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Nonwoven bags and other type of bags Life cycle analysis in UK

Nonwoven bags and other type of bags Life cycle analysis in UK

Executive Summary
This study assesses the life cycle environmental impacts of the production, use and
disposal of different carrier bags for the UK in 2006.
In recent years, the relative environmental impacts of lightweight carrier bags and other
options has been debated. By the Spring of 20098 leading supermarkets had halved the
number of single use carrier bags used. However, questions still remain about the
environmental significance of lightweight carrier bags, especially with regard to the wider
debate on global warming.
The report considers only the types of carrier available from UK supermarkets9. It does
not examine personal bags nor carriers given out by other high street retailers. The
report does not consider the introduction of a carrier bag tax, the effects of littering, the
ability and willingness of consumers to change behaviour, any adverse impacts of
degradable polymers in the recycling stream, nor the potential economic impacts on UK
business.
The following types of carrier bag were studied:
• a conventional, lightweight carrier made from high-density polyethylene (HDPE);
• a lightweight HDPE carrier with a prodegradant additive designed to break the
down the plastic into smaller pieces;
• a biodegradable carrier made from a starch-polyester (biopolymer) blend;
• a paper carrier;
• a “bag for life” made from low-density polyethylene (LDPE);
• a heavier more durable bag, often with stiffening inserts made from non woven
polypropylene (PP); and
• a cotton bag.
These types of carrier bag are each designed for a different number of uses. Those
intended to last longer need more resources in their production and are therefore likely to
produce greater environmental impacts if compared on a bag for bag basis. To make the
comparison fair, we considered the impacts from the number of bags required to carrying
one month’s shopping in 2006/07.
We then calculated how many times each different type of carrier would have to be used
to reduce its global warming potential to below that for conventional HDPE carrier bags
where some 40 per cent were reused as bin liners. Finally the carriers were compared for
other impacts: resource depletion, acidification, eutrophication, human toxicity, fresh
water aquatic ecotoxicity, marine aquatic ecotoxicity, terrestrial ecotoxicity and
photochemical oxidation (smog formation).
8 Based on 2006 baseline figures.
9 The study also included a paper carrier bag which are generally not available from UK supermarkets.
The study found that:
• The environmental impact of all types of carrier bag is dominated by resource use
and production stages. Transport, secondary packaging and end-of-life
management generally have a minimal influence on their performance.
• Whatever type of bag is used, the key to reducing the impacts is to reuse it as
many times as possible and where reuse for shopping is not practicable, other
reuse, e.g. to replace bin liners, is beneficial.
• The reuse of conventional HDPE and other lightweight carrier bags for shopping
and/or as bin-liners is pivotal to their environmental performance and reuse as bin
liners produces greater benefits than recycling bags.
• Starch-polyester blend bags have a higher global warming potential and abiotic
depletion than conventional polymer bags, due both to the increased weight of
material in a bag and higher material production impacts.
• The paper, LDPE, non-woven PP and cotton bags should be reused at least 3, 4,
11 and 131 times respectively to ensure that they have lower global warming
potential than conventional HDPE carrier bags that are not reused. The number of
times each would have to be reused when different proportions of conventional
(HDPE) carrier bags are reused are shown in the table below.
• Recycling or composting generally produce only a small reduction in global
warming potential and abiotic depletion.
Type of carrier HDPE bag (No
secondary reuse)
HDPE bag
(40.3% reused as
bin liners)
HDPE bag (100%
reused as bin
liners)
HDPE bag
(Used 3 times)
Paper bag 3 4 7 9
LDPE bag 4 5 9 12
Non-woven PP
bag 11 14 26 33
Cotton bag 131 173 327 393
The amount of primary use required to take reusable bags below the global
warming potential of HDPE bags with and without secondary reuse
Contents
CONTENTS ......................................................................................................................6
Abbreviations ................................................................................................................10
1 INTRODUCTION.......................................................................................................11
1.1 Project background..............................................................................................11
1.2 The different types of carrier bags .....................................................................11
1.2.1 Supermarket carrier bags studied ....................................................................12
1.2.2 Other options....................................................................................................13
2 GOAL DEFINITION...................................................................................................15
2.1 Goal of the study..................................................................................................15
2.2 Critical review .......................................................................................................16
2.3 Use of the study and target audience.................................................................16
3 SCOPE......................................................................................................................17
3.1 Function of the product system and functional unit.........................................17
3.2 Reference flow......................................................................................................17
3.3 System boundaries ..............................................................................................18
3.3.1 Excluded processes and cut-off criteria............................................................21
3.4 Allocation and system expansion.......................................................................22
3.5 Data requirements and data quality ....................................................................23
3.5.1 Data requirements............................................................................................23
3.5.2 Data quality ......................................................................................................23
3.6 Modelling and calculation of inventories and impacts .....................................24
3.7 Impact assessment ..............................................................................................24
3.8 Sensitivity analysis ..............................................................................................25
3.9 Reporting ..............................................................................................................25
4 INVENTORY ANALYSIS...........................................................................................26
4.1 Extraction/production of raw materials..............................................................26
4.2 Bag production processes ..................................................................................27
4.3 Transport...............................................................................................................28
4.4 Reuse, recycling & end-of-life .............................................................................30
5 IMPACT ASSESSMENT ...........................................................................................32
5.1 Global warming potential.....................................................................................33
5.2 Other impact categories ......................................................................................35
6 SENSITIVITY ANALYSIS..........................................................................................46
6.1 Secondary use of lightweight bags ....................................................................46
6.2 An increase in recycling and composting at end-of-life ...................................48
6.3 Changing the impact assessment method employed.......................................51
7 DISCUSSION............................................................................................................53
7.1 Comparison with other studies...........................................................................53
7.2 Discussion of results ...........................................................................................55
8 CONCLUSIONS........................................................................................................59
8.1 Conclusions related to individual carrier bags..................................................59
8.2 General conclusions ............................................................................................60
9 REFERENCES..........................................................................................................62
ANNEX A - A SUMMARY OF SELECTED LIFE CYCLE ASSESSMENTS OF CARRIER
BAGS..............................................................................................................................62
ANNEX B - A STUDY OF CARRIER BAG WEIGHT, VOLUME AND ITEM CAPACITY 77
ANNEX C - DESCRIPTION OF INVENTORY DATA.......................................................85
ANNEX D - DESCRIPTION OF IMPACT CATEGORIES..............................................102
ANNEX E – PEER REVIEW COMMENTS....................................................................105
Abbreviations
BRC British Retail Consortium
DEFRA Department for the Environment, Food and Rural Affairs
GWP Global Warming Potential
HDPE High density polyethylene
IPCC Intergovernmental Panel on Climate Change
ISO International Organization for Standardization
LCA Life cycle assessment
LCI Life cycle inventory
LCIA Life cycle impact assessment
LDPE Low density polyethylene
LLDPE Linear low density polyethylene
PA Polyamide
PE Polyethylene
PET Polyethylene terephthalate
PLA Polylactic Acid
PP Polypropylene
PVC Polyvinyl chloride
EfW Energy from Waste
WRAP Waste and Resources Action Programme
WRATE Waste and Resources Assessment Tool for the Environment
1 Introduction
1.1 Project background
This study was commissioned by the Environment Agency and assesses the life cycle
environmental impacts of the production, use and disposal of different carrier bags for
the UK in 2006.
In 2008, approximately 10 billion lightweight carrier bags were given away in the UK
which equates to around 10 bags a week per household (DEFRA 2009). In recent years,
a debate about the relative environmental impacts of these lightweight carrier bags and
their alternatives has emerged. This debate has arisen due to a combination of public,
media and legislative pressure to reduce the environmental and social impacts of food
packaging. In response the UK government, the British Retail Consortium (BRC) and
leading supermarkets agreed to cut the number of single use carrier bags used by 50%
by the spring of 2009 based on 2006 baseline figures. In July 2009, the Waste and
Resources Action Programme (WRAP) announced that this initiative had achieved a
reduction of 48% across the UK (WRAP 2009). However, lightweight carrier bags are still
seen as an important media and legislative issue and questions still remain on their
environmental significance, especially to the wider debate on global warming.
Life Cycle Assessment (LCA) is a standard method for comparing the environmental
impacts of providing, using and disposing of a product or providing a service throughout
its life cycle (ISO 2006). In other words, LCA identifies the material and energy usage,
emissions and waste flows of a product, process or service over its entire life cycle to
determine its environmental performance.
Previous studies in several countries have looked at the environmental impacts of
different carrier bag options. Their findings are interesting but are not directly applicable
to the UK because of their geographical coverage and the assumptions made about the
use and disposal of carrier bags by consumers.
This report considers only carriers available from UK supermarkets. It does not examine
personal bags nor carriers given out by other high street retailers. The report does not
consider the consequences of introducing a carrier bag tax, the effects of littering, the
ability to and willingness of consumers to change behaviour, any adverse impacts of
degradable polymers in the recycling stream, nor the potential economic impacts on UK
industry.
New types of bags have been introduced since the data was collected for this study and
these may have different environmental performance.
1.2 The different types of carrier bags
11 Environment Agency Lifecycle assessment of supermarket carrier bags available in 2006
The main function of a carrier bag is to carry groceries and goods from the shop to the
home. The bag therefore needs to be robust enough to hold a certain quantity of
shopping, but at the same time provide a convenient option for the consumer to carry or
transport the shopping home. The scope and findings of recent LCA studies of carrier
bags are summarised in Annex A.
1.2.1 Supermarket carrier bags studied
Supermarket carrier bags used in the UK have generally been categorised as disposable
(i.e. single use) or reusable. However, these descriptions are increasingly becoming
blurred as ‘disposable’ plastic carrier bags are now encouraged to be reused both as
carrier bags (primary reuse) and also to replace other products such as bin liners
(secondary reuse).
Most UK supermarkets offer several types of carrier bag, generally including a
conventional, lightweight, HDPE9 carrier bag (often termed disposable) and a heavy duty
LDPE10 plastic bag often referred to as a ‘bag for life’. These carrier bags vary in terms of
weight, capacity and recycled content. Supermarkets now also offer other, more durable,
carrier bags, generally made from woven, natural fibres, such as hemp or cotton. Carrier
bags recorded as being used in the main UK supermarkets and included in this study are
shown in Table 1.1 and are described below. Several of these were not available in UK
supermarkets during the reference period of the study but were included because of their
potential future use.
Conventional High-density polyethylene (HDPE) bags
This is the lightweight, plastic, carrier bag used in almost all UK supermarkets and often
provided free of charge. It is a vest-shaped bag and has the advantage of being thingauged
and lightweight. It has been termed “disposable” and “single use”
High-density polyethylene (HDPE) bags with a prodegradant additive
This type of lightweight, plastic, carrier bag is made from HDPE with a prodegradant
additive that accelerates the degradation process. These polymers undergo accelerated
oxidative degradation initiated by natural daylight, heat and/or mechanical stress, and
embrittle in the environment and erode under the influence of weathering. The bag looks
like the conventional HDPE bag being vest-shaped and thin-gauged.
Low-density polyethylene (LDPE) bags
These are thick-gauged or heavy duty plastic bags, commonly known as ‘bags-for-life’,
and are available in most UK supermarkets. The initial bag must be purchased from the
retailer but can be replaced free of charge when returned. The old bags are recycled by
the retailer.
Non-woven polypropylene (PP) bags
This type of bag is made from spunbonded non-woven polypropylene. The non-woven
PP bag is stronger and more durable than a bag for life and is intended to be reused
many times. To provide stability to the base of the bag, the bag comes with a semi-rigid
insert.
Cotton bags
This type of bag is woven from cotton, often calico, an unbleached cotton with less
processing, and is designed to be reused many times.
9 HDPE is high density polyethylene.
12 Environment Agency Lifecycle assessment of supermarket carrier bags available in 2006
10 LDPE is low density polyethylene.
Table 1.1 Carrier bag types used in UK supermarkets included in this study.
Bag type Picture example Weight*
[g]
Volume capacity*
[litres]
Conventional HDPE bag
7.5 – 12.6 17.9 – 21.8
HDPE with prodegradant additive
5.9 – 8.2 16 – 19.6
Heavy duty LDPE bag (‘bag for
life’)
27.5 – 42.5 19.1 – 23.9
Non-woven PP bag
107.6 - 124.1 17.7 – 21.8
Paper bag
55.2 20.1
Biopolymer bag
15.8 18.3
Cotton bag 78.7 – 229.1 17 – 33.4
* Some supermarkets have supplied data, others are based on measurements by the authors (see annex B).
Paper bags
These are generally no longer used in UK supermarkets, although they are available
from other retail shops. The paper bag was in effect the first “disposable” carrier bag, but
was superseded in the 1970s by plastic carrier bags which were seen as the perfect
alternative, as they did not tear when wet.
Biopolymer bags
Biopolymer carrier bags are a relatively recent development. They are only available in a
few UK supermarkets. The biopolymers are usually composed of either polylactic acid
(PLA), made from the polymerisation of lactic acids derived from plant-based starch, or
starch polyester blends, which combine starch made from renewable sources such as
corn, potato, tapioca or wheat with polyesters manufactured from hydrocarbons (Murphy
et al 2008). These biodegradable polymers decompose to carbon dioxide, methane,
water, inorganic compounds or biomass (Nolan-ITU 2003).
1.2.2 Other options
13 Environment Agency Lifecycle assessment of supermarket carrier bags available in 2006
There are several other types of carrier, none of which have been considered in this
study. These include woven polypropylene bags, jute or hemp bags and plastic boxes.
Figure 1.1 below shows some examples.
Figure 1.1 Examples of a vacuum formed box, a woven PP bag, a hemp bag, and
a jute bag.
Polypropylene (PP) vacuum formed boxes
An alternative to the carrier bag is a rigid box made from vacuum formed polypropylene
with separate detachable rigid handles. This is used by one supermarket in store but by
many for home deliveries. It is intended to be reused many times.
Woven polypropylene (PP) bags
This type of bag is produced from woven polypropylene “fibres”. Similarly to the nonwoven
PP and LDPE bags, it is strong and durable and intended to be reused many
times. To provide stability to the base of the bag, the bag comes with a semi-rigid insert.
Jute bags
Jute bags are made from jute fibres spun into coarse strong strands making a strong and
durable carrier bag. The jute bag is intended to be reused many times.
14 Environment Agency Lifecycle assessment of supermarket carrier bags available in 2006
2 Goal definition
The international standard on lifecycle assessment ISO 14040 (ISO 2006) requires that
the goal of an LCA study states the intended application, the reasons for carrying out the
study, the intended audience, and whether the results are intended to be used in
comparative assertions intended to be disclosed to the public.
2.1 Goal of the study
The goal of this study is to assess the potential life cycle environmental impacts of
various current and potential supermarket carrier bags in the UK.
The goal of the study has been split into the following objectives:
• To compile a detailed life cycle inventory of the environmental burdens associated
with the production, use and disposal of lightweight plastic carrier bags and three
to five other options;
• To use the life cycle inventory data to compare the environmental impacts arising
from lightweight plastic carrier bags and the alternatives under the various
scenarios considered; and
• To compare the results of this study with other key life cycle studies in this area
and identify the main reasons for any significant differences.
The types of carrier bag studied were agreed by the project board, based partly on the
market representation in supermarkets, and partly on new materials that were receiving
increased attention. A carrier bag is defined in this study as a bag with a capacity of over
15 litres, that could be used at a supermarket checkout. Therefore, this does not include
other bags available in supermarkets such as ‘deli’ bags.
The following types of carrier bag were studied:
• conventional high-density polyethylene (HDPE);
• high-density polyethylene (HDPE) with a prodegradant additive;
• starch-polyester (biopolymer) blend;
• paper;
• low-density polyethylene (LDPE);
• non woven polypropylene (PP); and
• cotton.
15 Environment Agency Lifecycle assessment of supermarket carrier bags available in 2006
2.2 Critical review
The study has been critically reviewed in accordance with ISO 14040. The review panel
consisted of:
• Mark Goedkoop (chairman), PRé Consultants, Amersfoort, the Netherlands.
• Keith Elstob (co-reviewer), Bunzl Retail, Manchester.
• Jane Bickerstaffe (co-reviewer), INCPEN, Reading.
The chairman of the review panel has been involved in the project from the start by
reviewing and commenting on the goal and scope. The co-reviewers were involved at the
end of the project. The panel’s report as well as the consultants’ responses to the
reviewers’ comments are included in Annex E.
In addition to the critical review, the project was also followed by a Project Advisory
Board and a Stakeholder Consultation Group. Membership of both groups was by
invitation. The members of the board and the stakeholder group were kept informed about the
project at regular intervals and were invited to comment and provide information.
2.3 Use of the study and target audience
The results of this life cycle study are intended to provide an independent, unbiased,
objective assessment of the environmental impacts of various carrier bags. It should
provide evidence for government and supermarkets in devising policies to reduce the
environmental impacts of carrier bags. The study also provides a potential baseline to
measure the degree of success by supermarkets in reducing the environmental impacts
of supermarket carriers.
The target audience for the report is:
• Interested parties such as supermarkets and other retailers, environmental
organisations, consumer organisations as well as consumers themselves.
• Public authorities, in particular the Department for Environment, Food and Rural
Affairs (DEFRA) responsible for national, environmental policy in England, the
Welsh Assembly Government (WAG) who have parallel responsibilities for Wales
and WRAP, the Waste and Resources Action Programme.
16 Environment Agency Lifecycle assessment of supermarket carrier bags available in 2006
3 Scope
3.1 Function of the product system and functional unit
A comparison of life cycle environmental impacts should be based on a comparable
function (or ‘functional unit’) to allow a fair comparison of the results. The carrier bags
studied are of different volumes, weights and qualities. The Environment Agency
commissioned a survey11 which found that, over a 4 weeks period, supermarket
shoppers purchased an average of 446 items. The functional unit has therefore been
defined as:
Carrying one month’s shopping (483 items) from the supermarket to the home in
the UK in 2006/07.
3.2 Reference flow
The reference flow is the number of carrier bags required to fulfil the functional unit (as
described in section 3.1). This depends on the volume of the bag, its strength and
consumer behaviour when filling and using the bags. Consumer behaviour determines
how many items are put into each bag, the number of times a bag is reused (primary
reuse), whether the bag is subsequently used to perform an alternative function
(secondary reuse), and in part the way they are managed as waste.
The primary12 reuse of carrier bags was excluded from the reference flow due to a lack
of independent data available on the reuse of each type of bag. However, as several
types are designed to be reused, we have calculated the primary reuse required to
reduce the global warming potential of each reusable bag to below that of the
conventional, lightweight HDPE bag The inclusion of primary reuse is detailed in section
.7
9.1 litres and the average volume of a “bag for life” (LDPE) carrier bag was 21.5 litres.
the
major supermarkets co-operated with the survey which showed that shoppers put an
3
The number of bags required to carry one month’s shopping (483 items) depends
whether weight or volume is the limiting factor in carrier bag use, Pira International
compared the volume and weight capacity of several carrier bags (detailed in Annex B).
We found that the weight capacity of the bags studied was 18 to 19 kg., which is more
than an average person can carry. Therefore, volume was selected as the limiting factor
for bag use. The average volume of a conventional lightweight (HDPE) carrier bag was
1
The consumer survey commissioned by the Environment Agency13 provided data on the
number of items purchased and the number of bags required to carry those items. All
11 Based on a 2007 survey by TNS Market Research specialists
12 Primary reuse in this study means reuse for the original purpose – to carry shopping from the
supermarkrt to the home. This is distinct from secondary reuse which here meansd reuse to replace
another product, e.g. a bin liner.
17 Environment Agency Lifecycle assessment of supermarket carrier bags available in 2006
13 ibid
average 5.88 items in the conventional HDPE carrier bag and an average 7.96 items into
the heavy duty LDPE carrier bag
The average weight, volume and item capacity for each carrier bag type included in this
study was then calculated. The material weights of the HDPE prodegradant and starchpolyester
bags were adjusted pro-rata to match the average volume of the conventional
lightweight HDPE bag (19.1 litres carrying 5.88 items). For the paper, LDPE, non-woven
PP and cotton bags, the item capacities were adjusted according to their volumes.
These revised bag capacities were then used to calculate the reference flow14 for each
type of bag as shown in table 3.1. The initial reference flows shown do not include any
primary reuse of carrier bags.
Table 3.1 The assumed volume, weight, items per bag and required reference
flow for each carrier bag (excluding primary reuse).
Supermarket policies and consumer behaviour have changed since the reference period
(2006/07) but there is no evidence to suggest the capacities of HDPE and LDPE bags
have changed significantly. However, while data used for starch polyester blend bags
were provided by the manufacturer, since the reference period the weight of some of
these bags may have been reduced and the effect of this is discussed in section 7.2
3.3 System boundaries
The study is a ‘cradle to grave’ life cycle assessment. Therefore, the carrier bag systems
investigated include all significant life cycle stages from raw material extraction, through
manufacture, distribution use and reuse to the final management of the carrier bag as
waste. The system boundaries are defined so that all inputs and outputs from the system
14 The reference flow is the number of each type of bag required to fulfil the functional unit (483 items of
shopping in one month).
18 Environment Agency Lifecycle assessment of supermarket carrier bags available in 2006
Bag type Volume per
bag (litres)
Weight per
bag (g)
Items
per bag
Refflow –
No. bags
Conventional high-density polyethylene
(HDPE) bag 19.1 8.12 5.88 82.14
High-density polyethylene (HDPE) bag
with a prodegradant additive 19.1 8.27 5.88 82.14
Starch-polyester blend bag 19.1 16.49 5.88 82.14
Paper bag 20.1 55.20 7.43 64.98
Low-density polyethylene (LDPE) bag 21.52 34.94 7.96 60.68
Non-woven polypropylene (PP) bag 19.75 115.83 7.30 66.13
Cotton bag 28.65 183.11 10.59 45.59
are either elemental flows15 or materials or energy entering another product life cycle
through recycling or energy recovery respectively. Therefore, the study quantifies all
energy and materials used, traced back to the extraction of resources, and the emissions
from each life cycle stage, including waste management. Recycled content and recycling
and composting at end-of-life were excluded from the system boundaries. This was due
to the large proportion of bags that contained no recycled content and the wide variation
in the amount of bag recycling and composting. The recycled content in carrier bags has
increased since the reference period and therefore the results of this study may be worse
than the current practice. The inclusion of recycling and composting at end-of-life is
considered during the sensitivity analysis. Figure 3.1 shows a simple flow diagram which
defines the system boundaries for the study.
Extraction/
cultivation and
production of raw
materials
Transport
(Lorry, freight ship,
rail etc)
Carrier bag
production
Excluded process/
material
Key
Recycling & End-of-life
avoided products
Extraction/
production of raw
materials
Transport
(Lorry, freight ship,
rail etc)
Extraction/
cultivation and
production of
secondary
packaging materials
Carrier bag
importer
Transport
(Lorry, freight ship,
rail etc)
Supermarket
Transport
(Consumer vehicle)
Consumer
primary reuse
Transport
(Consumer vehicle)
Consumer
secondary reuse
Avoided use and
production of bin
liners
Transport
(Municipal waste
collection)
Recycling of
secondary
packaging
(with avoided
production of
cardboard)
Waste depot
Landfill
(with avoided
production of natural
gas)
Incineration
(with avoided
production of heat
and power)
Recycling
(with avoided
production of primary
material)
Composting
(with avoided
production of
industrial fertiliser)
Production Transport
processes
Resource use
(e.g. crude oil)
Water use
Emissions
to air
Discharges
to water
and soil
Radiation
System boundary
Only included in
sensitivity analysis
Figure 3.1 System boundaries applied in this study (simplified flow diagram).
The study includes the following life cycle stages:
Extraction/production of raw materials
The extraction of resources, as well as any forestry, agriculture and the processing of
resources to produce materials such as HDPE, LDPE, PP, paper, cotton and starchpolyester
blend included in the study. The study covers material and energy resources,
emissions and waste. Where production data were not available, flows were estimated
from similar products.
Packaging
Primary packaging is included. Some secondary packaging (used for the distribution of
the bags from the importer to the supermarket distribution centre) has been excluded
due to consignments generally being a mix of different supplies depending on the needs
of the supermarket. Pallets have also been excluded due to lack of precise data about
19 Environment Agency Lifecycle assessment of supermarket carrier bags available in 2006
15 An elemental flow is material or energy entering the system being studied that has been drawn from the
environment without previous human transformation, or material or energy leaving the system being
studied that is released into the environment without subsequent human transformation (ISO 14040).
their material and reuse rates. However, due to their high reuse, this is not considered to
have any significant effect on the results.
Bag production processes
The conversion of the raw materials into carrier bags is included in the study.
Transport
The transport of materials from their producer to the carrier bag manufacturer, and the
distribution of the finished carrier bag from the manufacturer to the importer and then to
supermarket is included. Transportation by a municipal waste collection vehicle to a
waste management facility has also been included.
End-of-life
The management of wastes is included in the study. The choice of end-of-life process
reflects the realistic options for each type of bag. The options considered for each bag
are shown in table 3.2. Recycling and composting are considered in the sensitivity
analysis. The recycling of cotton bags has not been included as no evidence was found
to support this. The recycling of HDPE bags with a prodegradant additive has also been
excluded due to their negative impact on the quality of recycled HDPE.
Table 3.2 End-of-life processes considered for the different carrier bags
investigated.
Bag type Landfill Incineration Mechanical
recycling Composting
Conventional high-density polyethylene
(HDPE) bag

01 Ağustos 2019