Life cycle assessment as a tool for optimising the integrated waste management in Lombardia L. Rigamonti1, V. Brambilla2, R. Luglietti2, M. Giavini3 and M. Grosso2 1 Politecnico di Milano, DIIAR – Environmental section, Milan, 20133, Italy; firstname.lastname@example.org 2 Politecnico di Milano, DIIAR – Environmental section, Milan, 20133, Italy 3 ARS Ambiente Srl, Gallarate, Varese, 21013, Italy
Abstract Life cycle assessment (LCA) has been chosen by Regione Lombardia as a strategic support decision tool in the preparation of its new waste management program. The goal is to use the life cycle thinking approach to assess the current regional situation and thus to give useful strategic indications for the future waste management. The project is called GERLA: GEstione Rifiuti in Lombardia – Analisi del ciclo di vita (Waste management in Lombardia – Life cycle assessment). The first phase of the study consisted in the analysis of the current management of municipal waste in Lombardia Region (baseline scenario – reference year 2009). All the fluxes of materials (both the source-separated fractions and the residual waste) were characterised in terms of quantity, composition and destination, and the most important treatment plants were analysed in terms of their capacity, energy and materials consumption, emissions in the environment, energy and materials recovery. The baseline scenario was then evaluated by means of the LCA methodology. The critical analysis of the results has allowed the definition of four possible waste management scenarios for the year 2020, with the final goal to improve the environmental performance of the regional system. Keywords: Decision tool; Life cycle assessment; Lombardia Region, Waste management program
INTRODUCTION This paper summarises the main results obtained in the GERLA project, commissioned by CESTEC SpA for Regione Lombardia to the Environmental Section of Department IIAR of Politecnico di Milano. GERLA stays for GEstione Rifiuti in Lombardia: Analisi del ciclo di vita (Waste management in Lombardia: Life cycle assessment). Regione Lombardia is in fact drafting the new Regional Waste Management Program (RWMP) and, following a sustainability policy, has decided to consider the environmental performance as an evaluation criterion in future planning decisions. In particular, Life Cycle Assessment (LCA) has been identified as the most suited tool to reach this aim. In the GERLA project, LCA methodology has thus been applied to analyse the environmental performance of the current regional municipal waste management system. On the basis of the interpretation of the results, four management scenarios for the year 2020 were proposed and subsequently evaluated with LCA methodology to verify and quantify the improvements associated with the various actions implemented. This has allowed to provide Regione Lombardia with useful indications for the formulation of the new RWMP.
BASELINE SCENARIO: WASTE MANAGEMENT IN LOMBARDIA IN 2009 Setting up the life cycle assessment. The first phase of the study consisted in the analysis of the current waste management in Lombardia Region (baseline scenario). The focus was on municipal waste, in particular the six packaging materials (glass, aluminium, iron, paper, plastic and wood), the organic waste (food and green waste) and the residual waste. The baseline scenario was evaluated by means of the LCA methodology, following the ISO standards 14040 and 14044.
The functional unit adopted in the baseline scenario is defined as the amount of municipal waste (limited to the sole mentioned fractions) collected in Lombardia in 2009, which corresponds to 4,403,066 tonnes. The system boundaries include all treatment processes, from the moment the waste is collected till when it leaves the system as an emission (solid, liquid or gas) or as a secondary raw material, following the “zero burden assumption” (Ekvall et al. 2007). Cases of multifunctionality are resolved by expanding the system boundaries to include within them also avoided primary productions due to material and energy recovery from waste (Finnveden et al., 2009; EC JRC – IES, 2010). Figure 1 summarises the system under study: in addition to activities closely related to waste management (marked with gray boxes), the system boundaries were expanded to include the avoided products (white boxes). In the year 2009 the total production of the considered fractions was split between 51% of source separation for material recovery and 49% of residual waste. Out of this latter, 70% was sent directly to energy recovery in waste-to-energy (WTE) plants, 26% to mechanical-biological treatment plants (MBT) and only a negligible amount directly to landfill. In the inventory analysis, all the fluxes of materials (both the source-separated fractions and the residual waste) were characterised in terms of quantity, composition and destination, and the most important treatment plants were analysed in terms of their capacity, energy and materials consumption, emissions in the environment, energy and materials recovery. Most of the data used to model each unit (e.g. paper recycling, food waste composting, energy recovery from residual waste) are primary, i.e. acquired directly from the plants operators. For each unit we created in SimaPro software a new module, including also the avoided material and energy production (Rigamonti & Grosso 2009, Rigamonti et al. 2010). Avoided electricity was modelled as being produced by a gasfired combined cycle power plant, while avoided thermal energy was modelled as heat produced by domestic gas-fired boilers. This to be consistent with the Lombardia Region current situation, in which the natural gas represents 93% of primary energy of fossil origin used in both sectors. CML 2001 was adopted as characterisation method to evaluate the environmental impacts, whereas the Cumulative Energy Demand (CED) method was chosen to evaluate the energy consumption of the system (Guinée et al. 2001, Humbert et al. 2010).
Residues/ Process Loss
SELECTIVE MONO/MULTI MATERIAL COLLECTION
MSW 4,403,066 t
SEPARATION OF MULTIMATERIAL COLLECTION AND SELECTION OF EACH MATERIAL Residues
MECHANICAL BIOLOGICAL TREATMENT PLANTS
Secondary fuel in cement kiln: displacement of petcoke 1,506,711 t
Ferrous metals: 60,315 t Aluminium: 2567 t Glass: 363,944 t Paper: 563,590 t Wood: 144,876 t Plastic: 109,058 t
RDF 158,880 t
36,214 t 85,718 t
The residues are sent to incineration/cement kiln/landfill according to their characteristics.
DIGESTION+ POSTCOMPOSTING Residues/ Process loss
Green waste: 436,207 t Food waste: 419,038 t
Dry fraction/ bio-dried/biostabilised
Residual waste 2,166,350 t
Energy: displacement of fossil fuels
Energy + recovered material: displacement of fossil fuels and primary products
Recycled materials (Iron 53,119 t; Aluminium 2143 t; Glass 363,944 t; Paper 501,595 t; Wood 137,632 t; PET 44,298 t; HDPE 13,447 t; mix of polyolefins 21,266 t): displacement of primary products
Residues/ Process loss Compost (235,679 t): displacement of peat and mineral fertilisers
Compost (14,937 t) + energy: displacement of peat and mineral fertilisers, and of fossil fuels
Figure 1. Flow diagram of the municipal waste management system of Lombardia Region in 2009: activities with a positive impact on the environment are in gray boxes, while those that produce avoided impacts are in white boxes. LCA results. The LCA results of baseline scenario are shown in Table 1, expressed in terms of impact indicators. All impact indicators analysed - global warming, acidification, human toxicity, photochemical ozone creation and cumulative energy demand - are negative in sign, meaning that the benefits associated with material and energy recovery from waste outweigh the added impacts on the environment for the processing of the waste itself. The current integrated municipal waste management in Lombardia is, therefore, already characterized by good energetic and environmental performance. Table 1. Energetic and environmental impact indicators associated with the municipal waste management implemented in Lombardia in 2009 (baseline scenario). Impact category Acidification Global warming Photochemical ozone creation Human toxicity Cumulative energy demand
Unit kg SO2 eq. kg CO2 eq. kg C2H4 eq. kg 1,4-DCB eq. MJ
Per functional unit -1.51·106 -2.18·108 -1.77·105 -2.44·108 -2.59·1010
Per 1 tonne -0.34 -49.4 -0.040 -55.3 -5,873
However, a detailed contribution analysis of the results showed that there is still room for further improvement. Actions based on the one side on a further increase in recycling rates and on the other on a series of technological improvements, especially in the management of the organic fraction and of the residual waste, can be undertaken to improve the overall system. Those are: • focusing on anaerobic digestion (+ post-composting) of the organic fraction instead of simple aerobic composting; • maximising energy recovery in waste-to-energy plants, with particular reference to thermal
energy; • satisfying self-consumption of waste-to-energy plants and anaerobic digestion plants by using the energy produced by the plant itself; • recovering non-ferrous metals (in addition to ferrous ones) from bottom ashes produced by wasteto-energy plants; • phasing out landfill as the destination of residual waste and bio-dried material produced by MBT plants.
FUTURE SCENARIOS The critical analysis of the results of the baseline scenario has allowed the definition of four alternative perspective scenarios for the year 2020, with the final goal to improve the environmental performance of the regional system. First of all, a Business-As-Usual (BAU) scenario was defined. This assumes an inertial increase of separate collection (up to an overall value of 66%) without significant external interventions, except for the technological improvements previously listed. Starting from the BAU scenario, considering the same quantity of waste produced and the same treatment routes for the different fractions, two other scenarios were then defined. They involve a further increase of separate collection by strengthening the collection services already implemented and in particular the kerbside mono-material collection system: in the two scenarios “2020 65%” and “2020 70%”, an overall level of separate collection of 70% and 75% is obtained, respectively. Finally, a last scenario was defined, “2020 70% multi”, set at an overall level of separate collection of 75% (again considering only fractions included in this study) by developing the multi-material collection system. In particular, glass, plastics and metals (both ferrous and not ferrous) are collected together. These materials are first separated in a plant whose efficiencies are reported in Table 2, and then sent to the corresponding selection plant. This scenario can be seen as an alternative to “Scenario 2020 70%”, where the same overall level of separate collection is achieved with a different collection system. Table 2. Separation of the multi-material fraction. Material
Residues * Cullet ready for the recycling
The LCA of the four scenarios targeted at year 2020 was carried out following the same assumptions made for the analysis of the baseline scenario. The system boundaries include the municipal waste treatment processes estimated for Lombardia Region in 2020 and the avoided productions associated with material and energy recovery from waste. The functional unit is the amount of municipal waste (limited to the sole waste fractions considered) projected for Lombardia Region in the year 2020, which amounts to 4,838,297 tonnes.
COMPARISON BETWEEN THE SCENARIOS By analysing the detailed material balance of each scenario, a decrease in the efficiency of the recovery paths of packaging materials was observed moving from Scenario 2009 (baseline scenario) to “Scenario 2020 70% multi”: this last has an efficiency much lower than that of all other scenarios (Table 3). This is due to the increase of the amount of material collected in multi-material mode, which requires a further separation step before recycling and so inevitably implies a greater production of residues. It can be concluded that, in general, an overall level of separate collection in the range 50%-75% implies an amount of residues in the order of 20% of the separated material. These residues need to be properly managed according to the hierarchy set by the 2008/98/EC Directive, which indicates energy recovery as the preferable option for all non-recyclable combustible streams. The peculiar situation of Lombardia Region is favourable in this sense, as a number of WTE plants exist, some of them characterised by outstanding energy and environmental performances (Grosso and Rigamonti, 2009). Table 4 shows the total amount of residual waste, composed by the sum of the “true” residual waste and of the residues from selection activities carried out on source separated materials. It appears that waste management systems based on overall separate collections percentages in the range 50 to 75% imply the presence of residual waste included between 58% and 40%, respectively. Table 3. Overall efficiency of the recovery paths of packaging materials in the analysed scenarios.
Secondary materials produced/packaging materials collected (%)
Scenario 2020 BAU
Scenario 2020 65%
Scenario 2020 70%
Scenario 2020 70% multi
Table 4. Percentages of residual materials to be disposed of in the analysed scenarios. Scenario 2009
Scenario 2020 BAU
Scenario 2020 65%
Scenario 2020 70%
Scenario 2020 70% multi
Residues from the treatment of separated collected materials (A) Residual waste (B)
Total residues (A+B)
It is interesting at this point to compare the energy and environmental impacts for the five scenarios (Figure 2). For all of them, all indicators are negative in sign, which means that the benefits arising from material and energy recovery from waste are offsetting the impacts added in the environment for processing the waste itself. Moreover, all future scenarios perform better than baseline scenario in all the indicators, the greater improvement being for the global warming potential. When comparing only scenarios at the year 2020, in all the indicators there is a clear improvement trend moving from Scenario BAU to Scenario 70%; “Scenario 70% multi” behaves differently, as it performs better than the others only for human toxicity, whereas it is the worst in two indicators (global warming and cumulative energy demand).
Photochemical ozone creation
Cumulative energy demand
0 -50 -100 -150
-200 -250 -300 -350 -400 -450 -500 2009
2020 70% multi
Figure 2. Comparison among the scenarios in terms of impact indicators (impacts of Scenario 2009 are set equal -100% and the others are expressed in relative terms).
RECOMMENDATIONS FOR THE PREPARATION OF THE NEW REGIONAL WASTE MANAGEMENT PROGRAM The LCA of the integrated waste management in Lombardia Region showed that for all the examined scenarios all the analysed impact indicators (global warming, acidification, human toxicity, photochemical ozone creation and cumulative energy demand) are negative in sign, which means that the benefits arising from material and energy recovery from waste are offsetting the impacts added in the environment due to the processing of the waste itself. The current integrated municipal waste management of Lombardia Region is, therefore, already characterised by good energy and environmental performances. However, there is still room for further improvement: actions based on one side on a further increase in recycling rates and on the other side on a series of technological modifications, especially in organic fraction and residual waste management, can be undertaken to improve the overall system. These actions were analysed in four future scenarios, which actually resulted with better performance. The current situation can thus be improved by implementing a series of actions, such as: • treatment of organic waste by anaerobic digestion + post-composting rather than by traditional aerobic composting; • maximization of energy production in waste-to-energy plants, with particular reference to thermal energy; • satisfaction self-consumption of waste-to-energy plants and anaerobic digestion plants by using the energy produced by the plant itself; • recovery of non-ferrous metals from bottom ashes produced by waste-to-energy plants, in addition to ferrous ones; • phasing out of landfill as the destination of residual waste and of bio-dried material produced by MBT facilities; • RDF co-combustion in cement kiln where local conditions allow this practice; 6
â€˘ increase of packaging materials sent to recycling (especially paper, glass, aluminium and homogeneous polymers such as polyethylentereftalate - PET and high density polyethylene HDPE); â€˘ preference for mono-material separate collection with respect to multi-material.
CONCLUSIONS The detailed mass balances of the baseline scenario (year 2009) and of the four future scenarios (year 2020) revealed that waste management systems based on separate collections with an overall value included between 50% and 75% imply the presence of residual waste (composed by the residual waste + the residues from selection and recycling activities) included between 58% and 40%, respectively. Under the European Directive 2008/98 and its transposition into Italian law, all the possibilities for energy recovery for such flows should be explored. The LCA of the integrated waste management in Lombardia Region showed that for all the examined scenarios all the analysed impact indicators (global warming, acidification, human toxicity, photochemical ozone creation and cumulative energy demand) are negative in sign, which means that the benefits arising from material and energy recovery from waste are offsetting the impacts added in the environment due to the processing of the waste itself. The current integrated municipal waste management of Lombardia Region is, therefore, already characterised by good energy and environmental performances. However, there is still room for further improvement: actions based on one side on a further increase in recycling rates and on the other on a series of technological improvements, especially in organic fraction and residual waste management, can be undertaken to improve the overall system. LCA applied to integrated waste management systems has great potential for development, especially in supporting the decisions of planners and companies that manage waste collection, transportation and recovery activities. The application of LCA to waste management systems is thus a useful tool for decision support during the preparation and the updating of waste management programs and is a valuable tool in the planning stage for the evaluation and reduction of environmental impacts. Finally, the study highlighted the complexity of an evaluation of this kind when extended to a broad geographical area as that of Lombardia Region (nearly 10 millions inhabitants). In particular, the need to acquire large amounts of data, preferably collected directly at the plants (i.e. primary data), and the assessment of their quality are key elements to ensure the reliability of the results obtained. The applicability of the LCA methodology is in fact strongly subordinated to the availability of data and information on the processes involved and requires that the competent bodies (public and private) provide for a continuously updated information system for collecting and organizing these data. Failing that, LCA applied to waste management systems carried out on the basis of data inconsistent with reality could lead to weak results and thus to the risk of erroneous conclusions.
ACKNOWLEDGEMENTS The GERLA project was financially supported by CESTEC for Regione Lombardia. We wish to thank all plant operators who have supplied primary data for the LCA. REFERENCES Ekvall T., Assefa G., Bjorklund A., Erikson O., Finnveden G. (2007). What life-cycle assessment
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