Environmental Assessment of Paper Waste Management Options by

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Ind. Eng. Chem. Res. 2004, 43, 5702-5714

Environmental Assessment of Paper Waste Management Options by Means of LCA Methodology U. Arena,*,† M. L. Mastellone,† F. Perugini,† and R. Clift‡ Department of Environmental Sciences, University of Naples II, Via Vivaldi, 43-81100 Caserta, Italy, and Centre for Environmental Strategy, University of Surrey, GU2 7XH Guildford, Surrey, United Kingdom

Investigating the environmental sustainability of any recycling process demands full understanding and objective quantification of all the associated environmental impacts. Life cycle assessment is an internationally standardized method that is able to account for upstream and downstream inputs and emissions over the complete supply chain providing a product or service. It is generally considered the best environmental management tool that can be used to move from a generic statement about the environmental benefit of a given recycling or disposal system to reach an objective quantification of its environmental sustainability. In this study, it is used to assess and compare the environmental performances of three alternative options (landfilling, recycling, and combustion with energy recovery) that could be used in Italy to manage paper and board packaging waste. The results confirm that material recycling may not be the best environmental option. In this specific case, they show that paper use should be viewed in the context of the international trade in biofuels. Introduction Paper, board, and other products made from vegetable fiber are familiar everyday products. The introduction of electronic information systems has not displaced graphics-quality paper for office documents or newsprint for mass media, and board still competes successfully with plastic and composite packaging materials. Although the use of nonwood fiber is increasing, wood fiber remains the dominant material in paper and cardboard. Primary wood pulp is produced mainly in large integrated mills, which in Europe have an average output of some 180 000 tonnes per year (t/y) of fiber. Sweden and Finland have the largest mills, with a capacity of 250 000 t/y or more, with a few smaller mills producing 10 000 t/y or less, usually of more specialized pulp.1 In Western Europe about 30 × 106 t/y of postconsumer waste fiber is recycled, corresponding to about 45% of the total fiber used for paper making. Fiber not recycled is landfilled or incinerated, frequently with energy recovery. Rather than being recycled to the same use, paper fiber is commonly “down-cycled” into products with lower specifications than the original use. About two-thirds of recovered paper (22 Mt/y) is reused without deinking with about one-third (10 Mt/y) used for deinked products, including newsprint, graphics paper, and hygienic papers. The proportion of recycled fiber is relatively high in newsprint (49%), tissue and other hygiene papers (67%), packaging liners and fluted paper (86%) and carton boards (52%).1 The recycled paper sector has been beset by price volatility, particularly brought about by promotion of waste recovery before the industrial infrastructure was in place to process recovered fiber. However, the economic conditions have now stabilized so that most * To whom correspondence should be addressed. Tel.: +390823-274414. Fax: +39-0823-274605. E-mail: umberto.arena@ unina2.it. † University of Naples II. ‡ University of Surrey.

grades of recovered fibers are now cheaper than virgin fiber. Recycled fiber is particularly important in countries that are not producers of virgin pulp. In Italy, 49% of total paper and board is recovered and recycled, with the difference made up of 39% virgin wood fiber and 17% of other materials.2 In other parts of Europe, such as the UK, development of the market for recycled fiber means that significant quantities of wood resource will become available at a time when the demand for virgin fiber is much reduced; the wood will then be usable for other purposes, such as biofuel.3 Figure 1 shows in outline the industrial ecology for wood fiber in paper. Segregation or sorting of waste paper into different quality grades and selection of different processing routes enables recovered fiber to be used in a large variety of products. Segregation before recovery is advocated to eliminate contaminants such as plastics and “stickies” (e.g. glued labels), but source segregation is imperfect, so recovered paper usually passes through a sorting station to eliminate contaminants as completely as possible. The paper is then usually compacted into bales, to be transported to the reprocessing mill. The unit operations used in paper mills differ between different product types and grades. They also use a wide range of ancillary chemicals and also energy. Hence, the environmental benefits of recycling depend on the balance between the environmental impacts of primary fiber production, recycling, and other beneficial uses of waste paper, such as energy production. This comparison has been the subject of much debate in the literature, usually focusing on the question “recycle or burn”.4,5 The comparison has been shown to depend on the specific economic conditions in which the recycling operations are embedded, most importantly on the energy source which is displaced by energy recovery from waste, what energy source is used for the recycling operations, what material is replaced by the recycled fibers, and whether water is scarce in the region where the recycling mill is located. Comparison then depends, in turn, on whether

10.1021/ie049967s CCC: $27.50 © 2004 American Chemical Society Published on Web 08/25/2004

Ind. Eng. Chem. Res., Vol. 43, No. 18, 2004 5703

Figure 1. Patterns of virgin and recycled fibres utilization in the pulp and paper mills (CTMP ) chemi-thermo-mechanical pulp, LWC ) lightweight coated, SC ) supercalendered).

it represents current conditions or is directed at informing future policy.6 The study set out in this paper was carried out to compare three different scenarios for the management of paper and board packaging in Italy: (a) landfill only, (b) recycling back into paper and board for packaging, and (c) incineration with electricity generation. The fiber is assumed to have originated in Sweden, which is the source of most of the fiber used in Italy, with electricity produced from waste displacing production by the existing Italian system. System Analysis of Waste Management Life cycle assessment (LCA) is a systematic tool, developed from the principles of material and energy balances, to describe the full resource usages and environmental impacts associated with supply chains delivering products or services. The essence of LCA is that it considers all material and energy flows from the “cradle” of primary resources (such as oil or ore deposits) to “grave” of final disposal (such as stable inert material in a landfill). LCA studies are carried out for a number of different purposes.7 The type of study carried out here is a conventional or engineering LCA, characterized as “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; to assess the impact of those energy and material uses and releases to the environment; and to identify and evaluate opportunities to effect environmental improvements”.8 Following the international standards ISO 14040-43, the structure of a LCA consists of four distinct phases:9 (1) goal and scope definition, which defines the purpose and extent of the study, indicates the intended audience, and describes the system studied as well as the options that will be compared; (2) inventory analysis or LCI, which collects and analyses all the material and energy inputs and outputs (the so-called environmental burdens or interventions) that cross the boundary between the product or service system and the environment;10,11 (3) impact assessment or LCIA, which aims at understanding and evaluating the magnitude and significance of the potential environmental impacts of a system by organizing the LCI inputs and outputs into specific, defined impact categories; and (4) interpretation, which

Figure 2. Foreground and background systems for waste management (after Clift et al.10,17).

evaluates the study in order to derive recommendations and conclusions. Although the four phases are conventionally carried out sequentially, the overall process is iterative in that earlier phases may be revisited in the light of the outcome of later phases. The purpose of applying LCA to waste management is principally to ensure that the balance between the local impacts of waste collection and treatment are offset clearly and systematically against any benefits of recovering materials and/or energy from the waste. However, LCA is not the only tool for structuring and presenting information on environmental performance. Other approaches such as environmental impact assessment must be used, in conjunction with LCA, to describe local impacts on public health and natural ecosystems, land use, occupational health and safety, plus disamenity impacts such as odor, noise, and visual intrusion.10,12,13 The system boundary for life cycle assessment is defined as part of goal and scope definition. The approach commonly used in applying LCA to waste management4,10,14-16 is shown in Figure 2, in the form proposed by Clift et al.17 The overall system delivers the function management of waste. It is useful to distinguish between the two parts of the overall system: foreground, the set of processes whose selection or mode of operation is affected directly by decisions based on the study (in this case the waste management activities), and back-

5704 Ind. Eng. Chem. Res., Vol. 43, No. 18, 2004

Figure 3. System boundaries and principal environmental burdens (paper recycling scenario).

ground, all other processes which interact with the foreground, usually by supplying or receiving material or energy. Figure 2 embodies the approach of system expansion, recommended in ISO 14041 to avoid the problem of allocation, i.e., the attribution of environmental interventions and impacts between the outputs or services of multifunction systems.7 It is useful to distinguish between three sets of environmental burdens making up the complete inventory:10 direct burdens, which arise in the foreground waste management system; indirect burdens, which arise in the supply chains of materials and energy provided to the foreground; and avoided burdens, which are associated with economic activities displaced by material and/or energy recovered from the waste. Thus the avoided burdens represent the “environmental credits” for recycling or energy-from-waste, including reduction of demand for primary materials, virgin fiber in this case. The common assumption is that, apart from the operation of the foreground waste management system, demand for products and services and generation of waste are unaffected by the choice of foreground system. Thus recovering paper fiber and recycling into packaging is taken to reduce the demand for virgin fiber by the tonnage recycled, and electricity generated from paper waste is taken to reduce output from other sources. Goal and Scope Definition. The overall goal for this study is to evaluate the environmental performance of

the whole Italian system for treating paper and board packaging waste, collected from both household and commercial premises. The primary audience for the project was the Italian Consortium for Packaging (CONAI), which wanted to assess the environmental performance of the current waste management system, to compare it with possible alternative approaches and to identify and evaluate possible improvements. The functional unit, i.e., the common basis on which modifications and alternative systems are to be compared, was defined as the management of sufficient postconsumer waste, 1.17 t of paper and board packaging waste collected as a single material stream (with a moisture content of 15%), to produce 1 t of paper and board for packaging (with a moisture content of 7%). Consistent with the general approach illustrated by Figure 2, it was assumed that there is a demand for recovered material and that virgin and recycled materials are equivalent substitutable products. However, the study covered only environmental, not economic, performance. Scenarios, System Boundaries, and Inventory Data. Three different scenarios were considered: (a) landfilling, a hypothetical scenario in which all the waste material is landfilled; (b) recycling, a scenario actually utilized in Italy by Comieco, the Italian consortium for collection and recycling of paper and board packaging; and (c) combustion, a scenario in which the waste is burned with energy recovery as electrical power dispatched via the distribution grid.


Figure 4. System expansion method used in the study, with the indication of the functional output of primary interest and of avoided burdens coming from additional functional outputs from each systems.

Figure 3 shows the principal operations comprising the foreground system and the principal direct burdens and exchanges with the background system for the recycling scenario. Packaging waste enters the foreground system at the point where it is collected as a segregated stream or delivered to a drop-off site handling segregated waste. The foreground includes all the activities required to manage the waste: collection and other transport steps, compaction, sorting, and reprocessing with treatment of process waste. Figure 4 summarizes the expanded systems describing the three scenarios, showing the principal avoided burdens in each case. Primary inventory data describing the principal operations in the foreground system were obtained from on-site investigations obtained over a period of 12 months (July 2002-July 2003) covering all the main unit processesscollection sites, sorting stations, and recycled fiber (RCF) millssand all the commercial materials handled in Italy. They were calculated from plant operating records or from official documents and certified declarations of performance. For example, consumption of electrical energy and ancillary chemicals was compiled from power bills and invoices. The range of primary data obtained ensured that the data used in the LCA study was truly representative and as precise and complete as possible and also gave an indication of changes over time and of the range of variation between different sites and processing chains. Data quality was further improved by taking into account the specific characteristics of the packaging waste and of the process waste handled within the foreground system (see Figure 3), allowing for the dependence of the environmental performance of the recycling system on the grade of product. A parallel investigation18 shows the extent of these possible differences and the validity of the assumption that an “average” packaging product can be used as a reference in the LCA study. Life Cycle Impact Assessment. In the impact assessment phase of LCA, the considerable body of quantitative information contained in the inventory table is simplified to show the contributions to a recognized set of environmental impacts.7,10 It is commonly the case that a few environmental impacts dominate the results for a specific LCA comparison. In the case of the paper waste management scenarios considered here, the dominant impacts are energy use and emissions of greenhouse gases, with acid gas

emissions, water consumption, and solid waste volumes also considered. Waste Management Scenarios The recycling scenario b represents the reference case, with the other two scenarios defined by their differences from this scenario. Scenarios a and c were represented by the best available technologies, to represent a possible new investment in alternatives to scenario b. In each scenario, the paper waste management sites (landfilling, recycling, combustion with energy recovery) are located in Italy. Paper production from virgin fiber is located in Sweden (where most of the fiber used in Italy is produced) and includes silviculture and harvesting, debarking, and chipping. The burdens related to the transportation of virgin fiber, from Stockholm to Rotterdam by ship and from there to central Italy by train, are also incorporated. a. Landfilling. This scenario covers the collection of 1.17 t of paper waste and its transport to a landfill, as well as the conventional production of 1 t of packaging paper from virgin fiber to provide the product made by recycling in scenario b (Figure 4). A state-of-the-art landfill is considered, with high integrity bottom and top membranes for leachate containment, leachate treatment by reverse osmosis, high efficiency (55%) of biogas collection, and 60% of the collected biogas burned in a gas engine with an electrical conversion efficiency of 35%. The remaining 40% of collected biogas is flared to convert hydrocarbons to carbon dioxide and thus reduce its greenhouse warming effect.16 The amount of leachate produced was estimated to be 400 dm3/t of paper waste landfilled over a period of 30 years: the value mainly depends on local rainfall, the integrity of the sealing of the landfill, and the original water content of the buried waste. The conservative assumption was made that the composition of the liquid effluent just met regulatory requirements. Biogas production was estimated to be 120 standard cubic meters (at a reference temperature of 20 °C and 1 atm) per tonne of paper waste.15 The major components of the landfill gas are methane, typically 50-55%, with the balance being mainly carbon dioxide plus less than 1% of hydrogen sulfide and other organic compounds. The time scale for quantifying the leachate and biogas emissions is related to the time required for the landfill to become fully mineralized, that is, 30 years, on the


Figure 5. Flow diagram of the RCF mill taken as reference in the study (HD ) high-density cleaning).

basis of the climate conditions of Southern Italy. Atmospheric releases are diffuse emissions of the biogas not collected (45% of produced biogas) and also oxidized biogas from the gas engine and flare. Again the conservative assumption was made that the flue and flare gases just comply with emission regulations. b. Fiber Recycling. The recovered paper processing system varies according to the paper grade to be produced and the type of waste paper used. Recycled fiber (RCF) processes can be divided into two main categories (Figure 1): (1) processes with mechanical cleaning and deinking, which produce recycled products such as newsprint, tissue, printing and copy paper, magazine paper, coated board and cartonboard, and (2) processes with exclusively mechanical cleaning, i.e., without deinking, which produce down-cycled products such as testliner, corrugated medium, uncoated board, and cartonboard. All the processes aim to separate paper fibers from impurities and contaminants by defibration, deflaking, and removal of impurities. Figure 5 shows the process flow diagram of the RCF mill, dedicated to the preparation of secondary fiber

packaging paper and board (i.e. recycled product), which has been used as the reference system for this study. During the pulping stage, coarse rejects are separated, while in the successive multistage cleaning and screening stages heavy particles, flat contaminants, stickies, and fine sand are removed, leading to deflaking of the stock to give good optical homogeneity. The review by EIPPC1 details all the direct environmental burdens associated with this type of mill (Figure 6). The operations from entry to the foreground up to the RCF mill differ between different types of waste. For example, cartonboards collected from supermarkets and process scrap from paper manufacture require no sorting, only packing and transportation. However, some features are common to all wastes and products: all solid waste from sorting stations is routed to landfill (modeled as in scenario a), whereas waste from reprocessing is taken as 50% landfilled and 50% burned with energy recovery (as in scenario c). As noted above, the whole recycling chain was modeled for each of the principal Italian commercial products with the specific waste used for its production. Figure 7 shows the quantitative results for two typical


Figure 6. Mass stream overview of an integrated recovered paper-processing mill.1

RCF mill products: a liner board (“testliner 1”) and a fluted paper (“fluting”). Testliner 1 is a high-quality paperboard produced only from graphics paper collected from commercial premises, whereas fluted paper is a lower quality product which can be produced from lower quality, more variable waste. The direct burdens were evaluated for all the main commercial products in Italy and averaged over the relevant production tonnages to give the “average” Italian recycled packaging. The results are summarized in Table 1, showing the principal environmental burdens and the operations in the recycling chain from which they arise. c. Combustion with Energy Recovery. This scenario covers dedicated combustion of 1.17 t of collected paper waste with recovery of electricity despatched via the distribution grid and includes conventional production of 1 t of packaging paper in Sweden (Figure 4). A net calorific value (LHV) of 13 MJ/t has been evaluated on the basis of the composition of the collected waste. The waste-to-energy unit includes three sections: combustion, energy recovery, and flue gas treatment. A mobile grate furnace is the main component of the combustion section. The energy recovery section is assumed to have a conversion efficiency of 27.7%, which

is high but achievable with a state-of-the-art plant. A semidry scrubber for acid treatment, a fabric filter for removing fly ashes, and selective catalytic reduction to reduce NOx and organic micropollutants comprise the flue gas treatment. Final gas emissions are assumed to be those achievable with proper operation of these bestavailable technologies and are well within regulatory limits. The inventory also takes into account all the environmental burdens related to the conditioning of ashes and their disposal.16 Environmental Comparisons As noted above, environmental comparisons between different products and waste management scenarios are dominated by energy consumption and greenhouse gas emissions. Therefore, the comparisons are dependent on the very different energy mixes used to generate electricity in the background systems in Italy and Sweden. These are summarized in Table 2. It is particularly significant that paper manufacture, which is the activity with the highest energy consumption, is carried out in Sweden, where the energy mix is dominated by hydroelectric and nuclear generation, which are associated


Figure 7. System boundaries and inventory of direct burdens associated with the production of testliner 1 and fluting. Note that the superscript * indicates diesel consumption for transportation.

with negligible carbon dioxide emissions. Therefore, scenarios a and c, in which paper is not recycled, make greater use of these energy sources. Recycled Products. The indicators of some crucial environmental impact categories for each of the main recycled products for packaging paper and board were

quantified, to investigate differences between the ecoperformances of these products. Table 3 summarizes the main results of this LCIA while Figure 8 details energy consumptions and green-house gas emissions, indicating contributions from the different stages of the recycling chain. The impacts are seen to differ little, even though

Ind. Eng. Chem. Res., Vol. 43, No. 18, 2004 5709 Table 1. Inventory of Direct Environmental Interventions Related to the Production of 1 t of an “Average” Packaging Product Obtained from the Recycling Chain, As Obtained from On-Site Investigations or by Assuming Compliance with Regulatory Limits Collection paper and board waste from household premises (t) paper and board waste from commercial premises (t) transportation from household premises (km) from commercial premises (km) Sorting paper and board waste input (t) auxiliary energy diesel (MJ) electric energy (kWh) residues scraps (t)

3.42 8.97 1.168 15.80 6.86 0.045

Interunit Transportation from sorting to pulp and paper mill (km)

10.86

Pulp and Paper Mill paper and board waste input (t) auxiliary materials water (m3) used discharged chemicals (kg) aluminum chloride sodium hypochlorite limestone retentive starch glue auxiliary energy diesel (MJ) electric energy (kW h) steam (t) emissions air emissions (g) dusts CO NOxa HCla HFa water emissionsa (g) COD BOD Clsuspended solids residues scraps (t) to landfill to energy recovery products paperboard (t) electric energy from biogas combustion (kW h) a

0.253 0.915

1.123 5.81 4.91 7.00 0.32 7.30 0.24 18.30 0.30 27 436.11 0.99 0.34 27.00 23.00 0.24 0.02 680.53 162.03 2708.36 242.06 0.065 0.065 1 11.75

Assuming compliance with regulatory limits.

Table 2. Background Energy Mixes (%) for Electricity Generation in Italy and Sweden in the Reference Period July 2002-July 2003 primary energy source

Italy

oil gas coal

46 22 11

Sweden

primary energy source

Italy

Sweden

6 1 7

nuclear hydroelectric other

10 9 2

62 21 3

“testliner 1” and “fluting” represent the two extremes in the spectrum of products analyzed. In particular, the energy requirements of the RCF mill represent more than 90% of the totals, with limited contribution from the collection and sorting stages which provide the main differences between the products. This confirms

the conclusions of Arena et al.18 that it is valid to use an “average” recycled product as the reference scenario. The values of the global warming potential index, expressed as amount of CO2 equivalent, again highlight the predominant contribution from the stage of “stock preparation and paper making”, which results mainly from the steam and electrical energy required by the mill. Since much of this energy comes from the grid, total CO2 emissions would be decreased by using renewable sources or nuclear energy sources. LCIA Results for Paper Waste Management Scenarios. (i) Energy and Resource Consumption. Figure 9 shows the net energy consumptions for all three scenarios and indicates the contributions from the different stages. Avoided burdens due to energy savings from biogas combustion have been included as “landfilling”. The first observation is that scenario cs combustion with energy recoverysshows, as expected, much lower overall energy consumption: 41% less than recycling and 67% less than landfilling. Paperboard manufacture from virgin fiber in Sweden (scenarios a and c) and reprocessing of recycled fiber in Italy (scenario b) dominate the comparison, while transportation is less significant and energy consumption in collection is negligible. Figure 10 shows the total net energy consumption or saving in terms of the primary energy sources. In this form, the results show the consequences of the different energy mixes in Italy and Sweden. The nonrenewable resources required for 1 t of packaging paper are summarized in Table 4. The two nonrecycling scenarios (a and c) each consume 2.2 t of wood for each t of pulp, albeit from managed plantation forests; the final comparisons will be very different if the wood is not sourced from sustainably managed forests. Figure 11 shows that they also demand large quantities of watersmore than 50 t/t of paperboardsbut in Sweden, where water is much less scarce than in Italy. (ii) Climate Change. The basis of this impact category is the enhanced greenhouse effect caused by human activities. Note that, since the average tropospheric lifetime of all these gases exceeds the tropospheric mixing time, it is not important where the emissions occur; i.e., climate change is truly a global impact category. Figure 12 shows the emissions of greenhouse gases, expressed as kilograms of CO2 equivalent for a time horizon of 100 years, for each of the paper waste management scenarios, distinguishing between the contributions from the different stages of the life cycles. For carbon dioxide emissions, it is important to distinguish between the “nonrenewable” fraction, arising from fossil fuel use, and the “renewable” fraction, deriving from biological materials and therefore removed from the atmosphere in the next tree-cropping cycle. In this study, carbon in paper and carton board and in the organic fraction of the process wastes are treated as renewable and therefore not included in the GWP index. The recycling scenario b is associated with very large emissions of greenhouse gases, primarily indirect burdens from the background system providing the electrical energy and steam used in paperboard reprocessing. Because the recycling plant is located in Italy, the background energy system is very carbon-intensive. By contrast, the landfilling (a) and energy recovery (c) scenarios have substantial avoided burdens, again carbon-intensive because they displace energy produc-

5710 Ind. Eng. Chem. Res., Vol. 43, No. 18, 2004 Table 3. Indicators of Principal Environmental Impact Categories, As Evaluated for 1 t of Each of the Main Products Commercialized in Italy for the Preparation of Paper and Board Packaging

impact category

testliner 1

testliner 3

white testliner b

white testliner c

testliner 4

wellenstoff

medium

fluting

total energy consumption, MJ/t crude oil consumption, kg/t gas/condensate consumption, kg/t coal consumption, kg/t water consumption, m3/t CO2 equivalent, kg/t air emissions of organic compounds, kg/t air emissions of dusts, kg/t COD in water emissions, kg/t BOD in water emissions, kg/t

10 800.04 94.66 62.81 45.09 9.72 632.96 2.87 0.77 0.69 0.31

10 376.62 89.00 60.07 42.92 7.70 634.69 2.50 0.66 0.68 0.18

9016.86 76.17 55.45 38.29 10.02 634.79 2.48 0.70 0.78 0.31

9614.83 80.42 57.22 40.29 8.40 623.59 2.30 0.63 0.77 0.20

8941.14 73.71 54.58 37.75 7.62 608.15 2.14 0.60 0.69 0.18

9324.05 79.21 57.19 39.87 9.71 592.23 2.48 0.71 0.69 0.32

9718.21 81.85 57.76 40.78 7.67 637.43 2.37 0.65 0.69 0.19

7564.14 59.77 49.11 32.66 7.44 619.27 1.90 0.56 0.69 0.17

Figure 8. Energy consumption and greenhouse gas generation of the main products commercialized in Italy for production of paper and board packaging, indicating contributions from the different stages of the recycling chain. Note that the key legend must be read from left to right.


Figure 9. Net energy consumption related to each scenario with the indication of the contribution coming from the different stages.

Figure 10. Net energy consumption related to each scenario, reported in terms of primary sources.

Figure 11. Water consumption related to each scenario.

tion in Italy. These benefits are not offset by energy use in primary paper production, because this takes place in Sweden, where the energy system is much less carbon intensive. Furthermore, transport from Sweden to Italy,

which is part of scenarios a and c, represents a relatively small component of the total greenhouse gas emissions. (iii) Acidification and Other Emissions. Acidification refers to processes that increase the acidity of water


Figure 12. Generation of greenhouse gases (expressed as kilograms of CO2 equivalent) related to each scenario with the indication of contributions coming from the different stages.

Figure 13. Acidification potential (expressed as grams of SO2 equivalent) related to each scenario with the indication of contributions coming from the different stages. Table 4. Nonrenewable Resource Consumptions To Provide 1 t of Packaging Paper under Three Waste Management Scenarios scenario

coal (kg)

oil (kg)

gas (kg)

(a) landfilling (b) fiber recycling (c) energy recovery

59 39 21

175 77 59

9 56 -31a

a

Negative value ≡ net savings.

and soil systems. Emissions of potentially acidifying substances (NOx, SOx, NH3, HCl, etc.) lead to acid deposition, which in turn can lead to damage to animal and plant populations. In Figure 13 contributions to this impact category are expressed in the conventional way as grams of SO2 equivalent, with different species weighted by the hydrogen release potentials reported by Hauschild and Wenzel.19 The poor environmental performance of the landfilling scenario (a) is particularly notable: the acidification potential is more than double that of the other scenarios. It is also noteworthy that, for this impact indicator, the production of virgin packaging is significant because these emissions are nonrenewable and are therefore included in the comparison. The LCA study also quantified other emissions to air and water (Figure 14) as well as solid waste

production (Figure 15). The low emission of “volatile organic compounds non-methane” for the energy recovery scenario is again explained by the avoided burdens related to energy savings in Italy (see Figure 9) that are not offset by the electricity consumption in Sweden, where the energy mix is dominated by nonfossil sources. The performance is not so good for particulate emissions, since the LCA balance takes into account emissions from the production of chemicals necessary for treatment of combustion flue gas and for paperboard manufacture. These latter are also responsible for the bad environmental performance shown by the landfilling scenario. The recycling scenario shows good results in terms of very low emissions of dust into the atmosphere and pollutants into water. The only exception is for chlorine emissions, due to the high chlorine content of the paper waste and of the chemicals utilized in the RCF mill. The recycling scenario also shows a limited production of solid waste, which could be further reduced by recycling pulper residues to the process. Discussion and Conclusions The environmental comparisons presented here show that, for almost all the significant impact categories,


Figure 14. Air and water emissions related to each scenario.

Figure 15. Solid waste generation related to each scenario with the indication of the origin of the different streams.

recovery of energy from waste paper in Italy is to be preferred over recycling or landfilling. The comparison is particularly clear for nonrenewable resource use and climate change. Although this conclusion runs counter

to common perceptions, it confirms results from a number of previous studies (e.g. ref 4). However, the present study is unusual in taking explicit account of differences in the background economic system between


the country where the primary paper fiber is produced (Sweden in this case) and that where the paper is used and the waste arises. The benefits of energy recovery are strong because the primary producer has an energy sector dominated by low-carbon sources, while the waste arises in a country with a carbon-intensive energy sector. Other analyses (e.g. ref 6) have shown that recycling is preferred on environmental grounds if it displaces energy produced from biomass, in essence because wood is then used directly as a biofuel without requiring the energy needed to convert it to primary paper fiber. Thus, the results show how LCA can sometimes produce counterintuitive but well-founded results. It also shows how LCA can be used to inform policy decisions. For example, there are already signs that Italy will have difficulty in meeting its commitments on reducing greenhouse warming emissions made under the Kyoto protocol. Analyses such as the one presented here can be used to show how a country might modify its energy economy to reduce dependence on fossil carbon-based fuels. The results show that, in a highcarbon economy, waste paper should be viewed as a biofuel rather than a recoverable waste material. At a time when wood chips are starting to be traded internationally as a fuel, this should not appear to be a paradox. Sweden and other Baltic states are already exporting wood-fuel to countries with carbon-intensive energy sectors as a way of reducing their nonrenewable carbon dioxide emissions. The analysis here quantifies the benefits of converting wood to paper in a low-carbon economy and then using the postconsumer waste paper as an energy source in a carbon-intensive economy. The relative insignificance of emissions from transport confirms that international trade in raw or processed biomaterials (such as paper) can result in environmental benefits. Acknowledgment The study was carried out with the financial support of CONAI, the Italian National Consortium for Packaging Recycling. The technical assistance of SCA Packaging Lucca and critical discussions with Dr. Lido Ferri are gratefully acknowledged. The authors are indebted to the graduated students, Miss Francesca Mazzotti and Mr. Mario Menditto, for their assistance in data processing. Data reported in the paper are original calculations made by the authors and cannot be considered as official information of any of the Government Organizations and Companies identified above. Literature Cited (1) Reference Document on Best Available Techniques in the Pulp and Paper Industry; European Integrated Pollution Prevention and Control Bureau: Seville, Spain, July 2000 (http:// eippcb.jrc.es). (2) Handling of Packaging and Paper and Board Packaging Waste; Comieco Report 2003; Comieco: Milan, Italy, July 2003 (http://www. comieco.org).

(3) McKay, H., Ed. Woodfuel Resource in Britain; The Forestry Commission: Edinburgh, Scotland, 2003. (4) Finnveden, G.; Ekvall, T. Life Cycle Assessment as a Decision-Support Tool: The Case of Recycling versus Incineration of Paper. Resour., Conserv. Recycl. 1998, 24, 235-256. (5) Arena, U.; Mastellone, M. L.; Perugini, F. Life Cycle Assessment of a Plastic Packaging Recycling System. Int. J. LCA 2003, 8 (2), 92-98. (6) Ekvall, T.; Finnveden, G. The Application of Life Cycle Assessment to Integrated Solid Waste Management. Part 2s Perspectives on Energy and Material Recovery from Paper. Trans. Inst. Chem. Eng. B 2000, 78, 288-296. (7) Baumann, H.; Tillman, A.-M. The Hitch-Hiker’s Guide to LCA; Studentlitteratur: Lund, Sweden, 2004. (8) Consoli, F., Allen, D., Boustead, I., Fava, J., Franklin, W., Jensen, A. A., de Oude, N., Parrish, R., Perriman, R., Postlethwaite, D., Quay, B., Se´guin, J., Vigon, B., Eds. Guidelines for LifeCycle Assessment: A “Code of Practice”; SETAC: Brussels, Belgium, 1993. (9) sISO 14040-43, Environmental ManagementsLife Cycle AssessmentsPart 1: Principles and Framework; International Organization for Standardization (ISO): Geneva, Switzerland, 1997. (10) Clift, R.; Doig, A.; Finnveden, G. The Application of Life Cycle Assessment to Integrated Waste Management. Part 1s Methodology. Inst. Chem. Eng. B 2000, 78, 279-287. (11) Udo de Haes, H. A.; Lindeijer E. The Conceptual Structure of Life Cycle Impact Assessment. In Life-Cycle Impact Assessment: Striving Towards Best Practice; Udo de Haes, H. A., G. Finnveden, M. Goedkoop, M. Haushild, E. G. Hertwick, P. Hofstetter, O. Jolliet, W. Klopffer, W. Krewitt, E. Lindeijer, R. MullerWenk, S. I. Olsen, D. W. Pennington, J. Potting, B. Steen, Eds.; Setac Press: Brussels, 2002, pp 209-224. (12) SETACsEurope Working Group. Life Cycle Assessment and Conceptually Related Programs; SETAC Press: Brussels, Belgium, 1997. (13) Cowell, S. J.; Fairman R.; Lofstedt, R. E. Use of Risk Assessment and Life Cycle Assessment in Decision Making: A Common Policy Research Agenda. Risk Anal. 2002, 22 (5), 879894. (14) Weitz, K.; Barlaz, M.; Ranjithan, R.; Brill, D.; Thorneloe, S.; Ham, R. Life Cycle Management of Municipal Solid Waste. Int. J. LCA 1999, 4 (4), 195-201. (15) McDougall, F. R.; White, P.; Franke M.; Hindle, P. Integrated Solid Waste Management: A Life Cycle Inventory; 2nd ed., Blackwell Science: Cambridge, MA, 2001. (16) Arena, U.; Mastellone, M. L.; Perugini, F. The Environmental Performance of Alternative Solid Waste Management Options: A Life Cycle Assessment Study. Chem. Eng. J. 2003, 96, 207-222. (17) Clift, R.; Frischknecht, R.; Huppes, G.; Tillman, A.-M.; Weidema, G. A Summary of the Results of the Working Group on Inventory Enhancement. SETAC-Eur. News 1999, 10 (3), 1417. (18) Arena, U.; Mastellone, M. L.; Perugini, F. A Life Cycle Assessment of the Manufacturing of Totally Recycled Papers. In Proceedings of AIChE Annual Meeting; American Institute of Chemical Engineers (AIChE): New York, 2003; pp 16-21. (19) Hauschild, M.; Wenzel, H. Environmental Assessment of Products; Chapman & Hall: New York, 1998; Vol. 2.

Received for review January 8, 2004 Revised manuscript received April 8, 2004 Accepted April 12, 2004 IE049967S

Environmental Assessment of Paper Waste Management Options by

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