www.elsevier.com/locate/wasman

Waste Management 27 (2007) S85–S91

Assessment and comparison of the environmental performances ofa regional incinerator network

Luciano Morselli *, Joseph Luzi, Claudia De Robertis, Ivano Vassura, Viviana Carrillo,Fabrizio Passarini

Department of Industrial Chemistry and Materials, University of Bologna, viale Risorgimento 4, I-40136 Bologna, Italy

Accepted 16 February 2007Available online 9 April 2007

Abstract

In Emilia-Romagna region (Northern Italy) the integrated waste treatment system consists of material collection and recycling, incin-eration with energy recovery and landfill as final 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 different incinerators, to compare thedifferent 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 first result, it can be noted that while the combustion systems are rather similar, the main variables are ascribable to gas cleaningoptions and efficiency in energy recovery, which result in quite different 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 effective 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.

1. Introduction

Incineration 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 significant 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 asheavy metals, is a suitable procedure to understand themost direct impacts (Rumbold and Mihalik, 2002), moreintegrated information can be given by the joint applica-

0956-053X/$ - see front matter � 2007 Published by Elsevier Ltd.

doi:10.1016/j.wasman.2007.02.021

* Corresponding author. Tel.: +39 051 2093668; fax +39 051 2093863.E-mail address: luciano.morselli@unibo.it (L. Morselli).

tion of the monitoring approach and life cycle assessment(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 field ofwaste management: landfills (Camobreco et al., 1999),end-of-life of specific 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

S86 L. Morselli et al. / Waste Management 27 (2007) S85–S91

waste 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 identification 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 affecting the environmental efficiency, forthe same amount of combusted waste.

2. Materials and methods

This 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 flue gas, bottomand fly ash and, in this case, sewage sludge (Fig. 1). Allof the operations of waste collection (and their environ-mental impacts) are not included in this study, becausethese considerations would lead beyond the fixed aims.

A questionnaire was prepared and submitted to theplant managers for the collection of primary data, whofilled in data with regards to the most relevant input andoutput flows (mass and energy). The seven plants chosen

Fig. 1. Boundaries of t

for 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 differconsiderably in age, capacity, energy recovery devices, andpollutant abatement technologies. Table 1 shows an overallview of the most significant differences. 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 fly ash has to be disposed inlandfills (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 purification usedin an internal plant (not necessary in the cases of D andG plants, which have only a dry abatement system of fluegas) – 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 combustedwaste.

The normalisation of each mass flow rate for the mass ofcombusted waste is a typical calculation in order to com-pare pollutant emission from different 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.

Table 1Age and working conditions of the investigated incineration plants (Data relates to year 2004)

A B C D E F G

Incineration lines(L.)

L.1–3 L. 1 L. 1–2 L.1–3 L.1–3 L.1 L.1–2

Age (years) 32 (L.1, L.2);31 (L.3)

29 29 29 (L.1, L.2); 14(L.3)

25 (L.1, L.2); 9(L.3)

12 3

Combusted waste(t/y)

155,989 18,620 47,773 117,999 99,538 36,128 104,937

SNCR – –p p p p p

ESPp

–p p p

–p

Fabric filter –p

(activeC + NaHCO3)

p(active

C + lime)

p(active

C + NaHCO3)

p(active

C + NaHCO3)

p(active

C + lime)

p(active

C + NaHCO3)Scrubber Water,

NaOH, limeWater Water, NaOH – Water Water –

Auxiliary fuel (perton of waste)

Natural gas:4.02 Sm3

Oil: 3.04 L Natural gas:2.60 Sm3

Natural gas:4.07 Sm3

Natural gas:0.28 Sm3. Oil:0.2 L

Oil: 0.90 L Natural gas:1.43 Sm3

pExisting technologies.

Sm3: Standard cubic meters.SNCR: Selective non catalytic reactor.ESP: Electrostatic filter.

Table 2Consumption of chemicals and water for each plant (in 2004), normalised for 1 t of combusted waste

A B C D E F G

Urea (kg) – – 3.31 6.64 6.17 7.83 2.32NaHCO3 (kg) – 17.8 – 13.9 15.7 – 14.7Active C (kg) – 0.48 0.61 0.44 0.85 1.99 0.50Lime (kg) 2.59 – 5.46 – – 18.0 –NaOH (kg) 1.61 – 2.09 – 1.97 – –Water (m3) 1.47 2.35 2.51 0.12 2.10 0.53 0.63Deminer. water (m3) 0.045 – 0.126 0.206 0.094 0.116 0.076

Table 3Residues from the plants (2004), normalised based on 1 t of combusted waste

A B C D E F G

Gaseous emissions (Nm3/t of waste) 5.5 · 103 1.5 · 104 7.3 · 103 6.8 · 103 6.9 · 103 6.1 · 103 6.5 · 103

Bottom ash (t/t of waste) 0.265 0.303 0.257 0.302 0.252 0.284 0.211Ash from ESP (kg/t of waste) 31.9 – 14.2 20.8 21.0 – 29.8 (sum)Ash from fabric filter (kg/t of waste) – 25.4 6.1 9.7 – 39.0RSP* (kg/t of waste) – – – 9.7 10.2 – –Dry sewage (kg/t of waste) 3.5 – 8.4 – 5.1 – –

* Residual sodic products, resulting from flue gas cleaning and sent to recycling by Neutrec� process (Solvay, 2001).

Table 4Thermal and electric energy produced by each incineration plant (2004), normalised based on 1 t of combusted waste

A B C D E F G

Electric energy produced (minus internal consumption) (MW h/t) 0.183 – 0.141 0.284 0.134 0.178 0.540Thermal energy produced (GJ/t) 1.20 – 0.508 – – 1.63 –

L. Morselli et al. / Waste Management 27 (2007) S85–S91 S87

odically monitored micropollutants (Cd, Tl, Hg, As, Pb,Cr, Co, Cu, Mn, Ni, V, Sb, Sn, PCDD/Fs, PCBs, PAHs.).

3. Results and discussion

The reference unit for the stage of impact assessmentwas 1 ton of combusted waste. For the estimation of

avoided 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 the

-100

-80

-60

-40

-20

0

20

40

60

80

100

Human Health Ecosystem Quality Resources

%

Average A B C D E F G

Fig. 2. Damage assessment of incineration plants.

S88 L. Morselli et al. / Waste Management 27 (2007) S85–S91

influence of the investigated processes on the environment,summarizing the information of different 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 first two categories. Furthermore, B hasa 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 h

Table 5Relationship between damage and impact categories, defined according to the

Damage category: human health Dam

Impact category Unit of measure Imp

Carcinogenic substances Disability adjusted life years(DALY) a

AcideutrRespiratory effects (caused by organic

substances)Respiratory effects (caused by inorganic

substances)Eco

Climate changeOzone layer depletion LanIonizing radiation

a 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 m

c MJ surplus: A damage of 1 means that, due to a certain extraction, furtheenergy, due to the lower resource concentration, or other unfavourable chara

per t of waste burned; see Morris, 1996), only G shows asatisfactory energy recovery efficiency. However, it mustbe considered that in our case data were provided subtract-ing internal consumption from the entire energyproduction.

The single environmental issues affected by the plantsare represented in Fig. 3; the unit of measurement isexpressed in Pt, which is the single score deriving fromthe 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 effects (PRe Consultants, 2004).

Ecoindicator 99 method (PRe Consultants, 2001)

age category: ecosystem quality Damage category: resources

act category Unit of measure Impact category Unit ofmeasure

ification/ophication

Potentiallydisappearedfraction(PDF) · m2 · yb

Depletion ofminerals

MJ surplusc

toxicity

Depletion offossil fuelsd use

individual is lost, or 1 person suffers 4 years from a disability with a weight

hat 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 of

cteristics of the remaining reserve.

-8

-6

-4

-2

0

2

4

6

8

10

12

14

16

18

Carcinogens Respiratoryorganics

Respiratoryinorganics

Climatechange

Radiation Ozone layer EcotoxicityAcidification/Eutrophication

Land use Minerals Fossil fuels

Pt

Average A B C D E F G

Fig. 3. Single environmental issue affected by the different incineration plants. Pt is the unit of measurement of the single score provided by the Eco-indicator 99 method (PRe Consultants, 2001).

L. Morselli et al. / Waste Management 27 (2007) S85–S91 S89

It 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 effi-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 landfills in which sludge, bottom ash andfly ash are disposed. Their contribution in water is higherthan that due to their emission in air (Fig. 4). Dioxins,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+00

5.0E-05

1.0E-04

1.5E-04

2.0E-04

2.5E-04

3.0E-04

3.5E-04

4.0E-04

4.5E-04

5.0E-04

A B C D E F G

Plants

DA

LY

Cadmium, ion Water

Arsenic, ion Water

Dioxins, measured as2,3,7,8-PCDD AirCadmium Air

Arsenic Air

Fig. 4. Main substances which cause carcinogenic effects 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 fine 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 climatechange 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 reflects the energy recovery efficiency.

The final 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-05

0.0E+00

6.0E-05

1.2E-04

1.8E-04

2.4E-04

A B C D E F G

Plants

DA

LY

Nitrogen oxidesParticulates, 2.5 - 10umSulfur oxidesParticulates, < 2.5 umParticulates, SPMNitrogen dioxidesSulfur dioxideAmmoniaCarbon monoxide

Fig. 5. Main inorganic substances which cause respiratory disease.

-5.0E-06

1.5E-05

3.5E-05

5.5E-05

7.5E-05

9.5E-05

1.2E-04

1.4E-04

1.6E-04

A B C D E F G

Plants

DA

LY

CO2

CH4, fossil

CO, fossil

Fig. 6. Main substances inducing climate change.

0

5

10

15

20

25

30

35

40

45

All A B C D E F GPlants

Pt

Fig. 7. Final score of environmental impact of 1 t of combusted waste bythe different plants. The first bar refers to the average impact, consideringall plants.

S90 L. Morselli et al. / Waste Management 27 (2007) S85–S91

the correspondence between the age of the plants and theirenvironmental efficiency 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 influ-ence on the overall performance, because all plantsoperate with similar incineration technologies (gratefurnaces); however, the combustion efficiency 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 landfill disposalof solid residues;

� the main environmental advantages can be obtained inthe flue gas treatment step: in particular, the control ofthe substances inducing carcinogenic effects (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 efficient 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 efficient incinerator, compared to the others: itsfinal 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 effi-cient combustion, performs a more rigorous abatement ofthe different pollutants, avoids the formation of sewagesludge (due to the totally dry abatement system) and recov-ers electric energy more efficiently.

4. Conclusion

A complete survey of the incineration plants in Emilia-Romagna region has been performed, according to ascreening LCA procedure. The assessment relied on pri-mary data about input of waste, auxiliary chemicals, waterand fuels, and output of bottom ash and fly ash, emissionsin 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 different 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 effective-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 define the best system and model of incineration plant,from different points of view (environmental and eco-nomic), as suggested in the Integrated Pollution Preventionand Control (IPPC) Directive.

L. Morselli et al. / Waste Management 27 (2007) S85–S91 S91

Acknowledgements

Research 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’’.

References

ANPA (Italian Environmental Protection Agency), 2000. I-LCA ANPA,

Banca dati italiana a supporto della valutazione del ciclo di vita,

version 2. <http://www.sinanet.apat.it>.

Barton, J.R., Dalley, D., Patel, V.S., 1996. Life cycle assessment for waste

management. Waste Management 16, 35–50.

Camobreco, V., Ham, R., Barlaz, M., Repa, E., Felker, M., Rousseau, C.,

Rathle, J., 1999. Life-cycle inventory of a modern municipal solid

waste landfill. Waste Management and Research 17, 394–408.

Chevalier, J., Rousseaux, P., Benoit, V., Benadda, B., 2003. Environmen-

tal assessment of flue gas cleaning processes of municipal solid waste

incinerators by means of the life cycle assessment approach. Chemical

Engineering Science 58, 2053–2064.

Clift, R., Doig, A., Finnveden, G., 2000. The application of Life Cycle

Assessment to Integrated Solid Waste Management – Part 1 –

Methodology. Process Safety and Environmental protection 78, 279–

287.

Finnveden, G., Albertsson, A.-C., Berendson, J., Eriksson, E., Hoglund,

L.O., Karlsson, S., Sundqvis, J.O., 1995. Solid waste treatment within

the framework of life-cycle assessment. Journal of Cleaner Production

3, 189–199.

Finnveden, G., 1999. Methodological aspects of life cycle assessment of

integrated solid waste management systems. Resources, Conservation

and Recycling 26, 173–187.

Hellweg, S., Hofstetter, T.B., Hungerbuhler, K., 2001. Modeling Waste

Incineration for Life-Cycle Inventory Analysis in Switzerland. Envi-

ronmental Modeling and Assessment 6, 219–235.

Hofstetter, T.B., Capello, C., Hungerbuehler, K., 2003. Environmentally

preferable treatment options for industrial waste solvent management.

A case study of a toluene containing waste solvent. Process Safety and

Environmental Protection 81, 189–202.

Holmgren, K., Henning, D., 2004. Comparison between material and

energy recovery of municipal waste from an energy perspective: a study

of two Swedish municipalities. Resources, Conservation and Recycling

43, 51–73.

John, V.M., Zordan, S.E., 2001. Research and development methodology

for recycling residues as building materials – a proposal. Waste

Management 21, 213–219.

Mendes, M.R., Toshiya, A., Hanaki, K., 2004. Comparison of the

environmental impact of incineration and landfilling in Sao Paulo City

as determined by LCA. Resources. Conservation and Recycling 41,

47–63.

Morris, J., 1996. Recycling versus incineration: an energy conservation

analysis. Journal of Hazardous Materials 47, 277–293.

Morselli, L., Bartoli, M., Brusori, B., Passarini, F., 2002a. Application of

an integrated environmental monitoring system to an incineration

plant. The Science of the Total Environment 289, 177–188.

Morselli, L., Passarini, F., Bartoli, M., 2002b. The environmental fate of

heavy metals arising from a MSW incineration plant. Waste Manage-

ment 22 (8), 875–881.

Morselli, L., Bartoli, M., Bertacchini, M., Brighetti, A., Luzi, J., Passarini,

F., 2005. Tools for evaluation of impact associated to MSW

incineration: LCA and integrated environmental monitoring system.

Waste Management 25, 191–196.

PRe Consultants b.v., 2001. The Eco-Indicator 99. A damage oriented

method for life cycle impact assessment - Methodology Report and

Annex, 3rd ed., Amersfoort, NL.

PRe Consultants b.v., 2004. SimaPro 6 Database Manual – Methods

library, Amersfoort, NL.

Roth, L., Eklund, M., 2003. Environmental evaluation of reuse of by-

products as road construction materials in Sweden. Waste Manage-

ment 23, 107–116.

Riva, A., Morselli, L., Furini, M., 1998. LCA and LCI for the

management of municipal solid waste (MSW). Annali di Chimica –

Rome 88, 915–924.

Rumbold, D.G., Mihalik, M.B., 2002. Biomonitoring environmental

contaminants near a municipal solid-waste combustor: a decade later.

Environmental Pollution 117 (1), 15–21.

Solvay., 2001. US Patent 6171567, Process for the purification of a gas

containing hydrogen chloride, N. Fagiolini, Solvay.

Song, H.-S., Hyun, J.C., 1999. A study on the comparison of the various

waste management scenarios for PET bottles using the life-cycle

assessment (LCA) methodology. Resources, Conservation and Recy-

cling 27, 267–284.

Wilson, E.J., 2002. Life cycle inventory for municipal solid waste

management. Part 2: MSW management scenarios and modelling.

Waste Management and Research 20, 23–36.