The uncontrolled population growth and unregulated use of water for purposes such as agriculture, domestic, and industrial activities have resulted in the production of large volumes of wastewater. Wastewater is considered one of the main pollutants of the environment, and it must be collected and treated in appropriate and sanitary conditions. While industrial development and the expansion of industrial activities contribute to economic growth, they are also one of the primary sources of environmental pollution. Wastewater effluents and sludge contain significant amounts of heavy metals and trace elements, and their excessive discharge into the environment and agricultural lands causes irreparable harm to the ecosystem and the health of humans and other organisms.
In the present study, by integrating two wastewater treatment methods, IFAS-MBBR, and proposing an optimized mathematical model, the sustainable supply chain in wastewater systems was examined. In this study, fuzzy ANP and DEMATEL methods were combined to evaluate the criteria affecting wastewater treatment. The DEMATEL method was employed to determine and illustrate the internal relationships between criteria and sub-criteria, and in the next step, the weights of the criteria and sub-criteria were determined using the fuzzy ANP method, and these factors were ranked. Finally, through compromise programming, a multi-objective optimization model was developed by incorporating criteria, quantitative values, and their weights, considering economic, social, and environmental factors under three scenarios: locating the wastewater treatment plant near the city, inside the city, and outside the city.
The results revealed that among the eighteen sub-criteria categorized under environmental, economic, and social criteria used to evaluate relationships and assess the importance of each, the environmental criterion ranked first in importance, followed by economic, and lastly, social criteria. The sub-criteria related