Environment risk assessment of wastewater treatment using FMEA method based on Pythagorean fuzzy multiple-criteria decision-making

The purpose of this paper is to identify environmental aspects and provide solutions to reduce and eliminate environmental impacts using the Failure Mode and Effects Analysis (FMEA), which is a preventive measure against potential hazards. In spite of its simplicity, the limitations of this method can divert results from reality. This research presents a new approach in three phases that prioritizes the identified failures by covering some shortcomings of the traditional FMEA method, including non-assignment of different weights to risk factors and not considering uncertainty. Failure modes are detected by the FMEA team. Then, the factors are weighed using the Pythagorean Fuzzy Stepwise Weight Assessment Ratio Analysis (PFSWARA) method. Then, in final phase, the identified failures by the PF the Complex Proportional Assessment (COPRAS) method are ranked. In this paper, two risk factors including pollution range and cost based on the nature of the case study have been added to traditional RPN factors. Also, in this approach, different weights are assigned to risk factors and uncertainty is considered based on PFS theory. To prove the reliability and efficiency of the proposed approach, it was implemented in the Iranian wastewater treatment plant, and failure modes with high risk were identified. Finally, to confirm the validity and effectiveness of the results, the sensitivity analysis of the proposed method was performed with other common methods such as FMEA, FSWARA-FCOPRAS, and IFSWARA-IFCOPRAS. The results show that the ranking is complete in the proposed method and the results are more reliable. Also, the results of COPRAS, TOPSIS and VIKOR methods were compared and COPRAS was superior to other methods with a correlation of 0.91.