Structural characteristics and microbial function of biofilm in membrane-aerated biofilm reactor for the biodegradation of volatile pyridine.

In order to avoid the serious air pollution caused by the volatilization of high recalcitrant pyridine, membrane-aerated biofilm reactor (MABR) with bubble-free aeration was used in this study, with the structural characteristics and microbial function of biofilm emphasized. The results showed that as high as 0.6 kg·m·d pyridine could be completely removed in MABR. High pyridine loading thickened the biofilm, but without obvious detachment observed. The distinct stratification of microbes and extracellular polymeric substances were shaped by elevated pyridine load, enhancing the structural heterogeneity of biofilm. The increased tryptophan-like substances as well as α-helix and β-sheet proportion in proteins stabilized the biofilm structure against high influent loading. Based on the identified intermediates, possible pyridine biodegradation pathways were proposed. Multi-omics analyses revealed that the metabolic pathways with initial hydroxylation and reduction reaction was enhanced at high pyridine loading. The functional genes were mainly associated with Pseudomonas and Delftia, might responsible for pyridine biodegradation. The results shed light on the effective treatment of wastewater containing recalcitrant pollutants such as pyridine via MABR.