Efficient degradation of tetracycline by Mn(III)-microbial complexes mediated by mnOx@ACF in sequencing batch reactors: performance, mechanism, and effect on microbial community structure

Engineered nanomaterials are widely used in water and wastewater treatment processes, and minimizing their adverse effects on biological treatment processes in wastewater treatment plants has become the primary focus. In this study, activated carbon fiber (ACF)-loaded manganese oxide nanomaterials (MnOx@ACF) were synthesized. A small-scale sequencing batch reactor (SBR) was constructed to simulate the synergistic degradation of pollutants by nanomaterials and microorganisms and the effects of nanomaterials on the structure of the microbial community in a wastewater treatment plant. The MnOx@ACF exhibited efficient removal of pollutants (98.7% in 30 cycles) and chemical oxygen demand (COD 96.4% in 30 cycles) through the formation of Mn-microbial complexes and enhanced cycling between Mn(III) and Mn(II) over 30 operating cycles. Metagenome analysis results showed that the microbial population composition and functional abundance increased when the SBR was exposed to different dosages of MnOx@ACF for a long time, among which 0.2 g/L MnOx@ACF exhibited the highest stimulation and influence on the functional abundance of microorganisms, which showed optimum ecological effects.