Management of the construction and demolition waste (CDW) and determination of the best disposal alternative by FAHP (Fuzzy Analytic Hierarchy Process): A case study of Tehran, Iran.

Abstract

The study focused on the management of the final disposal of Construction and Demolition Waste (CDW) generated in Tehran and the determination of the best disposal method. For this purpose, three of final disposal alternatives such as reusing, recycling and landfilling were selected. Moreover, three effective criteria (environmental, economic and socio-cultural) and 16 sub-criteria were considered. A group of experts participated in the questionnaire in order to create a database. FAHP (Fuzzy Analytic Hierarchy Process) was used to determine the final disposal alternative considering to the sustainable development approach. The results obtained from the FAHP model showed that the weight of the environmental, economic and socio-cultural criteria was 0.330, 0.544 and 0.126, respectively. In the view of the environmental, the weight value of the sub-criteria of recyclable, water pollution, air pollution, soil pollution and natural resources protection were 0.035, 0.127, 0.069, 0.042 and 0.055, respectively. In terms of economic, the weight value of the sub-criteria of raw materials cost, land occupancy rate, profitability, mutual interests, exploitation cost and initial investment were 0.108, 0.045, 0.063, 0.083, 0.094 and 0.149 respectively. In addition, from the point of view of socio-cultural aspect, the weight value of the sub-criteria of community acceptance, government cooperation, people's awareness level, security in construction and employment were 0.015, 0.050, 0.011, 0.022, and 0.026, respectively. The reuse alternative with a weight of 0.439 was selected as the best disposal method and the recycling (0.312) and landfilling (0.250) were second and third alternatives, respectively. The results also indicated that the generated CDW in Tehran was mostly composed of reusable components such as metals, plastics, wood, glass and gypsum. Therefore, with the selection of this alternative as a final disposal method, the costs of raw materials and the pollution originated from landfilling can be significantly reduced.Implication: The main purpose of this study is to provide a framework in which the priority of criteria and sub-criteria and alternatives in CDW management in Tehran, Iran is determined. The novelty of this method included providing an efficient management method in CDW management, because the production of this type of waste in Iran has become a major problem. The most important part of this method was the decision of local experts to provide the best disposal alternative, since solving problems related to CDW management is achieved by participation and collaboration with experts working in the same system. The obtained results showed that reusing is the first priority in terms of all the studied criteria and sanitary landfilling is the last priority. Sanitary landfilling is currently in place in the study area and respondents are well aware of its disadvantages. The results in terms of each criterion show that economic criteria are the most important criteria. Investment cost in terms of economic criteria, public acceptance in terms of social criteria and water pollution in terms of environmental criteria as the most effective sub-criteria according to the main goal. Various complex factors affect CDW management systems and therefore the use of practical decision-making techniques such as FAHP to deal with the complexity of CDW management will be useful and valuable.