Life Cycle Assesoemnt of Plastic MSc Thesis
Short Description
About the life cycle of plastic from raw material until waste management...
Description
A STUDY OF THE PLASTIC LIFE CYCLE ASSESSMENT
KOO CHAI HOON
UNIVERSITI TEKNOLOGI MALAYSIA
PSZ 19:16 (PIND. 1/97)
UNIVERSITI TEKNOLOGI MALAYSIA
BORANG PENGESAHAN STATUS TESISυ A STUDY OF THE PLASTIC LIFE CYCLE ASSESSMENT
JUDUL:
SESI PENGAJIAN:
2005 / 2006
KOO CHAI HOON (HURUF BESAR)
Saya
mengaku membenarkan tesis (PSM/ Sarjana/ Doktor Falsafah)* ini disimpan di Perpustakaan Universiti Teknologi Malaysia dengan syarat-syarat kegunaan seperti berikut: 1. Tesis adalah hakmilik Universiti Teknologi Malaysia. 2. Perpustakaan Universiti Teknologi Malaysia dibenarkan membuat salinan untuk tujuan pengajian sahaja. 3. Perpustakaan dibenarkan membuat salinan tesis ini sebagai bahan pertukaran antara institusi pengajian tinggi. 4. **Sila tandakan (3) (Mengandungi maklumat yang berdarjah keselamatan atau kepentingan Malaysia seperti yang termaktub di dalam AKTA RAHSIA RASMI 1972)
SULIT
TERHAD
3
(Mengandungi maklumat TERHAD yang telah ditentukan oleh organisasi/ badan di mana penyelidikan dijalankan)
TIDAK TERHAD Disahkan oleh
(TANDATANGAN PENULIS)
Alamat Tetap: 2235, TAMAN MELATI, 09400 PADANG SERAI, KEDAH. Tarikh: CATATAN:
4 MAY 2006 * ** υ
(TANDATANGAN PENYELIA)
PROF. DR. MOHD. RAZMAN SALIM Nama Penyelia Tarikh:
4 MAY 2005
Potong yang tidak berkenaan. Jika tesis ini SULIT atau TERHAD, sila lampirkan surat daripada pihak berkuasa/ organisasi berkenaan dengan menyatakan sekali sebab dan tempoh tesis ini perlu dikelaskan sebagai SULIT atau TERHAD. Tesis dimaksudkan sebagai tesis bagi Ijazah Doktor Falsafah dan Sarjana secara penyelidikan, atau disertasi bagi pengajian secara kerja kursus dan penyelidikan, atau Laporan Projek Sarjana Muda (PSM).
“I hereby declare that I have read through this project report and to my opinion this project report is adequate in term of scope and quality for the purpose of awarding the degree of Master of Engineering (Civil-Environmental Management)”
Signature
: ____________________________________
Name of Supervisor : PROF. DR. MOHD. RAZMAN SALIM Date
: 4 MAY 2006
A STUDY OF THE PLASTIC LIFE CYCLE ASSESSMENT
KOO CHAI HOON
A project report submitted in partial fulfillment of the requirement for the award of the degree of Master of Engineering (Civil – Environmental Management)
Fakulti Kejuruteraan Awam Universiti Teknologi Malaysia
MAY 2006
ii
“I declare that this project report entitled “A Study of the Plastic Life Cycle Assessment” is the result of my own research except as cited in the references. The report has not been accepted for any degree and is not concurrently submitted in candidature of any other degree.”
Signature
: ________________
Name
: KOO CHAI HOON
Date
: 4 MAY 2006
iii
To my beloved father, mother, brother and also my supportive friends…
iv
ACKNOWLEDGEMENT
I would like to take this opportunity to express my gratitude and appreciation to my supervisor, Professor Dr. Mohd. Razman Salim for his guidance, patience and invaluable advice throughout this project.
I also would like to express my appreciation to my family and friends for their endless support whenever I face problems. Without the mentioned parties, it is impossible for me to complete this project report successfully.
THANK YOU.
Koo Chai Hoon May, 2006
v
ABSTRAK
Secara tradisi, rawatan sisa pejal mempunyai perhatian yang terhad berkaitan dengan penilaian kitaran hidup (LCA). Biasanya, hanya jumlah sisa pejal sahaja diambilkira. Ini adalah tidak memadai sedangkan rawatan sisa pejal, contohnya, tambak tanah atau penunuan ialah operasi yang memerlukan input dan menghasilkan output yang perlu diterangkan dalam pengenalan LCA. Kertas kerja ini menganalisis tentang plastik dari perspektif LCA, menentukan tanggungan utama alam sekitar dan mengembangkan
analisis
dalam
bidang
pembaikan
produk
untuk
tujuan
mengurangkan tanggungan alam sekitar. Dalam lingkungan had dan sempadan yang dikenakan pada penyelidikan ini, anggapan dibuat, kertas kerja ini menerangkan pelbagai kaedah pelupusan tiga jenis komponen plastik dalam sisa pejal perbandaran. Penyelidikan ini juga memberi pengurus-pengurus sisa pejal dan ahli-ahli penyelidikan alam sekitar dengan idea untuk menilai pelan pengurusan sisa pejal dan memperbaiki prestasi alam sekitar dalam strategi pengurusan sisa pejal. Keputusan mengilustrasikan kitar semula bahan plastik lebih dicadangkan dengan penggunaan plastik digantikan dengan plastic yang diperbuat daripada bahan asal, membimbing kepada pengurangan penggunaan jumlah tenaga dan penghasilan gas yang mendorong kesan pemanasan global.
vi
ABSTRACT
Traditionally, treatment of solid waste has been given limited attention in connection with Life Cycle Assessment (LCA). Often, only the amounts of solid wastes have been noted. This is unsatisfactory since treatment of solid waste, e.g., by landfilling or incineration, is an operation, requiring inputs and producing outputs, which should be described in the inventory of an LCA. This paper analyses the plastics from the LCA perspective, determines the main environmental burdens and expands the analysis on the improvement areas of the product for the purpose of lowering the environmental burdens. Within the constraints and boundaries imposed by the study, assumptions made, this paper describes different ways of disposing three plastic fractions in municipal solid waste. This study also provides solid waste decision-makers and environmental researchers with a mind set to evaluate waste management plans and to improve the environmental performance of solid waste management strategies. The results illustrated that recycling of plastic material, preferably combined with the use of plastics replacing plastics made from virgin materials, leads to decreased use of total energy and emissions of gases contributing to global warming effect.
vii
TABLE OF CONTENTS
CHAPTER
1
2
TITLE
PAGE
DECLARATION
ii
DEDICATION
iii
ACKNOWLEDGEMENTS
iv
ABSTRAK
v
ABSTRACT
vi
TABLE OF CONTENTS
vii
LIST OF TABLES
xii
LIST OF FIGURES
xiv
INTRODUCTION
1
1.1
Overview
1
1.2
Problem Statement
3
1.3
Objective of the Study
4
1.4
Scope of the Study
4
1.5
Significance of the Study
5
LITERATURE REVIEW
6
2.1
Environmental Management Issue
6
2.1.1
What is Waste?
6
2.1.2
Municipal Waste
7
2.2
The Concerns Over Waste
8
2.3
What is Life Cycle Assessment (LCA)?
9
2.3.1
History of LCA
10
2.3.2
The Product Life Cycle
11
viii 2.3.3
Key Features of LCA
13
2.3.4
Components of LCA
14
2.3.5
Uses and Application of LCA
16
2.3.6
Benefits of the Life Cycle Approach
17
2.3.7
Limitations of the Life Cycle Approach
19
2.3.8
International Standards Organisation (ISO) – The ISO 14040 series
20
2.4
Issues Related to Life Cycle Stages
21
2.4.1
Inventory Assessment
21
2.4.1.1 Raw Material Acquisition Stage
21
2.4.1.2 Material Processing Stage
22
2.4.1.3 Manufacturing Stage
22
2.4.1.4 Filling/Packaging/Distribution
22
2.4.1.5 Use/Reuse/Maintenance Stage
22
2.4.1.6 Recycle and Disposal Stage
23
2.4.2
Reutilization/Reprocessing/Remanufacturing
23
2.4.3
Impact Assessment
23
2.5
An Integrated Approach to Solid Waste Management
25
2.5.1
The Basic Requirement of WM
25
2.5.2
Integrated Waste Management in Countries with Developing Economics
27
2.6
Element of Integrated Waste Management
28
2.6.1
Solid Waste Generation
28
2.6.2
Waste Collection
31
2.6.3
Central Sorting
32
2.6.4
Biological Treatment
34
2.6.5
Thermal Treatment
35
2.6.6
Landfilling
35
2.6.6.1 Composition of Landfill Gas
36
2.6.6.2 Landfill Gas Production
36
2.6.6.3 Factors Affecting the Production of Landfill Gas
38
2.6.6.4 Factors Affecting the Migration of Landfill Gas
39
ix 2.6.7
3
4
Materials Recycling
40
2.6.7.1 Plastic Manufacturing
41
2.6.7.2 Plastic Recycling
42
2.7
Plastic
43
2.7.1
Types of Plastic and their Main Applications
43
2.7.2
Advantages of Using Plastic
43
2.7.3
Potential Impacts of Plastic
44
METHODOLOGY
47
3.1
Introduction
47
3.2
Life Cycle Inventory
47
3.3
Life Cycle Impact Assessment
48
3.4
Life Cycle Interpretation
49
3.5
Assumptions
49
3.6
Life Cycle Assessment Boundary
49
3.7
Methods
49
LIFE CYCLE INVENTORY
51
4.1
Plastic Production
51
4.1.1
Process of Making Plastics
51
4.1.1.1 Plastics from oil and gas
51
4.1.1.2 Additives
54
4.1.1.3 Plasticisers and stabilisers used in PVC
54
4.1.1.4 Brominated flame retardants
54
4.1.2
Production Stage – Emissions and Energy Requirements
56
4.1.2.1 Production Stage – Emissions and Energy Requirements for PET
56
4.1.2.2 Production Stage– Emissions and Energy Requirements for PVC
56
4.1.2.3 Production Stage– Emissions and Energy
4.2
Requirements for PP
57
Use of Plastic
57
x 4.3
Transport of Plastic
4.3.1
Transportation Stage – Emissions and Energy
57
Requirements for PET, PVC and PP
58
4.4
Disposal of Plastic Waste
58
4.4.1
Waste Recycled – Emissions and Energy
58
4.4.1.1 Waste Recycled – Emissions and Energy Requirements for PET
59
4.4.1.2 Waste Recycled – Emissions and Energy Requirements for PVC
59
4.4.1.3 Waste Recycled – Emissions and Energy Requirements for PP 4.4.2
60
Waste to Landfill – Emissions and Energy Requirements
60
4.4.2.1 Waste to Landfill – Emissions and Energy Requirements for PET
60
4.4.2.2 Waste to Landfill – Emissions and Energy Requirements for PVC
61
4.4.2.3 Waste to Landfill – Emissions and Energy Requirements for PP 4.4.3
61
Waste Incinerated – Emissions and Energy Requirements
61
4.4.3.1 Waste Incinerated – Emissions and Energy Requirements for PET
61
4.4.3.2 Waste Incinerated – Emissions and Energy Requirements for PVC
62
4.4.3.3 Waste Incinerated – Emissions and Energy Requirements for PP 4.5
Summary – Emissions and Energy Requirements for PET, PVC and PP
5
62
62
LIFE CYCLE IMPACT ASSESSMENT
64
5.1
Introduction
64
5.2
Energy Use
64
xi 5.3
Global Warming
65
5.3.1 Examples of Calculation for Global Warming Value 5.3.2 Carbon Dioxide (CO2)
66
5.3.3 Methane (CH4)
66
5.4
Other Impact of Using Plastics on the Environment and Human Health
6
66
67
LIFE CYCLE INTERPRETATION
69
6.1
Introduction
69
6.2
Process Improvement
70
6.2.1
Recycling
70
6.2.1.1 Emission Reduction
72
6.2.1.2 Energy Potential for Plastic Waste
72
6.2.1.3 Reduction of Global Warming Potential and Improvement of Energy Efficiency from Energy from Waste
7
73
CONCLUSIONS AND RECOMMENDATIONS
74
7.1
Conclusions
74
7.2
Recommendations
75
REFERENCES
77
xii
LIST OF TABLES
TABLE NO.
TITLE
PAGE
2.1
Types of solid waste
7
2.2
LCA Applications According to Objectives
17
2.3
LCA Applications According to User Type
18
2.4
Categories of solid waste
30
2.5
Composition of MSW (by weight) in North and Central America
31
2.6
Typical Landfill Gas Components
37
2.7
Uses of Major Plastic
45
2.8
Properties of Plastics and their Advantages
46
4.1
Additives and their function
55
4.2
Environmental Profile for PET – Plastic Production Stage
56
4.3
Environmental Profile for PVC – Plastic Production Stage
56
4.4
Environmental Profile for PP – Plastic Production Stage
57
4.5
Environmental Profile – Transportation Stage
58
4.6
Environmental Profile for PET – Waste Recycled
59
4.7
Environmental Profile for PVC – Waste Recycled
59
4.8
Environmental Profile for PP – Waste Recycled
60
4.9
Environmental Profile for PET – Waste to Landfill
60
4.10
Environmental Profile for PVC – Waste to Landfill
61
4.11
Environmental Profile for PP – Waste to Landfill
61
4.12
Environmental Profile for PET – Waste Incinerated
61
4.13
Environmental Profile for PVC – Waste Incinerated
62
4.14
Environmental Profile for PP – Waste Incinerated
62
4.15
Resources consumed and emissions released for entire
xiii
5.1
life cycle of 1kg of various polymers
63
Environmental impact for different treatment methods
65
xiv
LIST OF FIGURES
FIGURE NO.
TITLE
PAGE
2.1
Stages in the Life Cycle of a Product
13
2.2
Interactions Among LCA Components
16
2.3
Element of an Integrated Waste Management System
29
2.4
The spectrum of collection methods from bring to kerbside systems
32
2.5
The generic MRF with manual sorting
34
2.6
The categories of rigid plastic containers
42
3.1
Simplified life cycle of plastics
50
4.1
The role of additives in the production of plastics
53
4.2
Generalised process for making plastics
53
CHAPTER I
INTRODUCTION
1.1
Overview
Nowadays, world population has been increased rapidly especially in developing country like Malaysia. The rapid growth of population in a country has contributed to high production of waste. Municipal waste and industrial waste can bring unhealthy and unpleasant environment or even diseases to human being 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 products 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 be more understand on 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 (Allen et. al., 1993). 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 the inventory analysis component of an LCA, data on inputs
2 and outputs to and from the system under study are compiled and presented. Solid waste may be treated by different processes where landfilling and incineration are the most common. Through Life Cycle Assessment, researcher will be able to know which things contribute to pollution and how the pollution happens finally take an appropriate way to solve the problem.
In this case, plastics are a thoroughly investigated material because plastic waste is one of the components in municipal solid waste management. Besides, this is because there is least past research discussing on Life Cycle Assessment of plastics production. In addition, plastics are predominantly employed in packaging, construction and consumer products. The first commercial plastics were developed over one hundred years ago. Now plastics have not only replaced many wood, leather, paper, metal, glass and natural fiber products in many applications, but also have facilitated the development of entirely new types of products. The plastic fraction in municipal solid waste consists mainly of polyethylene (PE), polyethylene terephthalate (PET), polyvinyl chloride (PVC) and polypropylene (PP) and polystyrene (PS). Different types of plastics will perform differently in the environment, e.g. polyvinyl chloride (PVC) has caused concern because of their potential to cause environmental harms.
Plastic products are durable, which although having functional benefits, can cause problems at the end of products’ lives. As plastics have found more markets, the amount of plastic produced become increases. This phenomenal growth was caused by the desirable properties of plastics and their adaptability to low-cost manufacturing techniques. The life cycle of plastic products includes production, transportation, use and disposal which have contributed to the release of waste emissions. This results in toxins existing 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 impact of plastics on the environmental. Plastics end products and materials eventually contribute to the solid waste stream.
Since reliable scientific data have been lacking, an experimental investigation was required. According to life cycle thinking (LCT), potential burdens arising
3 during end-of-life management must be prevented in the course of the entire product chain. The question arose whether landfilling is an acceptable waste management option for plastics products. Landfills and deposited waste need to meet requirements with respect to the protection of human health and the environment. Any environmental impacts may either be due to landfilling practices, or due to inherent product properties and the resulting product-specific emissions.
By improving either products or end-of-life schemes, impacts and risks could thus be mitigated and investigated. Life cycle assessment (LCA) intends to aid decision-makers in this respect, provided that the scientific underpinning is available. Strategic incentives for product development and life cycle management can then be developed.
1.2
Problem Statement
In the last decades, with the increment of the world population and the society of consumption, the amount of waste generated has exponentially increased. Waste accumulation centres have been created culminating with the generation of epidemics and rodents, besides increasing the environmental contamination level. These facts generate the necessity of developing and using more rational methods for final waste disposal.
Over the past 20 years, environmental issues have gained greater public recognition. Production, use and disposal of virtually all goods present potential health and environmental impacts. The general public has become more aware that consumption of manufacturing products and marketed services, as well as daily activities of our society, adversely affects supplies of natural resources and the quality of the environment. These effects occur at all stages of the Life Cycle of a product, beginning with raw material acquisition and continuing through material manufacture and product fabrication. They also occur during product consumption and a variety of waste management options such as composting, biogasification, incineration, burning, landfilling and recycling. At each of these steps, pollutants
4 may be released into the environment with ecological consequences. Ecological consequences among other things also include the effects on the environment. The impacts because of the environment releases can occur during the life cycle stages, particularly manufacturing and disposal, for all consumer and commercial products. As public concern has increased, both government and industry have intensified the development and application methods to identify and reduce the adverse environmental effects.
1.3
Objective of the Study
The aim of the study is to compare the environmental performance of three polymer-based plastics which are polyethylene terephthalate (PET), polyvinyl chloride (PVC) and polypropylene (PP) in different disposal treatments.
The further objectives are: a) to evaluate environmental burdens associated with plastic product, process or activity by quantifying energy and wastes released to the environment. b) to determine the main environmental burdens. c) to expand the analysis on the improvement areas of the plastic product for the purpose of lowering the environmental burdens.
1.4
Scope of the Study
Scope of the study covers the entire life cycle of the product encompassing raw material processing, manufacturing, transportation, use, recycling and disposal. This study concentrates only on air emissions released within the life cycle of plastic which contributes to the impact of global warming. Therefore, this paper focuses on the plastic from the LCA perspective. Plastics are chosen because lack of plastics life cycle flow is being investigated and performed previously.
5 Life Cycle Assessment (LCA) is a tool to evaluate the impacts associated with all stages of a product’s lifecycle 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 plastic 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. This LCA is limited in scope to a basic inventory.
1.5
Significance of the Study
An LCA will help decision makers select the product or process that resulting the least impact to the environment. This information can be used with other factors, such as cost and performance data to select a product or process. LCA data identifies the transfer of environmental impacts from one media to another and from one life cycle stage to another. If an LCA was not performed, the transfer might not be recognized and properly included in the analysis because it is outside of the typical scope or focus of product selection processes.
The ability to track and document shifts in environmental impacts can help decision makers and managers fully characterize the environmental trade-offs associated with product or process alternatives. LCA also allows the plastic companies to identify an effective ways of designing and manufacturing the products themselves. LCA helps companies to keep a step ahead of rapidly changing regulatory requirements on solid waste, persistent toxic chemicals, emissions and effluent discharges. In addition, life cycle strategies for pollution prevention and minimizing energy costs are beginning to reveal economic benefits in term of more efficient production, improved product quality and minimization of the environmental risks.
CHAPTER II
LITERATURE REVIEW
2.1
Environmental Management Issue Nowadays, Malaysia is running out of space to dispose of the urban waste
generated daily by wasteful consumption. There simply aren’t enough landfills. According to Housing and Local Government Minister Datuk Seri Ong Ka Ting, 80% of the country’s landfills will be full in two years (Tan, 2005). In fact, landfills themselves cause many serious environmental problems both for us and for future generations. Not many realize it, but each Malaysian throws away an average 0.8 kg of waste daily.
Malaysia is among the countries that have a high rate of waste
generation. Our country generates around 15,000 tons of waste every day. It is only a matter of time before we ran out of space to dispose of them. If we put them all together, we have enough waste to fill up the KL Twin Towers in just 9.5 days. In fact, the amount of waste is expected to increase by 2% every year, depending on our population, economic activity and waste disposal methods (Tan, 2005).
2.1.1
What is Waste? Definitions of ‘waste’ invariably refer to lack of use or value or ‘useless
remains’ (Concise Oxford Dictionary).
Waste is by-product of human activity.
7 Physically, it contains the same materials as are found in useful products; it only differs from useful production by its lack of value. Waste can be classified by a multitude of schemes: by physical state (solid, liquid, gaseous) and then within solid waste by: original use (packaging waste, food waste, etc), by material (glass, paper, etc.), by physical properties (combustible, compostable, recyclable), by origin (domestic, commercial, agricultural, industrial, etc.) or by safety level (hazardous, non-hazardous). Household and commercial waste often referred to together as Municipal Solid Waste (MSW). Household waste is one of the hardest sources of waste to manage effectively. It consists of a diverse range of materials (glass, metal, paper, plastics, organics) totally mixed together. MSW composition is also variable, both seasonally and geographically from country to country and from urban to rural area. In contrast, commercial, industrial and other solid wastes tend to be more homogeneous, with larger quantities of each material (McDougall et al., 2001).
2.1.2
Municipal Waste The focus for this title is on municipal waste which not includes industries
waste. The municipal waste that was generated can be divided into recyclable and non-recyclable products. The breakdown of solid waste created by Malaysians is shown in Table 2.1. Table 2.1: Types of solid waste (Housing and Local Government Ministry) Types of solid waste
Percentage (%)
Household waste
36.5
Paper
27
Plastic
16.4
Others
12.5
Steel
3.9
Glass
3.7
8 2.2
The Concerns Over Waste Generally, health and safety are the major concerns in waste management.
Wastes must be managed in a way that minimizes risk to human health. Today, society demands more than this – as well as being safe, waste management must also be sustainable. Sustainability or Sustainable Development has been defined as development which meets the needs of the present without compromising the ability of future generations to meet their own needs (WCED, 1987). This identifies the synergy between economic development, social equity and the environment. Thus, sustainable waste management must be economically affordable, socially acceptable and environmentally effective. In the past, the economic cost of a waste management system was the major controlled factor in the decision-making process. Recently, environmental considerations have played a more important role in this process. The inclusion of the social aspects of waste management in the decision-making process, although not a new concept in itself, has been limited as research into how to measure social concerns is only just beginning (Nilsson-Djerf, 1999). Environmental concerns over the management and disposal of waste can be divided into two major areas: conservation of resources and pollution of the environment. The depletion of non-renewable is now not the urgent problem (UNDP, 1998) but two other concerns have become critical with respect to the ‘need of future generations’ are the generation of pollution and wastes that exceed the ability of the planet’s natural sinks to absorb and convert them into harmless compounds. The production and disposal of large amounts of waste is still seen by many to be a loss of the earth’s resources. Putting waste into holes in the ground certainly appears to be inefficient materials management. It needs to be remembered that although the earth is an open system regarding energy, it is essentially a closed system for materials. Whilst materials may be moved around, used, dispersed or concentrated, the total amount of the earth’s elements stays constant. Therefore, although resources of raw materials may be depleted, the total amount of each element present on Earth remains constant. In fact, the concentration of some useful materials is higher in
9 landfills than in their original raw material ores. Such materials could be dug up at a later date. Pollution is the basis for most current environmental concern over waste management. Materials have been released into the atmosphere or watercourses or dumped into landfills and allowed to dilute and disperse. At low levels of emissions, natural biological and geochemical processes are able to deal with such flows without resulting changes in environmental conditions. However, as the levels of emissions have increased with rises in human population and activity, natural processes do not have sufficient turnover to prevent changes in environmental conditions. In extreme cases of overloading natural processed may break down completely, leading to drastic changes in environmental quality. Therefore, waste has to be dealt with somehow, somewhere. This can be done by setting an overall strategy to manage waste that reduces environment burdens at an affordable cost.
2.3
What is Life Cycle Assessment (LCA)? Life Cycle Assessment is a framework and methodology for the identification
of environmentally friendly products or processes. It is characterized by the analysis of cumulative environmental impacts over extended system boundaries. While conventional
environmental
assessment
techniques
focus
only
on
either
manufacturing processes or end-of life disposal or reuse, LCA considers the life cycle of a system or the entire chain of events and activities that are necessary to support the product or process (SETAC, 1991: ISO, 1997). This is often called the cradle to grave approach and has the obvious advantage of revealing potentially significant but hidden environmental impacts. Instead of focusing attention on large, concentrated and readily apparent point sources of impacts. Life Cycle Assessment requirements have also been included in legislation. The European Community (EC) Ecolabelling Regulation (1992) requires that the whole Life Cycle be considered when setting labeling criteria. Provision for Life Cycle Assessment is also included in the EC Packaging and Packaging Waste
10 Directive (1994), which states that ‘Life Cycle Assessments should be completed as soon as possible to justify a clear hierarchy between reusable, recyclable and recoverable packaging.’ Practically, his will have to be carried out on a case-by-case basis. As it is develop further, it is likely that Life Cycle Assessment will find many additional applications (McDougall et al., 2001).
2.3.1
History of LCA The first attempt to look at extended product systems can be traced back to as
early as the 1960s. This work mainly focused on calculating energy requirements. Several such fuel cycle studies were conducted in the United States by the Department of Energy. Although they focused on energy characteristics, these studies also included limited estimates of environmental releases. With the oil shortages in the early 1970s, both the U.S. and British governments commissioned extensive studies of industrial studies to conduct detailed energy analyses. As the oil crises faded, so did interest in the product system or LCA, approach for evaluating energy use. Then in the mid-1970s, landmark studies which focused on environmental issues were performed by Arthur D. Little and Midwest Research Institute (MRI). The main investigators who conducted the studies at MRI later left to form Franklin Associates Ltd. Activity in the United States on environmental LCAs continued at a slow but steady, pace of around two or three studies per year. The exact number is not certain because most studies were performed for private clients and not released for public consumption. Similarly, extended system studies were conducted in Europe during this period; they looked mainly at packing systems such as beverage containers. But the 1980s found a renewed interest in LCA as the Green Movement in Europe brought the subject to public attention on issues related to recycling. As a result, environmental releases were routinely added to energy, raw materials and solid waste considerations (Curran, 1996).
11 Modern LCA methodology is rooted in the development of standards through the 1990s. The society for Environmental Toxicology and Chemistry (1991) published “A Technical Framework for Life Cycle Assessment,” the first attempt at an international LCA standard. It explicitly outlined the components of contemporary LCA: goal definition, inventory assessment, impact assessment and improvement analysis. By extending LCA beyond the mere quantification of material and energy flows, SETAC paved the way for the use of LCA as a comprehensive decision support tool. Similar developments took place some time later in North Europe, particularly in the Scandinavia. In 1995, detailed LCA protocols were specified in the “Nordic Guidelines on Life Cycle Assessments” (Nordic Council of Ministers, 1995). In the late 1990s, the International Organisation for Standardisation (ISO) releases the ISO 14040 series on LCA as an adjunct to the ISO 14000 Environmental Management Standards. The series includes standards for goal and scope definition and inventory assessment (ISO 14041, 1998), impact assessment (ISO 14042, 2000a) and interpretation (ISO 14043, 2000b) as well as general introductory framework (ISO 14040, 1997). The ISO 14040 series actually bears a strong resemblance to the original SETAC framework, Azapagic’s review (1999) gives a comparison between the LCA standards. However, because of ISO’s dominant position in the development of international standards, the ISO 14040 series may eventually supercede the SETAC guidelines among LCA practitioners.
2.3.2
The Product Life Cycle The life cycle a generic industrial product was defined by SETAC (1991) as
being composed of the following stages: (a)
Raw Material Acquisition All activities necessary to extract raw material and energy inputs from the environment, including the transportation prior to processing.
12 (b)
Process and Manufacturing Activities needed to convert the raw material and energy inputs into the desired product. In practice this stage is often composed of a series of substages with intermediate products being formed along the processing chain.
(c)
Distribution and Transportation Shipment of the final product to the end user.
(d)
Use, Reuse and Maintenance Utilization of the finished product over its service life.
(e)
Recycle Begins after the product has served its initial intended function and is subsequently recycled within the same product system (closed-loop recycle) or enters a new product system (open-loop recycle).
(f)
Waste Management Begins after the product has served its intended function and is returned to the environment as waste. The interaction of these stages with each other and with the external
environment are shown in Figure 2.1. The combined stages constitute the entire cradle to grave system. Truncation of the chain yields partial life cycles which in some cases may be sufficient for the analysis demanded by the study objectives (Todd, 1996). There are three variants of partial LCAs: (a)
Cradle to Gate – analysis upstream of point of truncation.
(b)
Gate to Grave – analysis downstream of point of truncation.
(c)
Gate to Gate – analysis between two points of truncation.
13
Life Cycle Inventory Inputs
Output Raw Materials Acquisition Processing/Manufacturing Water Effluents
Energy Transportation/Distribution Raw Material
Air Emissions Solid Wastes
Use/Reuse/Maintenance
Other Releases Products
Recycle Waste Management
System Boundary Figure 2.1: Stages in the Life Cycle of a Product (SETAC, 1991)
2.3.3
Key Features of LCA LCA is a holistic framework that is distinguished by the following features:
(a)
Macrosystem or “cradle to grave” perspective LCA analyzes environmental interactions throughout the chain of activities supporting a given process or product technology.
(b)
Multicriterion perspective LCA analyzes different pathways by which environmental damage is done. This approach gives a balanced scrutiny of both immediate or local impacts (e.g., human toxicity, smog formation) as well as long-term or global concerns (e.g., global warming, depletion of non-renewable resources).
14 (c)
Functional unit perspective Comparison and analysis of alternative technological systems is based on equivalency of service delivered. For example, instead of comparing the environmental impacts of 1 liter of gasoline with 1 liter of diesel, environmental assessment is normalized with respect to the final service delivered. A more appropriate basis is 1 km of travel by gasoline- and dieselpowered vehicles of equivalent size.
2.3.4
Components of LCA Early LCA-type studies focused exclusively on quantifying material and
energy flows. The emergence of modern LCA standards in the 1990s (SETAC, 1991; Nordic Council of Ministers, 1995; ISO, 1997; ISO, 1998) was characterized by an increase in the level of sophistication of the general life-cycle concept, which has now been extended to include four components for a full LCA. These components are:
(a)
Goal and Scope Definition Specifies the objective of the assessment as well as the assumptions under which all subsequent analysis is done. LCA objectives can be classified broadly into system improvement studies, in which the goal is to identify opportunities for reducing the environmental effects of an existing system or process, and comparative studies, in which the intent is to select an optimal product of process from a number of predetermined alternatives. Scope definition involves specifying system boundaries, functional unit, allocation assumptions, inventory parameters, and impact categories that will be used. Depending on the scope and objectives, it may not be necessary for an LCA to have all four components. In some cases, for example, a simple inventory assessment may be sufficient.
15 (b)
Inventory Analysis Involves the quantification of environmentally relevant material and energy flows of a system using various sources of data. Essentially, an accounting of system inputs and outputs is performed. The data used may come from a variety of sources, including direct measurements, theoretical material and energy balances, and statistics from databases and publications. `
(d)
Impact Assessment Analyzes and compares the environmental burdens associated with the material and energy flows determined in the previous phase. The conventional approach is to classify the inventory flows into specific impact categories
(e.g.,
global
warming,
resource
depletion,
ecotoxicity).
Normalization and weighting (or valuation) of the impacts is also included in this stage. If necessary, the individual impacts can then be aggregated into a single composite environmental index. (e)
Interpretation (ISO, 2000b) or Improvement Assessment (SETAC, 1991) Utilizes the results of the preceding stages to meet the specified objectives. Typically this phase will generate a decision or plan of action. For diagnostic LCAs, the data is used to identify critical segments or “hot spots” in the life cycle which contribute disproportionately to the total system environmental impact. These problem areas can then be eliminated or reduced through system modifications. In the case of comparative LCAs, the competing system life cycles are ranked based on environmental performance and the optimal alternative is selected. Azapagic (1999) points out the strong similarities between the SETAC and
ISO standards. Aside from terminology, the principal difference lies in the fourth component of LCA. In the SETAC framework, the principal focus of this final improvement assessment stage is to identify opportunities for improving environmental performance. Under the ISO framework, the fourth phase is called interpretation and is extended to include sensitivity analysis and final recommendations. The interactions among the four LCA components are shown schematically in Figure 2.2.
16
Inventory Analysis Impact Assessment
Improvement
Scoping
Goal Definition
Classification Characterization Valuation Figure 2.2 Interactions Among LCA Components (SETAC, 1991)
2.3.5
Uses and Application of LCA LCA is one of many environmental management tools (ISO, 1997). It can be
used by governments, private firms, consumer organizations and environmental groups as a decision support tool (Wenzel et al, 1997; Krozer and Vis, 1998; Field and Ehrenfeld, 1999). The scope of the decisions covered by LCA ranges from broad management and policy choices to specific selection of product or process characteristics during design. Also, LCA may be applied prospectively or retrospectively (Ludwig, 1997). LCA applications (ISO, 1997) can be classified into the following: (a)
Indentification of opportunities to improve the environmental aspects of products at various points in their life cycles.
(b)
Decision-making in industry, government, and non-government organizations (NGOs).
(c)
Selection of indicators of environmental performance and measurement procedures.
(d)
Marketing, including ecolabelling and improvement of corporate image
17 Table 2.2 lists LCA applications based on broad objectives of “focus” and “choice” as suggested by Wenzel et al (1997). “Focus” refers to a stand-alone diagnostic LCA to identify points of interest within a single life cycle system, whereas “choice” refers to comparative LCAs of competing alternatives with the ultimate objective of ranking and selection. They also give a more detailed description of the uses of LCA in the private and public sectors as well as NGOs. LCA applications grouped according to users are given in Table 2.3. Table 2.2: LCA Applications According to Objectives (Wenzel et al, 1997) Objective Diagnosis
Application Product Development
Support for Decision Background for environmental specifications; design strategies, principles and rules.
Ecolabelling
Identifies important environmental properties for the product category.
Community Action Plans
Identifies environmentally important product groups.
Selection
Product Development
On-going identification of the best choices from alternative solutions.
Cleaner Technology
Identifies the best available technology by means of LCA.
Community Action Plans
Identifies the best community strategy for a certain problem or product.
Consumer Information
Documents potential environmental impacts from a certain product.
2.3.6
Benefits of the Life Cycle Approach Life Cycle Assessment is an inclusive tool. The Life Cycle Inventory phase is
essentially an accounting process or mass balance for a system. All necessary inputs and emissions in many stages and operations of the Life Cycle are considered to be
18 within the system boundaries. This includes not only direct inputs and emissions for production, distribution, use and disposal but also indirect inputs and emissions, such as from the initial production of the energy used. It is essential that all of the processes are included in the boundaries to conduct a fair and transparent analysis. The reader should recognize that the analysis aggregates over time, i.e. all inputs and emissions over the whole Life Cycle, are included regardless of when they occur and aggregates over space, i.e. all of the sites are included, regardless of where they are located. If real environmental improvements are to be made, it is important to use LCA so that any system changes do not cause greater environmental deteriorations at another time or another location in the Life Cycle. Table 2.3: LCA Applications According to User Type (Wenzel et al, 1997) LCA User
Application
Government
Community Action Plans
Example Incineration versus Recycling Public Transport Systems
Environmentally Conscious Public
Cars, Office Supplies
Purchase Company
Consumer Information
Ecolabels & Standards
Establish Environmental
Identification of Areas of Improvement
Focus
Product-Oriented Environmental Policy Environmental Management
Design Choices
Concept Selection Component Selection Material Selection Process Selection
Environmental Documentation
ISO 14000 Certification, Ecolabels
LCA offers the prospect of mapping the energy and material flows as well as the resources, solid wastes and emissions of the total system, i.e. it provides a system ‘map’ that sets the stage for a holistic approach. Comparing such system maps for
19 different options, whether for different products or waste management systems, allows the identification of areas where environmental improvement can be made. Concern over the environment is sometimes expressed in terms of individual issues, such as acidification. Concentrating on one issue alone, however, ignores and may even worsen the system with respect to other environmental issues. The power of LCA is that it expands the debate on environmental concerns beyond a single issue and attempts to address a broad range of environmental issues. By using a quantitative methodology, at least for the inventory inputs and outputs, it also gives an objective basis for decision making. The system map also allows other environmental information and assessment tools to be incorporated to be used in conjunction with LCA. This helps to take some of the emotional element out of environmental debates.
2.3.7
Limitations of the Life Cycle Approach The seemingly all encompassing nature of LCA has proved very attractive. It
may appear to new users that it is a single tool that can accomplish ‘everything’ with regard to environmental assessment. Many people have viewed LCA as being able to give a comprehensive, overall assessment of a product, service or package. As a result, there have been ill-advised efforts to use LCA as the only measurement tool when developing product labeling systems and during policy making. Unfortunately, there is a dilemma at the heart of LCA. As LCA employs an overall system balance and functional unit to aggregate resource use, solid waste and emissions over time and space, it is not able to assess the actual environmental effects of the product, package or service system. The International Standards Organisation (ISO) Life Cycle Impact Assessment document (ISO/FDIS, 1999) specifically cautions that LCA does not predict actual impacts or assess safety, risks or whether thresholds are exceeded. The actual environmental effects of emissions and wastes will depend on when, where and how they are released into the environment and other assessment tools and information must be utilised.
20 For example, an aggregated emission if released in one event from a point source such as a refinery, will have a very different environmental effect than releasing it continuously over years from many diffuse sources. In addition to this, the inventory will allocate the inputs and outputs of are finery to many products, i.e. different product systems. Recalling that LCA deals with only the inputs to a dingle system, only a small percentage of the total activity will be considered for a single product. This problem is generally acknowledged and the term ‘indicator’ is now used to show that LCA does not predict actual environmental effects (ISO, 1999b, Owens, 1999). The dilemma, therefore, is that LCA is the only tool that attempts to include the whole Life Cycle and all environmental issues associated with a product, package or service system and the only one that relates this to the functional unit. Clearly, no single tool can do everything. Therefore, a combination of tools with complementary strengths is needed for overall environmental management.
2.3.8
International Standards Organisation (ISO) – The ISO 14040 series Based on the work carried out by the Society for Environmental Toxicology
and Chemistry (SETAC), the ISO has further developed and has managed to reach agreement among its global membership on a series of standards: the ISO 14040 series on Life Cycle Assessment. These ISO 14040 series are listed as below: (a) ISO 14040 Environmental Management –Life Cycle Assessment –Principles and Framework (ISO, 1997) (b) ISO 14041 Environmental Management –Life Cycle Assessment –Goal and Scope Definition and Life Cycle Inventory Analysis (ISO, 1998) (c) ISO 14040 Environmental Management –Life Cycle Assessment –Life Cycle Impact Assessment (ISO/FDIS, 1999)
21 (d) ISO 14040 Environmental Management –Life Cycle Assessment –Life Cycle Interpretation (ISO/FDIS, 1999)
2.4
Issues Related to Life Cycle Stages
2.4.1
Inventory Assessment The inventory consists of a horizontal (input-output) and vertical (life-cycle)
analysis. Each stage of the life-cycle receives input of material and energy and produces which move on subsequent life-cycle phases and emissions (solid, liquid, gaseous). (Brobak et al, 1995) According to Caduff and Zust, Product Systems should be subdivided into a set of unit processes such that each unit process encompasses the activities of a structured in terms of material, energy and resources. Material and energy go through various existing unit processes. The desired output of a unit process is the product. In addition to the product by-products and emissions are generated. The term emissions signify the many types of output released directly into the ecosphere. Products and by-products undergo existing unit processes.
2.4.1.1 Raw Material Acquisition Stage The resource requirements and environmental emissions are calculated for all of the processes involved in acquiring raw materials and energy. This analysis involves tracing materials and energy back to their sources.
22 2.4.1.2 Material Processing Stage This step involves converting a raw material into a form that can be used to fabricate a finished product. For example, material scarp from a subsystem can be reused internally, sold as industrial scrap or disposed of as solid waste. The inventory account for each option is handled differently.
2.4.1.3 Manufacturing Stage Manufacturing converts intermediate materials into products ready for their intended used by customers. Facilities for which date are reported on a plant wide basis will require allocation of the inputs and outputs to the product of interest.
2.4.1.4 Filling/Packaging/Distribution This step includes all manufacturing processes and transportation required to fill, package and distribute a finished product. Energy consumption and environmental releases are caused by transporting the product to the retail outlets or to the customers are accounted for in this step of a product’s life cycle.
2.4.1.5 Use/Reuse/Maintenance Stage This stage includes all of the activities undertaken by the user of the product or service as well as any maintenance that may be performed by the user or obtained elsewhere. Energy requirements and environmental wastes associated with product storage and consumption are included in this stage.
23 2.4.1.6 Recycle and Disposal Stage Recycle and disposal management is the last stage in a product’s life cycle. In open loop recycling, products are recycled into different products. In closed loop recycling, products are recycled again and again into the same product.
2.4.2
Reutilization/Reprocessing/Remanufacturing Reutilization includes any activity in which the product or package may be
reconditioned, maintained or serviced extend its useful life. Secondary utilization is considered as the reutilization phase in this studies. Reprocessing is the reformation or recycling of a recovered material. Reprocessing involves a series of activities including collection, separation and processing by which products or other materials are recovered in the form of raw materials for the manufacture of new product. Remanufacturing is an industrial process that restores worn products to a new like condition. This done by first disassembling the product, cleaning and refurbishing the reusable parts. A new product is then reassembled by mixing the old and new parts.
2.4.3
Impact Assessment Impact Assessment is at this time a poorly developed stage of LCA. Although
some impact assessment methods have been advanced as either complete or partial approaches, none has been agreed upon. Nevertheless, an approach to impact analysis, known as ‘less is better’ is typically practiced. With this approach, process and product changes are sought that reduce most, if not all, generated wastes and consumed resources.
24 According to Guinee and Heijungs (1994), impact assessment includes a characterization step in which the contribution of resource extraction and pollution emission to impact categories such as resource depletion, global warming and acidification are quantified and aggregated as far as possible. This is achieved by multiplying extraction’s and emissions by a factor and by aggregating the results of these multiplication’s into one ‘effect score’ for each impact category: Effect scoreproblem type = Σ equivalency factorproblem type x emission or extraction Approach to assessing impacts include relating loadings to environmental standards, modeling exposures and effects of the burdens on a site-specific basis and developing equivalency factors for burdens which an impact category. In the valuation step of impact assessment, impacts are weighted and compared to one another. It is important to recognize that an LCA impact assessment does not necessarily measure actual impacts. Rather, an impact in LCA is generally considered to be a ‘reasonable anticipation of an effect” or an impact potential (Sullivan and Young, 1995). The reason for sung impact potentials is that it is typically difficult to measure an effect resulting from the burdens of a particular product. As far as Environmental impacts are concerned the choice for a supplier of a given material might be as important as the choice of material itself (Epelly et al, 1995). Ecobillan evaluated a particular plastic part of a car made of polypropylene supplied by two sources. The environmental impacts were compared with a reference thermoset part. It was concluded that depending on which supplier was chosen, the propylene part might be better or worse than the thermoset one. If the environmental impacts are a concern, the choice of supplier for a given material might be as important as the choice of material itself because of the tremendous discrepancies among environmental impacts of different processed or plants producing the same material.
25 In the valuation step of impact assessment, impacts are weighted and compared to one another. Further, attaching weighting factors to various potential impacts for comparison purpose is value laden. Because a consensus on the relative importance of different impacts is anticipated to be contentious, a widely accepted valuation methodology is not expected to be adopted in the foreseeable future.
2.5
An Integrated Approach to Solid Waste Management An integrated approach to solid waste management can be delivered both
environmental and economic sustainability. It is clear that no one single method of waste disposal can deal with all materials in waste in an environmentally sustainable. Ideally, a range of management option is required. The use of different options such as composing or materials recovery will also depend on the collection and subsequent sorting system employed. Hence, any waste management system is built up of many closely related processes, integrated together. Instead of focusing on and comparing individual options, an attempt will be made to synthesise waste management systems that can deal with the whole waste stream and then compare their overall performances in environmental and economic terms. This approach looks at the overall waste management system and develops ways of assessing overall environmental burdens and economic costs. As part of this, the various individual techniques for collection, treatment and disposal of waste are discussed. This book gives an overall vision of waste management with a view to achieving environmental objectives using economically sustainable systems tailored to specific needs of a region or community.
2.5.1
The Basic Requirement of WM Waste is an inevitable product of society. Solid waste management practices
were initially developed to avoid the adverse effects on public health that were being
26 caused by the increasing amounts of solid waste being discarded without appropriate collection or disposal. Managing this waste more effectively is now a need that society has to address. In dealing with the waste, there are two fundamental requirements: less waste and then an effective system for managing the waste still produced. Generally, sustainable development could be achieved if society in general and industry in particular learned to produce ‘more form less’; more goods and services from less of the world’s resources while generating less pollution and waste. In this era of ‘green consumerism’ (Elkington and Hailes, 1998), this concept of ‘more from less’ has been taken up by industry. This has resulted in arrange of concentrated product, light-weighted and refillable packaging, reduction of transport packaging and other innovations (Handle et al, 1993). Production as well as product changes have been introduced, with many companies using internal recycling of materials as part of solid waste minimization schemes. All of these measures help to reduce the amount of solid waste produced either as industrial, commercial or domestic waste. In essence, they are improvements in efficiency, i.e. ‘eco-efficiency’, whether in terms of materials or energy consumption. The costs of raw materials and energy and rising disposal costs for commercial and industrial waste will ensure that waste reduction continues to be pursued by industry for economic as well as environmental reasons. There has been interest in promoting further waste reduction by the use of fiscal instruments. Pearce and Turner (1992) suggest ways to reduce the amount of packaging used by internalizing the costs of waste disposal within packaging manufacture, by means of a packaging levy. It is not clear how effective such taxes would be since they only affect a small section of the waste stream, packaging materials constitute approximately 3% by weight of the UK’s total waste stream (INCPEN, 1996) and 3% by weight of the total European waste stream (Pricewaterhouse Coopers, 1998). Furthermore, economic incentives for waste reduction already exist. Experience has often shown that extra taxes add to the total cost but do not reduce the base cost of waste management. Often they become in
27 effect an additional revenue stream rather than being used for specific environmental purposes. ‘Waste minimization’, ‘waste reduction’ or ‘source reduction’ is usually placed at the top of the conventional waste management hierarchy. In reality, however, source reduction is a necessary precursor to effective waste management, rather than part of it. Source reduction will affect the volume and to some extent, the nature of the waste but there will still be waste for disposal. What is needed, beyond source reduction is an effective system to mange this waste.
2.5.2
Integrated Waste Management in Countries with Developing Economics The management of Municipal Solid Waste (MSW) is an integral but not
much neglected aspect of environmental management in most low and middle income countries. Despite consuming a significant share of Municipal budgets, solid waste management services in the towns and cities of mist low and middle income countries are unreliable, provide inadequate coverage, conflict with other urban services and have adverse effects on public health and the environment (Bartone, 1999). The IWM approach is as valid in countries with developing economies as it is in countries with developed economies, but the actual establishment of integrated systems differs considerably. In countries with developing economies the combination of a lack of existing waste management infrastructure and severely limited resources change the approach that must be taken. Under these conditions, a relatively simple but effective Integrated Waste Management system is desired. The waste management systems that exist in the majority of countries with developing economies are often characterized by inadequate collection services, little or no treatment and uncontrolled dumping. The establishment of IWM systems will require the following:
28 (a) Data collection on waste composition. This in needed for the planning of collection, transport and treatment of MSW. Good date is the foundation of effective IWM systems. (b) Progress from uncontrolled dumping to the use of simple sanitary landfills. (c) Separation of organic waste from MSW which can then be composted. (d) Formal involvement of scavengers in the collection of recyclable materials.
2.6
Element of Integrated Waste Management Element of Integrated Waste Management is consisted of solid waste
generation, waste collection, central sorting, biological treatment, thermal treatment, landfilling and materials recycling. Every part of these elements play their role to bring the successfulness to the Integrated Waste Management. Basically, the Life Cycle of each material must be from the beginning stage of materials production to the final stage where the waste is to be disposed. The main stage and their interconnections in the Life Cycle of solid waste are shown schematically in Figure 2.3, comprising pre-sorting and collection, sorting, biological treatment, thermal treatment and landfilling.
2.6.1
Solid Waste Generation A complete overview of data on the amounts of solid waste generated
globally is difficult to obtain. This is because much of the date is simple not available and also due to the variety and quality of the available date sources. Different sources in each country use different definitions of total solid waste, Municipal Solid Waste (MSW), commercial waste (sometimes included in MSW, sometime not) and industrial waste. Solid waste data are often presented in different formats depending on the objectives of the reporter, further obscuring the true figures.
29
Figure 2.3 Element of an Integrated Waste Management System Data are often reported as one or even several of the following: Total waste arisings, Total household waste, Total municipal waste, Total residual waste, Total collected waste, Total landfilled waste and the permutations, which depend on local circumstances. The main data sources available are the Organisation for Economic Co-operation and Development (OECD), the European Environment Agency (EEA), countries’ own Environmental Agencies and statistical organisations. Table 2.4 shows the categories of solid waste generated from different sources. Data on the generation of MSW are difficult to interpret because of the different definitions used for MSW. National data that breaks down MSW according to the source of the materials, that is into collected household waste, delivered household waste, commercial waste and institutional waste are equally hard to obtain.
30 Collected household wastes are normally the best documented with poorer data available for delivered household and commercial waste. Knowledge of the material composition of MSW is essential for effective management and disposal. The composition of MSW by weight from various counties is given in Table 2.5. Table 2.4: Categories of solid waste Solid waste category
Description
Agricultural
Waste arising from agricultural practices, especially livestock production. Often either used (applied to land) or treated in situ.
Mining and quarrying
Mainly inert mineral wastes from coal mining and mineral extraction industries.
Dredging spoils
Organic and mineral wastes from dredging operations.
Construction and
Building waste, mainly inert mineral or wood wastes.
demolition Industrial
Solid waste from industrial processes. Sometimes will include energy production industries.
Energy production
Solid waste from the energy production industries, including fly ash from coal burning.
Sewage sludge
Organic solid waste, disposed of by burning, dumping at sea (soon to cease in the EU), application to land or composting. May result from industrial or domestic wastewater treatment.
Hazardous / Special
Solid waste which can obtain substances that are dangerous
waste
to life is termed ‘Special waste’ in UK or ‘Hazardous water’ in EU directives.
Commercial
Solid waste form offices, shops, restaurants, etc. often included in MSW.
Municipal Solid
Defined as the solid waste collected and controlled by the
Waste (MSW)
local authority or municipality and typically consists of household waste, commercial waste and institutional waste.
31 Table 2.5: Composition of MSW (by weight) in North and Central America. (OECD, 1997) North
Paper
and
Waste
Central
type
Year
America
/
Plastics
Glass
Metal
board
(%)
(%)
(%)
(%)
Food / garden (%)
Other (%)
Canada
MSW
1995
28
11
7
8
34
12
Mexico
MSW
1995
14
4
6
3
52
21
USA
MSW
1995
39
9
6
8
21
17
2.6.2
Waste Collection Collection methods are often divided into bring and kerbside collection
schemes. ERRA (1993b) defined bring collection systems as those where households are required to take recyclable materials to one of a number of collection points. In kerbside collection schemes the householder places recoverables in container/bag which they position on a specific day, outside their property for collection. Note that collection need not be from kerbside, the key distinguishing point being that in bring systems, the householders transport the materials from their home, whereas in kerbside collection they are collected form the home. In reality, ring and kerbside are just the two ends of a spectrum of collection methods. Figure 2.4 shows the spectrum of collection methods from bring to kerbside systems. The extreme form of bring system is the central collection site for householders transport materials such as bulky items and garden waste. This site often also has collection containers for recyclable materials such as glass bottles and cans. Next in the spectrum of bring systems come materials banks at low density often situated locally at supermarkets. As the density of bring material containers increases, they become close-to-home drop off containers (ERRA, 1993b), to which householders can walk rather than drive. This applies particularly to high-rise
32 housing where residents of apartment blocks usually take their waste to large communal containers positioned outside the apartment blocks or at the side of the street. This is essentially a waste container in the street, outside, rather than inside, the property. The only difference between his bring system and a kerbside collection from individual properties is that the containers are communal, rather than for individual households. The term bring system clearly includes a range of different schemes. Kerbside collection is more narrowly defined but collection can also be of separated fractions or of co-mingled waste. As a result, blankets comparisons of bring versus kerbside approaches must be made with caution.
Figure 2.4 The spectrum of collection methods from bring to kerbside systems. (Arrow lengths indicate distances traveled by residents to collection points.)
2.6.3
Central Sorting Sorting is an important part of any waste’s Life Cycle. Solid waste is almost
always mixed and household wastes are amongst the most heterogeneous in terms of
33 material composition. Separation of the different materials in waste to a greater or lesser extent is an essential part of almost all methods of treatment. This sorting can and odes occur at any point in the Life Cycle of waste; similarly it can occur any number of times. The earliest sorting will occur in the home, when, for example, materials are separated from the residual waste stream but the same materials can be sorted further during and after collection. Sorting of the input also represents the first stage of many waste treatment processes, such as composting, biogasification and in some cases sorting of the outputs also occurs. Two particular central sorting operations are the sorting of mixed recyclables at a Material Recovery Facility (MRF) and the sorting of mixed waste to produce Refuse-Derived Fuel (RDF). The aim of MRFs is to separate materials that have enough value to make their recovery worthwhile. MRFs are relatively inexpensive when compared to most other waste treatment processes such as incineration and it is technically feasible to recover almost any fraction of the waste stream either manually or mechanically. Figure 2.5 shows the generic MRF with manual sorting. RDF is produced by mechanically separating the combustible fraction from the non-combustible fraction of solid waste. The combustible fraction is then shredded and may also be pelletised. RDF production thus forms part of a thermal treatment system which aims to valorize part of the waste stream by recovering its energy content. The second stage, RDF combustion can either occur on the same site or RDF can be transported for combustion elsewhere. Production and combustion of RDF even if they occur on the same site, will be treated separately. There are two basic RDF processes, each producing a distinctive product, knows as densified RDF (dRDF) and coarse RDF (cRDF), respectively. DRDF is produced as pellets, often similar on size and shape to wine corks. Prior to pelletising it is dried, so is relatively stable and can be transported, handled and stored like other solid fuels, it can either be burned alone or co-fired with coal or other solid fuels. dRDF requires considerable processing, including drying and pelletising and so has relatively high processing energy requirement. As a result,
34
Figure 2.5 The generic MRF with manual sorting there has recently been interest in the alternative coarse RDF (cRDF). This comes in the form of a coarsely shredded product that has been compared in appearance to the fluff from a vacuum cleaner (Warmer Bulletin, 1993b). cRDF requires less processing but as it has not been dried, cannot be stored or long periods. It is suitable for immediate use in on-site combustion for power generation and local heating.
2.6.4
Biological Treatment Biological treatment can be used to treat both the organic and non-recyclable
paper fractions of solid waste. Biological treatment can be separated into two distinct processes which are aerobic and anaerobic treatment. Therefore, two main treatment types exist which are composting (aerobic) and biogasification (anaerobic). Either can be used as a pre-treatment to reduce the volume and stabilize material for disposal in landfills or as a way to produce valuable products such as compost and (from biogasification) biogas plus compost from the waste stream.
35 2.6.5
Thermal Treatment Thermal treatment can be regarded as either a pre-treatment of waste prior to
final disposal or as a means of valorizing waste by recovering energy. It includes both the burning of mixed MSW in municipal incinerators and the burning of selected parts of the waste stream as a fuel. Thermal treatment of solid waste within an Integrated Waste Management system can include at least three distinct processes, Mass burn, RDF burn an paper and plastic fuel burn. The most well known is massburning or incineration of mixed Municipal Solid Waste (MSW) in large incinerator plants but there are two additional select-burn processes whereby combustible fraction from the solid waste are burned as fuels. These fuels can be separated from mixed MSW either mechanically to form RDF or can be source-separated materials form household collections such as paper and plastic.
2.6.6
Landfilling Landfilling is considered as a waste treatment process with its own inputs and
outputs rather than as a final disposal method for solid waste. Landfilling essentially involves long-term storage for inert materials along with relatively uncontrolled decomposition of biodegradable waste. Landfilling is also considered the simplest and in many areas the cheapest of disposal methods, to has historically been relied on for the majority of solid waste disposal. A landfill is not a black hole into which material is deposited and form which it never leaves. Basically, landfilling is a waste treatment process, rather than a method of final disposal (Finnveden, 1995). Solid wastes of various composition form the majority of the inputs, along with some energy to run the process. The process itself involves the decomposition of part of the landfilled waste. The outputs from the process are the final stabilized solid waste, plus the gaseous and aqueous products of decomposition, which emerge as landfill gas and leachate. As in all processes, process effectiveness and the amounts and quality of the products depend on the process inputs and the way that the process is operated and controlled.
36 2.6.6.1 Composition of Landfill Gas Landfill gas is composed of a mixture of hundreds of different gases. By volume, landfill gas typically contains 45% to 60% methane and 40% to 60% carbon dioxide. Landfill gas also includes small amounts of nitrogen, oxygen, ammonia, sulfides, hydrogen, carbon monoxide, and nonmethane organic compounds (NMOCs) such as trichloroethylene, benzene, and vinyl chloride. Table 2.6 lists “typical” landfill gases, their percent by volume, and their characteristics.
2.6.6.2 Landfill Gas Production Three processes—bacterial decomposition, volatilization, and chemical reactions—form landfill gas. (i)
Bacterial decomposition
Most landfill gas is produced by bacterial decomposition, which occurs when organic waste is broken down by bacteria naturally present in the waste and in the soil used to cover the landfill. Organic wastes include food, garden waste, street sweepings, textiles, and wood and paper products. Bacteria decompose organic waste in four phases, and the composition of the gas changes during each phase. The box on page 5 provides detailed information about the four phases of bacterial decomposition and the gases produced during each phase. Figure 2.6 shows gas production at each of the four stages. (ii)
Volatilization
Landfill gases can be created when certain wastes, particularly organic compounds, change from a liquid or a solid into a vapor. This process is known as volatilization. NMOCs in landfill gas may be the result of volatilization of certain chemicals disposed of in the landfill. (iii)
Chemical reactions
Landfill gas, including NMOCs, can be created by the reactions of certain chemicals
37 present in waste. For example, if chlorine bleach and ammonia come into contact with each other within the landfill, harmful chlorine gas is produced. Table 2.6: Typical Landfill Gas Components Component methane
carbon dioxide
Percent by Volume 45–60
40–60
Characteristics Methane is a naturally occurring gas. It is colorless and odorless. Landfills are the single largest source of U.S. man-made methane emissions. Carbon dioxide is naturally found at small concentrations in the atmosphere (0.03%). It is colorless, odorless, and slightly acidic.
nitrogen
2–5
Nitrogen comprises approximately 79% of the atmosphere. It is odorless, tasteless, and colorless.
oxygen
0.1–1
Oxygen comprises approximately 21% of the atmosphere. It is odorless, tasteless, and colorless.
ammonia
0.1–1
Ammonia is a colorless gas with a pungent odor.
NMOCs (non-methane organic compounds)
sulfides
0.01–0.6
NMOCs are organic compounds (i.e., compounds that contain carbon). (Methane is an organic compound but is not considered an NMOC.) NMOCs may occur naturally or be formed by synthetic chemical processes. NMOCs most commonly found in landfills include acrylonitrile, benzene, 1,1-dichloroethane, 1,2-cis dichloroethylene, dichloromethane, carbonyl sulfide, ethylbenzene, hexane, methyl ethyl ketone, tetrachloroethylene, toluene, trichloroethylene, vinyl chloride, and xylenes.
0–1
Sulfides (e.g., hydrogen sulfide, dimethyl sulfide, mercaptans) are naturally occurring gases that give the landfill gas mixture its rotten-egg smell. Sulfides can cause unpleasant odors even at very low concentrations.
hydrogen
0–0.2
Hydrogen is an odorless, colorless gas.
carbon monoxide
0–0.2
Carbon monoxide is an odorless, colorless gas.
38 2.6.6.3 Factors Affecting the Production of Landfill Gas The rate and volume of landfill gas produced at a specific site depend on the characteristics of the waste (e.g., composition and age of the refuse) and a number of environmental factors (e.g., the presence of oxygen in the landfill, moisture content, and temperature). (i)
Waste composition
The more organic waste present in a landfill, the more landfill gas (e.g., carbon dioxide, methane, nitrogen, and hydrogen sulfide) is produced by the bacteria during decomposition. The more chemicals disposed of in the landfill, the more likely NMOCs and other gases will be produced either through volatilization or chemical reactions. (ii)
Age of refuse
Generally, more recently buried waste (i.e., waste buried less than 10 years) produces more landfill gas through bacterial decomposition, volatilization, and chemical reactions than does older waste (buried more than 10 years). Peak gas production usually occurs from 5 to 7 years after the waste is buried. (iii)
Presence of oxygen in the landfill
Methane will be produced only when oxygen is no longer present in the landfill. (iv)
Moisture content
The presence of moisture (unsaturated conditions) in a landfill increases gas production because it encourages bacterial decomposition. Moisture may also promote chemical reactions that produce gases. (v)
Temperature
As the landfill’s temperature rises, bacterial activity increases, resulting in increased gas production. Increased temperature may also increase rates of volatilization and chemical reactions.
39 2.6.6.4 Factors Affecting the Migration of Landfill Gas
The direction, speed, and distance of landfill gas migration depend on a number of factors, described below.
(i)
Landfill cover type
If the landfill cover consists of relatively permeable material, such as gravel or sand, then gas will likely migrate up through the landfill cover. If the landfill cover consists of silts and clays, it is not very permeable; gas will then tend to migrate horizontally underground. If one area of the landfill is more permeable than the rest, gas will migrate through that area.
(ii)
Natural and man-made pathways
Drains, trenches, and buried utility corridors (such as tunnels and pipelines) can act as conduits for gas movement. The natural geology often provides underground pathways, such as fractured rock, porous soil, and buried stream channels, where the gas can migrate.
(iii)
Wind speed and direction
Landfill gas naturally vented into the air at the landfill surface is carried by the wind. The wind dilutes the gas with fresh air as it moves it to areas beyond the landfill. Wind speed and direction determine the gas’s concentration in the air, which can vary greatly from day to day, even hour by hour. In the early morning, for example, winds tend to be gentle and provide the least dilution and dispersion of the gas to other areas.
(iv)
Moisture
Wet surface soil conditions may prevent landfill gas from migrating through the top of the landfill into the air above. Rain and moisture may also seep into the pore spaces in the landfill and “push out” gases in these spaces.
(v)
Groundwater levels
Gas movement is influenced by variations in the groundwater table. If the water table
40 is rising into an area, it will force the landfill gas upward.
(vi)
Temperature
Increases in temperature stimulate gas particle movement, tending also to increase gas diffusion, so that landfill gas might spread more quickly in warmer conditions. Although the landfill itself generally maintains a stable temperature, freezing and thawing cycles can cause the soil’s surface to crack, causing landfill gas to migrate upward or horizontally. Frozen soil over the landfill may provide a physical barrier to upward landfill gas migration, causing the gas to migrate further from the landfill horizontally through soil.
(vii)
Barometric and soil gas pressure
The difference between the soil gas pressure and barometric pressure allows gas to move either vertically or laterally, depending on whether the barometric pressure is higher or lower than the soil gas pressure. When barometric pressure is falling, landfill gas will tend to migrate out of the landfill into surrounding areas. As barometric pressure rises, gas may be retained in the landfill temporarily as new pressure balances are established.
2.6.7
Materials Recycling Material recycling also is one of the ways to decrease the environmental
burden. Recycling means using things that have been used to make new things. It also includes reusing things as they are and giving things you no longer need for other people to use. For recycling to work, they needs to be markets for the products made with recycled materials. This creates a demand for the materials recovered by recycling collection schemes. Buying materials made from recycled is called closing the recycling loop. Recycling is a campaign in the aim to reduce the production of waste and longer the life of landfills. Recycling reduces waste, which in turn reduces the need for landfills and dumpsites. It reduces pollution and saves energy. Making products from virgin or
41 raw materials results in pollution and uses more energy. In addition, it is cheaper in the long run compared to maintaining landfills and other systems. When recycling programmes become more efficient, there will be less rubbish to dispose of. It also creates up to 5 times more jobs than waste disposal alone and creates jobs for engineers, machine specialists, environmental personnel, general workers and many more. More but not less, it improves cleanliness and quality of life.
2.6.7.1 Plastic Manufacturing Plastics are made form oil, natural gas, coal and salt. The major feedstock is oil, the petrochemicals industry supplies the monomers for plastics production and manufactures a wide range of additives to modify their behaviour. Plastics are produced by polymerization, the chemical bonding of monomers into polymers. The size and structure of the polymer molecule determines the properties of the plastic material. In their form, plastics are produced as powders, granules, liquids and solutions. The application of heat and pressure to these raw materials produces the final plastic product. Plastics are classified as thermoplastic or thermosetting resins. When thermoplastic resins are heated, it soften and flow as viscous liquid; when cooled they solidify. The heating and cooling cycle can be repeated any times without the loss of specific properties. Thermosetting resins liquefy when heated and solidify with continued heating. The polymer undergoes permanent cross-linking and retains its shape during subsequent cooling and heating cycles. Thermoset plastics cannot be reheated and remoulded; however, thermoplastics can be reprocessed by melting and hence readily recycled. Figure 2.6 shows the categories of rigid plastic containers. Almost 85% of all resins produced are thermoplastics and over 70% of the total volume of thermoplastics is accounted for by the resins: polyethylene, polypropylene, polystyrene and polyvinyl choride (PVC) (Modern Plastics, 1994). They are made in a variety of grades and because of their low cost are the first choice for a large number of applications. A variety of processing and shaping methods are
42 available to form the desired product of these processes extrusion and injection moulding are the most common.
Figure 2.6 The categories of rigid plastic containers (SPI, 1998).
2.6.7.2 Plastic Recycling After separation of the resin types into individual or at least compatible fractions, plastics can be either mechanically or chemically recycled. In mechanical recycling the plastic sis shredded or crumbed in to a flake form and contaminants such as paper labels are removed using cyclone separators. The flake is then generally washed, dried and then extruded as pellets for sale to plastic market. Chemical recycling involves a more complex process whereby the plastic polymer is broken down into the monomer form and then re-polymerised. In this case, the recycled product is indistinguishable form the virgin material. This recycling
method
has
been
developed
for
certain
resins,
notably
polyethyleneterepthalate (PET), where chemical recycling via a methanolysis process is commonly used. However, the cost of the monomers obtained from chemical recycling is frequently higher than the cost of monomers derived form the traditional chemistry (La Manita and Pilati, 1996).
43 2.7
Plastic The term plastic describes a wide range of compounds and materials. Plastics
are materials that can be formed into desired shapes through processes such as extrusion, moulding, casting or spinning. Synthetic plastics are usually made from oil or gas. The building blocks derived from oil and gas are called monomers. These undergo a process called polymerisation to make them into polymers. Plastics are usually made by adding various chemicals, called additives, to the polymer.
2.7.1
Types of Plastic and their Main Applications The use of synthetic plastics has developed since the late 19th century. The
main sectors that use plastics: packaging, construction, electrical and electronics, and the automotive industry. The main uses of some of the major plastics are shown in Table 2.7.
2.7.2
Advantages of Using Plastic Plastics are very versatile and have a range of properties, for example, they
are relatively cheap, light, durable and strong, which have led to their widespread use. Table 2.8 presents the properties of plastics and their advantages. Plastics are used in preference to other materials in a specific application, either:
z
because they offer a better combination of advantages, such as lightweight, strength, durability and cost over other materials, principally metal, glass, wood, paper or cardboard, rubber, concrete and clay; or
z
because the application was developed as a direct result of the characteristics offered by the specific plastic, and is therefore restricted to that plastic. An example of this is transparent shatterproof windows, whose development was
44 only realized following the synthesis of polycarbonate.
2.7.3
Potential Impacts of Plastic As with other products, the use of plastic has potential impacts on the
environment across its life cycle. Making plastics uses energy and other resources and causes emissions and releases to the environment. Energy is used in transporting raw materials and goods. At the end of their life most plastics are landfilled. On the whole, plastics are very stable materials, but chemicals may be released to the environment or to food during their use and disposal. The extent to this is occurrence and its potential impact on the environment and human health. As a society, we benefit from these chemicals, but some may threaten the environment and human health.
45 Table 2.7: Uses of Major Plastic Type of plastic
Main applications
Thermoplastics High-density polyethylene
Containers, toys, housewares, industrial wrapping and film, gas pipes
Low-density polyethylene
Film, bags, toys, coatings, containers, pipes, cable insulation
PET
Bottles, film, food packaging, synthetic insulation
Polypropylene
Film, battery cases, microwave containers, crates, car parts, electrical components
Polystyrene
Electrical appliances, thermal insulation, tape cassettes, cups, plates
PVC
Window frames, pipes, flooring, wallpaper, bottles, cling film, toys, guttering, cable insulation, credit cards, medical products
Polymethyl methacrylate
General appliance mouldings
Polyamide
Films for packaging of foods such as oil, cheese and boil-inthe-bag products and for high temperature engineering applications
ABS/SAN
Transparent all-weather sheet, electrical insulators, domestic appliances
Thermosetting plastics Epoxy resins Adhesives, car components, components, sports equipment, boats Polyurethane
Adhesives, appliances, car parts, electrical components, trainer soles, furniture foam
Phenolics (phenol formaldehyde, ureaformaldehyde)
Adhesives, appliances, car parts, electrical components
46 Table 2.8: Properties of Plastics and their Advantages Property Low cost
Examples Can be cheaper than natural materials, for example, PET replacing feather down
Lightweight
Plastics are lighter than many conventional materials. For example, a paper carrier bag weighs roughly six times as much as a plastic carrier bag. A 1 litre plastic bottle for oil weighs only seven per cent of the equivalent glass bottle. This leads to reduced fuel consumption and transport costs
Durability
Greater durability of plastics in some applications compared with other materials such as metal, wood and glass is often a consequence of factors such as greater resistance to corrosion, strength and impermeability to water
High strength
Greater strength-to-weight ratio of many plastics compared to other materials means that less material is required. For example, use of polyamides in bullet-proof vests
Manufacturing versatility
Different plastic component parts can be integrated easily within a single product, which reduces processing and assembly costs. For example, a one-piece PVC window frame
Colour
Colour can be varied easily at the processing stage
Good thermal insulator
Polystyrene in building insulation
Low permeability to oxygen
PVC wrap to protect food, such as red meat, from exposure to the air
Impermeability to water
PVC waterproof flooring and coverings
Heat resistance
Polypropylene containers are a lightweight, low-cost alternative to glass, for example in use in microwaves
Electrical resistance
PVC and polypropylene wire and cable insulation
Corrosion resistance
Use of plastics in the building industry and car manufacture
CHAPTER III
METHODOLOGY
3.1
Introduction
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:
z
Quantifying the quantities of energies and materials used and the quantities of waste emissions released into the environment.
z
Assessing the impact of energy and emissions releases on the environment.
z
Evaluating opportunities to effect improvements.
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.
3.2
Life Cycle Inventory
In the inventory stage, the studies was conducted to define all aspects of the materials and manufacturing process. Steps in the manufacturing process are
48 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 haven been collected from various sources, the following Life Cycle Stages were being considered.
1. Manufacturing stage Plastic moulding processes
2. Use stage The environmental impact of the plastic product has been analysed considering a 10 years.
3. Recycling / Waste management stage Disposal to landfill and energy recovery through 100% waste incineration of plastic product were calculated.
3.3
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 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.
49 3.4
Life Cycle Interpretation
Assessments of all impacts are made for each material or process as are comparisons between alternatives courses of action. The alternative that provides some improvements over other alternatives is selected. Improvement is defines as compliance with saving of energy required while increasing performance and quality in term of lesser production of emissions.
3.5
Assumptions
The following assumptions have been made:
z
All calculations have been made for a kg weight of plastic product.
z
All plastic products are distributed by road whereas 0.001 MJ/kg/km.
z
All plastic products will have the product life of 10 years.
3.6
Life Cycle Assessment Boundary
Product system contributions to environmental effects can occur at every point of the life cycle of the product, right through from the extraction of the original materials and energy resources, the transformation of these into useable manufacturing inputs, the manufacturing process itself, the transport and distribution of intermediate and end products, and the use and final disposal. Thus, we chose to include all stages in the life cycle from ‘cradle to grave’ and even attempted to estimate construction energy for the main transport and processing equipment.
3.7
Methods
To carry out a life cycle analysis requires that, the boundaries of the global
50 system e.g. a set of subsystems must be defined precisely. The energy requirements for the hierarchy of alternatives are based upon the following global boundaries (Bisio and Xantos, 1994):
Input: One (1) kg of plastic fraction in a waste stream that can be either source separated, sorted, landfilled or combusted. Additional energy as required for each option considered.
Output: Identical finish plastic parts.
Figure 3.1 shows the simplified life cycle of plastics which covers from their manufacture to their use and to their disposal. Oil Raw materials Energy
Making plastics Transport Using plastics Plastic waste
Energy
Recycling Emissions
Landfill
Incineration
Emissions
Emissions
Energy
Figure 3.1 Simplified life cycle of plastics (Environmental Agency, 2001)
CHAPTER IV
LIFE CYCLE INVENTORY
4.1
Plastic Production
This section gives an overview of the complex and varied processes involved in making plastic. We also look at ‘additives’, which enhance the performance of plastic 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.
4.1.1
Process of Making Plastics
Plastics are made predominantly from oil and natural gas. There is increasing interest in developing technologies to use plants and bacteria as the source of hydrocarbons for plastics.
4.1.1.1 Plastics from oil and gas
Oil and natural gas are the main raw materials for producing the building blocks of plastics called ‘monomers’. Other natural resources such as wood and coal can be used, but this is not common. Four per cent of annual world oil production is
52 used as a feedstock for making plastics, in addition to the energy used to process plastics (BPF, 2000). The oil that is extracted from the ground is crude oil, and is not very useful in this form. It is made up of a mixture of hydrocarbons which can be separated into fractions, such as gasoline, naphtha and bitumen. Some of these can then be processed, by cracking or reforming, into compounds that provide the starting material for the petrochemical industry to produce materials such as plastics and synthetic rubber. The monomers undergo a process called polymerisation to form the polymer. To make plastics chemical additives are nearly always added to the monomer or polymer (Figure 4.1). The general steps in the process of converting the raw materials into plastic products, which involve several industrial processes and plants, are shown in Figure 4.2. An outline of the processes involved in making some of the plastics discussed is given below.
PET (polyethylene terephthalate) is an aromatic polyester (because it contains both carboxylic and benzene groups). It is prepared in a reaction between ethylene glycol and either terephthalic acid or the dimethyl ester of terephthalic acid.
PVC is made from oil and salt. The oil is ‘cracked’ to produce ethylene, and the salt is processed to produce chlorine. The two products are then combined to produce ethylene dichloride, which is further processed to produce the monomer vinyl chloride. This is then polymerised to make polyvinyl chloride (PVC). PVC is thermally unstable, so stabilisers and lubricants are added in a compounding process. This produces rigid PVC (often referred to as unplasticised PVC or PVC-U). Flexible PVC is made with the addition of plasticisers.
Polypropylene is made by polymerising propylene. There are three main types of processes; for example, in the gas-phase process propylene is dried over aluminium oxide and polymerised in a gas-phase reactor using a catalyst and activator. The polypropylene powder is separated using nitrogen, isopropyl alcohol and steam.
53
Figure 4.1 The role of additives in the production of plastics
Oil refinery
Oil cracking Feedstock polymerisation
Chemical plant
Polymer Additives Modifier Plastic processor
compounding Plastic Extrusion/casting/spinning etc Plastic product
Figure 4.2 Generalised process for making plastics
54 4.1.1.2 Additives
For most plastics, the finished product consists of the polymer and a number of additives that are incorporated to enhance the performance of the material or to aid its processing. Examples include colourants, flame retardants and stabilisers (Table 4.1). Some of the compounds used as additives are potentially more hazardous to human health and the environment than the monomers and polymers themselves. We have focused on providing information about the use of additives over which there is some environmental concern. The examples we give are plasticizers and stabilisers used in PVC and a flame retardant.
4.1.1.3 Plasticisers and stabilisers used in PVC
Plasticisers are used to make flexible PVC products. In 1997 most of the plasticisers used in PVC were phthalates (European Commission, 2000). About 850,000 tonnes of phthalates are used each year in the production of PVC in western Europe (ECPI, undated). They are made by reacting alcohols with phthalic anhydride and eliminating water. About 90 per cent of all phthalates are used in PVC; other uses include rubber products, paints, printing inks, lubricants and some cosmetics. Stabilisers are added to PVC to prevent degradation by heat and light.
4.1.1.4 Brominated flame retardants
A range of organic and inorganic compounds are used as flame retardants to improve the fire resistance of plastic products. They are used mainly in the plastic housings of electrical and electronic equipment, for example, computers, and in circuit boards, cables and textiles.
55 Table 4.1: Additives and their function Type
Description
Used to enhance performance Fillers
Inert materials used in bulk to reduce polymer costs, improve processability and can be used to improve mechanical properties.
Plasticisers
Enhance the flexibility of a plastic material.
Antioxidants
Reduce the degradation of polymers during the life of the product.
Coupling agents
Improve the bond between the polymer and fillers.
Colourants
Dyes and pigments.
UV and other
Mainly used for applications with a long life such as
weathering stabilisers
building product.
Polymeric impact
Used to retard or inhibit brittle fracture.
modifiers Anti-static agents
Inhibit the development of static.
Flame retardants
Reduce the risk of ignition and retard combustion.
Preservatives
Fungicides and bacteriocides are occasionally used in long service plastic products.
Used as processing aids Curing agents
Peroxides, amines and organotin compounds used to assist in the curing of thermosetting plastics.
Blowing agents
Chemicals or solvents are used that produce gas on heating.
Heat stabilisers
Organic or organometallic compounds used to reduce the degradation of PVC and other vinyl materials during processing and conversion into finished products.
Lubricants
Improve surface lubrication during processing and use.
Viscosity aids
Materials used to regulate the viscosity of PVC-plasticisersolvent mixtures during processing.
(Source: RAPRA Technology Limited and Building Research Establishment, 1994)
56 4.1.2
Production Stage – Emissions and Energy Requirements
The production of different kind of polymers has totally different total of energy required and the amount of emissions released. In the section, three types of polymer will be discussed separately in order to provide a clear result during production stage. The polymers involved are PET, PVC and PP.
4.1.2.1 Production Stage – Emissions and Energy Requirements for PET
Table 4.2: Environmental Profile for PET – Plastic Production Stage Raw material
Oil & natural gas
Main Product
1 kg 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
4.1.2.2 Production Stage– Emissions and Energy Requirements for PVC
Table 4.3: Environmental Profile for PVC – Plastic Production Stage Raw material
Oil & natural gas
Main Product
1 kg PVC is produced
Energy
64.93 MJ/kg
Solid waste
0.0.885 kg/kg
Transport
0.2 MJ/kg
Emissions
CO2 1750 g/kg SOx 13 g/kg NOx 15 g/kg CO 2.5 g/kg HCs 19 g/kg
57 4.1.2.3 Production Stage – Emissions and Energy Requirements for PP
Table 4.4: Environmental Profile for PP – Plastic Production Stage Raw material
Oil & natural gas
Main Product
1 kg PP is produced
Energy
80.03 MJ/kg
Solid waste
0.03103 kg/kg
Transport
0.2 MJ/kg
Emissions
CO2 1780 g/kg SOx 11 g/kg NOx 10 g/kg CO 0.7 g/kg HCs 13 g/kg
4.2
Use of Plastic
This section looks at the main sectors that use plastics: packaging, construction, electrical and electronics, and the automotive industry. During this stage, there are no energy and emissions released involved. Therefore, no data can be used to indicate the effect of plastic during using stage to the entire life cycle of plastic.
4.3
Transport of Plastic
In this process, the used plastic will be transported to consumers and eventually to recycling centres and disposal sites once it reaches the end of life of its services. Meaning to say, consumers dump it into theirs dustbin after the plastic products become spoil and broken. Similarly, the three types of polymer will be discussed independently as mentioned in production stage. We assumed the maximum of transport distance to consumers, recycling centres and disposal sites was 200 km. The energy required for transportation was 0.01 MJ/kg/km (Albu,1997). We assumed no emissions released during transportation stage because the emissions released was insignificant.
58
4.3.1
Transportation Stage – Emissions and Energy Requirements for PET, PVC and PP
Table 4.5: Environmental Profile – Transportation Stage PET Transport
4.4
PVC
PP
0.001 x 200
0.001 x 200
0.001 x 200
= 0.2 MJ/kg
= 0.2 MJ/kg
= 0.2 MJ/kg
Disposal of Plastic Waste
Plastic waste can be disposed off using different kind of methods. As mentioned before, the methods we reviewed were waste to landfill and incinerated. Recycling was also one of the methods to be considered in this study. The different was recycling activities will reduce the waste generated to the earth and eventually lessen the risks of environmental burdens.
4.4.1
Waste Recycled – Emissions and Energy Requirements
Where reuse is not the most environmentally sound way of extracting value from plastic 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 plastics from feedstock. Plastic waste has greater recycling of packaging. Most plastics are recycled mechanically, but chemical recycling is at a developmental stage. Plastic bottles are the main type of plastic collected and recycled from household waste. During the process of recycling, energy is required and emissions are released to environment.
59 4.4.1.1 Waste Recycled – Emissions and Energy Requirements for PET
Table 4.6: Environmental Profile for PET – Waste Recycled Raw material
-
Main Product
1 kg new PET 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
4.4.1.2 Waste Recycled – Emissions and Energy Requirements for PVC
Table 4.7: Environmental Profile for PVC – Waste Recycled Raw material
-
Main Product
1 kg new PVC is produced
Energy
9.13 MJ/kg
Solid waste
-
Transport
0.2 MJ/kg
Emissions
CO2 942 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
60 4.4.1.3 Waste Recycled – Emissions and Energy Requirements for PP
Table 4.8: Environmental Profile for PP – Waste Recycled Raw material
-
Main Product
1 kg new PP is produced
Energy
19.87 MJ/kg
Solid waste
-
Transport
0.2 MJ/kg
Emissions
CO2 942 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
4.4.2
Waste to Landfill – Emissions and Energy Requirements
4.4.2.1 Waste to Landfill – Emissions and Energy Requirements for PET
Table 4.9: Environmental Profile for PET – Waste to Landfill 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
61 4.4.2.2 Waste to Landfill – Emissions and Energy Requirements for PVC
Table 4.10: Environmental Profile for PVC – Waste to Landfill Energy
60.007 MJ/kg
Solid waste
-
Transport
0.2 MJ/kg
Emissions
CO2 674.597 g/kg SOx 12.848 g/kg NOx 6.928 g/kg HCs 2101.609 g/kg
4.4.2.3 Waste to Landfill – Emissions and Energy Requirements for PP
Table 4.11: Environmental Profile for PP – Waste to Landfill Energy
60.007 MJ/kg
Solid waste
-
Transport
0.2 MJ/kg
Emissions
CO2 644.597 g/kg SOx 14.848 g/kg NOx 11.928 g/kg HCs 2107.609 g/kg
4.4.3
Waste Incinerated – Emissions and Energy Requirements
4.4.3.1 Waste Incinerated – Emissions and Energy Requirements for PET
Table 4.12: Environmental Profile for PET – Waste Incinerated Energy
32.5MJ/kg
Solid waste
-
Transport
0.2 MJ/kg
Emissions
CO2 2016 g/kg SOx 0.609 g/kg NOx 2.436 g/kg CO 0.609 g/kg
62 4.4.3.2 Waste Incinerated – Emissions and Energy Requirements for PVC
Table 4.13: Environmental Profile for PVC – Waste Incinerated Energy
32.5MJ/kg
Solid waste
-
Transport
0.2 MJ/kg
Emissions
CO2 1426 g/kg SOx 0.479 g/kg NOx 1.916 g/kg CO 22.979 g/kg
4.4.3.3 Waste Incinerated – Emissions and Energy Requirements for PP
Table 4.14: Environmental Profile for PP – Waste Incinerated Energy
32.5MJ/kg
Solid waste
-
Transport
0.2 MJ/kg
Emissions
CO2 2567 g/kg SOx 1.023 g/kg NOx 4.09 g/kg CO 1.023 g/kg
4.5
Summary – Emissions and Energy Requirements for PET, PVC and PP
In this section, we had summed up and summarized the emissions released and energy required during the entire life cycle of plastic for three types of polymer which were PET, PVC and PP. Table 4.14 summarises the total energy required in MJ and total emissions released for the entire life cycle of 1 kg of the three polymers for different methods of waste disposal.
38 63
Table 4.15: Resources consumed and emissions released for entire life cycle of 1kg of various polymers
Waste Recycled
Waste to Landfill
Waste Incinerated
PET
PVC
PP
PET
PVC
PP
PET
PVC
PP
110.87
74.06
99.9
143.807
124.937
140.037
116.3
97.43
112.53
CO2
2493
2692
2722
2424.597
2424.597
2424.597
4346
3176
4347
SOx
25
13
11
25.848
25.848
25.848
25.609
13.479
12.023
NOx
20.281
15.081
10.081
21.928
21.928
21.928
22.636
16.916
14.09
CO
18.205
2.705
0.905
-
-
-
18.609
25.479
1.723
HCs
40.016
19.016
13.016
2120.609
2120.609
2120.609
-
-
-
6.95
6.95
6.95
-
-
-
-
-
-
Energy (MJ) Emissions (g)
VOCs
CHAPTER V
LIFE CYCLE IMPACT ASSESSMENT
5.1
Introduction
In this section we used the results from the life cycle inventory to assess the potential impacts of these three plastics treated with different disposal methods. The best way of making a comparison of the plastic waste disposal methods from the environmental point of view was to compare and analyse the energy involved and waste emissions released in the entire life cycle of plastic. Next step was to assign the air emissions to the impact of global warming chosen earlier.
5.2
Energy Use
Results for the total energy used are shown in Table 4.15 for PET, PVC and PP with different treatment methods of disposal. The energy required by recycling for polymers involved 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 providing the recycled product is used to substitute virgin polymer. 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. According to Table 4.15, landfilling option
65 required much more energy for the whole cycle of plastics 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 plastic 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.
5.3
Global Warming
Table 5.1 presents the environmental impact for each polymer treated with different treatment 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 various plastics materials are carbon dioxide and methane. Based on the results in Table 5.1, the order of preference is that recycling is better than incineration and landfilling for those various polymers. For PET and PP, the emissions’ contributing to global warming from incineration is rather similar to the emission from landfilling. This is because all the fossil carbon is released during incineration, as well as during landfilling.
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 that of CO2 (McDougall et. al., 2001). This is why the prevention of waste going to landfill is a key measure to reduce the greenhouse gas emissions. Table 5.1: Environmental impact for different treatment methods
Environmental
Waste Recycled
Waste to Landfill
Waste Incinerated
Impact
PET
PVC
PP
PET
PVC
PP
PET
PVC
PP
Global
3.333
3.091
2.995
47.0
47.0
47.0
4.346
3.176
4.347
Warming (kg CO2-eq)
66 5.3.1 Examples 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 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.
5.3.2
Carbon Dioxide (CO2) Carbon dioxide is a colourless gas which, when inhaled at high
concentrations (a dangerous activity because of the associated asphyxiation risk), produces a sour taste in the mouth and a stinging sensation in the nose and throat. These effects result from the gas dissolving in the mucous membranes and saliva, forming a weak solution of carbonic acid.
5.3.3
Methane (CH4) The simplest hydrocarbon, methane, is a gas with a chemical formula of CH4.
Pure methane is odorless, but when used commercially is usually mixed with small quantities of odorants, strongly-smelling sulfur compounds such as ethyl mercaptan to enable the detection of leaks. A principal component of natural gas, methane is a significant fuel. The CH4 emission is caused mainly by anaerobic degradation processes in landfills. Other sources with a minor contribution to the total system are the fuel chains.
67 Methane is not toxic by any route. The immediate health hazard is that it may cause thermal burns. It is flammable and may form mixtures with air that are flammable or explosive. Methane is violently reactive with oxidizers, halogens, and some halogen compounds. Methane is an asphyxiant and may displace oxygen in a workplace atmosphere. Asphyxia may result if the oxygen concentration is reduced to below 18% by displacement. The concentrations at which flammable or explosive mixtures form are much lower than the concentration at which asphyxiation risk is significant.
5.4
Other Impact of Using Plastics on the Environment and Human Health
Plastics are, on the whole, inert, but small quantities of chemicals can be released. Impacts on human health and the environment may occur during their use as a result. Possible exceptions to this include ingesting pieces of plastic.
Compounds that are lost or migrate from plastics during the use of a plastic product include the components of the final plastic such as the residual monomers and additives, and also compounds used in the manufacturing process, for example, chemicals used to initiate polymerisation. Compounds are lost from plastics either because they are not chemically bound to the polymer and are therefore free to migrate, or because during the use of the plastic product, the plastic becomes distorted, worn or weathered. This can lead to the exposure and loss of previously bound compounds. Exposure to sunlight (especially UVB) can degrade plastics. Increased levels of UVB as a result of the depletion of stratospheric ozone could therefore impact on plastics. Stabilisers are already added to most plastics to prevent UV degradation, and it is thought that significant ozone depletion would be necessary before any serious damage to plastics occurs.
It is impossible to predict exactly what will happen when potentially toxic compounds enter the natural world, so it is essential to monitor the fate of such substances. It is possible to measure directly the amounts of chemicals in fresh waters, marine waters, in soils or the air, but it is really the effects of these chemicals
68 on living organisms that are of interest. Thus, the detection of biological effects (such as hormone disruption or behavioural changes) can be used to indicate exposure of organisms to toxic levels of substances in the environment. Such biological effects may also be a warning that permanent or extensive damage to the biota could occur if there is continued exposure to these contaminants.
Many organisms accumulate chemicals in their tissues over long periods; this is called bioaccumulation. As predators eat their prey, they may gain the chemicals that have bioaccumulated in the tissues of that prey and hence the chemical concentration may increase up the food chain; this is called biomagnification. In the past most attention has been focused on the lethal effects of chemicals, but sublethal effects in organisms, such as altered reproductive rate, physiological function or behavioural changes, may be just as important in an ecosystem and may be used to predict more dramatic effects in the future. Sublethal effects may be seen at the molecular level through to the level of the whole ecosystem, and can be measured using ecotoxicological studies.
CHAPTER VI
LIFE CYCLE INTERPRETATION
6.1
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 plastic wastes is a matter of concern, 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 dispose into landfill or incineration without energy recovery.
Since the landfill method has created a great adverse impact to the environment, the continual growth of plastic waste buried in landfill is unacceptable in the long term. The environmental effects of plastic waste, as well as the global warming due to landfill’s emissions as a means of disposal, are leading to an increased need to designing processes with minimal environmental impact.
70 6.2
Process Improvement
Process improvement include the minimization of treating the plastic wastes with landfilling method for reducing the amount of carbon dioxide and methane gases released to the atmosphere. Thus, only treating the plastic waste whereas it cannot be recycled and only can be disposed of as landfill or incinerated. 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 dispose into landfill or incineration without energy recovery. Other efficient method is recovering the energy required to process the new origin plastic by recycling method.
6.2.1
Recycling
Nowadays, people often wonder why we need to recycle. Some may felt that it’s not their job to do so, and some felt 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 Malaysia, has not reach the level to be proud of. There are still plenty of loop holes here and there and it is important to educate them 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. plastic, 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
71 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 reduces pollution because recycling a product creates less pollution than producing a new one. For every ton of plastic recycled, 7 fewer kg (16 lb) of air pollutants are pumped into the atmosphere. Recycling can also reduce pollution by recycling safer products to replace those that pollute. Some countries still use chlorofluorocarbons (CFCs) to manufacture foam products such as cups and plates. Many scientists suspect that CFCs harm the atmosphere’s protective layer of ozone. Using recycled plastic instead for those products eliminates the creation of harmful CFCs.
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 by neighbours to noise and smells, and the hazard of leaks into underground water supplies. The two major ways to reduce the need for new landfills are to generate less initial waste and to recycle products that would normally be considered waste.
Recycling in the short term is not always economically profitable or a breakeven 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.
If we recycled all our recyclable waste materials, think of what a difference we could make in our lives, environment, and our natural resources. In practice though, recycling can be troublesome and expensive. If a company takes the time to think carefully and plan accordingly, then over time, the process and efficiency of recycling will improve and the payback will be enormous.
72 6.2.1.1 Emission Reduction
The use of recycling method also created lesser emission released to the atmosphere. From the studies that we had conducted, it showed that the emissions discharged were the least for treatment using recycling method. In addition to energy recovery, there is also a corresponding saving relevant to CO2 and CH4 emissions released into the atmosphere, since waste replaces other fossil fuels producing greater CO2 and CH4 levels. Besides, 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 that of CO2. This is why the prevention of waste going to landfill is a key measure to reduce the greenhouse gas emissions.
6.2.1.2 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, it would be equivalent to at least 17 million tons of coal. Energy from waste directly saves fossil fuels and makes an important contribution to the reduction of country dependency on foreign imports. Such a contribution is crucial, particularly with the growing country dependency on foreign fossil fuel supply, estimated to reach 70 per cent by 2010 in a business-as-usual scenario. Emission limits from power generation plants ensure that there is a safe environmental background for the use of plastic waste as an alternative fuel.
73 6.2.1.3 Reduction of Global Warming Potential and Improvement of Energy Efficiency from Energy from Waste
Energy from plastic waste reduces overall greenhouse gas emissions by more than 20% when compared with the imported coal which it can replace. For the estimated 17 million tons of imported coal, this 20% reduction would mean an equivalent of around 10 Million tons of CO2 or the equivalent of running over 2 million cars per year. Last but not least, in order to tackle the volume of plastic waste that requires disposal, close attention must be paid to reduce waste at every stage in a product's life; from cradle to grave. The waste management hierarchy prioritizes different measures and techniques for dealing with waste according to their environmental impact.
CHAPTER VII
CONCLUSIONS AND RECOMMENDATIONS
7.1
Conclusions
The aim of the study was to use a life cycle assessment approach to determine whether which waste disposal options will substantially reduce the environmental burdens. Several important observations can now be made.
1) Recycling of plastic products 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 conducting recycling option rather than landfilling option.
3) Quantity of waste emissions released from different disposal options was identified.
4) Recycling is the environmental preferable disposal method while polypropylene (PP) is the most desirable plastic product.
75 7.2
Recommendations
Plastics make a valuable contribution to the way we live, but as a society we need to find ways of using plastics more wisely. The way we make, use and dispose of plastics 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) The potential impact of chemicals leaching from plastics on human health and the environment The use of plastics in food packaging and toys aimed at young children increases the risk of exposure. Risk assessments have been carried out for some, but not all chemicals used in plastics. Where information exists, it suggests that the quantities released during the manufacture and disposal stages of the life cycle are much greater than those lost during the use phase, when humans are likely to be most exposed. This information gap needs to be addressed.
3) Reducing the waste generation As a society, we are generating an increasing amount of waste. As with other materials, more must be done to reduce the amount of plastic waste we produce. There has been a shift towards a ‘disposable’ culture, and the lower cost of plastics may have contributed to this and the associated growth in waste.
4) 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
76 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.
5) Charging for waste Although this practice is still not common in our country, but several recycling centers in Malaysia are already implementing this concept, as a way to encourage more people to recycle. This concept is mainly targeting specifically at those who don’t recycle, and in turn supports those who do. By charging for the waste sent to the recycling centers, this can help to encourage more recycling practices among the public.
6) Introducing more recyclable products By replacing the plastic shopping bags used in supermarkets and food stalls, with recyclable shopping bags; 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 nonrecyclable wastes. With such measures, it is hoped that the public will be more aware of the recyclable items available in the market.
77
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