Bisphenols removal from wastewater in a MBBR-photocatalysis system: Performance and biofilm community dynamics

Bisphenol A (BPA) and its analogs are priority emerging contaminants by major regulatory agencies, demanding treatment technologies capable of reliable removal from wastewater. The study evaluates a bench-scale Moving Bed Biofilm Reactor (MBBR) followed by a photocatalysis reactor to treat synthetic wastewater contaminated with bisphenols A, S, and F (BPA, BPS, and BPF) at an initial concentration of approx. 100 μg L −1 each. The biological reactor operated under continuous flow with a hydraulic retention time (HRT) of 6 h. High throughput 16S rRNA gene sequencing was employed to assess biofilm community and treatment performance. The MBBR exhibited a stable, functionally diverse microbial community dominated by Bacteroidota and Pseudomonadota, with enrichment, upon bisphenol feeding, of genera typically associated with the degradation of recalcitrant contaminants. Despite phylum-level stability, genus-scale restructuring revealed selective enrichment of bisphenol-tolerant taxa. Photocatalysis was performed using titanium dioxide (TiO 2 ) nanoparticles (0.15 g L −1 ) in suspended (TiO 2 -S) and immobilized (TiO 2 -I) configurations, compared to a catalyst-free control. At a total hydraulic retention time of 10 h, the combined MBBR + TiO 2 -I system achieved removal efficiencies of 99.2 ± 1.8% (BPA), 98.7 ± 2.5% (BPS), and 99.9 ± 0.2% (BPF). Adsorption tests confirmed an important contribution of biofilm-mediated sorption during the biological step (44,8% for BPA and BPF, and 21,8% for BPS), while photocatalysis with immobilized TiO 2 markedly enhanced bisphenol degradation. Overall, combining MBBR with photocatalysis proved to be an effective and stable strategy for enhanced bisphenol removal from wastewater. • MBBR biofilm stayed structurally resilient with bisphenol loading. • BPA/BPF relied on adsorption, whereas BPS removal occurred by biodegradation. • Coupling MBBR with photocatalysis boosted the overall bisphenols removal efficiency. • Immobilized TiO 2 outperformed suspended TiO 2 in bisphenols removal stability. • MBBR coupled to photocatalysis achieved >98% removal of BPA, BPS, and BPF.