Optimal energy recovery and wastewater reuse assessment in a batch industrial process using extended chemical exergy pinch analysis

• Extended chemical exergy pinch analysis was proposed for optimal PRO-RO retrofitting. • The numerical tool was detailed using storage cascade tables for batch operation network. • Determination of the optimal wastewater storage capacity. • A model-based techno-economic assessment was performed on batch process. • Implementation of proposed EChExPA for three system configurations. The study proposed a novel Extended Chemical Exergy Pinch Analysis (EChExPA) framework for batch water-using industries, integrating Pressure Retarded Osmosis (PRO) and Reverse Osmosis (RO) to simultaneously achieve sustainable power generation and water recovery. The numerical tool of EChExPA is integrated with multi-objective optimisation and concurrent batch scheduling, enabling systematic decision-making for process design and operation. The developed numerical tool optimises the capacity of wastewater storage tanks, total annual cost (TAC), and levelized cost of energy (LCOE) while maximising the utilisation of chemical exergy within the system. Concurrent scheduling of wastewater treatment units dynamically aligns discharge profiles with PRO and RO operation, enhancing overall system synergy. Three system configurations were evaluated: single-batch stand-alone PRO, single-batch PRO–RO hybrid, and cyclic batch PRO–RO hybrid. Among the three configurations, the PRO–RO cyclic batch system exhibited the lowest LCOE (0.094 €/kWh) and minimum water production cost (0.91 €/m 3 ), outperforming both stand-alone PRO and single-batch PRO–RO systems. This confirms the effectiveness of the integrated EChExPA framework in delivering a cost-efficient and energy-optimized solution. The work establishes a unified framework that couples exergy-based analysis, optimization, and operational scheduling, offering a new pathway for integrating water recovery and energy generation in batch industrial systems.