THE COMBINED USE OF VALUE-FOCUSED THINKING AND THOR 2 TO CHOOSE A BIODIGESTER IN A BRAZILIAN PUBLIC UNIVERSITY

ABSTRACT There are liabilities for society because of the increase in the amount of waste. This work will choose a biodigester to treat organic waste at Universidade Federal Fluminense. For this, the VFT approach was used to structure the problem and the multicriteria decision support method THOR 2 was used to choose the option that has the most excellent preference considering three scenarios. The experts say that six criteria can be used to choose a biodigester, namely Capacity, Input of organic matter, Input of water, Average expected production of biogas and average output of biofertilizer. The research showed that biodigester 7 had the best performance as a result. The relevance of the study refers to the contribution to the reduction of organic solid waste in the environment. This research applies THOR 2 method in a new context.


INTRODUCTION
The increase in consumption has caused some problems, one of which is an unbalanced environment.This is due to the inability to generate resources at a speed compatible with what humanity uses for consumption.(Vieira, 2018).Companies employ a management practice model to manage demand processes, operations, and assets (De Barros et al., 2015).
The concern regarding the damage caused by man to the environment also grew, and one of the concepts of sustainability became the form of development that meets the population's current needs without compromising those of future generations (WCED, 1987).
According to Cruz (2005), the dumping of waste in an inappropriate location generates pollution (water, soil, and others) that simultaneously causes environmental degradation and corroborates epidemiological aspects due to some components present in these wastes attracting macro vectors (flies, cockroaches, rats, pigs, dogs, vultures) and micro vectors (bacteria, fungi, and viruses), being pathogenic, that is, causing diseases and harm to man.
Even though there are considerable challenges to be solved, Higher Education Institutions (HEIs) are essential in the sustainable development process as they shape thought and opinion and can intensify the creation and dissemination of information (Leal Filho et al., 2015).Sustainability in organizations is important, including in public administration, with environmental education at all levels of education as a key factor so that the State can develop sustainable actions.The importance of HEIs is highlighted, due to their specificity in the development and dissemination of knowledge (Almeida, 2015).Sales (2017) also states that in Brazil wastepaper, plastic, and metal, for example, are largely recycled and/or reused, which does not occur with organic waste, which is placed inappropriately in the environment.
Considering the amount of waste generated by public universities, this work focuses on choosing a suitable biodigester for Universidade Federal Fluminense.
Among the existing methods, the research was carried out using the Value-Focused Thinking (VFT) approach and the THOR 2 method.
No papers about sustainability that used the combination of the VFT approach and the THOR 2 method were found.Thus, this combination is original and can be compared with the combination of other methods and approaches.
The VFT approach, according to Keeney (1992), is an approach that represents value-focused thinking for structuring problems, it can capture the values and objectives of individuals.
The THOR 2 method was applied because all the uncertainty present in the attribution of the classifications of the alternatives and the weights is quantified (Tenório et al., 2021).This method is used when the decision maker wants to measure, by fuzzy numbers, the certainty of the available data or the weight assigned to the criterion.Using algorithmic hybridity and the ability to eliminate redundancies and quantify imprecision, it combines theories from the American and French schools.For this reason, the method was chosen.

THEORETICAL FRAMEWORK
According to Albuquerque and Coluna (2018), organic waste, when placed in dumps or landfills, suffers the action of bacteria that generate methane, a process called methanization.However, methane gas generates harmful effects on health and the environment, considered a greenhouse gas, with a capacity 28 times greater than that of CO2.
One of the ways to minimize the emissions of this gas in landfills is the use of a system for capturing and burning the gas or using biogas for energy (Albuquerque and Coluna, 2018).
In higher education institutions, actions on sustainability are increasingly connected with the public and private sectors and occur through isolated actions with the participation of the academic community and the population (Huge et al., 2018).
At the Federal University of Campina Grande (UFCG) there was research in which the objective was to evaluate the reaction of the stages in the anaerobic digestion process, mainly in swine manure and food residues (Sales, 2017).

VFT Approach
The VFT has four procedures that enable and assist in the use of the method, they are: identify the objectives; classify goals (as means or ends); build alternatives; and examine objectives to identify decision opportunities (Keeney, 1996).
Using the techniques in Table 1, it is possible to create a list of essential goals and a basis for future observations that are expected to take place.This list may initially contain items that are not necessarily objective and may include alternatives, restrictions, and criteria.Therefore, each item will either be transformed into objectives or removed from the list, as they are both means and fundamental (Keeney, 1996).

Multicriteria decision support
Real-world decision problems are rarely using a single criterion.They generally involve a variety of criteria, often contradictory.In many practical situations, alternatives must be ranked given multiple, conflicting criteria of preference (Gomes et al., 2020).
Multicriteria decision-making is applied to select, rank, sort, or describe the alternatives in a complex decision-making process with multiple criteria and conflicting objectives (Silva et al., 2018).
The literature presents several applications combining Multiple Criteria Decision Analysis (MCDA) methods to support the decision-making process in personnel selection problems, in most cases applying a method to obtain the weights of the criteria and another one to evaluate the alternatives, taking advantage of each method's characteristics (Costa et al., 2021).
MCDA describes a set of formal approaches that seek to take explicit account of multiple criteria in helping stakeholders and groups explore decisions that matter.Despite the diversity of MCDA approaches, methods, and techniques, the basic ingredients of MCDA are a finite or infinite set of actions (alternatives, solutions, courses of action, etc.), at least two criteria, and at least one Decision-Maker (DM) (Costa et al., 2022).
MCDA seeks to assist in resolving issues that require a complex decision-making process by providing tools to managers; that is, multicriteria decision-making problems (Gonc ¸alves et al., 2021).The Multicriteria Approach has a set of methods developed to support and guide the decision-makers when evaluating the alternatives according to a variety of criteria.

THOR 2
According to Gomes (1999) and Gomes et al. (2010), three scenarios need to be evaluated, given alternatives a and b, when using the THOR method, so that an alternative is perceived as better.
For the review of each scenario, it is necessary to use the preference relations equations presented below (1)(2)(3): Equation ( 1) illustrates a strict preference relationship (P) of one alternative over the other.Equation (2) presents a relationship of indifference between one alternative and another (I).And equation (3) exposes a weak preference relation (Q) of one alternative compared to another.The equations also contain the incomparability of one option to another (aR j b).To quantify the alternatives, we will use the equations (4) presented below, for each of the scenarios (S 1 , S 2, and S 3 ).Each scenario is a different sorting algorithm, which allows the decision-maker to conduct a sensitivity analysis comparing the three results.

S1
: In the S 1 scenario, the alternatives will only have their attractiveness scored in cases where equation (1), aPb, occurs.In the S 2 scenario, more flexible than S 1 and more rigorous compared to S 3 , the alternatives will only present a point of attractiveness where equations ( 1) and (3), aPb or aQb will take place.Scenario S3, which is the least rigorous of the above scenarios, includes all the equations shown in equation 4, aPb and aIb, and aQb.
As reported by Gomes (2005), considering the state of the art in MDM (Multicriteria Decision Making), THOR made the following contributions: • Features a hybrid algorithm that simultaneously combines concepts from Approximate Set Theory (ACT), Fuzzy Set Theory, Utility Theory, and Preference Modelling.
• Sorts discrete alternatives in transitive or non-transitive decision-making processes.
• Eliminates redundant criteria, simultaneously considering whether the information is dubious (use of ACT) and whether there is an increase in imprecision in the decision process (use of fuzzy set theory).
• Quantifies imprecision and uses it in the MDM decision process.
• Allows the simultaneous entry of data from multiple decision makers, allowing them to express their value judgment (s) in a scale of ratios, intervals, or ordinal.
• The new formula used by THOR (to assign weights in the ordinal scale) was obtained after studying the three existing formulas in the literature.
• The decision maker can also execute the decision process without assigning weights to the criteria.
• Eliminates the need for some algorithms that rely on preference modeling to determine a value, usually arbitrary, for agreement.

METHODOLOGY
The research used the VFT and THOR 2 multicriteria decision support methods.
The VFT approach was chosen because it considers the intrinsic values of the organization, which does not necessarily occur in other Problem Structuring Methods (PSM), such as the Soft System Methodology (SSM) or the Strategic Options Development Analysis (SODA).
Real-world decision problems are rarely based on a single criterion.They generally involve a variety of criteria, often contradictory.In many practical situations, alternatives must be ranked given multiple, conflicting criteria of preference (Gomes et al., 2020).In the first phase of the VFT approach, an interview was conducted with a specialist with approximately 8 years of experience in biodigesters.In this first stage, we sought to understand what these professionals value and consider essential characteristics for acquiring biodigesters.The questions, adapted from Table 1, in section 2.1, are part of the theoretical framework that explains the VFT approach.The questions (interview) are presented in Table 2. Table 3 -Criteria for evaluation and decision making.

Criteria Measures Unit Goal Capacity
The total volume that the biodigester holds L ↑ Organic matter input The total amount of organic matter that the biodigester can process per batch kg ↑

Water input
The total amount of water needed by the biodigester to process organic matter L ↓

Average expected biogas production
The average daily amount of biogas generated by the biodigester from the decomposition of the amount of organic matter supported by its capacity m3 /day ↑

Average biofertilizer production
The average monthly amount of biofertilizer generated by the biodigester from the decomposition of the amount of organic matter supported by its capacity

↓
Cost monotonic -the lower the value, the better.

↑
Profit Monotone -The higher the value, the better.
Table 5 shows the decision matrix.The criteria were found in the work of Moreira (2017) and confirmed in the interview with the specialist.Table 6 shows the weight, preference threshold (p), indifference threshold (q), and disagreement (d) of each criterion: These weights, preferences (p), indifferences (q), and disagreement (d) of each criterion present in Table 6 above, chosen by the specialist, were placed in the THOR WEB software and used to analyze the option that best suits the choices made by is it over there.The parameters shown in Table 6 were obtained after consultation with specialists.THOR and THOR 2 use three sorting algorithms (S 1 , S 2 , and S 3 ).The comparison of these three results allows a sensitivity analysis.
In Table 7, the results obtained using the multicriteria decision support method software, THOR, are presented.And Table 8, presents the results using the multicriteria decision support method software, THOR 2.
The results in Tables 7 and 8 were generated so that in the most rigorous scenario (S 1 ), biodigester 7 (THOR 2), and biodigester 1 (THOR) were the best options.
In scenario S 2 , more flexible than S1, biodigester 7 was in the first position.
In the most flexible scenario of all, scenario S 3 : In the first dominant group, both methods (THOR and THOR 2) agree that Biodigesters 1, 2, and 7 are the best.
The second dominant group is formed by Biodigester 6 (it ranked fourth in both methods).
The set that follows is formed by Biodigesters 3 and 4.
And the group formed by Biodigester 5, which in both methods was in last place.

CONCLUSION
Since no sustainability document using a combination of VFT and THOR 2 has been found, this study seems original.
The VFT approach was chosen, as already mentioned because it represents a way of thinking focused on values to structure problems and one of the main advantages of its use is that it helps to identify better alternatives and reveal objectives and attributes that were not known or that had not been thought yet.
The THOR 2 method was used because it is a relatively new method where all uncertainty is quantified.As a result, it is a complete method that incorporates theories from both the American and French schools.It has a hybrid algorithm and can eliminate redundancies and quantify inaccuracies.
The THOR 2 method with the VFT approach, used for the analysis, proved to be effective for the article to reach its objective.It was possible to reduce the subjectivity of the criteria so that an analysis could be performed.
It was observed that the placement of biodigesters occurred with the criteria chosen and the weights given by the specialist, which means that the order of choice can be modified depending on the decision maker.
THOR 2 uses three algorithms to compare the results (S 1 , S 2 , and S 3 ), the comparison of the three allows a sensitivity analysis of the results.
In this case, biodigesters 1, 2, and 7 obtained the highest score in situations S 1 , S 2 , and S 3 , proving are the most appropriate options.
Furthermore, if the location of the choice was different, with a different structure, the biodigester model chosen as the most appropriate option might be another.
For future studies, it is suggested that there be a comparison of this result with other combinations of methods and approaches.

Table 1 -
Techniques for identifying objectives.
Keeney (1996) you have for your customers, employees, shareholders, and yourself?What environmental, social, economic, health, and safety objectives are important?9ºFindingstructuralgoals Follow means-ends: why is this goal important and how can you reach it?Specify: what do you mean by this objective?10ºMeasuregoalsHow do you assess the achievement of this objective?Why is goal A more important than goal B?Source:Keeney (1996).

Table 4 -
. O. G. R. SOUZA, M. SANTOS, C. F. S. GOMES, O. L. G. QUELHAS and N. A. BARUD 9 Legend of the figures indicated in the objective column of each criterion.

Table 7 -
Results obtained with the THOR method.

Table 8 -
Results obtained with the THOR 2 method.