Comparative Environmental and Economic Assessment of the Zahle Wastewater Treatment Plant in Lebanon under Different Scenarios

Abstract

Assessing the environmental impacts of wastewater treatment plants (WWTPs) is a growing concern that needs to be addressed. Although several studies have been published on the environmental performance of WWTPs, few have been reported from developing countries, especially in Lebanon. In this study, the environmental and economical performance of an oxidation ditch-based secondary treatment technology in Zahle, Lebanon, was evaluated using life cycle assessment (LCA) and life cycle cost (LCC) validated using GPS-X v. 80 software and three hypothetical scenarios were suggested and compared with its current state. The first scenario (S₁) included adding anaerobic sludge digestion. The second scenario (S₂) included using extended aeration. The third scenario (S₃) included using a five-stage Bardenpho (FSB) process. For this purpose, a series of LCAs were performed using SimaPro 9.3.0.3 together with the ecoinvent 3.8 database, and the ReCiPe midpoint (H) and endpoint (H/A) methodologies, A functional unit of 1 m³ of treated wastwater was used as a basis. The WWTPs costs were estimated using the CapdetWorks v4.0 software. Further, LCA was monetized using external costs. The analysis revealed that the environmental categories were primarily influenced by energy consumption. The current plant had a global warming effect of 0.678 kgCO₂ eq/m³. Normalized results showed that the first scenario was the most environmentally friendly alternative in the human carcinogenic toxicity impact category quantified as follows: S₂ < S₀ < S₃ < S₁. Normalized results also showed that freshwater ecotoxicity and human carcinogenic toxicity were the main impact categories....