Use of Multicriterial Decision Analysis to Optimize Integrated Municipal Solid Waste Management, Taking Into Account Air Pollution Issues: the Case Study Athens

Use of multicriterial decision analysis to optimize integrated municipal solid waste management, taking into account air pollution issues: the case study Athens

A. Karagiannidis, N. Moussiopoulos Laboratory of Heat Transfer and Environmental Engineering,

Aristotle University Thessaloniki, 54006 Thessaloniki, Greece

Abstract

The case study Athens shows the role that air pollution issues may play in the design and evaluation of complex systems such as integrated solid waste management at a regional level. The discipline that multicriterial analysis imposes is demonstrated, as three out of the family of 24 proposed evaluation criteria for the case study area are air-pollution-specific. Emphasis is put on the criteria regarding air pollution and the different ways that these may be approached and quantified. By the aid of these criteria, five selectively composed alternatives for the integrated management of household waste are compared and ranked. Preliminary results, further subject to robustness analysis, favour alternatives emphasizing on source collection.

1 Municipal waste management in Athens

National planning for solid waste management is necessary for the development of every long-term, reliable action on this subject. Regional planning is a kind of national planning's 'localized specialization' in the scale of larger agglomerations. It should be noted that although regional management has distinct advantages, the communities called for participation are usually reluctant to have wastes of another part of the region disposed in their area and are, therefore, unwilling to host waste-processing facilities. Such a medium- term programme has been composed for the Greater Athens area (population: 4 million, cf. Figure 1) by the Association of Municipalities and Communities of the Attiki region (ESDKNA) [1]. Furthermore, it is well known that air

60 Air Pollution Engineering and Management

Figure 1: Solid waste management system in the Greater Athens area. O Operating 'wild' landfills (23; the Vari, Pallini and Spata 'wild' landfills

have been shut down recently but still present strong leachate problems, due to lack of restoration works); 0 Large, currently operating landfill in Ano Liossia;

© Large, shut-down landfill in Schistos; O Proposed sites for 2 of the 3 new landfills (Avlona and Trikerato-Mandra); © Operating Transfer Stations (7: Schistos by the landfill, N. Smirni, N. Makri, local transfer stations in Ilioupoli, Argiroupoli, Kallithea,

Chalandri); © Proposed site for incineration plant (Phili); O Communities involved since Febr. 1994 in a paper recycling programme; © Communities having participated 1986 in a paper recycling programme;

pollution levels are very high in the Attiki region. It can therefore be expected that air pollution will always play a key role in the evaluation of various kinds of systems for this region.

2 Employed methodology

Solid waste management is especially difficult and costly today, due to the increasing volumes of produced waste and the need to control (what are now recognised as) potential serious environmental and health effects of disposal.

For the integrated management of household municipal solid wastes in the Greater Athens Area, the following alternatives have been considered ([2]-[5]): 1) 'Sanitary' landfilling in the landfill of Ano Liossia (present case); this potential action is fictive, in the sense that it is a priori excluded for the

future, since the site's shut-down and restoration has already been scheduled, together with the restoration of the already shut-down landfill in Schistos (required investments of 15 and 11 million ECU respectively).

However, a comparison with other potential actions (particularly in view of the expected increase of the disposal costs for new landfills) was considered interesting and, therefore, this 'potential' action has been included in the

present analysis. 2) Sanitary landfilling in three new landfills (two proposed, in Avlona and Trikerato-Mandra, together with a third one in the Mesogia-Lavrio area), according to ESDKNA plans that also received lately some political support,

which may decisively facilitate their short-term implementation. All three landfills will probably be constructed with composite-liner and landfill-gas utilization systems; the overall project requires an investment of about 84

million ECU, according to ESDKNA calculations. 3) Sanitary landfilling in three new landfills (cf. 2), a material recovery facility in each one and separate collection of paper in all municipalities and communities, according to medium-term plans of ESDKNA. The investment

for landfills and material recovery facilities has been calculated to be in the order of 150 million ECU. The material recovery facilities might utilize the over-3-year experience gained by the pilot facility in Ano Liossia.

Alternatively, if the co-composting of sewage sludge (300 t/d in winter and 170 t/d in summer) from the wastewater treatment plant in Psitalia is also considered, then some help might be found from gained experience by a similar plant, currently under construction in Peloponnese, which is

expected to be delivered within 1994. 4) Sanitary landfilling in three new landfills (cf. 2) and separate collection of paper, glass, aluminium and fermentable s. Extension of separate collection to other recoverable waste materials beyond paper is an ESDKNA vision,

whereas it has already been proposed, particularly for the organic fraction, by some Municipalities of the area. This scenario could be considered competitive to (3), in the sense that it does not require sophisticated material

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recovery facilities. However, the separate collection of fermentables (compostables, putrescibles, fines) still requires the existence of a treatment

facility, since the unavoidable presence of non-compostable material in the collected fraction should be taken for granted and, in any case, compostable materials require space and time for their maturing and stabilization. Separate collection may, however, highly increase the efficiency of the

process and the quality of the final product; therefore it is highly recommended today. 5) Incineration in one facility (100% of the area's remaining solid 'waste) and

separate collection ofpaper , glass and aluminium. Investment costs for the incinerator are considered to be in the order of 470-670 million ECU, whereas the municipality of Phili has already proposed to let such a plant be

constructed in its grounds. ESDKNA, together with ecological movements like Greenpeace, have openly expressed their emphatic opposition against incinerators in Attiki, due to concerns about their local technical reliability (mostly related to fears of possible PCDD/PCDF emissions) and the already

particularly high air pollution and smog problems of the area (Phili is in Thriasio plain, a major industrial area in Attiki). However, since the multicriterial software specifically allows for such eventual 'strict'

requirements (in the form of veto thresholds and/or coefficients of importance), it was considered useful to include this potential action in the analysis too, particularly since it is the only one including thermal treatment

of solid waste. Separate collection of paper was preserved in the scenario, because it is already happening and expanding. Incidentally, such programs should not be abandoned after their initiation, particularly on purpose like here, because of the (almost irreversible) bad impression to the population.

Glass and aluminium are included in this scenario, too, in view of the fact that their absence is profitable for the incinerator (heating value increase of the remaining waste, decrease of heavy metal content in both the flue gas

and solid residues), since they are non-combustibles. The family of criteria that was applied here has been a result of synthesis among a number of concise candidates proposed by Skordilis [6], Caruso et al. [7] and Hokkanen & Salminen [8]; it is consisting of the following 24 family members (their hierarchy is presented in Figure 2): 1.1. Increase of the degree of implementation of the environmental legislation. This relates to national planning and policy, as prescribed by the authorised ministry (currently facilitating construction of new sanitary

landfills, shutting-down of the existing 'wild' landfills and separate collection of recoverable waste materials), also considering that some European directives on solid waste management have not been adopted

into national legislation (e.g., incineration directives). 1.2. Better use and application of environmental legislation. This refers to the applicability of the legislation (effectiveness and efficiency of the state's or the local government's controlling mechanisms).

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1.3. Reduction of unemployment. It is important for a special reason: According to the present situation, the municipal cleaning services are generally over- populated, but operate rather inefficiently. A reorganization of the solid-

waste collection system may cause a reaction from their syndicate, if they feel that their interests are threatened.

Better disposal of solid wastes

(proved 4. Improved omical implementation of resources ibility of technology

12.1. Lower acoustic Til. Lower cost of [4.1. Improved pollution 1 lane operationally 1

112. Lower 13.2.Low er costs of "v 4.2. Greater atmospheric invejstment and sensibility in pollution operation changes of MSW composition

2.3. Lower soil | 3.3. Lov *v~ pollution 1 (rep 4.3. Improved I adapting to new requirements 2.4. Lower water 1 3.4. Grcwth of the pollution matket 1 *v. 4.4. Longer life 2.2.1. Greenhouse cycle I effect 2.5. Better aesthetics 3.5. Impmovement (lower optical of economical pollution) development in ^4.5. Faster oth;r sectors completion of 2.2.2. Acidificative the installation emissions 5.1. Recovered 3.6. Better ^N, materials utilization of 4.6. Higher 2.2.3. Emissions finzmcing credibility of with health effects the installation 5.2. Recovered energy

Figure 2: Composed criteria hierarchy.

2.1. Lower noise pollution', main relevant noise sources are (i) the waste

treatment/disposal plant itself and (ii) traffic associated with it. 2.2. Lower air pollution', it is particularly important (among environmental criteria) in Athens, because of the already high air pollution levels. Airborne releases are created during waste transport and treatment.

Landfill fires and possible disturbances in incinerator flue-gas purification systems were not included. Hokkanen & Salminen [8] propose a methodology for calculating airborn releases from waste transport and

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processing: The present criterion's performance, as well as the corresponding thresholds, were all quantified in terms of emissions (since, measuring actual impacts is an unclear and premature field yet); due to its

above explained importance and nature, it was further decomposed into: 2.2.1. Emissions related with the greenhouse effect (CC^, CH^). 2.2.2. Acidificative emissions (SC^, NOJ.

2.2.3. Emissions with health effects (Cd, Pb, PCDD/PCDF). Concerning incineration with energy recovery (alternative 5), no substitution of alternative fuel, which would still be consumed in the other

alternatives (1-4), was assumed, in the framework of a conservative assumption. 2.3. Lower soil pollution', this relates to the various kinds of depositions of air

and water pollutants at the ground. This is a function of the soil vulnerability also, as well as of the source size, type and distance. 2.4. Lower water pollution, both for underground and surface water bodies. Greater Athens area has been facing for many years problems concerning

drink-water supply, particularly in the summer. Although these problems are expected to be solved in the near future by securing the supply of the Athens basin with water from rather remote water bodies (e.g., Evinos),

this criterion remains important due to the multi-lateral uses of water. 2.5. Lower optical pollution', this relates to aesthetics, i.e. sight of wastes, gulls, fleet of trucks, etc.

3.1. Lower land cost', it is ownership dependant (public, municipal or private). 3.2. Lower investment/operating cost. It was decided to exclude investment costs from the criteria, since it is highly probable that any treatment/ disposal plants built in Attiki will be financed (to the major part, at least)

by the European Union. Therefore, operating cost does not include depreciation, although it can be easily introduced in the present simulation- evaluation model (approx. figures are already available). 3.3. Lower gate (tipping) fees', waste collection, treatment and disposal is a

service to the community and, therefore, the community should pay the price for this service. For municipal waste, this price is secured by the citizens' taxation on waste and is a direct function of running costs but also

depend on political decisions, therefore being non-redundant due to the operating-cost criterion. 3.4. Market reinforcement for recycled materials (also subject to the supply- and-demand law).

3.5. Better financial development in other sectors (e.g., heating of greenhouses with landfill gas). 3.6. Better utilisation of financing', substantial funds are expected to be available for Greece in the years 1995-99 from the European Union.

Previously available funds were not utilized to the maximum possible extent, mostly due to unavailability of an adequate number and size of reliable proposals for financing.

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4.1. Better operationality, it was chosen to be measured in an ordinal scale. It describes, more or less, the prospects of a certain method to work effectively, considering all existing conditions in the place of application.

4.2. Better sensitivity to a change in waste composition', e.g., the compostable fraction of municipal solid waste is decreasing continuously in Greece in the last 10 years (specifically for the Greater Athens Area by about 8%

according to ESDKNA's calculations), as result of the increasing consumption of packaged goods. 4.3. Better adaptability to new demands', these refer mostly to legislation of the European Union that is converted into national Greek laws; e.g., by July

1996, the guideline for packaging material must be made operational in Greece; this will pose much higher recycling requirements than those already achieved or considered achievable today.

4.4. Longer operational life', finding a site for new treatment/disposal plants has become almost an unsolvable problem due to the NIMBY (Not In My Back Yard) syndrom; therefore, a maximum lifetime of facilities that are

either operating or under construction, should be pursued. This is also a function of recycling levels, but in general of waste diversification levels. 4.5. Quick completion of installation', most politicians that start a project would like to 'be still around to collect' when it is finished and made operational.

4.6. Better reliability of installation', this refers to previous local experience with relevant technology. 5.1. Recovered materials. This does not refer to the profit from selling

recovered material, but to the profit for the next generations, due to the preservation of scarce resources like oil, metals and land (ethical criterion). 5.2. Recovered energy. The logic behind this remains the same as behind the last one.

3 Results and conclusions

The potential action ranking highest is No (4). An interesting feature, despite the qualitative determination of most criteria, is that No (4) seems to dominate No (3), which suggests that a system emphasizing on separate collection might be more advantageous than one relying on 'convenient' material recovery facilities. However, such comparative conclusions of technical nature may be elicited only after a more thorough determination of all parameters than the one conducted here mainly for reasons of demonstration. The multicriterial analyst can play the role of mediator very effectively in issues concerning solid waste management, because his equipment allows him taking into account a variety of interests and points of view for his consulting services.

Concerning further research, a first priority following from the present work is the more accurate determination of criteria scores, without excluding the possible alteration of the proposed family of criteria (composing and synthesizing a concise family of criteria alone is a by no means negligible task;

66 Air Pollution Engineering and Management

quite on the contrary). Once the criteria performances have been determined (or, better, approximated) more accurately, further sensitivity analyses should be conducted to determine the robustness and stability of the results. Further aspirations on the analysis surely include considering more alternatives in the discrete case and experimenting with the continuous approach of modelling, either in parallel or individually.

Another task of interest would be to try determining the effect of integrated systems in the scores of a participating functional element on some criteria, by comparing them with the scores of the same functional element when considered alone. E.g., what is the change on the market price of compost if a programme for separate collection of batteries and lamps is implemented, thereby reducing the heavy-metal content of waste sent to material recovery facilities? Issues like these are strongly related to consequence (what-if) analysis and it would be very helpful to be able to answer them in an efficient way, e.g., by suitable software also combining or allowing for MCDA. It is important to always keep in mind that, already in the face of data collection and interface with the decision maker, many important aspects of the problem are being cleared out. Interactive software, simply asking the right questions as input data, would greatly facilitate getting a clear view of the entire system with all its parameters from the very beginning of the planning process.

References

1. Karagiannidis, A. & Moussiopoulos N., Application of ELECTRE III for the integrated management of municipal solid wastes in the Greater Athens Area, to be presented in the 12th International Conference on Multiple

Criteria Decision Making, Hagen, Germany, June 1995. 2. Newspaper TO VIMA, "Ecological crime in Phili", A47, 16.05.93. 3. Newspaper TO VIMA, "Delay in the new landfills", A41, 16.05.93. 4. Newspaper TO VIMA, "Six plans for garbage", A49, 27.02.94.

5. Newspaper TO VIMA,"In Avlona & Trikerato new landfills", A34, 24.7.94. 6. Skordilis, A., Lectures at the Seminar 'Management and treatment of

municipal waste and recycling', TEE/TKM, Oct.-Dec. 1992. 7. Caruso, C., Colorni, A. and Paruccini, M., The regional solid waste management system: A modelling approach, EJOR, 1993, 70, 16-30. 8. Hokkanen J. and Salminen P., The choice of a solid waste management

system by using ELECTRE III multicriterial decision-aid method, Applying MCDA to environmental management, ed. M. Paruccini, pp 111- 153, Kluwer Academic Publishers, Brussels and Luxembourg, 1994.