Atıksu arıtma tesislerinin aralıklı veri zarflama analizi ile etkinliklerinin değerlendirilmesi

The biggest problem that we face to face in the current century is considered to be the climate crisis. In this context, one of the 17 "Sustainable Development Goals" (SDGs) determined by the United Nations to manage the climate crisis is "clean water and sanitation". Wastewater treatment plants (WWTPs) with the process of treatment, discharge under appropriate conditions, and recycling of the wastewater are strategic elements that directly serve the purpose of access to clean water and prevention of water pollution. WWTPs in the world increase in number with urbanization and industrialization and develop in parallel with technology. In addition, the issue of the effective, efficient and sustainable operation of WWTPs is also examined by researchers and experts, and studies and research that will guide public and private sector organizations are carried out. Data envelopment analysis (DEA) is a method that allows the relative effectiveness of decision-making units (DMUs) to be measured and evaluated when there are multiple input and output variables. As will be examined in this study, there are valuable study and application examples in the international literature for the evaluation of the effectiveness of WWTPs using DEA. Nevertheless, there are a limited number of academic studies in this field in Turkey, and it is seen that the literature is open to development in terms of research and practice. In this study, a three-stage methodology has been proposed to evaluate the effectiveness of WWTPs considering the uncertainties and some hesitations in the data. The case study has been carried out using the data of 88 WWTPs of the Istanbul Metropolitan Municipality. Firstly, expert opinions have been taken to determine the input and output variables for calculating efficiency values. These opinions have been evaluated with the extended weight assessment ratio analysis (SWARA). Secondly, the data of the WWTPs have been converted into interval values to allow the evaluation of different year efficiencies at once and to eliminate the hesitations and uncertainties. Efficiency scores have been calculated using output-oriented DEA for the best-case, original, and worst-case scenarios that form the interval values. Finally, it has been examined whether there is a difference in the efficiency values of WWTPs based on age and type of facility. This thesis study, with its proposed methodology, allows the evaluation of DMUs under uncertain situations and different time intervals, taking into account expert opinions. Beside this, it is an exemplary study for public and private institutions in the evaluation and development of the effectiveness of WWTPs in Turkey with its application.