Assessment and comparison of the environmental performances of a regional incinerator network

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heeePsityFebine1. Introductionheavy metals, is a suitable procedure to understand themost direct impacts (Rumbold and Mihalik, 2002), moreintegrated information can be given by the joint applica-tion of the monitoring approach and life cycle assessmentwaste management: landlls (Camobreco et al., 1999),end-of-life of specic product categories (Song and Hyun,1999; John and Zordan, 2001; Roth and Eklund, 2003),incineration (Hellweg et al., 2001; Chevalier et al., 2003;Morselli et al., 2005), liquid waste treatment (Hofstetteret al., 2003), municipal policy (Mendes et al., 2004), general* Corresponding author. Tel.: +39 051 2093668; fax +39 051 2093863.E-mail address: luciano.morselli@unibo.it (L. Morselli).Waste Management 2Incineration is one of the most important activities in anintegrated waste management system, due to the capacityof destroying hazardous waste, reducing mass and volumeof residues and recovering energy content from unrecycla-ble materials having a signicant heat value. However, itsusefulness is sometimes questioned because of its environ-mental impact, particularly on a small scale due to the pol-lutant dispersion in the vicinity (Morselli et al., 2002a,b). Ifa monitoring network close to the plant, designed to assessthe environmental fate of environmental indicators such as(LCA) methodology. Indeed, LCA can provide a morecomplete view of environmental impacts, not limited tothe local implications, and at the same time, can suggestto intensify the analytical investigation to those contami-nants that can produce the greatest danger to humanhealth and ecosystem.Recently this methodology, which was initially designedfor the environmental impact assessment of products, wasfurther developed for a wide range of applications, partic-ularly for waste management activities and strategic plan-ning. The following are a few applications in the eld ofAbstractIn Emilia-Romagna region (Northern Italy) the integrated waste treatment system consists of material collection and recycling, incin-eration with energy recovery and landll as nal disposal. In particular, at least one incineration plant is working in almost every prov-ince of the region. In this work, a screening life cycle assessment approach is applied to seven dierent incinerators, to compare thedierent plant technologies and identify the most relevant environmental impacts and processes. The characterization method used inthe life cycle impact assessment step is Eco-indicator 99. The functional unit is 1 ton of waste input.As a rst result, it can be noted that while the combustion systems are rather similar, the main variables are ascribable to gas cleaningoptions and eciency in energy recovery, which result in quite dierent environmental performances. Among heavy metals, particularattention must be paid to Cd and As, due to their high toxicity, despite their low quantities. The impact due to dioxin emission is ordersof magnitude lower than other contaminants (e.g., heavy metals). Furthermore, a catalytic system could be useful for a complete removalof organic contaminants and for a more eective abatement of nitrogen oxides. Finally, the environmental impact assessment sorts thevarious plants according to their age, i.e., the most recent plants provide the best environmental performances for the same quantity ofcombusted waste. 2007 Published by Elsevier Ltd.Assessment and comparison of ta regional incinLuciano Morselli *, Joseph Luzi, Claudia DFabrizioDepartment of Industrial Chemistry and Materials, UniverAccepted 16Available onl0956-053X/$ - see front matter 2007 Published by Elsevier Ltd.doi:10.1016/j.wasman.2007.02.021environmental performances ofrator networkRobertis, Ivano Vassura, Viviana Carrillo,assariniof Bologna, viale Risorgimento 4, I-40136 Bologna, Italyruary 20079 April 2007www.elsevier.com/locate/wasman7 (2007) S85S91waste management (Finnveden et al., 1995; Barton et al.,1996; Riva et al., 1998; Finnveden, 1999; Clift et al.,2000; Wilson, 2002).The aim of this work is the identication of the mostimportant environmental impacts due to the incinerationplants of municipal solid waste (MSW) operating in theEmilia-Romagna region of Italy, and the comparisonbetween the plants in order to highlight the technologicalsolutions most aecting the environmental eciency, forthe same amount of combusted waste.2. Materials and methodsThis study has been performed using SimaPro 6.0 LCASoftware (PRe Consultants, NL), implemented, when nec-essary, with Data Base I-LCA of the Italian EnvironmentalProtection Agency (ANPA, 2000). For the environmentalimpact assessment (the LCIA phase), the Eco-indicator99 method was chosen (PRe Consultants, 2001).The system boundaries are comprised (as generallyoccurs when a LCA is applied to a waste management sys-tem) from the waste input into the plant to the emission inthe environment (air, water and soil) of ue gas, bottomand y ash and, in this case, sewage sludge (Fig. 1). Allfor the investigation were labelled from A to G, accordingto their age (see Table 1), from the older to the younger.All plants are equipped with grate furnaces. They dierconsiderably in age, capacity, energy recovery devices, andpollutant abatement technologies. Table 1 shows an overallview of the most signicant dierences. They all have post-combustion chambers and burn waste in an excess of oxy-gen, at temperatures ranging from 950 C to 1150 C.Waste heat value is almost constant for each plant, rangingfrom about 10,100 to about 10,900 kJ/kg.In Table 2, chemical and water consumptions arereported, and in Table 3 the residues coming from the plantare reported. All data are normalised based on 1 t of com-busted waste. Bottom and y ash has to be disposed inlandlls (the latter, previously made inert).The entire balance of water and chemical consumptionfor gaseous pollutant abatement like urea, NaHCO3,activated carbon, lime and for water purication usedin an internal plant (not necessary in the cases of D andG plants, which have only a dry abatement system of uegas) like H2SO4, FeCl2, FeCl3, EDTA, NaOH, lime,Na2S, NaClO can thus be calculated.Thermal and electric energy recoveries for each plant arereported in Table 4, normalised based on 1 t of combustedS86 L. Morselli et al. / Waste Management 27 (2007) S85S91of the operations of waste collection (and their environ-mental impacts) are not included in this study, becausethese considerations would lead beyond the xed aims.A questionnaire was prepared and submitted to theplant managers for the collection of primary data, wholled in data with regards to the most relevant input andoutput ows (mass and energy). The seven plants chosenFig. 1. Boundaries of twaste.The normalisation of each mass ow rate for the mass ofcombusted waste is a typical calculation in order to com-pare pollutant emission from dierent plants, obtainingthe so called Emission Factors. These have been calculatedfor all continuously measured parameters (CO2, O2, totalparticulate, CO, TOC, HCl, NO2, SO2, HF) and for peri-he studied system.relaanaTable 1Age and working conditions of the investigated incineration plants (DataA B CIncineration lines(L.)L.13 L. 1 L. 12L. Morselli et al. / Waste Modically monitored micropollutants (Cd, Tl, Hg, As, Pb,Cr, Co, Cu, Mn, Ni, V, Sb, Sn, PCDD/Fs, PCBs, PAHs.).3. Results and discussionThe reference unit for the stage of impact assessmentwas 1 ton of combusted waste. For the estimation ofAge (years) 32 (L.1, L.2);31 (L.3)29 29Combusted waste(t/y)155,989 18,620 47,773SNCR pESPppFabric lter p(activeC + NaHCO3)p(activeC + lime)Scrubber Water,NaOH, limeWater Water, NaOHAuxiliary fuel (perton of waste)Natural gas:4.02 Sm3Oil: 3.04 L Natural gas:2.60 Sm3pExisting technologies.Sm3: Standard cubic meters.SNCR: Selective non catalytic reactor.ESP: Electrostatic lter.Table 2Consumption of chemicals and water for each plant (in 2004), normalised forA B CUrea (kg) 3.31NaHCO3 (kg) 17.8 Active C (kg) 0.48 0.61Lime (kg) 2.59 5.46NaOH (kg) 1.61 2.09Water (m3) 1.47 2.35 2.51Deminer. water (m3) 0.045 0.126Table 3Residues from the plants (2004), normalised based on 1 t of combusted wasteA B CGaseous emissions (Nm3/t of waste) 5.5 103 1.5 104 7Bottom ash (t/t of waste) 0.265 0.303 0Ash from ESP (kg/t of waste) 31.9 1Ash from fabric lter (kg/t of waste) 25.4 6RSP* (kg/t of waste) Dry sewage (kg/t of waste) 3.5 8* Residual sodic products, resulting from ue gas cleaning and sent to recycTable 4Thermal and electric energy produced by each incineration plant (2004), normAElectric energy produced (minus internal consumption) (MW h/t) 0.183Thermal energy produced (GJ/t) 1.20tes to year 2004)D E F GL.13 L.13 L.1 L.12gement 27 (2007) S85S91 S87avoided impact, the environmental impact due to the sameamount of energy produced considering Italian energy mix,has been calculated.In Fig. 2, according to the Eco-indicator 99 method, thedamage assessment is reported, divided into three catego-ries: human health, ecosystem and resources, comparingall plants. Damage categories synthetically describe the29 (L.1, L.2); 14(L.3)25 (L.1, L.2); 9(L.3)12 3117,999 99,538 36,128 104,937p p p pp ppp(activeC + NaHCO3)p(activeC + NaHCO3)p(activeC + lime)p(activeC + NaHCO3) Water Water Natural gas:4.07 Sm3Natural gas:0.28 Sm3. Oil:0.2 LOil: 0.90 L Natural gas:1.43 Sm31 t of combusted wasteD E F G6.64 6.17 7.83 2.3213.9 15.7 14.70.44 0.85 1.99 0.50 18.0 1.97 0.12 2.10 0.53 0.630.206 0.094 0.116 0.076D E F G.3 103 6.8 103 6.9 103 6.1 103 6.5 103.257 0.302 0.252 0.284 0.2114.2 20.8 21.0 29.8 (sum).1 9.7 39.09.7 10.2 .4 5.1 ling by Neutrec process (Solvay, 2001).alised based on 1 t of combusted wasteB C D E F G 0.141 0.284 0.134 0.178 0.540 0.508 1.63 -80-60-40-20020406080100yste%BentS88 L. Morselli et al. / Waste Management 27 (2007) S85S91inuence of the investigated processes on the environment,summarizing the information of dierent impact catego-ries, as shown in Table 5.It can be immediately observed that the lowest environ-mental impact (and the highest avoided impact, as forResources) is associated with the newest plant (G). Onthe contrary, the oldest plants, A, B and C, show the high-est damage for the rst two categories. Furthermore, B has-100Human Health EcosAverage AFig. 2. Damage assessma positive impact also on Resources; this is merely due tothe lack of energy recovery, being quite similar to the otherplants as for other parameters (chemicals, fuel and waterconsumption).Compared to the values reported in the literature forelectric energy production from MSW (about 500 kW hTable 5Relationship between damage and impact categories, dened according to theDamage category: human health DamImpact category Unit of measure ImpCarcinogenic substances Disability adjusted life years(DALY) aAcideutrRespiratory eects (caused by organicsubstances)Respiratory eects (caused by inorganicsubstances)EcoClimate changeOzone layer depletion LanIonizing radiationa Disability adjusted life years (DALY): a damage of 1 means 1 life year of 1of 0.25.b Potentially disappeared fraction (PDF) m2 y: A damage of 1 means tdisappear from 10 m2 during 1 year, or 10% of all species disappear from 1 mc MJ surplus: A damage of 1 means that, due to a certain extraction, furtheenergy, due to the lower resource concentration, or other unfavourable charaper t of waste burned; see Morris, 1996), only G shows asatisfactory energy recovery eciency. However, it mustbe considered that in our case data were provided subtract-ing internal consumption from the entire energyproduction.The single environmental issues aected by the plantsare represented in Fig. 3; the unit of measurement isexpressed in Pt, which is the single score deriving fromm Quality ResourcesC D E F Gof incineration plants.the weighting process. Weighting is performed accordingto the Egalitarian perspective, which is the most conserva-tive one; in it, the chosen time perspective is extremelylong-term, and substances are included even if there is justan indication (not necessarily a consensus) regarding theirenvironmental eects (PRe Consultants, 2004).Ecoindicator 99 method (PRe Consultants, 2001)age category: ecosystem quality Damage category: resourcesact category Unit of measure Impact category Unit ofmeasureication/ophicationPotentiallydisappearedfraction(PDF) m2 ybDepletion ofmineralsMJ surplusctoxicityDepletion offossil fuelsd useindividual is lost, or 1 person suers 4 years from a disability with a weighthat all species disappear from 1 m2 during 1 year, or 10% of all species2 during 10 years.r extraction of this resource in the future will require 1 additional MJ ofcteristics of the remaining reserve.-6-4-2024681012141618Ozone layer EcotoxicityAcidification/ Land use Minerals Fossil fuelsPtBantsL. Morselli et al. / Waste Management 27 (2007) S85S91 S89It can be noted that the most important environmentalimpacts of incineration process are caused by the emissionof carcinogenic substances, inorganic compounds whichcause respiratory disease (but for the newest plant, G, anegative value results in this category, due to the high e-ciency in energy recovery), and gases which induce the glo-bal climatic change. On the other hand, a considerableavoided impact is obtained by the non-consumption of fos-sil fuel (except for the already cited B).For all plants, the main carcinogenic impact is ascrib-able to Cd and As in water, mainly to the estimated lossesof leachate from landlls in which sludge, bottom ash andy ash are disposed. Their contribution in water is higherthan that due to their emission in air (Fig. 4). Dioxins,-8Carcinogens RespiratoryorganicsRespiratoryinorganicsClimatechangeRadiationAverage AFig. 3. Single environmental issue aected by the dierent incineration plindicator 99 method (PRe Consultants, 2001).which are often seen as the main critical point in gaseousemission from incinerators, result from one (A and Bplants) to three (E, F and G) orders of magnitude lessimpacting than the previously cited heavy metals. Damagesto human health are expressed in disability adjusted lifeyears (DALYs), according to the Eco-indicator 99 method(PRe Consultants, 2001).0.0E+005.0E-051.0E-041.5E-042.0E-042.5E-043.0E-043.5E-044.0E-044.5E-045.0E-04A B C D E F GPlantsDALYCadmium, ion WaterArsenic, ion WaterDioxins, measured as2,3,7,8-PCDD AirCadmium AirArsenic AirFig. 4. Main substances which cause carcinogenic eects and type ofemission. These damages are expressed in disability adjusted life years(DALYs), according to the Eco-indicator 99 method (PRe Consultants,2001).Among the inorganic substances that produce respira-tory diseases, nitrogen oxides represent the main contribu-tors, followed by ne particulates (Fig. 5). It can be notedthat A and B, the only two plants not equipped with theSNCR (selective non catalytic reactor for NOx abatement)are the most impacting in this category. Surely, a morestressed technology in reducing NOx to N2 (e.g., a catalyticconverter like SCR) could be useful to reduce this environ-mental problem, which is one of the main issues for incin-eration plants, in a LCA perspective. However, it would benecessary to assess if the production and the periodic main-tenance of the catalyst could be environmentally advanta-geous, compared to the non-catalytic system.Finally, the most important contributor to climateEutrophicationC D E F G. Pt is the unit of measurement of the single score provided by the Eco-change is CO2, many order of magnitude more than meth-ane and CO (Fig. 6). In this case, the behaviour of the dif-ferent plants roughly reects the energy recovery eciency.The nal evaluation, after the calculation of a singlescore according to the Eco-indicator 99 method (PRe Con-sultants, 2001), is given in Fig. 7. From this point of view,-6.0E-050.0E+006.0E-051.2E-041.8E-042.4E-04A B C D E F GPlantsDALYNitrogen oxidesParticulates, 2.5 - 10umSulfur oxidesParticulates, < 2.5 umParticulates, SPMNitrogen dioxidesSulfur dioxideAmmoniaCarbon monoxideFig. 5. Main inorganic substances which cause respiratory disease.ana-5.0E-061.5E-053.5E-055.5E-057.5E-059.5E-051.2E-041.4E-041.6E-04A B C D E F GPlantsDALYCO2CH4, fossilCO, fossilFig. 6. Main substances inducing climate change.2530354045S90 L. Morselli et al. / Waste Mthe correspondence between the age of the plants and theirenvironmental eciency is apparent.The less performing plant appears to be B (42 Pt/t ofcombusted waste), particularly due to the absence ofenergy recovery from waste combustion. Indeed, it is oneof the oldest plants in the region, and is going to be closedin the next few years. After that, the other oldest plants fol-low at a short distance: C, D, A and E.From the above reported remarks, the interpretation ofthis comparative LCA can be summarised as follows: the combustion process seems to have a scarce inu-ence on the overall performance, because all plantsoperate with similar incineration technologies (gratefurnaces); however, the combustion eciency appearsmuch higher in the most recent plant (G): lower auxil-iary fuel consumption per 1 t of combusted waste(Table 1) and lower fraction of bottom ash (Table 3)(approximating the performances of well-managedEuropean plants; see Holmgren and Henning, 2004,who indicate 19%), which can result in a reduction ofCO2 emissions and reduced impacts in landll disposalof solid residues;mary data about input of waste, auxiliary chemicals, waterand fuels, and output of bottom ash and y ash, emissions05101520All A B C D E F GPlantsPtFig. 7. Final score of environmental impact of 1 t of combusted waste bythe dierent plants. The rst bar refers to the average impact, consideringall plants.in air and (eventually) in water, provided by plant manag-ers. Material and energy balances were calculated and theemission factors for each contaminant were determined.The comparison between the environmental perfor-mance of the dierent plants demonstrate a clear depen-dence on the age of the incinerators. In particular, one ofthe oldest plants (which is going to be closed) shows thegreatest damage in all the categories examined (humanhealth, ecosystem, resources), mainly due to the absenceof energy recovery. In contrast, the most recently built plantshows the lowest impact, due to the highest level of eective-ness in energy production and in pollutant abatement.This demonstrates that a plant built with updated tech-nologies can considerably reduce environmental impactsand can match the needs of modern legislation, helpingto consider incineration with energy recovery a suitableactivity in an integrated waste management system.A further improvement of this research will be the inte-gration of detailed data and an expansion of the systemboundaries, including other processes. Moreover, a lifecycle cost analysis (LCC) could complement the criteriato dene the best system and model of incineration plant,from dierent points of view (environmental and eco- the main environmental advantages can be obtained inthe ue gas treatment step: in particular, the control ofthe substances inducing carcinogenic eects (speciallyCd and As) and those provoking respiratory diseases(above all, NOx and particulate) is crucial to reducethe environmental impact; furthermore, the other decisive step is energy recovery:the most ecient plant is again the most recent one(G); however, the thermal energy production by the old-est one (A), used for district heating, makes it better per-forming than some of the newer plants (see Fig. 2, inwhich it is apparent that the better performance is onthe category Resources).In short: G, the most recently built plant, proved to be amuch more ecient incinerator, compared to the others: itsnal score is less than the half of the regional average(26 Pt/t), being about 12 Pt/t of combusted waste. Indeed,it can be observed that this plant can manage a more e-cient combustion, performs a more rigorous abatement ofthe dierent pollutants, avoids the formation of sewagesludge (due to the totally dry abatement system) and recov-ers electric energy more eciently.4. ConclusionA complete survey of the incineration plants in Emilia-Romagna region has been performed, according to ascreening LCA procedure. The assessment relied on pri-gement 27 (2007) S85S91nomic), as suggested in the Integrated Pollution Preventionand Control (IPPC) Directive.AcknowledgementsResearch supported by the Research Project betweenEmilia-Romagna region and University of Bologna,Department of Industrial Chemistry, LCA of waste man-agement in relation to the incineration system in Emilia-Romagna region.ReferencesANPA (Italian Environmental Protection Agency), 2000. I-LCA ANPA,Banca dati italiana a supporto della valutazione del ciclo di vita,version 2. .Barton, J.R., Dalley, D., Patel, V.S., 1996. Life cycle assessment for wastemanagement. Waste Management 16, 3550.Camobreco, V., Ham, R., Barlaz, M., Repa, E., Felker, M., Rousseau, C.,Rathle, J., 1999. Life-cycle inventory of a modern municipal solidwaste landll. Waste Management and Research 17, 394408.Chevalier, J., Rousseaux, P., Benoit, V., Benadda, B., 2003. Environmen-tal assessment of ue gas cleaning processes of municipal solid wasteof two Swedish municipalities. Resources, Conservation and Recycling43, 5173.John, V.M., Zordan, S.E., 2001. Research and development methodologyfor recycling residues as building materials a proposal. WasteManagement 21, 213219.Mendes, M.R., Toshiya, A., Hanaki, K., 2004. Comparison of theenvironmental impact of incineration and landlling in Sao Paulo Cityas determined by LCA. Resources. Conservation and Recycling 41,4763.Morris, J., 1996. Recycling versus incineration: an energy conservationanalysis. Journal of Hazardous Materials 47, 277293.Morselli, L., Bartoli, M., Brusori, B., Passarini, F., 2002a. Application ofan integrated environmental monitoring system to an incinerationplant. The Science of the Total Environment 289, 177188.Morselli, L., Passarini, F., Bartoli, M., 2002b. The environmental fate ofheavy metals arising from a MSW incineration plant. Waste Manage-ment 22 (8), 875881.Morselli, L., Bartoli, M., Bertacchini, M., Brighetti, A., Luzi, J., Passarini,F., 2005. Tools for evaluation of impact associated to MSWincineration: LCA and integrated environmental monitoring system.L. Morselli et al. / Waste Management 27 (2007) S85S91 S91incinerators by means of the life cycle assessment approach. ChemicalEngineering Science 58, 20532064.Clift, R., Doig, A., Finnveden, G., 2000. The application of Life CycleAssessment to Integrated Solid Waste Management Part 1 Methodology. Process Safety and Environmental protection 78, 279287.Finnveden, G., Albertsson, A.-C., Berendson, J., Eriksson, E., Hoglund,L.O., Karlsson, S., Sundqvis, J.O., 1995. Solid waste treatment withinthe framework of life-cycle assessment. Journal of Cleaner Production3, 189199.Finnveden, G., 1999. Methodological aspects of life cycle assessment ofintegrated solid waste management systems. Resources, Conservationand Recycling 26, 173187.Hellweg, S., Hofstetter, T.B., Hungerbuhler, K., 2001. Modeling WasteIncineration for Life-Cycle Inventory Analysis in Switzerland. Envi-ronmental Modeling and Assessment 6, 219235.Hofstetter, T.B., Capello, C., Hungerbuehler, K., 2003. Environmentallypreferable treatment options for industrial waste solvent management.A case study of a toluene containing waste solvent. Process Safety andEnvironmental Protection 81, 189202.Holmgren, K., Henning, D., 2004. Comparison between material andenergy recovery of municipal waste from an energy perspective: a studyWaste Management 25, 191196.PRe Consultants b.v., 2001. The Eco-Indicator 99. A damage orientedmethod for life cycle impact assessment - Methodology Report andAnnex, 3rd ed., Amersfoort, NL.PRe Consultants b.v., 2004. SimaPro 6 Database Manual Methodslibrary, Amersfoort, NL.Roth, L., Eklund, M., 2003. Environmental evaluation of reuse of by-products as road construction materials in Sweden. Waste Manage-ment 23, 107116.Riva, A., Morselli, L., Furini, M., 1998. LCA and LCI for themanagement of municipal solid waste (MSW). Annali di Chimica Rome 88, 915924.Rumbold, D.G., Mihalik, M.B., 2002. Biomonitoring environmentalcontaminants near a municipal solid-waste combustor: a decade later.Environmental Pollution 117 (1), 1521.Solvay., 2001. US Patent 6171567, Process for the purication of a gascontaining hydrogen chloride, N. Fagiolini, Solvay.Song, H.-S., Hyun, J.C., 1999. A study on the comparison of the variouswaste management scenarios for PET bottles using the life-cycleassessment (LCA) methodology. Resources, Conservation and Recy-cling 27, 267284.Wilson, E.J., 2002. Life cycle inventory for municipal solid wastemanagement. Part 2: MSW management scenarios and modelling.Waste Management and Research 20, 2336.Assessment and comparison of the environmental performances of a regional incinerator networkIntroductionMaterials and methodsResults and discussionConclusionAcknowledgementsReferences

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