Siting MSW landfill using weighted linear combination and analytical hierarchy process (AHP) methodology in GIS environment (case study: Karaj)

Selection of landfill site is a complex process and needs many diverse criteria. The purpose of this paper is to evaluate the suitability of the studied site as landfill for MSW in Karaj. Using weighted linear combination (WLC) method and spatial cluster analysis (SCA), suitable sites for allocation of landfill for a 20-year period were identified. For analyzing spatial auto-correlation of the land suitability map layer (LSML), Maron’s I was used. Finally, using the analytical hierarchy process (AHP), the most preferred alternative for the landfill siting was identified. Main advantages of AHP are: relative ease of handling multiple criteria, easy to understand and effective handling of both qualitative and quantitative data.As a result, 6% of the study area is suitable for landfill siting and third alternative was identified as the most preferred for siting MSW landfill by AHP.The ranking of alternatives were obtained only by applying the WLC approach showed different results from the AHP. The WLC should be used only for the identification of alternatives and the AHP is used for prioritization. We suggest the employed procedure for other similar regions.     

Assessment of health-care waste disposal methods using a VIKOR-based fuzzy multi-criteria decision making method

Nowadays selection of the appropriate treatment method in health-care waste (HCW) management has become a challenge task for the municipal authorities especially in developing countries. Assessment of HCW disposal alternatives can be regarded as a complicated multi-criteria decision making (MCDM) problem which requires consideration of multiple alternative solutions and conflicting tangible and intangible criteria. The objective of this paper is to present a new MCDM technique based on fuzzy set theory and VIKOR method for evaluating HCW disposal methods. Linguistic variables are used by decision makers to assess the ratings and weights for the established criteria. The ordered weighted averaging (OWA) operator is utilized to aggregate individual opinions of decision makers into a group assessment. The computational procedure of the proposed framework is illustrated through a case study in Shanghai, one of the largest cities of China. The HCW treatment alternatives considered in this study include “incineration”, “steam sterilization”, “microwave” and “landfill”. The results obtained using the proposed approach are analyzed in a comparative way.     

Multi-criteria decision analysis for waste management in Saharawi refugee camps

The aim of this paper is to compare different waste management solutions in Saharawi refugee camps (Algeria) and to test the feasibility of a decision-making method developed to be applied in particular conditions in which environmental and social aspects must be considered. It is based on multi criteria analysis, and in particular on the analytic hierarchy process (AHP), a mathematical technique for multi-criteria decision making (Saaty, T.L., 1980. The Analytic Hierarchy Process. McGraw-Hill, New York, USA; Saaty, T.L., 1990. How to Make a Decision: The Analytic Hierarchy Process. European Journal of Operational Research; Saaty, T.L., 1994. Decision Making for Leaders: The Analytic Hierarchy Process in a Complex World. RWS Publications, Pittsburgh, PA), and on participatory approach, focusing on local community’s concerns.The research compares four different waste collection and management alternatives: waste collection by using three tipper trucks, disposal and burning in an open area; waste collection by using seven dumpers and disposal in a landfill; waste collection by using seven dumpers and three tipper trucks and disposal in a landfill; waste collection by using three tipper trucks and disposal in a landfill.The results show that the second and the third solutions provide better scenarios for waste management. Furthermore, the discussion of the results points out the multidisciplinarity of the approach, and the equilibrium between social, environmental and technical impacts. This is a very important aspect in a humanitarian and environmental project, confirming the appropriateness of the chosen method.     

Integrating multi-criteria decision analysis for a GIS-based hazardous waste landfill sitting in Kurdistan Province, western Iran

The evaluation of a hazardous waste disposal site is a complicated process because it requires data from diverse social and environmental fields. These data often involve processing of a significant amount of spatial information which can be used by GIS as an important tool for land use suitability analysis. This paper presents a multi-criteria decision analysis alongside with a geospatial analysis for the selection of hazardous waste landfill sites in Kurdistan Province, western Iran. The study employs a two-stage analysis to provide a spatial decision support system for hazardous waste management in a typically under developed region. The purpose of GIS was to perform an initial screening process to eliminate unsuitable land followed by utilization of a multi-criteria decision analysis (MCDA) to identify the most suitable sites using the information provided by the regional experts with reference to new chosen criteria. Using 21 exclusionary criteria, as input layers, masked maps were prepared. Creating various intermediate or analysis map layers a final overlay map was obtained representing areas for hazardous waste landfill sites. In order to evaluate different landfill sites produced by the overlaying a landfill suitability index system was developed representing cumulative effects of relative importance (weights) and suitability values of 14 non-exclusionary criteria including several criteria resulting from field observation. Using this suitability index 15 different sites were visited and based on the numerical evaluation provided by MCDA most suitable sites were determined.     

Suitability analysis for siting MSW landfills and its multicriteria spatial decision support system: Method,implementation and case study

Multicriteria spatial decision support systems (MC-SDSS) have emerged as an integration of geographical information systems (GIS) and multiple criteria decision analysis (MCDA) methods for incorporating conflicting objectives and decision makers’ (DMs’) preferences into spatial decision models. This article presents a raster-based MC-SDSS that combines the analytic hierarchy process (AHP) and compromise programming methods, such as TOPSIS (technique for order preference by similarity to the ideal solution) and Ideal Point Methods. To the best of our knowledge it is the first time that a synergy of AHP and compromise programming methods is implemented in raster-driven GIS-based landfill suitability analysis. This procedure is supported by a spatial decision support system (SDSS) that was developed within a widely used commercial GIS software package. A real case study in the Thrace region in northeast Greece serves as a guide on how to conduct a suitability analysis for a MSW landfill site with the proposed MC-SDSS. Moreover, the procedure for identifying MSW disposal sites is accomplished by performing four computational models for synthesizing the DMs per criterion preferential system. Based on the case study results, a comparison analysis is performed according to suitability index estimations. According to them Euclidean distance metric and TOPSIS present strong similarities. When compared with Euclidean distance metric, TOPSIS seems to generate results closer to that derived by Manhattan distance metric. The comparison of Chebychev distance metric with all the other approaches revealed the greatest deviations.     

Combining AHP with GIS for landfill site selection: A case study in the Lake Beyşehir catchment area (Konya,Turkey)

Landfills are the most common method for the disposal of municipal solid waste (MSW) in Turkey. However, determining the location of landfill sites is a difficult and complex process because it must combine social, environmental and technical parameters. Additionally, it depends on several criteria and regulations. The main objective of this study was to select of a landfill site for the Lake Bey?ehir catchment area. The Bey?ehir Lake is the largest freshwater lake and drinking water reservoir in Turkey, but there is no controlled landfill site in the region. Therefore, the landfill site should be determined such that the lake is protected. To determine the most suitable landfill site, an analytical hierarchy process (AHP) was combined with a geographic information system (GIS) to examine several criteria, such as geology/hydrogeology, land use, slope, height, aspect and distance from settlements, surface waters, roads, and protected areas (ecologic, scientific or historic). Each criterion was evaluated with the aid of AHP and mapped by GIS. Data were assorted into four suitability classes within the study area, i.e., high, moderate, low and very low suitability areas, which represented 3.24%, 7.55%, 12.70% and 2.81%, of the study area, respectively. Additionally, 73.70% was determined to be completely unsuitable for a landfill site. As a result, two candidate landfill sites are suggested and discussed. The final decision for landfill site selection will require more detailed field studies.     

Multi-criteria GIS-based siting of an incineration plant for municipal solid waste

Siting a municipal solid waste (MSW) incineration plant requires a comprehensive evaluation to identify the best available location(s) that can simultaneously meet the requirements of regulations and minimise economic, environmental, health, and social costs. A spatial multi-criteria evaluation methodology is presented to assess land suitability for a plant siting and applied to Santiago Island of Cape Verde. It combines the analytical hierarchy process (AHP) to estimate the selected evaluation criteria weights with Geographic Information Systems (GIS) for spatial data analysis that avoids the subjectivity of the judgements of decision makers in establishing the influences between some criteria or clusters of criteria. An innovative feature of the method lies in incorporating the environmental impact assessment of the plant operation as a criterion in the decision-making process itself rather than as an a posteriori assessment. Moreover, a two-scale approach is considered. At a global scale an initial screening identifies inter-municipal zones satisfying the decisive requirements (socio-economic, technical and environmental issues, with weights respectively, of 48%, 41% and 11%). A detailed suitability ranking inside the previously identified zones is then performed at a local scale in two phases and includes environmental assessment of the plant operation. Those zones are ranked by combining the non-environmental feasibility of Phase 1 (with a weight of 75%) with the environmental assessment of the plant operation impact of Phase 2 (with a weight of 25%). The reliability and robustness of the presented methodology as a decision supporting tool is assessed through a sensitivity analysis. The results proved the system effectiveness in the ranking process.     

Waste management project's alternatives: A risk-based multi-criteria assessment (RBMCA) approach

This paper examines the evaluation of a waste management project’s alternatives through a quantitative risk analysis. Cost benefit analysis is a widely used method, in which the investments are mainly assessed through the calculation of their evaluation indicators, namely benefit/cost (B/C) ratios, as well as the quantification of their financial, technical, environmental and social risks. Herein, a novel approach in the form of risk-based multi-criteria assessment (RBMCA) is introduced, which can be used by decision makers, in order to select the optimum alternative of a waste management project. Specifically, decision makers use multiple criteria, which are based on the cumulative probability distribution functions of the alternatives’ B/C ratios. The RBMCA system is used for the evaluation of a waste incineration project’s alternatives, where the correlation between the criteria weight values and the decision makers’ risk preferences is analyzed and useful conclusions are discussed.     

GIS-based approach for optimized siting of municipal solid waste landfill

The exponential rise in the urban population of the developing countries in the past few decades and the resulting accelerated urbanization phenomenon has brought to the fore the necessity to develop environmentally sustainable and efficient waste management systems. Sanitary landfill constitutes one of the primary methods of municipal solid waste disposal. Optimized siting decisions have gained considerable importance in order to ensure minimum damage to the various environmental sub-components as well as reduce the stigma associated with the residents living in its vicinity, thereby enhancing the overall sustainability associated with the life cycle of a landfill. This paper addresses the siting of a new landfill using a multi-criteria decision analysis (MCDA) and overlay analysis using a geographic information system (GIS). The proposed system can accommodate new information on the landfill site selection by updating its knowledge base. Several factors are considered in the siting process including geology, water supply resources, land use, sensitive sites, air quality and groundwater quality. Weightings were assigned to each criterion depending upon their relative importance and ratings in accordance with the relative magnitude of impact. The results from testing the system using different sites show the effectiveness of the system in the selection process.     

A decision support system for assessing landfill performance

Designing environmentally sound landfills is a challenging engineering task due to complex interactions of numerous design variables; such as landfill size, waste characteristics, and site hydrogeology. Decision support systems (DSS) can be utilized to handle these complex interactions and to aid in a performance-based landfill design by coupling system simulation models (SSM). The aim of this paper is to present a decision support system developed for a performance-based landfill design. The developed DSS is called Landfill Design Decision Support System – LFDSS. A two-step DSS framework, composed of preliminary design and detailed design phases, is set to effectively couple and run the SSMs and calculation modules. In preliminary design phase, preliminary design alternatives are proposed using general site data. In detailed design phase, proposed design alternatives are further simulated under site-specific data using SSMs for performance evaluation. LFDSS calculates the required landfill volume, performs landfill base contour design, proposes preliminary design alternatives based on general site conditions, evaluates the performance of the proposed designs, calculates the factor of safety values for slope stability analyses, and performs major cost calculations. The DSS evaluates the results of all landfill design alternatives, and determines whether the design satisfies the predefined performance criteria. The DSS ultimately enables comparisons among different landfill designs based on their performances (i.e. leachate head stability, and groundwater contamination), constructional stability and costs. The developed DSS was applied to a real site, and the results demonstrated the strengths of the developed system on designing environmentally sound and feasible landfills.     

Two decision analysis approaches: Choosing a chemical analysis method

This article illustrates how two different decision analysis (DA) methods can be used to assist in making environmental remediation decisions. The two DA methods are Multiattribute Utility Theory (MAUT) and the Analytic Hierarchy Process (AHP). MAUT and AHP differ greatly in their underlying philosophies. MAUT employs an interval scale and constructs utility functions that quantify the total utility to the decision maker of each technology alternative; AHP employs a ratio scale and uses pairwise comparisons to produce a final ranking of the alternatives that reflects the decision maker's comparative preferences. In this study, the same technology was ranked first by both methods; however, the remaining rankings did not agree. Also, statistical analysis indicated that some score differences may be statistically insignificant. These results are presented and discussed along with a comparison of the features, advantages, and disadvantages of these two DA approaches.     

An integrated multi criteria approach for landfill siting in a conflicting environmental, economical and socio-cultural area

Landfill site selection is a complicated multi criteria land use planning that should convince all related stakeholders with different insights. This paper addresses an integrating approach for landfill siting based on conflicting opinions among environmental, economical and socio-cultural expertise. In order to gain optimized siting decision, the issue was investigated in different viewpoints. At first step based on opinion sampling and questionnaire results of 35 experts familiar with local situations, the national environmental legislations and international practices, 13 constraints and 15 factors were built in hierarchical structure. Factors divided into three environmental, economical and socio-cultural groups. In the next step, the GIS-database was developed based on the designated criteria. In the third stage, the criteria standardization and criteria weighting were accomplished. The relative importance weights of criteria and subcriteria were estimated, respectively, using analytical hierarchy process and rank ordering methods based on different experts opinions. Thereafter, by using simple additive weighting method, the suitability maps for landfill siting in Marvdasht, Iran, was evaluated in environmental, economical and socio-cultural visions. The importance of each group of criteria in its own vision was assigned to be higher than two other groups. In the fourth stage, the final suitability map was obtained after crossing three resulted maps in different visions and reported in five suitability classes for landfill construction. This map indicated that almost 1224 ha of the study area can be considered as best suitable class for landfill siting considering all visions. In the last stage, a comprehensive field visit was performed to verify the selected site obtained from the proposed model. This field inspection has confirmed the proposed integrating approach for the landfill siting.     

Using an innovative criteria weighting tool for stakeholders involvement to rank MSW facility sites with the AHP

The main aim of this study was to verify the efficacy of using an innovative criteria weighting tool (the “priority scale”) for stakeholders involvement to rank a list of suitable municipal solid waste (MSW) facility sites with the multi-criteria decision-making (MCDM) technique known as analytic hierarchy process (AHP). One of the main objectives of the study was to verify the behaviour of the “priority scale” with both technical and non-technical decision-makers. All over the world, the siting of MSW treatment or disposal plants is a complex process involving politicians, technicians as well as citizens, where stakeholders who are not effectively involved strongly oppose (or even obstruct) the realization of new facilities. In this study, in order to pursue both the technical (select the best site) and social aims (all the stakeholders have to give their aware contribution), the use of the “priority scale” is suggested as a tool to easily collect non-contradictory criteria preferences by the various decision-makers. Every decision-maker filled in “priority scale”, which was subsequently uploaded in the AHP tool in order to indirectly calculate the individual priority of alternatives given by each stakeholder (not using group aggregation techniques). The proposed method was applied to the siting of a composting plant in an area suffering from a serious MSW emergency, which has lasted for over 15 years, in the Campania Region, in Southern Italy. The best site (the “first choice”) was taken as the one that appeared the most times at the first place of each decision-maker ranking list. The involved technical and non-technical decision-makers showed the same behaviour in (indirectly) selecting the best site as well as in terms of the most appraised criteria (“absence of areas of the highest value for natural habitats and species of plants and animals”). Moreover, they showed the same AHP inconsistency ratio as well as the same behaviour in comparison with a “balanced decision-maker” (who assigns identical weights to all the considered criteria). Therefore, the proposed criteria weighting tool could be widely as well as easily used for stakeholders involvement to rank MSW facility sites (or other kinds of alternatives) with the AHP or with other MCDM techniques, taking or not into consideration group aggregation methods.     

Evaluation of remedial countermeasures using the analytic network process

The aim of this paper is to present an evaluation method to aid decision makers in the prioritization and selection of appropriate countermeasures at the planning stage of site remediation. We introduced a hierarchical network (hiernet) decision structure and applied the Analytic Network Process (ANP) supermatrix approach to measure the relative desirability of the remedial alternatives using the decision maker's value judgment as input. A simplified illustrative example is presented to elucidate the process, as it is being applied to evaluate the feasible remedial countermeasures of a contaminated site caused by uncontrolled landfill. Four decision models derived from the generalized hiernet were examined to describe the effect of hierarchic functional dependence, inner dependence and feedback cycle on the derivation of the priority weights. The ANP could provide a more flexible analytical framework to break down one's judgment through a more elaborate structure in a systematic way to understand the complexity of the decision problem. The proposed method therefore may not only aid in selecting the best alternative but also may help to facilitate communication to understand why an alternative is preferred over the other alternatives through the analysis of the derived weights and its underlying decision structure.     

Probabilistic approach for estimating the release of contaminants under field management scenarios

A probabilistic approach is presented for estimating the release of contaminants by leaching, when wastes are being considered for disposal in a class of landfills but the specific landfill disposal site is uncertain. A simple percolation and equilibrium-based release model is used in conjunction with laboratory testing results and observations of field leachate characteristics for municipal solid waste landfills, hazardous waste landfills and industrial co-disposal landfills. The approach is applied for assessing the efficacy of potential treatment processes for mercury contaminated soils. For each landfill scenario, historical values of leachate pH and annual leachate generation quantities were used to derive the probability distribution functions of the field pH and LS ratio that may be expected to contact the disposed material over an estimated time period of 100 years. For each potential treatment process, laboratory testing was used to establish the treated material's leaching characteristics as a function of pH LS ratio. This approach allowed determination of distribution frequencies and limit values for release estimates instead of single point estimates. The probability of the mass of a constituent of interest released exceeding a hypothetical threshold was examined for each treatment process and landfill system. Results of the probabilistic analysis allowed for integration of a range of data and provided a good basis for assessing the efficacy of the examined treatment processes over the three assumed disposal scenarios.     

Multi-objective optimization of solid waste flows: environmentally sustainable strategies for municipalities

An approach to sustainable municipal solid waste (MSW) management is presented, with the aim of supporting the decision on the optimal flows of solid waste sent to landfill, recycling and different types of treatment plants, whose sizes are also decision variables. This problem is modeled with a non-linear, multi-objective formulation. Specifically, four objectives to be minimized have been taken into account, which are related to economic costs, unrecycled waste, sanitary landfill disposal and environmental impact (incinerator emissions). An interactive reference point procedure has been developed to support decision making; these methods are considered appropriate for multi-objective decision problems in environmental applications. In addition, interactive methods are generally preferred by decision makers as they can be directly involved in the various steps of the decision process. Some results deriving from the application of the proposed procedure are presented. The application of the procedure is exemplified by considering the interaction with two different decision makers who are assumed to be in charge of planning the MSW system in the municipality of Genova (Italy).     

Application of interval 2-tuple linguistic MULTIMOORA method for health-care waste treatment technology evaluation and selection

The management of health-care waste (HCW) is a major challenge for municipalities, particularly in the cities of developing countries. Selection of the best treatment technology for HCW can be viewed as a complicated multi-criteria decision making (MCDM) problem which requires consideration of a number of alternatives and conflicting evaluation criteria. Additionally, decision makers often use different linguistic term sets to express their assessments because of their different backgrounds and preferences, some of which may be imprecise, uncertain and incomplete. In response, this paper proposes a modified MULTIMOORA method based on interval 2-tuple linguistic variables (named ITL-MULTIMOORA) for evaluating and selecting HCW treatment technologies. In particular, both subjective and objective importance coefficients of criteria are taken into consideration in the developed approach in order to conduct a more effective analysis. Finally, an empirical case study in Shanghai, the most crowded metropolis of China, is presented to demonstrate the proposed method, and results show that the proposed ITL-MULTIMOORA can solve the HCW treatment technology selection problem effectively under uncertain and incomplete information environment.     

Siting MSW landfills with a spatial multiple criteria analysis methodology

The present work describes a spatial methodology which comprises several methods from different scientific fields such as multiple criteria analysis, geographic information systems, spatial analysis and spatial statistics. The final goal of the methodology is to evaluate the suitability of the study region in order to optimally site a landfill. The initial step is the formation of the multiple criteria problem's hierarchical structure. Then the methodology utilizes spatial analysis processes to create the evaluation criteria, which are mainly based on Greek and EU legislation, but are also based on international practice and practical guidelines. The relative importance weights of the evaluation criteria are estimated using the analytic hierarchy process. With the aid of the simple additive weighting method, the suitability for landfill siting of the study region is finally evaluated. The resulting land suitability is reported on a grading scale of 0-10, which is, respectively, from least to most suitable areas. The last step is a spatial clustering process, which is being performed in order to reveal the most suitable areas, allowing an initial ranking and selection of candidate landfill sites. The application of the presented methodology in the island of Lemnos in the North Aegean Sea (Greece) indicated that 9.3% of the study region is suitable for landfill siting with grading values greater than 9.     

Pricing landfill externalities: emissions and disamenity costs in Cape Town, South Africa

The external (environmental and social) costs of landfilling (e.g. emissions to air, soil and water; and 'disamenities' such as odours and pests) are difficult to quantify in monetary terms, and are therefore not generally reflected in waste disposal charges or taken into account in decision making regarding waste management options. This results in a bias against alternatives such as recycling, which may be more expensive than landfilling from a purely financial perspective, but preferable from an environmental and social perspective. There is therefore a need to quantify external costs in monetary terms, so that different disposal options can be compared on the basis of their overall costs to society (financial plus external costs). This study attempts to estimate the external costs of landfilling in the City of Cape Town for different scenarios, using the benefits transfer method (for emissions) and the hedonic pricing method (for disamenities). Both methods (in particular the process of transferring and adjusting estimates from one study site to another) are described in detail, allowing the procedures to be replicated elsewhere. The results show that external costs are currently R111 (in South African Rands, or approximately US$16) per tonne of waste, although these could decline under a scenario in which energy is recovered, or in which the existing urban landfills are replaced with a new regional landfill.     

The use of LCA in selecting the best MSW management system

This paper focuses on the study of eleven environmental impact categories produced by several municipal solid waste management systems (scenarios) operating on a provincial scale in Southern Italy. In particular, the analysis takes into account 12 management scenarios with 16 management phases for each one. The only difference among ten of the scenarios (separated kerbside collection of all recyclables, glass excepted, composting of putrescibles, RDF pressed bales production and incineration, final landfilling) is the percentage of separated collection varying in the range of 35–80%, while the other two scenarios, for 80% of separate collection, consider different alternatives in the disposal of treatment residues (dry residue sorting and final landfilling or direct disposal in landfill). The potential impacts induced on the environmental components were analysed using the life cycle assessment (LCA) procedure called “WISARD” (Waste Integrated System Assessment for Recovery and Disposal). Paper recycling was the phase with the greatest influence on avoided impacts, while the collection logistics of dry residue was the phase with the greatest influence on produced impacts. For six impact categories (renewable and total energy use, water, suspended solids and oxydable matters index, eutrophication and hazardous waste production), for high percentages of separate collection a management system based on recovery and recycling but without incineration would be preferable.