The recalcitrant nature of pharmaceutical wastewater, which contains high concentrations of active pharmaceutical ingredients (APIs), poses a significant challenge for conventional treatment systems. The present study examines a novel hybrid treatment process based on biological acclimatization after the use of secondary sewage and coagulation after the application of natural plant-based coagulants. Initially, a biological batch process was optimized in a period of 110 days using different ratios of wastewater to sewage, with the 1:3 ratio showing the best stability of degradation. Subsequently, a mixture of acclimatized and raw wastewater was treated using Azadirachta indica (Neem) and Moringa oleifera (Moringa) leaf powder. Results indicated that M. oleifera significantly performed better as compared to A. indica that is 94% reduction in Chemical Oxygen Demand (COD) as against 70% by Neem, at an optimal hydraulic retention time of 8 hours and a size of 150 µm. Mechanistic understandings based upon FTIR and NMR spectroscopy confirmed drug compound “partial degradation” of complicated aliphatic and aromatic molecules to less complicated by-products. Furthermore, FE-SEM and EDX analysis showed different morphological alterations and changes in the element composition, confirming the adsorption and bridging mechanisms of the natural coagulants. A techno-economic analysis indicates that this hybrid protocol is cost-effective with respect to the conventional chemical methods, with the sludge produced showing promise for valorization to serve as bio-fertilizer, this implies a circular economy approach to sustainable wastewater management.
