Secondary wastewater treatment using peroxymonosulfate activated by a carbon nanofiber supported Co3O4 (Co3O4@CNF) catalyst combined with ultrafiltration

In this study, a heterogeneous carbon nanofiber supported Co3O4 (Co3O4@CNF) catalyst was prepared, and peroxymonosulfate (PMS) oxidation activated by Co3O4@CNF integrated with ultrafiltration (UF) membranes was proposed for treating secondary wastewater. The micromorphology and chemical composition of Co3O4@CNF were characterized by various techniques, demonstrating the successful synthesis of Co3O4@CNF. The prepared catalyst exhibited superior catalytic performance for PMS, accompanied by the formation of various reactive oxygen species, including •OH, SO4•−, 1O2 and O2•−. The Co3O4@CNF/PMS system substantially enhanced the removal of effluent organic matter (EfOM), and the DOC and UV254 values were decreased to 3.8 mg/L and 0.032 cm−1, with removal rates of 46.5% and 58.4%, respectively. The reduction efficiency of various fluorescent components was also improved, while macromolecular and humic substances were significantly reduced, accompanied by the generation of some small molecular organics. For both polyether sulfone and ceramic membranes, the fouling caused by EfOM was effectively mitigated, with the irreversible fouling resistance reduced by 65.6% and 83.9%, individually. The main fouling mechanism was also changed by increasing the specific filtration volume for the formation of cake filtration. The effectiveness of Co3O4@CNF/PMS for fouling mitigation was verified through the characterization of the surface morphology and functional groups of the membranes. The results suggest that the process of PMS activated by Co3O4@CNF integrated with UF has an application potential for secondary wastewater treatment.