Smart and sustainable approaches for self-sufficiency: Modeling energy-efficient effluent treatment and water...

Pharmaceutical effluents contain high concentrations of antibiotics, active pharmaceutical ingredients (APIs), nutrients, and complex organics, generating ecotoxicity and antimicrobial-resistance risks that challenge conventional treatment. Whereas in India, Zero-Liquid-Discharge (ZLD) mandates on-site treatment, recovery, and reuse of treated wastewater, motivating smarter, resource-efficient solutions. Thus, this study assesses and optimizes an "Activated Sludge Process" based effluent treatment plant (ETP) at a southern-India pharmaceutical industry using a BioWin digital twin to diagnose bottlenecks and model energy-efficient upgrades. Plant monitoring showed high removal of turbidity (98.8 %) and Biological Oxygen Demand (93 %), but limited reduction of total nitrogen (62 %) and Chemical Oxygen Demand (COD) (48 %). Model-guided optimizations targeted reduced aeration time (20 % energy savings), alternating aerobic-anoxic conditions and enhanced ammoniacal‑nitrogen and COD removal, reaching National Green Tribunal standards. To address recalcitrant APIs and E. coli, non-thermal plasma advanced oxidation and microalgal technologies are recommended. A facility-wide water audit revealed substantial freshwater dependence; consequently, rainwater harvesting (23,292.5 KL/annually) and internal reuse were incorporated to strengthen ZLD compliance and progress toward water self-sufficiency. The combined framework digital-twin modeling, targeted treatment augmentation, and water-conservation measures offers a practical pathway to smart, energy-efficient, and sustainable ETP operation in the pharmaceutical industry.