Enhancing sustainability in pharmaceutical industries: advancing circular economy and resource recovery in wastewater treatment

Earth has limited water and energy resources, and the rapid growth of the pharmaceutical sector is intensifying pressure on these finite supplies through high water demand and complex wastewater discharges. Pharmaceutical manufacturing generates highly polluted effluents containing active pharmaceutical ingredients (APIs), solvents, salts, nutrients, and metals that often escape conventional treatment and pose chronic ecological and human health risks. At the same time, existing reviews tend to focus either on generic industrial effluents or on single treatment technologies, and rarely integrate circular economy concepts with specific resource recovery options for pharmaceutical wastewater. This review addresses this gap by: (i) characterising liquid, solid, and gaseous waste streams from fermentation- and chemical synthesis-based pharmaceutical production; (ii) synthesising state-of-the-art treatment trains combining biological, physicochemical, and advanced oxidation processes; and (iii) evaluating how zero-liquid-discharge and resource recovery strategies (e.g. solvent, metals, nutrients, enzymes, and energy recovery) can operationalise circular economy principles in this sector. Particular attention is given to technological and regulatory constraints, including the persistence of APIs, high operational costs, and inadequate discharge standards, which currently limit the widespread adoption of advanced treatment and circularity practices. The review provides a decision-oriented framework to support industry and regulators in selecting feasible treatment-recovery combinations that reduce freshwater dependence, minimise pollutant releases, and align with SDGs 6, 7, 11, and 12.