Fuzzy Approach for Evaluating Critical Factors in the Design and Construction of Conventional Wastewater Treatment Plants

Abstract

Conventional wastewater treatment plant (CWTP) construction and operation are challenging, and identifying critical factors is a foremost task in its initial stage. This study aims to evaluate the critical factors considering expert judgment-based data so that field professionals can address them on a priority basis in CWTP design, construction, and operation. Accordingly, 29 critical factors were identified from the literature and evaluated by 20 experts in Saudi Arabian CWTP projects. A fuzzy group decision-making approach was applied to assess and prioritize them, considering the design and construction phases of CWTP projects of varying types, sizes, capacities, and contracts. Among 29 factors, 14 were found to be extremely important in CWTP design, whereas eight have similar importance in CWTP construction and operation. Extremely important factors in both phases include design/operation code, institutional setup and personnel capacity, neighborhood community, and environmental rules and regulations. The importance levels of some factors are varied with project variables. Among others, not complying with standard operation procedures is the top-ranked factor for privately funded, design–bid–build contact, and medium-sized projects. The government’s political commitment is significant for the privately funded and cost-plus-profit contract projects. The variance analysis also shows that factors such as the government’s political commitment, lack of proper equipment monitoring, and distance from wastewater sources have higher uncertainties in different project contexts. Thus, managing those factors is critical with the presented fuzzy-based decision analysis considering varying project scenarios. The study further provides guidelines for the sustainable design and construction of CWTP plants by overcoming critical challenges and constraints.