Municipal solid waste composition determination supporting the integrated solid waste management sys

Country report

Municipal solid waste composition determination supporting the integrated solid waste management system in the island of Crete

E.Gidarakos *,G.Havas,P.Ntzamilis

Laboratory of Toxic and Hazardous Waste Management,Department of Environmental Engineering,

Technical University of Crete,GR-73100Polytechnioupolis Chania,Crete,Greece

Accepted 27July 2005

Available online 3October 2005

Abstract

A one-year survey was conducted in the greater region of Crete (located at the lower region of the Aegean Sea)for the purpose of identifying waste composition (including chemical and physical characterization),as well as any seasonal variation.

The investigation was carried out repeatedly at seven land?lls and one transfer station in Crete,in four phases.Each sampling phase corresponded to a season (autumn,winter,spring,summer).ASTM D5231-92(2003)standard method and RCRA Waste Sampling Draft Technical Guidance were used.Hand sorting was used for classifying the collected wastes into the following cate-gories:plastics,paper,metals,aluminium,leather–wood–textiles–rubbers,organic wastes,non-combustibles and miscellaneous.Further analysis included proximate and ultimate analysis of combustible materials.Metals such as lead,cadmium and mercury were also investigated.

The results show that there has been a signi?cant decrease of organic wastes during the last decade due to the increase of pack-aging materials,as a result of a change in consumption patterns.Three main waste categories were determined:organic wastes,paper and plastics,which combined represent 76%of the total waste in Crete.Furthermore,a high fraction of glass and a seasonal variation of aluminium indicate a strong correlation of waste composition with certain human activities,such as tourism.There is also a variation between the municipal solid waste (MSW)composition in the region of Crete (2003–2004)and MSW composition suggested in the National Solid Waste Planning (2000)[National Solid Waste Planning,https://www.360docs.net/doc/cd10366707.html,pletion and particularization of Common Ministerial Act 113944//1944/1997:National Solid Waste Planning,June 2000].

The results of this survey are to be utilized by the regional solid waste authorities in order to establish an integrated waste treat-ment site,capable of ful?lling the regional waste management demands.ó2005Elsevier Ltd.All rights reserved.

1.Introduction

The cornerstone of successful planning for a waste management program is the availability of reliable infor-mation about the quantity and the type of material being generated and an understanding about how much of that material that collection program managers can expect to prevent or capture.E?ective waste manage-ment through MSW composition studies is important for numerous reasons,including the need to estimate material recovery potential,to identify sources of com-ponent generation,to facilitate design of processing equipment,to estimate physical,chemical,and thermal properties of the waste and to maintain compliance with national law and European directives.The composition of generated waste is extremely variable as a conse-quence of seasonal,lifestyle,demographic,geographic,and legislation impacts.This variability makes de?n-ing and measuring the composition of waste more di?-cult and at the same time more essential.

0956-053X/$-see front matter ó2005Elsevier Ltd.All rights reserved.doi:10.1016/j.wasman.2005.07.018

*

Corresponding author.Tel.:+302821037789;fax:+302821037850.

E-mail address:gidarako@mred.tuc.gr (E.Gidarakos).

https://www.360docs.net/doc/cd10366707.html,/locate/wasman

Waste Management 26(2006)

668–679

In Greece several waste composition studies have been conducted in the past twenty years (Parisakis et al.,1990,1991,1992),but they were not carried out using the same method or under a systematic approach dictated by organized regional waste management strat-egies (Table 1).One can observe a correlation between demographic and socio-economic conditions of a region with the respective MSW composition data.Further-more,MSW composition data of National Planning for the year 2000are di?erent from respective data of more recent studies.In recent studies,for example in Salonica and Pylaia in 1998(Papachristou et al.,2002;Koufodimos and Samaras,2002),one can observe a sig-ni?cant decrease of putrescibles (food stu?,leaves,etc.)and a great increase of plastics and packaging material (see Table 1)(Papachristou and Chatziaggelou,1991;Papachristou et al.,2002;PERPA,1985).

The island of Crete (Fig.1)is one of the greatest tour-ist resorts in Greece (Table 2)and numbers almost half a million residents (2001).Furthermore,Crete is a combi-nation of urban,mountainous,rural and purely tourist regions.Heraklion,geographically located in the centre of Crete (Fig.2)with nearly 140,000residents,is the metropolis of Crete.Chania and Rethymnon lie in the west,and Agios Nikolaos in the east.Regions with high seasonal variability in population due to tourism are Her-sonisos and Malia,located east of Heraklion and west of Agios Nikolaos.Ierapetra,located south of Agios Niko-laos,quali?es as rural mainly because of the numerous greenhouses located there.Taking into account the above special characteristics of the island of Crete,one would expect that a special solid waste management strategy is implemented.Unfortunately,in past years,solid waste management in Crete has consisted mainly of illegal dumping.It was only in the last decade that the ?rst re-gional solid waste management strategy was designed and started being implemented in the region of Chania.According to Waste Framework Directive 75/442/EEC (EEC,1975),member states are obliged to take the necessary measures in order to ensure that the ?nal disposal or exploitation of waste is performed without endangering public health and without causing any damage to the environment.In its 1996Communication on the Review of the Community Strategy for Waste Management 1the EU Commission enacted the waste management hierarchy:prevention/minimization,reuse,recycling,energy recovery and safe disposal.It should be pointed out that this hierarchy is just a proposal and not a result of a detailed environmental and economic eval-uation of each alternative.Such an evaluation has to be performed so that the regional solid waste authorities are able to choose the appropriate management scheme.Essential primary data used in this evaluation are recentreliable waste composition data.

T a b l e 1M S W c o m p o s i t i o n (%)i n s o m e G r e e k r e g i o n s a n d c i t i e s (a d a p t e d f r o m P a r i s a k i s e t a l .),w e t w e i g h t

R e g i o n /c i t y :

A t h e n s 6/83-6/84

S a l o n i c a 4/86-3/87

S a l o n i c a 1998P y l a i a 1998

H e r a k l i o n 1987

R h o d e s 9/87-8/88K o s 1989C h a n i a 1990K o m o t i n i 1992–1993

X a n t h i 1992–1993

K a l a m a t a 1992N a t i o n w i d e p l a n n i n g 2000

P u t r e s c i b l e 595226.64152.542375567624747P a p e r 19.518292317.214

25199152520I n e r t +m i s c .4.5691011.8

5613

11

815.5

L W T R 3.58964546A l u m i n i u m 4

514

0.310

21330.54.5

M e t a l s 3.42.5333P l a s t i c s 77181314.312118677.58.5G l a s s

2.54

4

3

1.4

2

124

22

3

4.5

1

COM 96(399)?nal,30.07.1996.

E.Gidarakos et al./Waste Management 26(2006)668–679669

The primary goal of this study was to develop a rep-resentative,statistically defensible estimation of the waste composition for the region of Rethymnon,Herak-lion and Lassithi (Agios Nikolaos).A survey was con-ducted by the Department of Environmental Engineering of the Technical University of Crete,in the region of Rethymnon,Heraklion and Lassithi,for the purpose of identifying waste composition (including chemical and physical characterization),as well as any

seasonal variation.The sampling plan consisted of one-week sampling period in each of seven land?lls in the region of Crete and was carried out in four phases,corresponding to each season (winter,spring,and sum-mer,autumn)(see Table 2).

In comparing these data with composition data from other regions,certain variations can be observed,which can be attributed to speci?c social activities,such as tourism.This study can hopefully be used to establish a baseline for monitoring progress in achieving waste management objectives and to assist the regional solid waste authorities in setting future policy directions and management priorities.

As it was mentioned above,the geographical areas studied in this analysis are the Prefectures of:Rethym-non,Heraklion and Lassithi in the island of Crete (Fig.2).Regions of Chania and Sitia were excluded from this

study.

Fig.1.Region of Crete.

Table 2

Main characteristics of the study area

Rethymnon

Heraklion Lassithi Population a 81.976292.48957.290b Hotel beds c

24.857

52.616

19.846

a 2001National Census,www.statistics.gr .

b Sitia region excluded.

c

National Tourist Organization (NTO,2002),www.statistics.gr .

670

E.Gidarakos et al./Waste Management 26(2006)668–679

2.Materials and methods 2.1.Waste quantities estimation

The lack of essential equipment (weigh-bridges)at each ?nal disposal site makes the direct determination of disposed waste quantities impossible.Therefore,there is no information on generation rates as a function of season.The estimation of generated quantities of MSW (kg/resident/day)is based on previous studies (Technical Chamber of Greece,1993;OANAK,2000),on o?cial National Census data (2001),as well as on National Tourism Organization (NTO)data for the years 2001/2002.As mentioned above the regions of Si-tia and Chania were not studied.

In this survey the generated MSW quantities in each municipality of the study area were estimated according to the following assumptions:

For communities with population less than 10,000residents:0.8kg MSW per resident per day.

For communities with population more than 10,000residents:1kg MSW per resident per day.

For the Municipalities of Rethymnon,Agios Niko-laos and Ierapetra:1kg MSW per resident per day. For Heraklion:1.2kg MSW per resident per day.

The assumption made for the largest municipalities is based mainly on the Regional Planning of Solid Waste Management for the Prefectures of Rethymnon,Lassithi and Heraklion.

Apart from these quantities,the daily quantities of MSW due to tourism will be taken into account.For the estimation of the number of tourists,o?cial data of NTO are used.The aim of this study was not to verify the reliability of NTO data and therefore these data were accepted as the only available o?cial information.

The estimation of these quantities was carried out using the following data:

The total number of tourist beds in each municipality or community.

The number of tourist beds in use (fullness).

The mean produced quantity of MSW per tourist per day (=1.2kg/tourist/day).

It must be noted that the considered mean produced quantity of MSW per tourist per day is overestimated in an e?ort to take into account unregistered rooms to let (not included in the o?cial NTO data,being used by tourists,visitors,

etc.)

Fig.2.Island of Crete study area (sampling sites are marked with an ‘‘X’’).

Table 3

MSW production estimation for the Prefectures of Rethymnon,Heraklion and Lassithi (2001national census,2001–2002National Tourist Organization data)County

Population

MSW

production (kg/d)MSW

production (ton/y)MSW production from tourists (kg/d)MSW production from tourists (ton/y)Total MSW production (kg/d)Total MSW production (ton/y)Rethymnon 81.97671.37826.05324.113 5.064105.04034.228Heraklion 292.489289.522105.67652.93611.117376.704128.471Lassithi 57.29066.30124.20016.670 3.50175.49930.471Total

431.755

427.201

155.928

93.719

19.681

557.243

193.170

E.Gidarakos et al./Waste Management 26(2006)668–679671

2.2.Waste composition analysis

Sampling was carried out at several?nal disposal sites(land?lls)around Crete,according to international standard ASTM D5231-92(2003),2and RCRA regulation.3

The determination of the mean composition of MSW was based on the collection and manual sorting of a number of samples of waste over a selected time period covering one week for each season and site.Therefore, four phases of seven sampling weeks(twenty eight weeks in total)were carried out.

Vehicle loads of waste were designated for sampling, and a sorting sample was collected from the discharged vehicle load.The sample was sorted manually into waste components.The weight fraction of each component in the sorting sample was calculated by the weights of the components.The mean waste composition was calcu-lated using the results of the composition of each of the sorting samples.

Vehicles for sampling were selected at random dur-ing each day of the one-week sampling period,as to be representative of the waste stream.According ASTM D5231-92,for a weekly sampling period of k days,the number of vehicles sampled each day should be approximately n/k,where n is the total number of vehicle loads to be selected for the determination of waste composition.A weekly period is de?ned as5 days.

According ASTM D5231-92,the number of sorting samples(that is,vehicle loads(n)required to achieve a desired level of measurement precision)is a function of the component(s)under consideration and the con?-dence level.The governing equation for n is as follows: n?et?s=exT2;e1Twhere t*is the student t statistic corresponding to the desired level of con?dence,s the estimated standard deviation,e the desired level of precision,and x is the estimated mean.

Suggested values of s and x for waste components are listed in Table6.Values of t*are given in statistical ta-bles.Table6is the result of one-week sampling at Pera Galinoi land?ll(Fig.2),performed by the investigators, prior to the main sampling period.

Each sorting sample weighed91–136kg and was pre-pared properly(mixed,coned and quartered)from each discharged MSW vehicle load using a front-end loader with at least a1m3bucket.

After sampling,hand sorting was applied for the clas-si?cation of MSW into the following categories:

Organics:

–Paper(all kinds,magazines,newspapers,books, packaging materials,cardboard).

–Putrescibles(food waste,yard waste,leaves).

–Plastics(PVC,PET,HDPE,LDPE,others).

–LWTR(leather,wood,textiles,rubber).

Inorganic:

–Glass(all kinds and colours).

–Metals(all kinds except aluminium).

–Aluminium(all kinds).

–Inert materials(stones,ground,construction and demolition wastes).

Miscellaneous(nappies,sanitary napkins,materials that do not?t in any of the above categories).

Prior to the sampling,land?ll sites were ranked according the following speci?cations:

1.Percentage coverage of urban-tourist and mountain-

ous-rural regions.

2.Total sample size>75%of total MSW production in

the study area.

3.Sampling in regions where a great production

of recycling materials(e.g.,Hersonisos)is expected.

4.Availability of each land?ll during the sampling

period.

According to these requirements,the following sam-pling sites were selected:

Rethymnon Prefecture:

–Amari S.A.sanitary land?ll.

–Maroulas sanitary land?ll.

Heraklion Prefecture:

–Pera Galinoi land?ll(Autumn)and Heraklion Transfer Station(Winter).

–Kazantzakis sanitary land?ll.

–Hersonisos sanitary land?ll.

Lassithi Prefecture:

–Ierapetra land?ll.

–Agios Nikolaos sanitary land?ll.

The above sampling sites appear in Fig.2and are marked with an‘‘X’’.

The laboratory analyses of MSW included:

Proximate analysis:The determination of%moisture content,%ash content,%volatile matter content and the calculation of%?xed carbon.The above analyses were conducted according to ASTM standards E790, E830and E897.

2Standard test method for determination of the composition of

unprocessed municipal solid waste.

3Waste Sampling Draft Technical Guidance,EPA,530-d-02-002.

672 E.Gidarakos et al./Waste Management26(2006)668–679

Elemental analysis:The determination of%content in carbon(C),hydrogen(H)and nitrogen(N).The analyses were conducted according to ASTM stan-dards E777and E778.

Calori?c value determination:According to ASTM standard E955or with other international standard. Heavy metal content determination.

The laboratory sample consisted of four sub-samples: putrescibles(food waste),LWTR,plastics(packaging materials,bottles,etc.)and papers(paper,cardboard ex-cept sanitary papers).The quantity of each fraction was 200–500g according to New Zealand Ministry for the Environment guidelines(Ministry for the Environment, 2002).For the temporary storage and transport of each sample to the laboratory,water-proof sealed bags were used(USEPA,2001,2002).The time interval between col-lection and analysis was1–4h.For the preparation of lab-oratory samples,necessary safety equipment(gloves, masks,goggles)was used,while size reduction of materi-als was achieved using knives and scissors(hand work)so that the moisture content of waste was not a?ected.

For the size reduction a cutting mill(type P-19with cyclone separator,Fritsch GmbH,Germany)was used. Moisture content determination became feasible after 24h of solid waste sample drying(105°C)in an oven (type Jouan EU2118,Innovens).For volatile matter (at950°C)and ash(at550°C)content determination, a furnace capable of high($1200°C)temperatures(type L24/12with control panel B170,Nabertherm)was used. Elemental analysis was performed using an automatic elemental analyser(type CHN600,LECO).The calo-ri?c value of solid waste samples was determined by using a bomb calorimeter(type AC300,LECO).The heavy metal content of samples was determined by?ame atomic-absorption spectroscopy(AAS)(C.A.U.GmbH, Germany).3.Results

3.1.Estimated waste quantity

The estimation of MSW production and disposal in the study area is shown in Table3.Assuming that monthly MSW production from permanent residents is constant,we can assess how tourism a?ects the monthly MSW production.During‘‘high season’’months(months with increased number of tourists),in-creased MSW quantities are produced(tourism e?ect, Fig.3).

3.2.Waste composition

The results of the waste composition analysis for the period2003–2004are shown in Figs.4and5.Fig.6is used to compare current analysis results(mean values) with respective results in other regions of Greece.

Three main waste categories can be identi?ed: Putrescibles Papers and Plastics(P3Dominance),which share about76%of total MSW.Putrescibles represent 39%,while plastics and paper are second with17%and 20%,respectively.The share of glass(7%)is also con-siderable,mainly consisting of disposable(not re?ll-able)bottles.Especially in tourist regions such as Hersonisos and Malia,the glass share reached18%in autumn.

Inert materials are particularly low(2%),as construc-tion and demolition wastes(C&D wastes)are trans-ported to separate disposal sites.

A great seasonal variation in the glass fraction(au-tumn and summer>6.5%,winter$4%),mainly in re-gions of intense tourist activity(e.g.,Hersonisos with peak value$18%)was identi?ed.It was also found that there is an extended use of non-re?llable,non-returnable bottles(e.g.,bottles of low alcohol drinks).

Table4

Laboratory analysis of MSW(mean values a)

Putrescibles LWTR b Plastics Papers Total RDF c %Moisture66.9921.41 2.9317.1136.7211.65 %Ash9.728.86 2.397.077.30 5.31 %Volatile matter76.6983.8794.9584.0983.1988.63 %Fixed carbon13.607.27 2.678.849.52 6.07 C(%)45.5644.9979.5344.4953.0059.20 H(%) 6.24 6.0110.64 6.587.328.22 N(%) 2.290.550.460.57 1.320.52 HHV(kJ/kg) 6.15014.12938.63114.10616.13924.414 LHV(kJ/kg) 4.56312.77136.22812.62214.40822.558 Pb(ppm)na na na na16.7na

Cd(ppm)na na na na0.07na

Hg(ppm)na na na na0.02na na,not available.

a Dry weights.

b Leather,wood,textile,rubber.

c Refuse derive

d fuel,consists of paper,plastics and LWTR fractions.

E.Gidarakos et al./Waste Management26(2006)668–679673

There is also a great seasonal variation for the alu-minium fraction (autumn and summer $2%,winter <1%).Its absolute value is similar to the one in other re-gions in Greece (Fig.7).

Comparing the winter and summer periods,there is a signi?cant decrease in the concentration of papers ($23%),while metals ($3.5%)bulky materials and old cars (end-of-life vehicles)concentrations are not present.Furthermore,in Ierapetra,where there is an extensive use of greenhouses,there is a great seasonal variation of plastics share in MSW.This variation was named ‘‘green e?ect’’(Fig.8).

The ‘‘miscellaneous’’fraction in MSW is the result of the co-mixture of organics (putrescibles)with other fractions.

Furthermore,a comparison of the MSW composi-tion in the region of Crete (2003–2004)and the MSW composition suggested in the National Solid Waste Planning (2000)demonstrates a great

variation.

Fig.3.Monthly variation of MSW production (tourism e?ect),wet

weight.

Fig.4.Waste composition analysis (annual),wet weight.

674 E.Gidarakos et al./Waste Management 26(2006)668–679

As far as the proximate analysis is concerned,a resemblance(HHV,LHV,%moisture content)and a lower value of C/N ratio(20.4)in compari-son to other regions in Greece(Chania,Kos) was found.

The heavy metals content did not present any remarkable di?erence compared to the one available for Chania or Kos(Tables4and5).

Speci?c gravity of waste was determined to be130–135kg/m3,showing no considerable

variance.

4.Discussion

According to the ASTM D5231-92(2003)standard method,a full year of sampling at several ?nal disposal sites around Rethymnon,Heraklion and Lassithi was conducted (see Table 6).

This test method is applied for the determination of the mean composition of MSW based on the

collection

676 E.Gidarakos et al./Waste Management 26(2006)668–679

and manual sorting of a number of samples of waste over a selected time of period covering a minimum of one week.This test method includes procedures for the collection of a representative sorting sample of unprocessed waste,manual sorting of the waste into individual waste components,data reduction,and reporting of the results.

This test method may be applied at land?ll sites, waste processing and conversion facilities,and transfer stations.Its level of con?dence and precision values are,respectively,90%and0.1%.

Current studies results are related to each region sam-pled.A higher share of putrescibles was found in rural regions,whereas a higher share in papers and plastics was determined in urban regions.

Some useful remarks can be noted by observing study results:

There is a clearchange in waste composition during the last decade.

There is a strong relationship between certain social activities(e.g.,tourism)and MSW composition.

There is a variation in the MSW composition among di?erent regions of the country.

There is a variation between National Solid Waste Planning and the current situation in Greece regard-ing the MSW composition.

Speci?cally,while in the previous decade(1985–1995, Table1)the putrescibles share was about55–67%,in re-cent years(1995–2003,Table1,Fig.7)this share has de-creased to27–41%,while National Solid Waste Planning (2000,Table1)suggests a concentration of47%.

Comparing the two decades,a40%decrease of putrescibles share can be observed.This reduction can be explained by an increase of plastic and paper concen-trations.In the previous decade(1985–1995)papers ac-counted for no more than20%and plastics for less than 10%.In contrast,recent studies(1995-current)suggest that papers now comprise25%and plastics percentage doubled reaching20%.This represents an increase of 25%for paper and100%for plastics,or60%in total. In the most recent studies(Salonica1998,Pylaia1998 and Cretan Region2003–2004),there is also an increase in packaging materials.This change is not only a result of the prevailing consumption patterns,but also an out-come of modern practices for marketing of products and goods.

The main point of this study is P3Dominance (Putrescibles,Papers and Plastics)which share in total about76%of MSW.Papers and plastics comprise to-gether about37%or71,000tonnes per year of MSW. This relatively high share of plastics and papers in Crete can be attributed to the extensive use of paper packaging

Table5

Physicochemical analysis of MSW in the region of Crete and in other regions

Region of Crete a Municipality of Chania Municipality of Kos Municipality of Pylaia

%Moisture content36.7b40.830.140.6

%Ash content7.21 3.7 3.9 6.2

HHV(kJ/kg)

Putrescibles 6.6297.0637.410 4.892

Paper14.106––12.037

Plastics38.155––32.617

LWTR13.733––15.617

LHV(kJ/kg)

Putrescibles 5.237 5.524– 1.486

Paper12.621––10.123

Plastics35.702––29.003

LWTR13.069––13.810

C/N20.429.3–25.36

Lead(Pb)(ppm)16.821.4B(d)16.8C(d)7.6

Cadmium(Cd)(ppm)0.070.6B(d) 1.5C(d)0.4

Mercury(Hg)(ppm)0.02–––

d,dry fraction;B,analysis aiming to biological stabilization;C,analysis aiming to combustion.

a Prefectures of Rethymnon,Heraklion and Lassithi,2003–2004.

b Calculation based on mean values of moisture content in each laboratory analysis sub-sample and the%share of each fraction in MSW as determined by?eld analysis.

Table6

Values of mean(x)and standard deviation(s)for within-week

sampling to determine MSW component composition(Pera Galinoi

land?ll,Heraklion,Crete,2003)

Component Standard deviation(s)Mean value(x)

Inert0.46 1.93

Metals 1.79 4.44

Aluminium0.66 3.01

Glass0.52 4.58

LWTR 1.22 3.60

Paper 6.7419.71

Putrescibles 1.9635.45

Plastics 5.6122.49

Misc. 1.33 4.79

E.Gidarakos et al./Waste Management26(2006)668–679677

materials(especially in summer)and mass production of greenhouses wastes(plastic?lms).

The concentration of plastics is higher in winter and autumn(Fig.8),likely as a result of the extensive use of plastics in greenhouses construction.Greenhouses are the major waste producers in Crete(as far as plastics are concerned)and that is why the Municipality of Iera-petra(where most greenhouses are constructed)pro-duces by itself more than30%of the total MSW in Lassithi Prefecture(Fig.6).

The concentration of papers in the Municipality of Agios Nikolaos is also high,as a result of high levels of tourist activities(hotel accommodation,paper pack-aging materials like tetrapak,etc.).

In regions of intense tourist activity(Prefectures of Rethymnon,Heraklion and Lassithi),this study also re-vealed an increased share of glass.Speci?cally,glass reached7%,while in mainly tourist regions,such as Her-sonisos and Malia,it was18%.In comparison,a recent study of Salonica(1998)showed glass share to be about 3%.This di?erence may be explained by the fact that the ratio between the number of tourists and the permanent population is considerably lower in Salonica than in Her-sonisos.Furthermore,glass bottles(e.g.,juices,beer)that are consumed in non-tourist regions are mainly re?llable, while in Hersonisos signi?cant quantities of non-re?llable bottles(mainly low-alcohol drinks)are consumed.

Moreover,it is obvious that modern living standards considerably a?ects MSW composition.For example, in the rural region of Rodopi(Komotini,1993,Fig.1) the putrescibles share is67%while in the metropolis of north Greece,Salonica(1998),it is only27%.The putres-cibles concentration in the region of Crete(2003–2004)is 39%(annual mean value).The same e?ect of the living standards on MSW composition is also observed among the various municipalities of Crete.For example,in the region of Nikos Kazantzakis municipality,a region mainly rural,the putrescibles fraction is almost45%.

Comparing the region of Chania(Chania,1990)with the results of this study,an important di?erence in MSW composition can be noticed.Speci?cally in1990 the putrescibles concentration in Chania region reached 55%,while the corresponding concentration for the re-gions of Rethymnon,Heraklion and Lassithi is now about39%.Taking into account the fact that between the four regions of Crete there are not any important di?erences regarding the total socio-economic character-istics,one can claim that in Crete,in the last decade,the putrescibles content has decreased considerably.This is in accordance with the total change of MSW composi-tion for the whole country that was reported previously.

Furthermore,the highest putrescibles share(41.3%)is observed at Lassithi Prefecture,likely because of the greenhouses operation(not sold putrescibles quantities).

Also,the information published by the National So-lid Waste Planning(2000)presents an important di?er-ence from the results of newer studies(Salonica1998, Pylaia1998and Region of Crete2003–2004).Therefore, the MSW composition that is suggested in the National Solid Waste Planning is not suitable for direct applica-tion in Crete,as it does not consider the local peculiar-ities and social characteristics of the area or the seasonal variations(tourist period).

In order to compare MSW laboratory analysis data with respective data from other regions of Greece,the Municipalities of Chania,Kos and Pylaia(Fig.1)are used.The?rst two municipalities perform in similar way with the region studied,regarding the activities of MSW production,as they are mainly tourist attractive regions.The comparison with the Municipality of Pylaia is useful to test whether di?erent activities and consump-tion patterns and habits are the cause of di?erences in MSW composition.

No di?erences can be identi?ed between the region of Crete(2003–2004)and the region of Chania(1990)(and partly the region of Kos)regarding the MSW calori?c value(HHV and LHV)and the moisture content.The C/N ratio in the region of Crete(2003–2004)has a lower value compared to other regions.The heavy metals con-tent(Pb,Cd and Hg)does not present any remarkable variations between the di?erent studied regions.

5.Conclusion

This study was carried out in order to establish up-to-date waste composition data for local solid waste authorities.

This analysis revealed that in the study area(Rethym-non,Heraklion and Lassithi),there is a strong correla-tion between certain social activities and solid waste composition and quantity.The main activities reviewed in this study are tourism and cultivation.During‘‘high season’’months(months with increased number of tour-ists),not only are increased MSW quantities produced, but also MSW composition is accordingly altered.High fractions of materials like aluminium cans and glass bot-tles(especially non-re?llable ones)and paper and/or plastics packaging materials are representative charac-teristics of intense tourist activities and greenhouses operation in the area.This double impact phenomenon (quantity and quality)was named‘‘tourism e?ect’’and ‘‘green e?ect’’(Figs.3and8).This relationship is a peculiarity of tourist regions and as a result,solid waste authorities have to consider it in Integrated Solid Waste Management Planning.

Of course,tourism and greenhouses are not just a Greek problem,but they are an international one,too. There are still a lot of illegal dumping sites in Greece and Europe,and therefore this methodology and the re-sults of this study are a valuable tool to every solid waste manager.

678 E.Gidarakos et al./Waste Management26(2006)668–679

Comparing the MSW composition data from the present study with other regions?data,various MSW composition changes can be identi?ed.Putrescibles con-centration decreased and papers–plastics concentration increased during the last decade.Moreover,composi-tion data shows a di?erence between various regions in Greece(rural and urban).

In addition,there is a disparity between MSW com-position in the region of Crete(2003–2004)and MSW composition suggested in the National Solid Waste Planning(2000).This is observed not only in the putres-cibles and plastics fractions,but also in materials that seem to have an important seasonal variation in the re-gion of Crete(e.g.,glass).Hence,MSW composition data of National Solid Waste Planning cannot be ap-plied in the region of Crete or in other regions with sim-ilar characteristics to Crete.

This study is the?rst integrated study in Greece,con-ducted in such a great number of?nal disposal sites. Moreover,it was conducted at various types of?nal dis-posal sites(sanitary or not)and transfer stations,so that this study can be utilized in other areas nationally or internationally.

In order to accommodate this study,weigh-bridges have to be installed and used at every?nal disposal site, so that there is a continuous data logging of waste quan-tities produced.The present study is the?rst step to-wards an Integrated Solid Waste Database for the region of Crete.

Acknowledgement

The?nancial support of the United Association of Waste Management of Crete(E.S.D.A.K.)is greatly acknowledged.

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