Waste Management 29 (2009) 1158–1162
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Perspectives for integrated municipal solid waste management in Thessaloniki, Greece E. Papachristou, H. Hadjianghelou, E. Darakas *, K. Alivanis, A. Belou, D. Ioannidou, E. Paraskevopoulou, K. Poulios, A. Koukourikou, N. Kosmidou, K. Sortikos Laboratory of Environmental Engineering and Planning, Division of Hydraulics and Environmental Engineering, Department of Civil Engineering, Aristotle University of Thessaloniki, GR-541 24 Thessaloniki, Greece
a r t i c l e
i n f o
Article history: Accepted 14 April 2008 Available online 14 July 2008
a b s t r a c t Local authorities need updated and reliable data on the quantity and the quality of the waste generated in their area, in order to establish an integrated solid waste management system capable of fulﬁlling regional and national waste management targets. This paper presents information about the quantity and the characteristics of the municipal solid waste generated in Thessaloniki, which is the second largest city in Greece. It is based on the results of three research programs investigating the evolution of municipal solid waste. The investigations were carried out over the last 20 years at the landﬁll of Thessaloniki by the same research group using statistically acceptable practices for sampling and hand sorting. The results show a great increase in the incoming quantities during the last years and a signiﬁcant increase of the per capita generation. There is also a signiﬁcant change in the composition, demonstrated mainly by a decrease in the organic fraction followed by an increase of packaging materials (paper and plastic). Ó 2008 Elsevier Ltd. All rights reserved.
1. Introduction 1.1. The situation in Greece Municipal solid waste (MSW) management in Greece is not yet as developed as in many EU-15 countries. Land disposal is still the predominant method for managing MSW. Of the total amount of municipal solid waste, approximately 8% is recycled at the source and the remaining 92% is disposed without prior treatment. Of the disposed waste, 40% is dumped in non-engineered sites, whereas the remaining 52% is disposed in sanitary landﬁlls. Of household waste, 85% is subject to organized collection and transportation; the other 15% is generated in the mountainous and island areas where collection and disposal are not performed properly (Papaioannou and Economopoulou, 2004). Municipalities are mostly responsible for collection, treatment and ﬁnal disposal of the MSW. The quantity of solid waste generated in Greece continues to be somewhat lower than in other European countries, reﬂecting less intense consumption patterns (Papaioannou and Economopoulou, 2004). In 2000, approximately 4.6 million ton of MSW was generated in Greece, which is an increase of 50% compared to 1990. The greater area of Athens contributed approximately 39%, and the city of Thessaloniki contributed approximately 9% of the total amount
* Corresponding author. Tel.: +30 2310 995719. E-mail address: [email protected]
(E. Darakas). 0956-053X/$ - see front matter Ó 2008 Elsevier Ltd. All rights reserved. doi:10.1016/j.wasman.2008.04.015
of MSW generated in Greece (Papaioannou and Economopoulou, 2004). According to the National Waste Management Planning, MSW in 2000 consisted of 47.0% organic material, 20.0% paper, 8.5% plastic, 4.5% metal, 4.5% glass and 15.5% other waste (National & Regional Solid Waste Planning, 2003). In the same year, the quantity of recyclable materials (potentially available for separate collection) was estimated at 1.5 million ton, corresponding to 37.5% by weight of the total MSW, 21% of which (i.e., 975.000 ton) was packaging material (Ministerial Act 50910/2727, 2003). Presently, the main policy orientation in Greece is the maximization of material recovery through the implementation and extension of recycling programs with source separation in all the large municipalities of Greece, in addition to the construction of material recovery facilities. Absolute priority is given to the gradual phasing out of the non-engineered and uncontrolled dumpsites and the remediation of the major ones. Construction of new sanitary landﬁlls, as in Thessaloniki, is already under way. 2. Description of study area and sampling methodology Thessaloniki is the second largest city in Greece located in the northern part of the country. The population in the greater Thessaloniki area is approximately 1,100,000, with a high population density in most of the municipalities. The entire area is served by one sanitary landﬁll, which has been operated by the Association of Local Authorities of Greater Thessaloniki for the last 25 years. The
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landﬁll is located 35 km southeast of Thessaloniki. The total area of the landﬁll is approximately 100 ha, and its main part is already covered. Over the last 20 years, three MSW characterization studies were conducted by a joint research team of scientists from the University of Thessaloniki and experts from the Association of Local Authorities, in order to provide accurate ﬁeld data on the MSW quantities and composition. The studies were all performed at the landﬁll and were based on sampling and consequent manual sorting. The scope of the study was municipal solid waste, i.e., waste collected from municipalities, which includes waste from households and businesses generated within the study area. Furthermore, only waste from category 20 of the European Waste Catalogue was included in the sample taken for hand sorting. The ﬁrst study (study 1) took place from April 1986 to March 1987 and was one of the ﬁrst MSW characterization studies conducted in Greece. Weekly sampling was undertaken, and as a result a total of 53 samplings took place. Samples were taken from 15 selected collection vehicles and combined into a ﬁnal composite sample. The composite sample was subsequently hand sorted into the following categories: compostable organics (mainly food and plant waste), other organic (LWTR) (leather, wood, textiles and rubber), paper, plastic, glass, metals and inert material (soil, stones, bricks, etc.). The second study (study 2) was conducted 10 years later, during the period 1998–1999. Quantity and composition were measured in order to be used in a new MSW management plan, set up by the Association of Local Authorities of Greater Thessaloniki (Papachristou et al., 2002). The sampling program was based on Random Uniform Sampling. Between December 1998 and December 1999, 54 samples were collected and analyzed. The sampling was conducted weekly following a rolling schedule based on days of the week, i.e., starting with monday in the ﬁrst week, tuesday in the second week, etc. and covered a 1 yr period. Samples were taken from the daily cell, representing 80% of the incoming amount a day. Bulky objects and special waste, e.g., hospital waste, chemicals, sewage sludge, debris, etc. were excluded. On each sampling day, from 08.30 am to 12.00 pm in evenly distributed intervals, an excavator collected 16 bucketfuls of waste from the working front where the waste was dumped. A total sample of 32 m3 was compiled in this way, which was thoroughly mixed before the ﬁnal representative waste sample was taken. The representative waste sample was then placed into a 1 m3 bucket and any material sticking out of the bucket was removed. The remaining material in the bucket was hand sorted into the main categories used in study 1. Aluminum (mainly cans) was sorted separately, and another fraction of materials like plastic-coated paper, diapers, tetrapack, etc. (named ‘‘total others unclassiﬁed”) was also separated.
Two laboratory samples were taken, one from the organics fraction and one composed from the combustible materials, i.e., LWTR, paper, plastic and total others unclassiﬁed, according to their respective percentages in the hand sorting results. The laboratory analyses of the MSW included determination of moisture content, ash content (I), volatile matter content (W), carbon (C), hydrogen (H), nitrogen (N), higher heating value (Ho) and lower heating value (Hu). All of the analyses were conducted according to ASTM standard methods. Elemental analysis of carbon, hydrogen and nitrogen was performed using an automatic elemental analyzer. The caloriﬁc value was determined according to ASTM standard E955. The lower heating value was determined using Eq. (1)
Hu ¼ H o
100 ðI þ WÞ —5:85 W kcal=kg 100 W L
where Hu is the lower heating value, Ho is the higher heating value, I is the content (%) in ash, W is the content (%) in volatile matter, WL is the relative moisture of the environment (negligible). The heavy metals (Pb, Cd, Cu, Ni) content in the organics fraction was determined using a Perkin-Elmer Model 372 atomic absorption spectrophotometer equipped with a graphite furnace (Perkin-Elmer Model HGA 300). In order to implement the recent Regional Waste Management Planning, a new investigation (study 3) was conducted in 2005– 2006 in the greater area of Thessaloniki, aimed at identifying waste composition and possible changes since the previous study. The methodology applied for this investigation was similar to that applied in 1998–1999, as described above. A total of 12 samples were collected. This study focused on more hand sorting categories, especially packaging waste, taking into account new legislation for the separate collection and treatment of this waste stream. This was the ﬁrst attempt to sort and classify packaging materials separately in Greece. In the same time, the quantities of the separately collected recyclables were recorded. 3. Results and discussion 3.1. Quantities and ‘‘unit per capita” generation of solid waste Systematic weighing of all loads incoming at the landﬁll of Thessaloniki has been practiced since 1986. The evolution of the incoming quantities is presented in Fig. 1. The population of Thessaloniki, based on census data, the incoming quantities and the estimated per capita MSW generation are shown in Table 1. The amounts are compared to the European Union average and recent studies on MSW composition in Pilea (a suburb of Thessaloniki) and Heraklion (Crete) (Gidarakos et al., 2006; Koufodimos and Samaras, 2002).
800000 700000 600000 500000 400000 300000 200000 100000
YEAR Fig. 1. Incoming quantities of solid waste at the landﬁll of Thessaloniki.
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Table 1 Generation of MSW in Thessaloniki, Pilea, Heraklion and EU Area
Thessaloniki (greater area)
EU (27 countries)
Year Population (kg/person/yr)
1987 750,000 280
1999 28,000 343
2004 106,000 438
2004 – 518
1998 1,000,000 460
2006 1,100,000 560
Mixed packaging waste 7.3%
3.2. Composition of MSW in Thessaloniki
The average (% by weight) composition from each of the three studies is presented in Table 2. The changes in the main categories (1987–2006) are presented in Fig. 2. Results show signiﬁcant differences between the ﬁrst two studies, particularly a decrease in the organics fraction, and an increase in paper and plastic. On the other hand, there are no signiﬁcant differences between the second and third studies. The average composition of the MSW in Thessaloniki is similar to that of other European cities with a similar population. The more detailed MSW classiﬁcation, including packaging waste, conducted during 2006 provided information about the
Fig. 3. Composition of packaging waste (% by weight) in Thessaloniki, 2006.
fraction of these speciﬁc waste subcategories which are considered to be crucial when planning further treatment and disposal of waste. The packaging waste was approximately 38% of the total waste stream. Plastic and paper were the main packaging materials followed by mixed packaging materials, glass and metals. The composition of packaging waste in Thessaloniki in 2006 is presented in Fig. 3, while the percentage of the packaging materials in the speciﬁc categories is shown in Fig. 4.
Table 2 Composition (% by weight) of Thessaloniki’s MSW Category
Food rests, plants, yard waste Leather, wood, textiles, rubber
Packaging paper Ofﬁce paper Other paper
13.07 6.95 5.84 25.86
17.55 2.16 19.71
2.53 1.13 3.66
0.40 0.26 1.67 1.05 3.39
2.77 2.92 5.60
Packaging plastic Other plastic
Packaging glass Other glass
Packaging aluminum Other aluminum Packaging (other metals) Other metal items
Total metals Inert materials
Soil, stones, bricks, cement, etc.
Packaging mixed materials Other mixed materials
Total mixed materials Unclassiﬁed materials including hazardous waste
Dye, ink, batteries, medicines, solvents, etc.
60.0% 50.0% 40.0% 30.0% 20.0% 10.0% 0.0% Organics
Fig. 2. Average composition (% by weight) of Thessaloniki’s MSW (development 1987–2006).
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100% 90% 80% 70% 60% 50% 40% 30% 20% 10% 0% Plastics
Fig. 4. Packaging waste by category (% by weight) in Thessaloniki, 2006.
During 2006, recycling programs applied by the Association of Local Authorities of Greater Thessaloniki yielded approximately 6000 ton of paper, 950 ton of glass, 170 ton of plastics and 19 ton of aluminum. Ten years ago the respective quantities were approximately 4000 ton of paper, 16 ton of plastic, 47 ton of glass and 4 ton of aluminum. Although there has been a signiﬁcant increase in the quantities collected, the absolute numbers show that the recycling targets have not yet been achieved. 3.3. Physical–chemical characteristics The results (mean values) of the physical–chemical characteristics derived from the laboratory analyses in 1998 and 2006 are presented in Table 3. The physical and chemical characteristics indicate that the MSW is suitable for energy recovery. The high concentration of paper, plastic and other combustible materials showed incineration as a feasible solution, as well as RDF production. The values of the relevant parameters (combustible materials, ash and volatile matter) are placed within the area of ‘‘self-sustaining combustion” in the Tanner diagram. The composting potential of the organic waste stream depends on the chemical characteristics and the moisture content that deﬁne the quality of the produced compost. The chemical characteristics that affect the quality are the concentration of carbon and nitrogen and consequently the C/N ratio. The analysis showed that the average C/N ratio of the organic waste fraction was 27, i.e., suitable for composting (ratios over 30 and below 15 are not appropriate). Nevertheless, a speciﬁc investigation concerning the market for the composting product is always necessary.
Table 3 Analyses of MSW in Thessaloniki during 2006 (mean values) Parameter
Moisture (%) Ash (%) Higher heating value (Ho) (kJ/kg) Lower heating value (Hu) (kJ/kg) C (%) H (%) N (%) C/N (%) Pb (mg/kg) Cd (mg/kg) Cu (mg/kg) Ni (mg/kg)
Average mean values (wet weight) 1998
24.9 17.2 21,305 12,418 39.82 5.7 1.8 22.1 17.4 0.5 21.3 32.9
27.7 29.0 21,580 8420 43.6 5.9 1.8 27.0 18 0.1 31 36
4. Conclusions The European Union policy and legislative framework, national legislation and local conditions set high standards for waste management demanding high recycling rates and overall environmental protection. During recent years, local authorities have shown great interest in waste management. Several innovative policies aimed at sustainable development have been implemented, but some ﬁnancial and organizational problems are still to be faced. Decision makers must try to ﬁnd solutions that will satisfy both the environmental and economic criteria. The development of an integrated waste management system must be adapted to the social, economic and climatic conditions of the area. The system design and development must be based on the analysis, evaluation and pilot implementation of different waste collection and treatment methodologies addressing both MSW and special waste (e.g., hazardous waste) produced by small and medium enterprises. The full spectrum of the waste stream generated must be examined, as well as the possibility for source separation and recycling of household waste, especially fractions that need special attention: garden waste, bulky waste, construction and demolition waste, animal waste, batteries, hazardous waste, etc. In the case of Thessaloniki, the analysis of the quantities generated showed a signiﬁcant increase in MSW generation during the last 20 years, which tripled from 1987 to the present day. This has led to an increase of MSW management expenses (i.e., staff, equipment and monitoring systems for environmental control). Additionally, it is leading to the shortening of the actual service life of the existing landﬁll site, especially if alternative treatment options cannot be found. Even though there has been a tendency for stabilization of the incoming quantities at the landﬁll of Thessaloniki since 2002 (Fig. 1), it is obvious that waste must be effectively reduced both in terms of quantities and environmental impact. The increase in per capita MSW generation is due to changes in living standards and consumption patterns, which involve more packaged goods and a general tendency towards throwing away rather than reusing or repairing products. The composition of MSW is the most crucial factor affecting possible disposal solutions, since the organics fraction determines the viability of composting, while the paper and plastic fractions determine the feasibility of recycling or incineration. The results show a signiﬁcant decrease over time of the organic waste percentage due to the increase of paper and plastic; 20 years ago the predominant category was organics whilst today there are three major categories, i.e., paper, organics and plastic. This has been conﬁrmed in the last two investigations (1999 and 2006).
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This indicates a disparity between MSW composition in Thessaloniki and the typical composition suggested by the National Solid Waste Planning ﬁve years ago, hence updated results of the recent studies should be considered. The evaluation of the composition of Thessaloniki’s MSW showed high percentages in packaging materials and sufﬁcient fractions of other recyclables. The implementation of integrated recycling programs to recover materials such as paper, plastic, glass and metals must be intensiﬁed. Acknowledgement This research study was funded by the Association of Local Authorities of Greater Thessaloniki, whose contribution the authors gratefully acknowledge.
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