Hybrid membrane bioreactor-filler system enables efficient nitrogen removal from semiconductor wastewater through engineered microbial niche differentiation: Process optimization, biofilm-enhanced kinetics, and multi-omics insights.

) without external carbon addition. Normalized stochasticity ratio (NST) analysis confirmed that the anoxic microenvironment within fillers shifted community assembly toward deterministic processes (NST = 37% vs. 76% in suspended sludge). This shift enriched Methanomethylovorans (5.1-fold) for anaerobic TMAH demethylation and Hyphomicrobium for methylotrophic denitrification. Untargeted metabolomics identified tryptophan and succinate depletion in filler biofilm, with strong metabolite-gene correlations (tryptophan-norB, r = 0.90; succinate-dmmA, r = 0.83) linking organoamine catabolism to respiratory denitrification. Co-occurrence network analysis confirmed tightly coupled anaerobic demethylation and denitrification modules in filler biofilm (216 edges, density 0.53). This work demonstrates that engineered niche differentiation can overcome carbon limitation in organoamine-rich industrial wastewater, providing a transferable design paradigm for carbon-efficient biological nitrogen removal.