J Mater Cycles Waste Manag DOI 10.1007/s10163-017-0611-7

ORIGINAL ARTICLE

Investigating utility level of waste disposal methods using multicriteria decision-making techniques (case study: Mazandaran-Iran) Fereshteh Mirzazadeh1 · Farhad Hadinejad2 · Narges Akbarpour Roshan3 

Received: 3 January 2015 / Accepted: 20 March 2017 © Springer Japan 2017

Abstract  Regardless of collection and disposal systems of wastes, which are the main causes of pollution in cities and villages, attention to the health and hygiene of a society is not possible. Hence, we try to identify the most appropriate waste disposal method considering geographical and environmental conditions of Mazandaran province using multicriteria decision-making techniques (Analytical Hierarchy Process and Fuzzy Analytical Hierarchy Process), in an applied and descriptive research. To do so, we, first, identified the most effective alternatives and criteria in the field of waste disposal by taking into account the region’s environmental and geographical conditions through library studies and investigating various internal and external sources. Then, after compilation of questionnaires and distributing them among experts of municipalities and governor of the province, we determined effectiveness of the criteria and utility of the alternatives using the mentioned Electronic supplementary material  The online version of this article (doi:10.1007/s10163-017-0611-7) contains supplementary material, which is available to authorized users. * Farhad Hadinejad [email protected] Fereshteh Mirzazadeh [email protected] Narges Akbarpour Roshan [email protected] 1

Science Affiliation Research Institute of ShakhesPajouh, Isfahan, Iran

2

Department of Industrial Management, Faculty of Management and Accounting, Allameh Tabataba’i University, Tehran, Iran

3

Faculty of Economics and Administrative Sciences, University of Mazandaran, Babolsar, Mazandaran, Iran





techniques. Our findings suggest that soil type and water level are the most important factors in selecting waste disposal method and recycling is the most appropriate waste disposal method in Mazandaran province. Keywords  AHP · Fuzzy AHP · MCDM · Waste · Waste disposal

Introduction Solid waste is an inherent part of human life whose generation is constantly increasing as the result of population growth, and is considered one of the most serious environmental problems of contemporary societies. All materials resulting from human’s activities which are produced in human settlement environments and are considered solid, unusable, and discarded by their owners are called waste [1]. Waste disposal is to take waste away from human’s living environment or to change it into recyclable materials [2]. Waste is regarded as one of the invaluable national properties of each country which can be used as an energy-generating source, a raw material needed by industries, and an organic fertilizer (by composting) by proper management. Since humans abandoned nomadism and chose to live in villages and cities, they have considered organizing and managing wastes resulting from their activities. In the past, a little attention was paid to solid-waste management, because the destructive effect of solid wastes had not been identified. In addition, lack of technology, and national and personnel resources prevented an effective management of solid waste [3]. However, nowadays, various solid wastes from human and industrial activities are increasing because of population growth and technology promotion; therefore,

13

Vol.:(0123456789)



waste management has become one of the primary responsibilities of city councils. Principles of Environmental Hygiene and Sanitation necessitate that all the waste be taken away from houses and human’s living environment as soon as possible. In Iran, taking into account 0.8  kg waste per capita (292  kg per person per year), more than 50,000 t of solid waste are produced every day [4]. Among the common methods applied for waste disposal in Iran and other countries, one can refer to open dumping (surface disposal), sanitary landfill, sea and ocean dumping, filling holes and vacant mines, recycling and reuse, composting, animal feeding, open burning, and incineration. According to the results of investigations and considering geographical and climate conditions of Iran’s cities and features of urban waste in Iran, over 70% of which comprise organic materials, the methods of sanitary landfill, composting, incineration along with recycling method have been found to be quite useful, so authorities have paid great attention to them. Among the most common criteria for selecting appropriate waste disposal methods, it can be referred to the cost of method, soil type and emulsion penetrability level in soil, air pollution and stench odors emissions, water level, and separation of waste materials. Recent related studies have made few efforts to investigate the utility of waste disposal methods with regard to environmental and geographical conditions of the studied region (case). However, choosing an appropriate method is regarded as the most important stage in the process of optimized waste disposal. Some similar studies on investigating waste disposal methods and negative effects of improper disposal in Mazandaran province and other countries are as follows: In their case study done in Babolsar, Mazandaran, Poorahmad et al. [5] concluded that landfill method is the most effective method used by urban managers for waste disposal. The results of their study also showed that current landfill sites are unfavorable, ignoring many site-choosing principles and criteria, and it is expected that its environmental effects emerge in the future [5]. The findings of another study by Yaqubi et  al. [2] in Babol, Mazandaran, revealed that landfill method has been used for many decades, which has led to the pollution of drinking water of the residents of the region due to high levels of underground waters. In addition, landfill site is located in a forest area, which, in turn, causes the destruction of nature. The authors recommended thoughtful deliberation and serious efforts of the authorities [2]. In a similar study, Hassani asserted that the urban waste management system of Babol and the other cities of Mazandaran province is critical, without favorable environmental criteria [6]. Mohammadi et  al. investigated the effects of waste management on tourism industry of Bahnamir, Mazandaran, and concluded that improper waste

13

J Mater Cycles Waste Manag

disposal has had negative effects on tourists’ tastes and attitudes [7]. Aliakbari et al. studied waste disposal method in Behshahr, Mazandaran, and found out that 70 t of waste is produced daily in this city, incinerated by stack method in the suburbs and adjoining residential areas [8]. As a related study done in a foreign context, in a study entitled “solid-waste management in Macao”, Jin et  al. [9] concluded that large amounts of waste are recyclable, and waste burial is the lowest priority for waste disposal regarding high costs of lands. Furthermore, over 80% of the total waste was incinerated in Macao in the last decade [9]. Gomes et  al. studied the features of Brazil and topography of the region, and using analytical hierarchy process (AHP) technique, and found that waste recycling is the most appropriate disposal method in this country [10]. “Urban waste management” is the title of another study by Shan et al. [11] in Beijing, the results of which showed that 90% of wastes in Beijing are buried, 8% are incinerated, and the remaining 2% are changed into composting. The authors suggested that recycling, and especially source separation of the waste, reduces the volume of wastes [11]. In a research study done in Turkey, Ekmekcioglu et al. [12] concluded that each city has to choose the most appropriate method for waste disposal based on its specific conditions. Considering the current criteria and methods, they finally evaluated incineration as the most suitable method for Turkey [12]. Using ELimination Et Choice in Translating to Reality (ELECTRE) technique, El Hanandeh et  al. found that non-aerobic digestion and composting may not be compatible with Australia’s environmental conditions, whereas incineration and energy recovery are the most appropriate methods [13]. In a study by Dursun et al. done in Istanbul, Turkey, steam sterilization was placed first in the hierarchy; therefore, this method was selected as the most appropriate method in the city [14]. Abu Qdais and Alshraideh studied the appropriate disposal method of solid waste from olive oil industry in Jordan using the analytical hierarchy analysis [15]. Finally, in a recent study by Mirzazadeh and Hadinejad, applying fuzzy AHP technique in waste disposal method selection in Iran was examined [16]. As it can be seen, existence of numerous alternatives and various criteria affected by environmental and geographical conditions makes the selection of the optimal method of waste disposal highly challenging. In such a vague and complicated situation, the use of mathematical techniques and methods such as multiple criteria decision-making method can reduce the complication of current conditions and play an effective role in choosing the most appropriate method. Hence, in the present study, we tried to investigate the utility of waste disposal methods in Mazandaran province through library and field studies and using AHP and fuzzy AHP (FAHP) methods to choose the most appropriate disposal method and the most effective criterion with

J Mater Cycles Waste Manag

regard to the climate and environmental conditions of Mazandaran.

Introducing the studied region Mazandaran province with the area of 24,091  km2 is located in the north of Iran and southern coasts of Caspian Sea. This province has common borders with Caspian Sea, Tehran, Semnan, Golestan, and Guilan provinces from north, south, east, and west, respectively. Mazandaran has a population of over 2.6  million. 45.9% of the population resides in urban areas (36 cities), and 54.1% of its population lives in rural areas (36,549 villages) [17]. In general, Mazandaran has a moderate and humid climate known as “the moderate Caspian climate”. Vast forests, moderate climate, and rivers in this province have an important and fundamental role in urban structure of the region. Alborz mountain range prevents the penetration of the humidity of Caspian Sea into the central areas of Iran. Underground water level in this province is so high that one can reach water by digging a 1–2 m deep pit. Improper waste disposal in many regions of the province, especially in coastal regions, has caused soil and water pollution, and has created serious crises because of humidity and the lack of availability of land. This has posed critical threats to people’s life and ecosystems. Population growth in Mazandaran and its suitable geographical situation and the annual influx of 15  million Iranian citizens to this province as tourists has led to an increase of urban waste, and exacerbated the problem of urban solid-waste disposal. Totally, about 2500 t of waste is produced daily in Mazandaran, and the average per capita production of solid waste is 700–900 g, 35% of which are transferred to the rivers, 50% to the coasts, and the rest to the forest zones, causing terrible environmental problems. There are about 34 sites of waste disposal in the province. Seventy percent of the province waste is recyclable considering its type and the climate conditions; however, no effective action has been taken in this domain [2]. In recent years, because of non-sanitary disposal of waste in the cities of Mazandaran and lack of deliberation of authorities for sanitary disposal, urban view of the province has become unfavorable, which has caused irreparable damages to the tourism situation of the province. In addition, one can observe the destruction of the nature and beautiful views, forests and natural resources, and subsequently increasing pollution of the air and surface and underground water, and totally threats to aquatic and terrestrial ecosystems, and ultimately threats to the health of the society. Unfortunately, because of their low population, forests and river margins are selected as the waste landfills in the province.

Investigations show that waste is disposed by landfills in most cities of the province. Considering high prices of lands and high levels of underground waters, it can be concluded that landfill is not a proper solution for waste disposal, and more effective alternatives such as composting, recycling, or energy generation must be taken into account [17]. The most important factor of sanitary landfill is the required lands. Regarding Iran’s geographical conditions, the required lands for sanitary methods of burial are acceptable in most regions; however, in many regions such as “Khazar”, available lands are not entirely adequate to consider sanitary landfill as an efficient method. Therefore, it is necessary to apply an appropriate method of waste disposal in each region regarding its conditions [18].

Choosing alternatives and research criteria Considering the opinions of the expert team (including 15 professors of University of Mazandaran and specialists of municipalities of the province) and taking into account the specific circumstances of the region, four methods were investigated amongst different methods of waste disposal in this paper. These methods were “sanitary landfill”, “composting”, “incineration”, and “recycling”, which have largely been introduced as the main methods in similar studies (for example references 6, 8, 9, 11, 13, 14, 16, 17, and 18), and have been approved by the expert team of this research. Then, five criteria of “cost of method”, “soil type and emulsion penetrability level in soil”, “water level”, “air pollution and stench odors emissions”, and “separation of waste materials”, retrieved from former domestic and foreign studies (such as references 2, 7, 12, and 16) were analyzed and confirmed by the expert team to be consistent with the specific circumstances of the region. It should be noted that some other criteria such as technical reliability, feasibility, number of employees, energy recovery, and emission levels were found; however, they were omitted from the study following the expert team opinion. Some reasons for removing these criteria are that they are less important; it is difficult to integrate them with other criteria; their removal avoids the complexity of the calculations and also prevents the decrease of speed and accuracy of AHP process. The methods and the criteria used in the paper as well as the relationship between them will be discussed in the following subsections. Alternatives used in the research Sanitary landfill In this method, solid waste is dumped into natural or constructed pits, or dumped on the ground and compacted as

13



J Mater Cycles Waste Manag

much as possible. Then, it is covered with soil or other covering materials in a quite systematic and hygienic way [4].

correlated with all the alternatives. However, its effect on landfill is more than the other methods.

Incineration

Water level

Due to the development of industries and the lack of available land, England tried to build the first incineration plant in 1870. After that, other Western countries attempted to create their own incineration plants using the energy from the burning of waste, which were provided to international markets in different ways [4].

This criterion explains how high the groundwater level in the region is. It affects all the considered methods, so it is necessary to take into account its effects. For example, after applying each waste disposal method (either implementation of a method or combination of methods), some waste materials remain which should be buried. Therefore, this measure should be considered as an important criterion. Otherwise, the pollution of groundwater resources will happen.

Composting Composting is the controlled decomposition of organic materials in the heat and humidity by bacteria, fungi, molds, and other aerobic or anaerobic microorganisms. Composting has a large percentage of humus which is a soil amendment and improves the living conditions and performance of soil organisms [1]. Recycling The process of reusing waste materials is called recycling. In other words, recycling is the process of collection and processing consumed products in a way that they can be used again. Criteria used in the research and their relation to research alternatives Cost of method Cost of method is an economic criterion that considers the cost of methods from beginning to end. According to the region’s circumstance, composting and sanitary landfill are economically more costly than other methods discussed in this paper. Soil type and emulsion penetrability level in soil This measure shows the relationship between soil type and emulsion penetrability in soil for all four methods. When the emulsion penetrability in soil is high due to the type of the soil, some irreparable effects such as groundwater pollution will be out, especially in the areas with high groundwater levels such as Mazandaran. For example, burying some parts of waste which cannot be converted to energy through burning or compositing has damaging consequences on the life of the region’s people and other fauna, and even destroys the environment, since groundwater level in Mazandaran is high and the soil type of the region shows a high level of penetrability. Therefore, this criterion is

13

Air pollution and stench odors emissions This measure shows how much air pollution and stench odors emissions the application of each method causes. For example, because of high groundwater levels in Mazandaran, it is not possible to bury waste deep underground. It seems that burying is done superficially, and in some cases, even open dump is used, causing high level of air pollution along with stench odors emissions. The amount of air pollution is different for various methods. Separation of waste materials Separation of waste materials means removing hazardous toxins, plastic materials, chlorine, iron, non-ferrous metals, etc [12]. The possibility of this operation is different in the four above-mentioned methods.

Research method The purpose of this paper is to investigate the choice and utility of the appropriate method of waste disposal in Mazandaran province. The research study is applied and descriptive, considering the nature of the object. In addition to conducting interviews, a standard AHP questionnaire was used as the main instrument to gather information and assess the views of statistical samples in this research. This questionnaire comprises six tables which are provided in supplementary explanation about the methodology and questionnaire. In Table  1, respondents were asked to make pairwise comparisons between criteria in two stages, so that they chose the superior option by comparing two criteria in the first stage. In the second stage, the preferences (numerical judgments using the related tables) were recorded. Similar to AHP algorithm, in other five tables, pairwise comparisons of alternatives were made in each of the five separate criteria. In addition, there was an

J Mater Cycles Waste Manag Table 1  Fuzzy numbers corresponding to preferences in pairwise comparisons Definition

Triangular fuzzy numbers

Equal importance Moderate importance Strong importance Very strong importance Extreme importance

(1, 1, 1) (0.5, 1, 1.5) (1, 1.5, 2) (1.5, 2, 2.5) (2, 2.5, 3)

example of pairwise comparison with the completed table at the beginning of the questionnaire to increase the accuracy of the completion. Furthermore, to better understand the different aspects of considered criteria and alternatives, some basic explanations about them (including definitions, concepts, the way of implementation, advantages, and disadvantages) were also provided at the beginning of the questionnaire in a way that did not direct respondents. Meanwhile, all the questionnaires were filled out in front of the authors, and whenever needed, the respondents were provided with some complementary explanations. It must be noted that the criteria and alternatives of the questionnaire were selected using library studies and related internal and external papers, and were finally revised and confirmed by the experts to ensure its content validity. In addition, in such research in which the mentioned questionnaire was used to gather information, reliability of the method was evaluated by consistency rate. For reasonable and acceptable comparisons, consistency rate must be less than 0.1 in all stages (considering comments of 5.1.3 subsection). Statistical society of the research included specialists of urban services in municipalities, experts of municipality cooperation organization, and experts of Mazandaran’s governor. Considering the limited number of experts all over the province, there was no need for sampling. Therefore, 48 questionnaires were distributed among them, and totally, 42 questionnaires were properly filled out (with consistency rate of less than 0.1). These questionnaires were analyzed using three different types of software (Excel, Expert Choice, and SPSS).

Choosing the problem solving technique In recent years, scientists of behavioral sciences, researchers of operational sciences, and theorists in the field of decision-making have proposed a series of various methods to explain how a decision-maker makes a decision among multiple criteria choices according to priorities. In such techniques, many criteria are used simultaneously to

determine the best possible choice. These criteria might be quantitative, qualitative, compatible, or opposite. Research in the field shows that each of the multiple criteria decision-making techniques has its own specific advantages and disadvantages, and none of them outclasses the others. However, the features of the investigated issue determine the priority and efficiency levels of the different techniques. In other words, the selection of the method based on which the decision is made is a multiple criteria decision-making problem by itself [19]. In spite of various proposed techniques, there is no single best method for different decision-making problems which performs optimally [20]. Taking into account the conditions of decision-making environment and the nature of considered issue on one hand, and utilizing expert opinions on the other hand, the authors made use of AHP and fuzzy AHP techniques to increase the validity and reliability of the research results by comparing obtained data from two different techniques. Clearly, when there is a lot of uncertainty and in the situations which data are collected by human judgment, it is difficult to select the precise amount of numerical comparisons. Thus, it is proposed by different researchers to use fuzzy approach to increase the credibility of the results. The other reasons which can be referred to for the selection of these techniques are reputation, extensive use, ease of use, fitness to structure of problem, existence of simple and standard AHP questionnaire, ease of understanding for respondents, possibility of checking the consistency of comparisons made by the respondents, ability to transform qualitative values into quantitative values, and strong software. Analytic hierarchy process (AHP) The analytic hierarchy process (AHP) is a powerful and flexible decision-making process [21], which makes the best decision when both qualitative and quantitative aspects of a decision need to be considered [22]. The AHP is one of the extensively used multicriteria decision-making (MCDM) methods [23–25], and has successfully been used in maintenance policy selection [26], environmental decision-making [27, 28], resources planning [29], and conflict management [30, 31]. AHP has also been employed for the risk assessment [32–34]. Based on what has been reported in the above-mentioned studies, one of the main advantages of the AHP method is its simple structure. The AHP is designed in a way that represents human mind and the nature. Therefore, AHP can create the chance of searching and evaluating the cause and effect relationship between the goal, factor, subfactor, and alternatives, using breaking down the structure of the problem [35]. Moreover, the use of AHP does not

13



involve cumbersome mathematics; thus, it is easy to understand, and it can effectively handle both qualitative and quantitative data [36]. The AHP mainly addresses how to solve decision problems with uncertainty and with multiple criteria characteristics. It is based on three principles: constructing the hierarchy, priority setting, and logical consistency. Construction of the hierarchy A complex decision problem, centered around measuring contributions to an over objective or focus, is structured and decomposed into sub-problems (sub-objectives, criteria, alternatives, etc.), within the hierarchy.

J Mater Cycles Waste Manag

between the entries of A: aij·ajk  =  aik. The “consistency index” (CI) is (3) The final consistency ratio (CR), on the basis of which one can conclude whether the evaluations are sufficiently consistent, is calculated as the ratio of the CI and the random consistency index (RI), as indicated in (4). The number 0.1 is the accepted upper limit for CR. If the final consistency ratio exceeds the number, the evaluation procedure has to be repeated to improve the consistency. The measurement of consistency can be used to evaluate the consistency of decision-makers as well as the consistency of all the hierarchy.

CI = (𝜆max − n)∕(n − 1).

CR = CI∕RI. Priority setting The relative “priority” given to each alternative in the hierarchy is determined by pairwise comparison of each alternative at a lower level in terms of the criteria [37]. In AHP, multiple-paired comparisons are based on a standardized comparison scale of nine levels [21]. Let C  =  {Cj| j = 1, 2,…, n} be the set of criteria. The result of the pairwise comparison on n criteria can be summarized in a (n × n) evaluation matrix A in which every element aij is the quotient of weights of the criteria, as shown in the following equation: (1) The relative priorities are given by the right eigenvector (w) corresponding to the largest eigenvalue (λmax), as:

A = (aij ), (i, j = 1, … , n).

(2) In case the pairwise comparisons are completely consistent, the matrix A has rank 1 and λmax = n. In that case, weights can be obtained by normalizing any of the rows or columns of A. The procedure is repeated for all the subsystems in the hierarchy. To synthesize the various priority vectors, these vectors are weighted with the overall priority of the parent criteria. This process starts at the top of the hierarchy. As a result, the overall relative priority to be given to the lowest level elements is obtained. These indicate the degree to which the alternatives contribute to the focus. These priorities represent a synthesis of the local priorities, and reflect an evaluation process which permits researchers to integrate the perspectives of the various stakeholders involved [37].

Aw = 𝜆max w.

Consistency check A measure of consistency of the given pairwise comparison is needed. The consistency is defined by the relation

13

(4)

Fuzzy AHP There is extensive literature addressing the situation where the comparison ratios are imprecise judgments [38]. In most of the real-world problems, some of the numerical values of judgments can be precisely assessed, while others cannot. Humans are unsuccessful in making quantitative predictions, whereas they are comparatively promising in qualitative ones [39]. Essentially, the uncertainty in the preference judgments gives rise to uncertainty in the ranking of alternatives as well as difficulty in determining consistency of preferences [38]. These applications are performed with many different perspectives and proposed methods for fuzzy AHP. Fuzzy AHP method has widely been used by various authors and turned out to be one of the best methods among various assessment methods [40]. Chang introduced a new approach for handling pairwise comparison based on triangular fuzzy numbers followed by the use of extent analysis method for synthetic extent value of the pairwise comparison [41]. Weck et al. adopted a method to evaluate different production cycle alternatives using mathematics of fuzzy logic to the classical AHP [40]. In another study, Yu presented a group decision-making fuzzy AHP problem using a linearization and fuzzy rating techniques [42]. Kuo et al. also developed a decision support system using the fuzzy AHP to locate new convenience store [43]. Huang et  al. used a fuzzy AHP method and crisp judgment matrix to evaluate subjective expert judgments made by perception [44]. Pan applied fuzzy AHP method for the selection of the suitable bridge construction methods [45]. Cakir and Canbolat proposed an inventory classification system based on the fuzzy AHP method [46]. Dagdeviren and Yuksel applied fuzzy AHP approach to determine the level of faulty behavior risk in work systems [47]. Finally, Gumus used the fuzzy AHP and the technique for order preference by similarity to

J Mater Cycles Waste Manag

ideal solution (TOPSIS) to evaluate hazardous waste transportation firms [48]. In the following, the outlines of the extent analysis method on fuzzy AHP are given. Let X = {x1, x2,…, xn} be an object set, and U = {u1, u2, …, um} be a goal set. According to Chang’s extent analysis [41], each object is taken and extent analysis for each goal, gi, is performed, respectively. Therefore, m extent analysis values for each object can be obtained, with the following signs: 𝟏 𝟐 m M𝐠i ,M𝐠i , … M𝐠i , i=𝟏, 𝟐, … ,n

(5)

where all Mgi (j = 1, 2, ..., m) are triangular fuzzy numj

bers (TFNs) whose parameters are a, b, and c. They are the least possible value, the most possible value, and the largest possible value, respectively. A TFN is represented as (a, b, c), as illustrated in Fig. 1. The steps of Chang’s extent analysis can be given as follows [49]. Step 1 The value of fuzzy synthetic extent with respect to the ith object is defined as

∑ m

Si =

j

Mgi ⊗

j=1

To obtain

( n m ∑∑

)-1 j

Mgi

i=1 j=1 ∑m j Mgi, perform j=1

(6)

.

the fuzzy addition opera-

tion of m extent analysis values for a particular matrix, such that (m ) m m m ∑ ∑ ∑ ∑ j Mgi = aij , bij , cij , i=1,2, … ,n. (7) j=1

j=1

j=1

j=1

�

In addition, to obtain

n m ∑ ∑

i=1 j=1

�−1 j Mgi

, perform the fuzzy

addition operation of Mgi (j=1,2, … ,m) values, such that j

Fig. 1  Triangular fuzzy number, P̃ = (a, b, c).

n m ∑ ∑

( j Mgi

i=1 j=1

=

n m ∑ ∑ i=1 j=1

aij ,

n m ∑ ∑

bij ,

i=1 j=1

n m ∑ ∑

) cij .

(8)

i=1 j=1

And then, compute the inverse of the vector in Eq. (8), such that

�

n m � � i=1 j=1

⎞ �−1 ⎛ ⎟ ⎜ 1 1 1 j Mgi =⎜ n m , n m , n m ⎟. ⎜∑ ∑ ∑∑ ∑∑ ⎟ cij bij aij ⎟ ⎜ ⎠ ⎝ i=1 j=1 i=1 j=1 i=1 j=1

(9)

Step 2 The degree of possibility of M2 = (a2, b2, c2) ≥ M1 = (a1, b1, c1) is defined as

( ) [ ( )] V M2 ⩾ M1 = supy⩾x min 𝜇M1 (x), 𝜇M2 (y) ,

(10)

and can be equivalently expressed as follows:

� � V M2 ⩾ M1 = hgt (M1 ∩ M2 ) ⎧ ⎪ =𝜇M2 (d) = ⎨ ⎪ ⎩

(b2

1, if b2 ⩾ b1 0, if a1 ⩾ c2 a1 − c2 , otherwise − c ) − (b − a ) 2

1

(11)

1

where d is the ordinate of the highest intersection point between 𝜇M1 and 𝜇M2 (see Fig. 2). To compare M1 and M2, we need both the values of V(M1 ≥ M2) and V(M2 ≥ M1). Step 3 The degree of possibility for a convex fuzzy number to be greater than k convex fuzzy numbers Mi (i = 1, 2, …, k) can be defined by ( ) V(M ⩾ M1 ,M2 , … ,Mk ) = V[ M ⩾ M1 ( ) ( ) and M ⩾ M2 and … and M ⩾ Mk ] ( ) (12) = min V M ⩾ Mi , i = 1, 2, 3, … , k.

Fig. 2  Intersection between M1 and M2

13



J Mater Cycles Waste Manag Separation of waste materials (C5); 0.15

Separatio n of waste materials (C5), 0.19

Cost of method (C1); 0.19

Air pollution and stench odors emission (C4); 0.18 Water level (C3); 0.21

Air pollution and stench odors emission (C4), 0.19

Soil type and emulsion penetrability level in soil (C2); 0.26

Cost of method (C1), 0.2 Soil type and emulsion penetrability level in soil (C2), 0.21

Water level (C3), 0.22

Fig. 3  Final importance level of criteria using AHP technique

Fig. 4  Final importance level of criteria using fuzzy AHP technique

Table 2  Final ranking of alternatives using AHP technique

Table 3  Finale ranking of alternatives using fuzzy AHP technique

Alternatives

Recycling

Composting

Incineration

Sanitary landfills

Alternatives

Recycling

Composting

Incineration

Sanitary landfills

Importance level Ranking

0.362

0.237

0.236

0.164

0.31

0.29

0.23

0.22

Rank 1

Rank 2

Rank 3

Rank 4

Importance level Ranking

Rank 1

Rank 2

Rank 3

Rank 4

Assume that ( ) ( ) d Ai = min V Si ⩾ Sk . ′

by

Investigating the results using AHP technique (13)

For k = 1, 2, …, n; k ≠ i. Then, the weight vector is given

( ( ) ( ) ( ))T W � = d� A1 , d� A2 , … , d� An

(14)

where Ai (i = 1, 2,…, n) are n elements. Step 4 Via normalization, the normalized weight vectors are

( ( ) ( ) ( ))T W = d A1 , d A2 , … , d An

(15)

where W is a non-fuzzy number. The triangular fuzzy conversion scale given in Table  1 is used in the evaluation model of this paper (adapted from [41]).

Results In this section, the questionnaires were investigated and the expert opinions were analyzed using AHP and Fuzzy AHP techniques. Then, the importance level of the criteria and final ranking of the alternatives were determined, and finally, the results were compared and analyzed.

13

In this stage, the experts’ views were investigated using AHP technique. To increase the precision and speed of calculations group decision-making option of the software, Expert Choice related to this technique was used. After determining the importance level of the criteria (Fig.  3), the final ranking of the alternatives was extracted (Table 2). Expert Choice is a multiobjective decision support tool based on the AHP, a mathematical theory first developed by Saaty [21]. As it can be seen, the results of the analysis of experts’ views showed that the second criterion (soil type and emulsion penetrability level in soil) is the most important factor in choosing appropriate waste disposal method. The results also suggested that recycling is the most appropriate waste disposal method for this purpose. Furthermore, composting and incineration (incinerator) methods were placed second and third, respectively, and sanitary landfill was in the last place of the ranking. Investigating the results using fuzzy AHP technique In this section, first using Table  1, the data related to experts’ views were changed into fuzzy numbers. Then, the arithmetic mean of views was calculated, and the importance coefficients of criteria and final ranking of the alternatives were finally extracted using fuzzy AHP technique, which are shown in Fig. 4 and Table 3.

J Mater Cycles Waste Manag

As seen, final results of fuzzy AHP technique showed that the third criterion (water level) has the most considerable importance among the others, and recycling is ranked in the first place in the final ranking of the alternatives. Composting and incineration (incinerator) were in second and third places of the ranking, respectively, and sanitary landfill was in the last place.

Discussion In this section, the results of experts’ views using fuzzy AHP and AHP techniques are investigated and compared as shown in Tables 4 and 5. Comparison of the results in Table 4 suggests that second criterion (soil type and emulsion penetrability level in soil) is selected as the most important criterion in the final prioritization of the criteria by AHP technique, and the third criterion (water level) is selected as the most important criterion in the prioritization by fuzzy AHP technique. Other criteria have similar status in both cases. Thus, based on the opinions of respondents and according to the geographical location of the province, the soil type and emulsion penetrability level in soil and water level are the most important determinants of the process of waste disposal method selection. The criteria of cost of method, amounts of air pollution, and the possibility of separation of waste materials are the next priorities. Therefore, this prioritization should be considered by authorities at all stages of planning and executing the process of waste disposal. The comparison of the results in Table 5 shows the similar status of alternatives in the two techniques. It means that recycling is selected as the most important waste disposal method using both AHP and fuzzy AHP techniques, and

has the highest utility level. On the other hand, sanitary landfill has the lowest utility level. Due to its ease of use and low costs, sanitary landfill is the method generally used all over the province, and other methods of solid-waste disposal have been forgotten because of numerous reasons such as high costs and shortage of experts and experienced human resources. However, based on the opinions of experts and considering Mazandaran’s especial features (particularly proximity to the sea and importance of tourism in the province), the results show that recycling is the best waste disposal method in the region. After that, the methods of composting, incineration, and sanitary landfill are the next priorities. Therefore, the results of this research stress a more serious use of recycling, followed by composting and incineration methods, while criticizing the current method of waste disposal in the province (sanitary landfill) at the same time.

Conclusions The purpose of the study was to investigate the utility level of waste disposal methods (urban solid waste) in Mazandaran province, and to suggest the most appropriate disposal method considering environmental and geographical conditions of the province using AHP and fuzzy AHP techniques. The findings of the research show that soil type and emulsion penetrability level in soil, and water level are the most effective criteria among the other criteria affecting choice of waste disposal method, and this must be considered in determining the method and place of waste disposal. In addition, studies and investigations reveal that waste is usually disposed by burial in lands in most of the cities of the province. However, the results of this research

Table 4  Comparing importance level of criteria resulted from AHP and fuzzy AHP Criteria

Cost of Soil type and emulsion method penetrability level in soil

Water level Air pollution and stench odors emission

Separation of waste materials

The most important criterion

Prioritization using AHP

3

1

2

4

5

Prioritization using fuzzy AHP

3

2

1

4

5

Soil type and emulsion penetrability level in soil Water level

Table 5  Comparing finale ranking of alternatives resulted from AHP and fuzzy AHP

Alternatives

Recycling

Composting

Incineration

Sanitary landfills

The most appropriate choice

Ranking using AHP Ranking using fuzzy AHP

1 1

2 2

3 3

4 4

Recycling Recycling

13



show the lowest utility level for this method because of its incompatibility with environmental and geographical conditions. Our findings suggest recycling method as the most appropriate method, followed by composting and incineration methods as the next priorities. Although implementation of one single method of waste disposal for all the cities and regions is neither possible nor proper, this paper has tried to optimally prioritize waste disposal methods with respect to geographical and environmental features of the considered region in order to provide a desired, scientific, and native pattern to authorities for obtaining maximum return in the process of waste disposal. Thus, according to the results, authorities in different cities of the province should consider and investigate recycling, composting, incineration, and sanitary landfill, respectively, and then choose a single method or a combination of them with regard to the priorities proposed in this study. Meanwhile, studying the waste disposal methods by other criteria and alternatives with the use of other techniques and models of decision-making in different geographical situations can be a proper subject for future research.

References 1. Saeednia A (1999) Green book of municipalities, 7th ed. Publication of Municipalities Organization, Tehran, pp 24–52 2. Yaqubi Tahamtan A, Nasirnia N (2008) Investigating the problems of urban waste disposal in Babol city. Dissertation, social and humanistic sciences, Mazandaran University 3. Botkin D, Keller E (2007) Environmental science: earth as a living planet, 5th edn. Wiley, New York 4. Omrani Q (1998) Solid waste, first edn. Scientific publication center of Islamic Azad University, Tehran 5. Poorahmad A, Habibi K, Mohammad Zahraee S, Nazari Adli S (2007) Using fuzzy algorithm & GIS for positioning urban equipments (case study: waste burial place of Babolsar city). J Environ Stud 33(42):31–42 6. Hassani A (2005) Navigation program of urban solid waste disposal (case study: Babol city). Dissertation, art & architecture faculty, Mazandaran University 7. Mohammadi S, Ranjbar Z (2008) The effect of waste management on Bahnamir city tourism. Dissertation, social and humanistic sciences faculty, Mazandaran University 8. Aliakbari E, Jamal Livani A (2011) Positioning the place of urban solid waste hygienic burial using AHP, case study; Bahnamir city. Geogr J Sci Res Season Mag Iran Geogr 9(30):95–111 9. JinJ, wang z, Ran S (2006) Solid waste management in Macao: practices and challenges. Waste Manage (Oxford) 26:1045–1051 10. Gomes C, Nunes K, Xavier L, CardosoR, Valle R (2008) Multi criteria decision making applied to waste recycling in Brazil. Omega 36:395–404 11. Shan L, Lie Y, Yan Q, Mei S (2009) Municipal solid waste management in Beijing City. Waste Manage (Oxford) 29:2596–2599 12. Ekmekciog˘lu M, Kaya T, Kahraman C (2010) Fuzzy multi criteria disposal method and site selection for municipal solid waste. Waste Manage (Oxford) 30:1729–1736 13. El hanandeh A, El-zeinA (2010) The development and application of multi criteria decision making tool with consideration

13

J Mater Cycles Waste Manag of uncertainty: the selection of a management strategy for the bio-degradable fraction in the municipal solid waste. BioResourc Technol 101:555–561. 14. Dursun M, Karsak EE, Karadayi MA (2011) A fuzzy multicriteria group decision making framework for evaluating health-care waste disposal alternatives. Expert Syst Appl 38:11453–11462 15. Abu Qdais H, Alshraideh H (2014) Selection of management option for solid waste from olive oil industry using the analytical hierarchy process. J Mater Cycles Waste Manag 18(1):1–9. doi:10.1007/s10163-014-0321-3 16. Mirzazadeh F, Hadinejad F (2015) Applying fuzzy AHP technique in waste disposal method selection, Waste Management, 38, a glance at the world, II. 17. Naser Harati A, Vafaee F, Abdollahzadeh R (2010) Apply ing SWOT analysis on integrated management of coastal zones (case studies: 3 northern provinces). J Environ Sci Technol 12(4):129–142 18. Hassanvand M, Nabizadeh R, Heidari M (2008) Analysis of urban solid wastes in Iran. Health Environ Mag 1(1):9–18 19. Shemmeri T, Al-Kloub B, Pearman A (1997) Model choice in multicriteria decision aid. Eur J Oper Res 97(3):550–560 20. Marinoni O (2005) A stochastic spatial decision support system based on PROMETHEE. Int J Geogr Inf Sci 19(1):51–58 21. Saaty TL (1980) The Analytical hierarchy process. McGraw Hill, New York 22. Sanjay V, Ramachandran M (2006) Multi Criteria evaluation of demand side management (DSM) implementation strategies in the Indian power sector. Energy 31(12):2210–2225 23. Bagranoff NA (1989) Using an analytic hierarchy approach to design internal control system. J Account EDP 4(4):37–41 24. Arbel AY, Orgler E (1990) An application of the AHP to bank strategic planning: the mergers and acquisitions process. Eur J Oper Res 48(1):27–37 25. Moutinho L (1993) The use of the analytic hierarchy process (AHP) in goal assessment: the case of professional services companies. J Prof Serv Mark 8(2):97–114 26. Arunraj NS, Maiti J (2010) Risk-based maintenance policy selection using AHP and goal programming. Saf Sci 48(2):238–247 27. Patrick E, Laurence W (1999) Application of analytic hierarchy process techniques to streamlined life-cycle analysis of two anodizing processes. Environ Sci Technol 33(9):1495–1500 28. Chiang CM, Lai CM (2002) A study on the comprehensive indicator of indoor environment assessment for occupants’ health in Taiwan. Build Environ 37(4):387–392 29. Willett K, Sharda R (1991) Using the analytic hierarchy process in water resources planning: selection of flood control projects. Socio-Econ Plan Sci 25(2):102–112 30. Saaty TL (1990) The analytic hierarchy process in conflict management. Int J Conflict Manag 1(1):47–68 31. Kang HY, Ogunseitan O, Shapiro AA, Schoenung JM (2007) A comparative hierarchical decision framework on toxics uses reduction effectiveness for electronic and electrical industries. Environ Sci Technol 41(2):373–379 32. Mustafa MA, Al-Bahar JF (1991) Project risk assessment using the analytic hierarchy processes. IEEE Trans Eng Manage 38(1):46–52 33. Gaudenzi B, Borghesi A (2006) Managing risks in the supply chain using the AHP method. Int J Logist Manag 17(1):114–136 34. Zayed T, Amer M, Pan J (2008) Assessing risk and uncertainty inherent in Chinese highway projects using AHP. Int J Project Manage 26(4):408–419 35. Milosevic DZ (2003) Project management toolbox. Tools and techniques for the practicing project manager. Wiley, New York 36. Cengiz K, Ufuk C, Ziya U (2003) Multi-criteria supplier selection using fuzzy AHP. Logist Inf Manag 16(6):382–394

J Mater Cycles Waste Manag 37. Macharis C, Springael J, De Brucher K, Verbeke A (2004) PROMETHEE and AHP: the design of operational synergies in multicriteria analysis. Strengthening PROMETHEE with ideas of AHP. Eur J Oper Res 153(2):307–317 38. Leung LC, Chao D (2000) On consistency and ranking of alternatives in Fuzzy AHP. Eur J Oper Res 124:102–113 39. Kulak O, Kahraman C (2005) Fuzzy multi-criterion selection among transportation companies using axiomatic design and analytic hierarchy process. Inf Sci 170:191–210 40. Weck M, Klocke F, Schell H, Ruenauver E (1997) Evaluating alternative production cycles using the extended fuzzy AHP method. Eur J Oper Res 100(2):351–366 41. Chang DY (1996) Applications of the extent analysis method on fuzzy AHP. Eur J Oper Res 95(3):649–655 42. Yu CS (2002) A GP-AHP method for solving group-decision making AHP problems. Comput Oper Res 29(14):1969–2001 43. Kuo RJ, Chi SC, Kao SS (2002) A decision support system for selecting convenience store location through integration of fuzzy AHP and artificial neural network. Comput Ind 47(2):199–214

44. Huang CC, Chu PY, Chiang YH (2008) A fuzzy AHP application in government sponsored R&D project selection. Omega 36(6):1038–1052 45. Pan NF (2008) Fuzzy AHP approach for selecting the suitable bridge construction method. Automat Constr 17(8):958–965 46. Cakir O, Canbolat MS (2008) A web-based decision support system for multicriteria inventory Classification using fuzzy AHP methodology. Expert Syst Appl 35(3):1367–1378 47. Dagdeviren M, Yuksel I (2008) Developing a fuzzy analytic hierarchy process (AHP) model for behavior-based safety management. Inf Sci 178(6):1717–1733 48. Gumus AT (2009) Evaluation of hazardous waste transportation firms by using a two step fuzzy-AHP and TOPSIS methodology. Expert Syst Appl 36(2):4067–4074 49. Bozbura FT, Beskese A (2007) Prioritization of organizational capital measurement indicators using fuzzy AHP. Int J Approx Reason 44:124–147

13