Exergy Analysis for Evaluating the Performance of an Integrated Leachate Treatment System

Exergy analysis provides a unified framework for assessing environmental, technical, and economic aspects in energy terms, enabling the identification of irreversibilities that reduce process efficiency. In wastewater treatment, its application remains limited, focusing on municipal effluents and chemical exergy derived from chemical oxygen demand. This study proposes an advanced exergy analysis model for wastewater treatment, structured in three phases: (i) system data, (ii) exergy analysis, and (iii) optimization through exergoenvironmental, exergoeconomic, and exergotechnical indicators, statistically assessed using the desirability function approach (DFA). The model was validated using a case study of a leachate treatment system that combined coagulation-flocculation, three photo-Fenton configurations, and activated sludge. The highest desirability (0.59) in exergy terms for the pretreatment was achieved with 1 g L^-1 iron chloride at pH 5, while DFA was 0.74 in the photo-Fenton process involved pretreated leachate with residual iron (0.08 g L^-1 of iron) and a single 2.5 g L^-1 dose of hydrogen peroxide followed by biological treatment. Irreversibilities were greatest in the biological stage due to electricity demand followed by influent composition, reagent consumption, and sludge generation. The model offers robust criteria for optimizing treatment design and supports the achievement of Sustainable Development Goals 6, 11, and 12.