Application of AHP Model for Evaluation of Solid Waste Treatment Technology

Transcription

1 Mohd Armi Abu Smah et al Int J Engg Techsci Vol 1(1) 2010,35-40 Application of AHP Model for Evaluation of Solid Waste Treatment Technology Mohd Armi Abu Samah, Latifah Abd Manaf and Nur llyana Mohd Zukki Faculty of Environmental Studies,Universiti Putra Malaysia,43400 Serdang, Selangor, Malaysia. Abstract Solid waste management is a major challenge for Malaysia to address in the light of Vision Therefore, a better strategy and planning is important to improve the efficiency and effectiveness of solid waste management. A multicriteria decision making technique, Analytical Hierarchy Process (AHP), which utilizes a multi-level hierarchical structure consists of objective, criteria, subcriteria, and alternatives is applied in selection of an appropriate solid waste treatment technology. The input from the experts has been used in pairwise comparison matrix in order to rank the technologies. These comparisons have been used to obtain the weights of importance of the decision criteria, and the relative performance measures of the alternatives. Based on consistency ratios, a value of 10 percent or less will be accepted; otherwise the process must be revaluated. A case study was conducted at Sepang Municipal Council (SMC) to demonstrate the application of AHP on that area. The finding of this study shows that the combination of recycling and composting technology is the most appropriate solid waste treatment technology and recommended to be implementing in Sepang Municipal Council. Keywords: Solid Waste; Analytical Hierarchy Process (AHP), Sepang Municipal Council Introduction In Malaysia there were too much discussion and problem about solid waste management. Solid waste management is a major challenges for Malaysia to address in the light of vision 2020, which lays out the direction for Malaysia to become a fully developed nation by 2020 (MHLG, 2005). Basically the volume of solid waste generated in Malaysia is estimated to exceed 15,000 tonnes daily. The current systems as used of manual labour, waste collection trucks and open dumps for disposal suffer from insufficient modern equipments and environmental control pollution technologies. However the average amount of municipal solid waste generated in Malaysia is about kg/person/day and has increased to 1.7 kg/person/day in major city (Kathirvale et al., 2003). There are many landfills in Malaysia are very crucial. As we know Malaysia is developing country and should improve their landfill to achieve the EPA standard. Thus the Malaysia government try to aim that used privatization would attain an efficient solid waste management with application of advanced technology and hope that the concept of privatization can enhance environmental quality through awareness, resources, reuse, waste minimization and many more. However, Malaysia still needs about RM 400 million just to manage the solid waste (The Star, 2003). Therefore finding the best and effective technology system based on multicriteria decision making tools is important for the development and sustainability of future environment. The Analytical Hierarchy Process (AHP) Basically a tool that permits explicit presentation of evaluation criteria and possibly improves selection of technology for solid waste managment plan is the Analytical Hierarchy Process (AHP). Multicriteria decision analysis (MCDA) models, such as the AHP, are used to consider waste management options. The AHP (Saaty, 1980, 1990) is known multi attribute weighting method for IJETS 35

2 decision support (Madu, 1994). AHP is a decision approach designed to aid in the solution of complex multiple criteria problems in a number of application domains (Saaty, 2000). Keeney (1982) has divided decision analysis into four phases (the previous three plus one addition aspect: - (1) structure the decision problem, (2) assess possible impact of each alternative, (3) determine preference of decision makers, and (4) evaluate and also compare decision alternative. Thus, Analytical Hierarchy Process (AHP) is suitable to be applied in solid waste management because it can help in making decision in selecting solid waste treatment technology more effectively. Structuring the Decision Problem The knowledge acquisitions process for structuring the decision are obtained from many sources such as availability of human expert, literature and secondary information about the waste management in Malaysia and Sepang area. Basically, gaining human expertise was done with communication process, in which series of site visits to various related solid waste management centres as listed in Table 1 below. The domain experts are chosen individuals whom posses criteria such as actively practicising and applying their expertise, knowledgeable and experiences, good time management skills, good communication skills, their expertises are well recognized. Table 1: Sources of Human Expertise Shah Alam City Council Ministry of Housing and Local Government Economic Planning Unit (EPU) Nuclear Agency Department of Environmental (DOE) PJS Environmental Services Solid Waste Disposal Putrajaya Holdings Malaysia Nature Society (MNS) Universiti Kebangsaan Malaysia Besides human experts interview, knowledge are also acquired from sites observation to obtain more information on recycling, composting and incineration practicing in Malaysia. Analysis from data in Table 2 shows all of the selected subcriteria are to be filled in the General Hierarchy Structure Model (GHSM). There are twelve subcriteria that have been selected based on survey distribution and interview with domain experts in solid waste management. The selection of subcriteria is carried out using simple statistical analysis to obtain average value of the given scales. This technique is relatively similar with Delphi method which only those with the highest percentage in data analysis will be considered as subcriteria in order to choose the best technology for solid waste treatment. Development of Hierarchy Structure Model Knowledge on selection of solid waste treatment technology which acquired from multiple sources were structured into hierarchy which shown in Figure 1. The AHP technique is performed with the goal to select an appropriate solid waste treatment technology that will be able to produce the best and optimum outcome in long term. There are 6 important criteria resulted from in the hierarchy structure namely, political support, technical expertise, environmental impact, market potential, community involvement and cost. Therefore, location, public acceptance, feasibility, experience, water pollution, public health, estimates cost, financial management, cooperation, interest message, operation cost and capital cost (Wilson, 1981), were selected as the subcriteria to support the main criteria that had been selected before. The components of Recycling, Composting and Incineration were selected as single technology alternative. Furthermore combination of Recycling + Composting, combination of Recycling + Incineration, combination of Composting + Incineration and also combination of Recycling + Composting + Incineration was selected as the combination technology alternative in the General Hierarchy Model Structure (GHSM). IJETS 36

3 Table 2: Data Analysis for Selection of Criteria in Solid Waste Management Criteria Political Support Total Percentage (%) Location Public Acceptance Criteria Technical Expertise Total Percentage (%) Feasibility Experience Criteria Environmental Impact Total Percentage (%) Water Pollution Public Health Criteria Market Potential Total Percentage (%) Estimates Cost Financial Management Criteria Community Involvement Total Percentage (%) Cooperation Interest Message Criteria Cost Total Percentage (%) Operation Cost Capital Cost Figure 1: General Hierarchy Structure Model Where: R : Recycling C : Composting I : Incineration R+C : Combination of Recycling + Composting R+I : Combination of Recycling + Incineration C+I : Combination of Composting + Incineration R+C+I : Combination of Recycling + Composting + Incineration IJETS 37

4 Application of Pairwise Comparison Matrix (PCM) To apply pairwise comparison method, at first step we need to form a pairwise comparison matrix for all the criteria. The degree of preference of the decision makers in the choice for each pairwise are quantified based on a ratio scale of (1/9, 9). The scale was originally because the comparison will be made within a limited range where perception is sensitive enough to make a distinction. The interpretation of this scale is provided in Table 3. Table 3: Scale of preference Verbal judgment of importance (Adapted from Saaty, 2000) Numerical rating Equal importance 1 Equal to moderate importance 2 Moderate importance 3 Moderate to strong importance 4 Strong importance 5 Strong to very strong importance 6 Very strong importance 7 Very strong to extremely strong importance 8 Extreme importance 9 To find out the weight, at first we determined the largest eigen value maks. Then the weight wi s are determined by solving the following system of linear simultaneous equation: n Wi = 1/ maks aijwj, i = 1,2,,n j=1 for uniqueness, we normalize the set of weight such that n wi=1 i=1 The consistency index is defined by As usual, Ci = maks n / n-1 CR = CI / RI = < 0.1 = Acceptable = > 0.1 = Not Acceptable The overall results for the solid waste treatment technology at Sepang Municipal Council (SMC) This analysis is based on data obtained from the user namely policy maker at the Sepang Municipal Council (SMC) who hold the position as a director under the Department of Environmental Health which responsible in supervising solid waste management throughout Sepang District. Basically, IJETS 38

5 the overall result from Table 4 shows that the combined recycling and composting technology is ranked first for Sepang municipal solid waste treatment technology with weight of Others technologies such Incineration is weighted 0.12, combination recycling and Incineration is weighted 0.10, combination technology composting and incineration is weighted 0.09, recycling is weighted 0.08, composting is weighted 0.07 technologies with last ranking is combination recycling, composting and incineration with weight of Thus, it is expected that the finding from this study will be used as decision support system and guideline in term of selecting an appropriate solid waste treatment technology for Sepang Municipal Council and reducing the problems regarding to solid waste management in Sepang Selangor. Table 4: The Ranking of Solid Waste Treatment Technology Solid Waste Treatment Technology Weight Ranking Recycling + Composting Incineration Recycling + Incineration Composting + Incineration Recycling Composting Recycling + Composting + Incineration Conclusion These papers basically focus on the evolution of selecting solid waste treatment technology using AHP approach. The selecting of an appropriate solid waste treatment technology consists of multiple criteria and alternatives that were evaluated by a decision maker in order to achieve an objective. The Analytic Hierarchy Process (AHP) is a theory of relative measurement on absolute scales of both tangible and intangible criteria based on the paired comparison judgment of knowledgeable experts. Normally, evaluation of a set of alternatives is carried out on the basis of a number of criteria. For evaluation, in addition to the identification of criteria, it is important to assign selection of an appropriate set of weight to the criteria on solid waste treatment technology. The AHP was used to assign priorities to the alternatives based on the model hierarchy structure for solid waste treatment technology. Obviously, a variation in the criteria weights impacts the ranking of the alternatives in order to find the best selection to apply as well as suitable techniques, technologies and management programs to achieve specific technology for managing solid waste in municipal in Sepang. However based on the information obtained was showing something positive where acquired weight decision is almost same with what they will make to Sepang Municipal Council (MPS) for the future planning. Acknowledgment The authors would like to thank Ministry of Sciences, Technology and Innovation (MOSTI), Malaysia for sponsoring this research under Science Fund Research Grant ( SF0675). IJETS 39

6 References : Kathirvale, S., Muhd Yunus, M.N., Sopian, K. and Samsuddin, A.H Energy potential from municipal solid waste in Malaysia. Renewable Energy. (29): Keeney, R.L Decision analysis: An overview. Operation Research. (30): Ministry of Housing and Local Government Malaysia National Strategic Plan For Solid Waste Management. The strategic Plan. Local Government Department. V(1) pp:1-65 Morrissey, A.J., Browne, J., Waste management models and their application to sustainable waste management. Waste Management 24, Saaty, T.L Fundamentals of decision making and priority theory. 2 nd ed. Pittsburgh,: RWS publications. Saaty, T.L Multicriteria Decision Making: The Analytic Hierarchy Process. RWS Pittsburgh : Publications. Saaty, T.L The Analytic Hierarchy Process. New York: Mc Graw Hill Inc. Madu, C.N A quality confidence procedure for GDSS application in multicriteria decision making. IIE Transactions. (3): The Star, Do you bit for recycling, urges Ong. January Wilson, D.C Waste management: Planning, evaluation and technologies. Oxford. Oxford University Press: New York. IJETS 40