Water quality index and life cycle assessment of wastewater treatment plant: Feasibility of effluent reuse

The overexploitation of water resources in Iran has intensified water scarcity and reduced the availability of clean water. Reusing effluent from wastewater treatment plants (WWTPs) is a practical approach to addressing this challenge. Therefore, this study was conducted to comprehensively evaluate the feasibility of effluent reuse in municipal WWTPs in northern Iran. The integrated Canadian Water Quality Index (CWQI) and life cycle assessment were applied to determine the most suitable effluent applications. The influent and effluent characteristics, as well as their environmental impacts at both the midpoint and endpoint levels, were monitored based on 1 m(3) wastewater treatment using the ReCiPe method. The results showed that copper (0.641 mg/L) and chromium (0.88 mg/L) concentrations hindered the use of effluent for discharge into surface water as well as agricultural and irrigation applications. CWQI values indicated that the effluent quality was excellent for recreational use (100) and marginal for livestock use (46). The environmental burdens of effluent discharge were primarily related to the marine and freshwater ecotoxicity (0.14-0.15 kg 1,4-dibromobenzene (DB) eq) with the lowest uncertainty (<9 %). This was mostly relevant to the quality of treated wastewater (84 %) and sodium and chemical oxygen demand (COD) contents with 3.5-8 % contributions. In addition, the endpoint approach illustrated that the most environmental impacts were on resources (66.12 %). The total CO2 release was 1.06 kg CO2 due to fossil fuel consumption. Overall, this solution-oriented study highlights the utmost significance of environmental indicators in decision-making and supports the adoption of applicable and promising strategies in WWTP management.