk city and the data obtained may therefore be used to make predictions and analysis in general. This LCA therefore will be limited in scope to a basic inventory whose results will be used to evaluate the environmental impacts of the PET bottle in the Tomsk region of Siberia, Russia.

II. METHODOLOGY

A. Life Cycle Inventory An analysis of the flow of energy involved in the

production of a product is one aspect of a life cycle assessment, an objective process of analysis that attempts to evaluate the environmental burdens associated with a product, process, or activity by:

• Quantifying the quantities of energies and materials used and the quantities of waste emissions released into the environment.

• Assessing the impact of energy and emissions releases on the environment.

• Evaluating opportunities to effect improvements in the final disposal of the product.

The assessment, if at all possible, should consider all the activities related to the manufacture of a product or operation of a process; this includes activities such as processing of raw materials, manufacturing, transportation and distribution, use/reuse, recycling, and final disposal.

In the inventory stage, the study was conducted to define all aspects of the materials and manufacturing process. Steps in the manufacturing process were followed, and individual processes are evaluated to determine the material used and emissions released to the atmosphere.

The environmental profile of manufacturing processes, use of product, recycling and disposal have been collected from various sources, and the following Life Cycle Stages were being considered.

1. Manufacturing stage Plastic molding processes 2. Use stage The environmental impact of the plastic product has been

analyzed considering a 10 year period. 3. Recycling / Waste management stage

Disposal to landfill and energy recovery through 100% waste incineration of PET bottle product were calculated.

B. Life Cycle Impact Assessment Once the inventory has been completed, a LCA considers

the impacts. This phase of the LCA is called the impact assessment: LCAs can be very large-scale studies quantifying the level of inputs and outputs. This LCA is limited in scope to a basic small scale inventory. Based on the inventory information, the required environmental impacts are assessed. Additionally, the effect and extent of recycling is determined. The energy demands for the process are then added.

C. Life Cycle Interpretation Assessments of all impacts are made for each material or

process. The alternative that provides some proper waste disposal improvements over other alternatives is selected. Improvement is defined as compliance with saving of energy required while increasing performance and quality in terms of lesser production of emissions.

D. Assumptions The following assumptions were made:

• All calculations have been made on a 1kg weight of PET bottle.

• All PET bottles that were distributed by road required 0.001 MJ/kg/km.

• The PET bottle will have the product life of 10 years.

E. Life Cycle Assessment Boundaries and limitations The Life Cycle Assessment (LCA) approach is widely

accepted in industries as a method to evaluate the environmental impacts of a product, and to identify the resource and emission-intensive processes within a product’s life cycle. The method is defined in the ISO standards 14040 and 14041 [2, 3]. The main strengths of LCA lie in its ability to provide a holistic assessment of production processes, in terms of resource use and environmental impacts, as well as to consider multiple parameters (ISO, 2002) [4, 5].

The methodology also provides a framework to broadly identify effective approaches to reduce environmental burdens. Further, the approach is recognized for its capacity to evaluate the effect that changes within a production process may have on the overall life-cycle balance of environmental burdens. This enables the identification and exclusion of measures that simply shift environmental problems from one phase of the life cycle to another.

However, LCA also presents significant challenges. First, the data intensive nature of the method places limitations on the comprehensive assessment of complex, interconnected networks. Limited data availability can force the researcher to make simplifications, which can lead to losses of accuracy. A second difficulty lies in the fact that methodological choices and assumptions - such as system boundary delineation, functional units, and allocation techniques - may be subjective and affect the results. These complications call for a thorough sensitivity analysis.

III. LIFE CYCLE INVENTORY

A. Plastic Production This section gives an overview of the complex and varied

processes involved in making the PET bottle plastic. We also look at ‘additives’, which enhance the performance of plastic bottle or aid its processing. These chemicals often have a greater potential impact on the environment than the polymer itself. Finally, we consider information on the impact of making plastics on the environment and human health. Fig. 1 shows the simplified processing and manufacturing of PET.

Figure 1. The simplified processing and manufacturing of PET

B. Production Stage – Emissions and Energy Requirements for producing a 1L PET bottle The production of different kinds of polymers has totally

different energy requirements and the amount of emissions released [1]. In this section, PET plastic bottle will be discussed in order to provide a clear result during the production stage.

TABLE I. ENVIRONMENTAL PROFILE FOR PET – PET PRODUCTION STAGE

Raw material Oil & natural gas

Main Product 1kg PET is produced

Energy 83.8 MJ/kg Solid waste 0.045130 kg/kg Transport 0.2 MJ/kg Emissions CO2 2330 g/kg

SOx 25 g/kg NOx 20.2 g/kg CO 18 g/kg HCs 40 g/kg

C. Use of PET bottle This section looks at the main sector that uses PET plastic

bottle: packaging. During this stage, there are no energy and emissions released involved. Therefore, no data can be used to indicate the effect of PET plastic bottle during the use stage to the entire life cycle of plastic bottle.

D. Transport of PET bottle In this section, the produced PET bottle will be transported

to consumers and eventually to recycling centers and disposal sites once it reaches the end of life of its services. Meaning to say, consumers dump the bottles into their dustbins after the plastic product becomes useless. We assumed the maximum of transport distance to consumers, recycling centers and disposal sites to be 200 km. The energy required for transportation was 0.01 MJ/kg/km according to [6].

Environmental Profile – Transportation Stage of PET Transport = 0.01*200=2MJ/Kg. We assumed no emissions released during transportation stage because the emissions released are most like to be insignificant.

E. PET Waste Recycle – Emissions and Energy Requirements Plastic waste can be disposed-off using different kinds of

methods. Recycling was also one of the improvement methods to be considered in this study. The idea being that recycling activities will reduce the waste generated to the earth and eventually lessens the risks of environmental burdens caused by the PET bottle.

Where reuse is not the most environmentally sound way of extracting value from plastic bottle wastes, an alternative is to recycle them into feedstock or into energy recovery so that their intrinsic value is not lost. These two technological methods of plastic waste recovery have been developed in the industrialized countries on a large scale, mechanical recycling and incineration with energy recovery. Once the recyclates have been cleaned and shredded, the process is much the same as for the production of the PET plastic bottles from feedstock. Most plastics are recycled mechanically, but chemical recycling is at a developmental stage. Plastic bottles are the main type of plastics collected and recycled from household waste. During the process of recycling, energy is required and emissions are released to environment.

TABLE II. ENVIRONMENTAL PROFILE FOR PET – WASTE RECYCLED (EMISSIONS AND ENERGY REQUIREMENTS FOR A 1 KG PET BOTTLE)

Raw material - Main Product 1 kg new PET bottle is produced

Energy 27.07 MJ/kg Solid waste -Transport 0.2 MJ/kg Emissions CO2 163 g/kg

SOx 0 g/kg NOx 0.081 g/kg CO 0.205 g/kg HCs 0.016 g/kg VOCs 6.95 g/kg

TABLE III. ENVIRONMENTAL PROFILE FOR PET – WASTE TO LANDFILL (EMISSIONS AND ENERGY REQUIREMENTS FOR A 1 KG PET BOTTLE)

Energy 60.007 MJ/kg Solid waste -Transport 0.2 MJ/kg Emissions CO2 94.597 g/kg

SOx 0.848 g/kg NOx 1.728 g/kg HCs 2080.609 g/kg

TABLE IV. ENVIRONMENTAL PROFILE FOR PET – WASTE INCINERATED (EMISSIONS AND ENERGY REQUIREMENTS FOR A 1 KG PET BOTTLE)

Energy 32.5 MJ/kg Solid waste -Transport 0.2 MJ/kg Emissions CO2 2016 g/kg

SOx 0.609 g/kg NO2 2.436 g/kg CO 0.609 g/kg

F. Summary – Emissions and Energy Requirements for a Kg PET bottle In this section, we summed up and summarized the

emissions released and energy requirements during the entire life cycle of a PET bottle. Table V summarizes the total energy required in MJ and total emissions released for the entire life

cycle of 1 kg of the PET bottle for the different methods of waste disposal.

TABLE V. ENERGY CONSUMED AND EMISSIONS RELEASED FOR THE ENTIRE LIFE CYCLE OF 1KG PET BOTTLE

Waste Recycled

Waste to Landfill

Waste Incinerated

Total Energy

(MJ) 113.27 144.2 118.7

Total Emissions (g)

2603.45 4610.98 4452.85

IV. LIFE CYCLE IMPACT ASSESSMENT

A. Energy Use In this section we used the results from the life cycle

inventory to assess the potential impacts of PET bottle treated with different disposal methods. The best way of making a comparison of the PET bottle waste disposal method from an environmental point of view was to compare and analyze the energy involved and waste emissions released in the entire life cycle of the PET bottle. Next step was to assign the air emissions to the impact of global warming.

Results for the total energy used are shown in Table V for PET with different treatment methods of disposal. The energy required to recycle 1Kg PET bottle is relatively lower than the energy consumed by the other two options. This is because it takes less energy to make recycled products due to its greatest environmental benefit provided that the recycled product is used to substitute virgin polymers. Besides, recycling is advantageous because every time that the material is reused, it is not produced again and, therefore, only half the waste remains in the soil than if virgin resin is used. The more times a material is recycled, the less the amount that remains in the soil and this will subsequently reduce the environmental load in the waste stream [6]. According to Table V, landfilling option required much more energy for the whole cycle of a kg PET bottle maybe due to vehicle fuel consumption on transportation, maintenance and the continuous monitoring on the landfill area. On the other hand, incineration is also one of the options to manage the PET bottle waste. Incinerator will burn all waste in ovens and the energy recovered is equivalent in amount to the heat of combustion of the different components [8].

B. Global Warming Table VI presents the environmental impact for a 1kg PET

bottle treated with different waste disposal methods. Global warming is the rising of the global temperature due to emissions of greenhouse gases. The only greenhouse gas emissions of any significance in the manufacture and disposal stages of the PET bottle are carbon dioxide and methane. Based on the results in Table VI, the order of preference is that recycling is better than incineration and landfilling in terms of energy and emissions. The emissions contributing to global warming for incineration of PET bottle is rather similar to the emission for landfilling. This is because all the fossil carbon is released during incineration, as well as during landfilling.

PET can also be co-incinerated with other combustible products from the waste stream which will give even greater contributions to the reduction of greenhouse gases by the prevention of the emission of methane gas from landfills. Methane has a global warming potential of 30 times that of CO2 [7]. This is why the prevention of waste going to landfill is a key measure to reduce the greenhouse gas emissions.

TABLE VI. ENVIRONMENTAL IMPACT FOR DIFFERENT TREATMENT METHODS OF THE PET BOTTLE

Environmental Impact

Waste Recycled

Waste to Landfill

Waste Incinerated

Global Warming

(kg CO2-eq) 3.33 47 4.3

Example of Calculation for Global Warming Value Process X releases 2.495 kg CO2 and 0.040016 kg CH4 The equivalency factors are the 100-year Global Warming

Potentials (GWPs): Q global warming-CO2 = GWPCO2 = 1 g CO2 Q global warming-CH4 = GWPCH4 = 21 g CO2/ g CH4.

The potential contribution to global warming of methane is: Q global warming-CH4 x gCH4 = 21 g CO2/ g CH4 x 40 g =

840 g CO2-Eq. The total contribution of Process X to global warming is: Total global warming = (2.495 + 840) g CO2 = 3.33 g

CO2-Eq.

V. LIFE CYCLE INTERPRETATION

A. Introduction The use of plastics can make a significant contribution to

conserving natural resources, reducing energy consumption and minimizing the generation of wastes. Many applications of plastics have long useful lives and end-of-life plastics can often be recycled into second life applications. Nevertheless, the production, processing and use of plastics do generate wastes. It is essential that these wastes are properly and safely managed to protect human health and the environment.

The final disposal of PET bottle plastic wastes is a matter of concern in Tomsk, as it is for any waste. If plastic wastes cannot be recycled, they can be disposed of as landfill or incinerated under certain conditions. The incineration of plastics, with or without energy recovery, at high temperatures and with appropriate scrubbing techniques for flue-gases, can be carried out under environmentally sound conditions. Incineration under environmentally sound conditions with energy recovery should be the preferred option as opposed to disposal into landfill or incineration without energy recovery.

B. Recycling Nowadays, people often wonder why we need to recycle.

Some may feel that it’s not their job to do so, and some may feel that it’s a waste of time and money. Often people never realize about the advantages of recycling. So, it is suggested that the level of awareness among citizens in Tomsk, has not reached the level that we can be proud of. There are still plenty of loop holes here and there and it is important to educate the citizens of the advantages of recycling practices.

Rare materials, such as gold and silver, are recycled because acquiring new supplies is expensive. Other materials may not be as expensive to replace e.g. PET bottles, but they are recycled to conserve energy, reduce pollution, conserve land, and to save money. Several advantages of recycling can be highlighted here. This includes resource conservation, energy conservation, pollution reduction, land conservation and economic savings.

Recycling conserves natural resources by reducing the need for new material. Some natural resources are renewable, meaning they can be replaced, and some are not. Plastic products come from nonrenewable oil and natural gas. This oil can be conserved once raw material for making plastic is not required when new plastic can be produced from used plastic.

Recycling saves energy by reducing the need to process new material, which usually requires more energy than the recycling process. Recycling saves valuable landfill space, land that must be set aside for dumping trash, construction debris, and yard waste. Landfills fill up quickly and acceptable sites for new ones are difficult to find because of objections from neighbors to noise and smells, and the hazard of leaks into underground water supplies. Recycling in the short term is not always economically profitable or a break-even financial operation. Most experts contend, however, that the economic consequences of recycling are positive in the long term. Recycling will save money if potential landfill sites are used for more productive purposes and by reducing the number of pollution-related illnesses.

C. Emission Reduction The recycling method proved to release lesser emissions

into the atmosphere. From the studies that we had conducted, it showed that the emissions discharged were the least in comparison to other PET waste disposal methods.

Besides, PET bottle plastics can also be co-incinerated with other combustible products from the waste stream which will give even greater contributions to the reduction of greenhouse gases by the prevention of the emission of methane gas from landfills. Methane has a global warming potential of 30 times greater than that of CO2. This is why the prevention of waste going to landfill is a key measure to reduce the greenhouse gas emissions.

D. Energy Potential for Plastic Waste Energy recovery from plastic waste can make a major

contribution to energy production. If all of Europe's plastic waste which is not feasible to recycle were turned to energy, millions of tonnes of coal would be saved. Energy from waste directly saves fossil fuels and makes an important contribution to the reduction of a country’s dependency on fossil fuels. Such a contribution is crucial, particularly with the growing need of using renewable instead of non-renewable sources of energy [8].

VI. CONCLUSIONS AND RECOMMENDATIONS

The aim of the study was to use a life cycle assessment approach to determine which waste disposal options that will

substantially reduce the environmental burdens posed by the PET bottle. Several important observations can now be made.

1) Recycling of PET bottle waste can significantly reduce the energy required across the life cycle because the high energy inputs needed to process the requisite virgin materials greatly exceeds the energy needs of the recycling process steps.

2) Greenhouse gases can be reduced by opting for recycling instead of landfilling and incineration.

3) Quantity of waste emissions released from different disposal options was identified.

4) Recycling is the environmentally preferable disposal method for the PET bottle.

PET bottle plastics make a valuable contribution to the way we live, but as a society we need to find ways of using these plastics more wisely. The way we make, use and dispose of PET plastic bottles should have a minimal impact on the environment. Some of the methods to reduce the impacts on the environment are:

1) A greener plastics industry

The manufacture of plastic materials is one of the major industries with potential for serious pollution to the surrounding environment. Different types of plastics manufacturing processes and disposal methods will contribute to different effects on the environment. Therefore, government agency must ensure that industry operates in a way that minimises adverse effects on people and the environment, and contributes to the achievement of sustainable development.

2) Practicing recycling habit

The attitude of the public in recycling practices should be improved. The public should be well informed of the importance to recycle. Environmental influences appear particularly effective among members of the public who have a “strong belief in personal responsibility and influence, as well as the power of self-determination”. The public would recycle more if they had a greater understanding of the environmental benefits of recycling.

3) Introducing more recyclable products

By replacing the PET plastic bottles for packaging beverages, with recyclable and biodegradable ones; this can initially encourage more people to recycle. By displaying the international standard ‘Recycling Logo’ on recyclable products, the consumer will be fully informed whether the items can be recycled or not. When the consumer is aware that the items can be recycled, they will automatically categorize the items as recyclable products and will not dump them together with non-recyclable wastes. With such measures, it is hoped that the public will be more aware of the recyclable items available in the market.

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Green Paper. Office for Official Publications of the European Communities, Luxembourg, 39pp.

[2] ISO 14040 (1999). Environmental Management. Life Cycle Assessment. Principles and Framework. ISO/FDIS.

[3] ISO 14041 (2001). Environmental Management. Life Cycle Assessment. Goal and Scope Definition and Life Cycle Inventory Analysis. ISO/FDIS.

[4] ISO 14042 (2002). Environmental Management. Life Cycle Assessment. Life Cycle Impact Assessment. ISO/FDIS.

[5] ISO 14043 (2002). Environmental Management. Life Cycle Assessment. Life Cycle Interpretation. ISO/FDIS.

[6] La Manita, G. P. and Pilati, G. (1996). Introduction. Polymer Recycling. Vol. 2. No. 1, pp. 1-2.

[7] McDougall, F. R., White, P. R., Franke, M. and Hindle, P. (2001). Integrated Solid Waste Management: A Life Cycle Inventory (2nd Edition). Blackwell Science Inc., USA. pp.1.

[8] Warmer Bulletin (1993b). Refuse derived fuel. Warmer Bulletin Information Sheet, Warmer Bulletin, No. 39, November. 81