ETH Library
End-of-life and waste management
in life cycle assessment - Zurich, 6
December 2011
Other Journal Item
Author(s):
Saner, Dominik; Walser, Tobias ; Vadenbo, Carl O.
Publication date:
2012
Permanent link:
https://doi.org/10.3929/ethz-b-000423090
Rights / license:
In Copyright - Non-Commercial Use Permitted
Originally published in:
The International Journal of Life Cycle Assessment 17(4), https://doi.org/10.1007/s11367-012-0390-2
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CONFERENCE REPORT: 46TH DISCUSSION FORUM ON LCA
End-of-life and waste management in life cycle
assessment—Zurich, 6 December 2011
Dominik Saner & Tobias Walser & Carl O. Vadenbo
Received: 27 January 2012 / Accepted: 10 February 2012 / Published online: 24 February 2012
#
Springer-Verlag 2012
Abstract
Introduction Waste management is a key component in
society's strategy to mitigate the adverse effects of its eco-
nomic activities. Through its comprehensive system ap-
proach, life cycle assessment (LCA) is frequ ently put
forward as a powerful tool for the assessment of waste
management activities. Howe ver, many methodological
challenges regarding the environmental assessment of waste
treatment systems still remain, and conse nsus is still far
from being reached in areas like the definition of (temporal)
system boundaries, life cycle inventory generation, selection
and use of environmental indicators, and interpretation and
communication of the LCA results.
Summary of the topics presented in DF-46 The 46th Swiss
Discussion Forum on Life Cycle Assessment (DF-46) con-
sisted of three sessions. The first session tried to address
policy making and implications for sustainable waste man-
agement of consumer products, e.g., information and commu-
nication technology, and food packaging. The second session
focused on recent methodological developments in LCA for
end-of-life treatment (EoL) activities and waste management
assessment. The third session was dedicated to E-waste treat-
ment and scarce metal recovery processes. DF-46 closed with
short presentations on decision support in the areas of copro-
cessing, food waste, and after-treatment technologies for mu-
nicipal waste incineration residues.
Conclusions The main conclusions drawn from DF-46 are:
(a) the option of waste prevention, despite its prominent
position in the so-called waste hierarchy, is rarely consid-
ered in LCAs on waste and EoL management, (b) although a
general problem in many other applications of LCA, the
differences in scope definitions and time perspectives, the
use of proxies or data of poor quality, allocation, or system
expansion procedures, and weighting in the impact assess-
ment a re prominent issues in LCAs of waste and EoL
management and thus have to be minimized and inventory
data must be as transparent as possible, (c) life cycle inven-
tory formats have to be adapted to be able to account for new
materials, such as nanoparticles and scarce metals in LCA, (d)
the selection of environmental indicators requires clear guid-
ance on their appropriate use and open communication. The
selection of a set of complementary indicators is of particular
importance in order to avoid that the adverse effects on the
environment are merely shifted between impact categories,
and (e) useful LCA tools for the environmental assessment of
waste management options are currently developed to meet
the evolving demands and expectations for support in decision
making related to waste and EoL management today and in
the future. The presentations from DF-46 are available for
download (www.lcaforum.ch).
Keywords Emerging contaminants
.
E-waste
.
Optimization
.
Waste management
.
Waste policies
1 Introduction
With no vel emerging products and materials, established
waste management systems are continuously presented with
new challe nges to protect humans an d the environment.
Several studies (Ekvall et al. 2007; Riber et al. 2008) have
suggested that life cycle assessment (LCA) is a suitable
decision support method for the assessment of waste
D. Saner (*)
:
T. Walser
:
C. O. Vadenbo
Group for Ecological Systems Design,
Institute of Environmental Engineering, ETH Zurich,
Schafmattstrasse 6,
8093 Zurich, Switzerland
e-mail: dominik.saner@ifu.baug.ethz.ch
Int J Life Cycle Assess (2012) 17:504–510
DOI 10.1007/s11367-012-0390-2
management activities. However, many unsolved methodo-
logical and data quality issues impede extensive application
of LCA to end-of-life (EoL) and waste management. Pro-
viding a suitable platform for the discussion of such chal-
lenges, the 46th Swiss Discussion Forum on LCA (DF-46)
was held at ETH Zurich (Switzerland) on 6 December 2011.
The goal of the discussion forum was, on one hand, to
elucidate some of the latest methodological developments
in LCA and novel practical applications related to EoL, and
on the other hand, to discuss strategies for strengthening the
position of LCA as a decision support tool in waste man-
agement and waste-related policy making.
2 Policies and implications for end-of-life in LCA
The first session of the day was focused on general issues in
LCA related to the assessment of waste treatment options
and the implications for waste-related policy making. Wol-
fram Scharnhorst (Sustainable | Water | Management, Swit-
zerland) presented an analysis of the drivers for sustainable
EoL treatment in the telecommunication indus try and in the
building and construction sector. As GSM (2G) and UMTS
(3G) networks in Europe are to be replaced durin g the
period 2012–2016, the telecommunication industry will face
large amount of EoL equipment requiring treatment. The
limited availabil ity of some of the materials used in tele-
communication equipment and the concern regarding the
treatment procedures in emerging economies were men-
tioned as two prominent environmental aspects which influ-
ence the EoL treatment. Additional incentives for recycling
and material recovery are created by the rising raw material
prices on the world market and the geopolitical instability in
some of the regions outside Europe where the primary
resources are found. Hence, the European telecommunica-
tion industry has a unique opportunity to strengthen its
position and to adapt sustainable EoL treatments. The situ-
ation in the European building and construction industry, on
the other hand, is different: Although a w ide range of
building standards and norms exist to facilitate sustainable
construction, these aspects were often considered as an add-
on rather than an integral part of everyday practice in the
past. The fragmented interests and sharp division of stake-
holders, e.g. , between awa rding authority, investor, co n-
structor, owner, and tenant, were sug gested as key
obstacles for progress towards sustainability in the industry.
Even though the gap between research and practice has
resulted in numerous “lighthouse” projects, large-scale im-
plementation is still lacking. Hence, the major challenge is
to facilitate the implementation of interdisciplinary thinking
into the strong and well-established engineering thinking in
the industry. The necessity to sensitize the stakeholders for
sustainability issues and the creation of incentives were
identified as key challenges for the future to achieve more
sustainable EoL treatment in the building and construction
industry.
Laurence Hamon (Quantis, France) presented an over-
view of LCAs of alternative waste treatments, i.e., studies
with “gate-to-grave” system boundaries. It was noted that
the option of waste prevention is rarely considered in these
studies because the functional unit is commonly defined as a
certain amount of waste to b e treated. Hence, the assess-
ments of waste treatment options are frequently influenced
by the perspective chosen and the assumptions made regard-
ing energy and material recovery. In particular, the assump-
tion of avoided production systems and the choice between
a marginal and an average perspective in the assessment
proved crucial for the recommendations in various waste
management studies. Two issues related to carbon and car-
bon emission in waste treatments were highlighted in the
presentation: First, the release of bioge nic carbon in the
form of carbon dioxide is commonly not assigned to any
global warming potential, whereas methane with biogenic
carbon is treated as methane emission with fossil origin.
Recent guidelines for life cycle impact assessment, howev-
er, recommend that these emissions are considered separate-
ly (JRC 2010). The second issue dealt with the temporary or
permanent storage of carbon in soils and landfill. It was
stated that a consensus exists for inte grating this aspect in
the assessment but that stored carbon should be reported
separately. A potential solution might be offered by dynamic
LCA where the time of release of environmental exchanges
is included. This discussion was followed by an illustrative
case study in which three treatment options for 1 million
tons of alcohol-containing grape pomace in Fra nce were
assessed. The treatment options were distillation, compost-
ing, and land spreading. With respect to impacts on climate
change, the option of distillation offers the largest net ben-
efit due to the avoided burdens of the substituted product
systems, followed by composting which showed a small net
benefit, and direct land spreading which resulted in a small
net burden. With respect to other impact categories, the
general trend was similar. However, several implications
of the results were highlighted:
& The result for the distillation process could be further
improved by replacing fossil energy carriers consumed
in the process with bio-based alternatives.
& For this study, four distilleries were included. Among
the 50 distilleries operating in France, the recovery of
the various coproducts of the distillation process varies
which makes general conclusions on the net benefi ts of
distillation as waste treatment option for grape pomace
uncertain.
& The data quality and assumptions with regard to substi-
tuted products and the related avoided impact from
Int J Life Cycle Assess (2012) 17:504–510 505
alternative production systems are essential for assess-
ments of waste treatment options with energy or material
recovery.
In the presented study, characterization of the potent ial
benefits of compost or land spreading on soil properties was
lacking. Hence, the full effects of these treatment options
were not captured in the assessment. However, it is impor-
tant to take the regional conditions into account, as agricul-
tural soils in some regions might already be overloaded with
nutrients.
Nina Cleeve -Edwards (Nestlé Research Centre, Switzerland)
gave an overview of how LCA is used at Nestlé to
assess alternative EoL options for packaging. Packaging
provides the consumer with the first impression of foodstuff
and beverages and often remains after the consumption. From
a consumer perspective, packaging waste is a big concern and
recyclable materials are perceived as very positive although
studies have shown that recyclable packaging solutions do not
always result in the lowest environmental burden in com-
parison to disposable options (Humbert et al. 2009). In
addition, high recycling rates might come at the expense
of high energy requirements for collection and sorting.
In order to increase recycling rates, innovative approaches and
collaborations and technological solutions for recycling are
needed in conjunction with consumer education and policy
incentives. An example from Singapore illustrated how mo-
bile phone applications can be used to provide packaging
sorting advice by scanning the barcode on the product and
reading in GPS coordinates of the user in order to find a nearby
collection point.
Two major challenges in LCA of EoL packaging were
highlighted: First, a set of allocation rules for recycling
which is accepted by all stakeholders is missing (The
Consumer Goods Forum 2011). The solution of Nestlé is
therefore the use of a 50:50 allocation rule if there is no
generally accepted guidance available. The second challenge
concerns the availability and application of EoL packaging
statistics, for which three issues were highlighted: Firstly,
there is no uniform database for collecting statistics on EoL
packaging. Secondly, waste statistics are reported and pre-
sented with different geographic boundaries, e.g., on either
state- or country-level. Furthermore, waste statistics typically
do not encompass the large informal waste sectors in devel-
oping countries. It was concluded that in order to reduce
environmental impacts of packaging in the EoL phase, the
following approaches, which have proven to be successful,
should be adopted:
& Identify available recovery options with the lowest en-
vironmental impact
& Design recoverable packaging
& Communicate and support programs to encourage
consumers
To assist an environmentally sound decision making, we
need to ensure that the LCA data and methodology for the
EoL phase are reliable, transparent, and widely accepted.
The first session ended with a study of EoL options for
two biodegradable packaging materials, presented by Vin-
cent Rossi (Quantis, Switzerland). The Waste Framework
Directive of the Eur opean Uni on (EU) prescribes that waste
legislation and policy of the EU Member States shall apply a
priority order where prevention of waste represents the most
desirable measure followed by preparation for reuse, recy-
cling, o ther recovery, and finally d isposa l of waste (EC
2008). However, when applying the waste hierarchy, “Mem-
ber States shall take measures to encourage the options that
deliver the best overall environmental outcome. This may
require specific waste streams departing from the hierarchy
where this is justified by life-cycle thinking on the overall
impacts of the generation and manag ement of such waste”
(EC 2008). Public perception of the different waste treat-
ments coincides well with the relative position of the treat-
ments in the waste hierarchy. The relevance of the waste
hierarchy's priority order to two biodegradable plastics,
polylactic acid (PLA), and thermoplastic starch (TPS) was
investigated in a case study which covered the following
EoL treatment options:
& Municipal solid waste incineration (MSWI ) with energy
recovery
& Landfill
& Direct fuel substitution
& Mechanical recycling
& Industrial composting
& Anaerobic digestion
The results indicated that industrial compo sting of both
PLA and TPS results in high impacts in comparison to the
other treatment options, both with respect to contribution to
global warming and resource depletion. This is mainly due
to the relatively small credits awarded to this treatment
option based on avoided burden from material and energy
recovery. For the disposal in landfill, the impact with respect
to global warming for PLA was relativel y low due to its low
degradability, whereas high degradability of TPS and con-
sequently large amounts of methane emitted resulted in high
impacts. Based on the case study results, it was concluded
that contrary
to public perception, composting is not neces-
sarily the best alternative for EoL of biodegradable plastics.
The results hence support a flexible applicati on of the waste
hierarchy.
3 Recent developments in scientific research
The second session of the DF-46 was focused on methodo-
logical development s in LCA relate d to EoL and waste
506 Int J Life Cycle Assess (2012) 17:504–510
management decision support. Gabor Doka (Doka LCA,
Switzerland) presented how waste treatment activities are
handled in ecoinvent v3, the upcoming version of the ecoin-
vent database. In the current version 2.2 of ecoinvent, the
creator of a life cycle inventory (LCI) of a waste-producing
activity predetermines the type of disposal process by
choosing a certain disposal dataset for a specific waste
material (e.g., disposal, paper, 11.2% water, to municipal
incineration). This concept is omitted in ecoinvent v3 and
the waste material is separated from the waste treatment
activity, i.e., a waste material automatically enters a treat-
ment market appropriate for the geographic location and the
temporal setting of the waste-producing activity. The treat-
ment activities available in a specific market are determined
by the so-called database service layer of ecoinvent. If the
author wishes, there is still the possibility to define a hard
link between waste material and waste treatment activity.
But in general, the author of an LCI dataset is relieved of the
decision of how a certain waste material is treated, i.e.,
energy recovery, recycling, or final disposal. H ence, the
dataset author does not even have to judge if an output
material is a waste or a valuable by-product. It is just an
intermediate exchange, leaving the activity to a market. The
second new concept in ecoinvent v3 is that any activity can
take up an output material and thereby become a treatment
activity competing in a treatment market. There is no clear
distinction anymore between disposal process and recycling
process. As a third new feature, EoL t reatment activity
datasets can be parameterized. It is possible to enter param-
eters, e.g., gross efficiency of heat recovery, and mathemat-
ical relations directly into the w aste treatment dat asets.
In t er m ed ia t e ex c ha ng e s (i.e., waste material and by-
product) can be enhanced with proper ties (e.g., chemical
composition, heating value, degradability, binning type,
and collection type). The new concepts allow for more
flexibility and higher complexity in modeling the EoL phase
in life cycle inventories.
Grégoire Meylan (NSSI, ETH Zurich, Switzerland)
showed in his presentation how the current Swiss cullet
(waste glass) recycling system works and what challenges
it faces in the future. In the study which has been carried out,
future management options for discarded glas s packages
were environmentally and economically assessed. A hybri d
LCA was combined with scenario and sensitivity analysis.
The options were recycling within Switzerland or abroad
and were evaluated by three recycling paradigms:
& Closed-loop recycling through color-separated cullet
collection
& Closed-loop recycling through color-mixed cullet col-
lection and optical color sorting
& Closed-loop recycling through color-separated cullet
collection and high-grade downcycling
The results presented suggest that the eco-efficiency of
the Swiss cullet disposal system is not dependent on color
quality (i.e., color separation) nor on the type of processing
(i.e., recycling or downcycling), but that the substitution of
domestically produced packaging glass by imports would
lead to an economical loss and higher environmental
impacts. With the goal of identifying opportunities for im-
proving the environmental performance of complex waste
management syste ms, Carl Vadenb o (ESD , ETH Zurich,
Switzerland) presented a method concept in which process
models, LCA, and mathematical optimization techniques
are combined. Optimization techniques like linear program-
ming (LP) offer a systematic approach to identify (Pareto)
optimal solutions, in this case in terms of waste and resource
allocation among available waste treatment options. The
feasible solutions, i.e., the decision space of the LP, are
limited by model constraints which are formulated to reflect
the regional context, e.g., the installed treatment capacities,
waste-related policies and regulations, cost constraints, etc.
The LCA methodology is applied to avoid suboptimal sol-
utions, for which the environmental burdens are simply
shifted between life cycle stages or between impact catego-
ries. Process models enable the assessment of the burdens as
well as the benefits from resource substitution or from
energy and material recovery in the treatment of a given
waste stream, based on waste characteristics and on treat-
ment technology levels (Boesch e t al. 2009). A simple
hypothetical case was used to illustrate how the resulting
model can support decision making regarding the allocation
of waste and resources in a waste management system. By
comparing the performance of different single criteria sol-
utions with respect to multiple environmental indicator s and
to system operating costs, not only improvement potentials
but also tradeoffs could be identified. Future work related to
the proposed method concept involves, among others, the
inclusion of further process models to broaden the scope,
strategies to address data and model uncertainty, and the
application in a real-world case study.
The second session was closed by the presentation an
emerging challenge for waste incineration plants, presented
by Tobias Walser (ESD, ETH Zurich, Switzerland). Engi-
neered nanoparticles (ENPs) are increasingly applied to
consumer products and hence appear more and m ore in
waste treatment processes. Even though the EoL of nano-
enabled products is seen as a potential final sink for ENPs
with minimal emissions to the environment, the ENP re-
moval ability of flue gas cleaning syste ms has not been
thoroughly investigated so far. Moreover, the trend of clos-
ing material cycles by recovery of materials from slag and
fly ash might be hampered by ENP impurities. This knowl-
edge gap is currently being addressed by a research consor-
tium from ETH Zurich. Introd ucing stable nano- CeO
2
particles in the kilogram range into a full-scale incineration
Int J Life Cycle Assess (2012) 17:504–510 507