Elucidating removal pathways of endocrine-disrupting compounds in aerobic granular sludge: Process performance and microbial community dynamics

Contamination of aquatic environments by endocrine-disrupting compounds (EDCs) poses ecological and human health risks due to their persistence and estrogenic activity. This study evaluated an aerobic granular sludge (AGS) sequencing batch reactor (SBR) treating simulated domestic wastewater spiked with representative EDCs: 17β-estradiol (E2), 17α-ethinylestradiol (EE2), and bisphenol A (BPA). Besides evaluating organic matter and nutrient removal efficiencies, the fate of the EDCs was assessed through adsorption onto granular biomass and biological degradation under alternating anaerobic–aerobic conditions. The results showed that E2 was fully removed by biodegradation, with substantial consumption under anaerobic conditions. BPA removal was initially limited but improved as biomass acclimated, achieving full elimination predominantly through biodegradation. In contrast, EE2 was poorly degraded, being mainly adsorbed anaerobically and partially desorbed during aeration, resulting in persistent effluent concentrations. While chemical oxygen demand (COD) removal remained stable under EDCs exposure, EE2 impaired phosphate uptake and nitrification, indicating the sensitivity of polyphosphate-accumulating organisms and ammonia-oxidizing bacteria. Estrogenic activity decreased in the presence of E2 and BPA but increased when EE2 was introduced. Microbial community analyses by 16S rRNA sequencing revealed transient shifts, reduced richness under EE2 exposure, and resilience after its withdrawal. Overall, AGS demonstrated robust performance and adaptive capacity, although limitations remain for recalcitrant estrogens such as EE2. These findings support optimization strategies for enhanced micropollutant removal in practice. • AGS efficiently removed E2, EE2, and BPA from simulated domestic wastewater • Phosphate-accumulating organisms were reversible affected by EE2 addition • EE2 temporarily inhibited nitrification, with low AOB and NOB abundance • AGS performance remained stable for organic matter despite EDC addition • AGS showed strong resilience, adapting microbial communities under EDC stress