Water treatment technology selection using hesitant Pythagorean fuzzy hierachical decision making

Water treatment technology (WTT) selection is an excessively important problem since dramatic increases in health problems originated from drinking waters occur day by day. WTTs have high initial investments and operating and maintenance costs with different lives and capacities. Besides, their selection depends on the output quality of the water, capacity, land structure, and environmental issues. Therefore, WTT selection problem is a multi-criteria problem, which requires linguistic evaluations rather than exact numerical evaluations. In this paper, we propose a multi-expert and multi-criteria hesitant Pythagorean fuzzy decision analysis to select best fit WTT for clarification process in water treatment. Aggregation operators and pairwise comparisons for hesitant Pythagorean fuzzy sets (HPFSs) are applied in the analysis. Comparative analyses are additionally realized to show the validity of the proposed approach and the robustness of the givendecisions.