Treatment of Greywater with Emerging Contaminants Using Hollow Fiber Membrane Bioreactor

Abstract

Greywater reuse has emerged as a promising strategy to reduce pressure on freshwater resources, but little is known about the impact that emerging contaminants may have on its safe application. This study evaluated the performance of hollow fiber membrane bioreactors (HFMBs) for synthetic greywater treatment under control conditions and exposure to two widely used pharmaceutical compounds: ibuprofen and diclofenac. Nine HFMBs were operated for 11 days using synthetic greywater without pharmaceuticals (control), ibuprofen-amended greywater, or diclofenac-amended greywater. Reactor performance was assessed through physicochemical parameters and microbial community analysis. Turbidity and soluble chemical oxygen demand (sCOD) decreased in all reactors and were adequately described by an empirical temporal stabilization model. Turbidity removal was comparable among treatments, whereas final sCOD removal differed among reactor conditions. Anionic surfactants were markedly reduced, with removal efficiencies above 98% in all systems. In contrast, ibuprofen and diclofenac showed small and variable decrease in measured concentrations, but no statistically significant differences were detected between initial and final concentrations. Microbial community analysis revealed that Pseudomonadota was the dominant phylum in the HFMB reactors. Functional prediction further indicated an enrichment of pathways associated with aromatic compound degradation and biofilm-related processes across the reactor configuration and operating conditions. Moreover, the diclofenac treatment exhibited an additional enrichment of functions related to environmental stress resistance and an enhanced potential for aromatic compound degradation compared with the control treatment.