Metal-organic framework material-derived Fe-Si micro-nuclei drive a robust anammox process via multiple pathways:...

Anaerobic ammonium oxidation (anammox) has emerged as a pivotal biotechnology for sustainable nitrogen removal owing to its energy efficiency and low carbon footprint. However, persistent challenges in microbial growth rate, process stability, and nitrate byproduct accumulation constrain its full-scale implementation. This study addresses these limitations through the innovative synthesis of a metal-organic framework (MOF)-derived Fe-Si micro-nucleus (PFMS), engineered to drive a robust anammox system at lower micro-nuclei doses and mitigate potential risks of excessive iron inhibition. Its coral reef-like mosaic structure provides "habitat" and "shelter" for anammox bacteria. Multivalence-Fe in PFMS was identified with X-ray adsorption fine structure spectra and facilitated the growth and nitrogen metabolism of anammox bacteria. Density functional theory calculations provided unprecedented atomic-level insights into substrate-material-microbe interfacial interactions. Meanwhile, PFMS drives the optimization of extracellular polymeric substances for enhancing aggregation and resistance of anammox sludge. Microbial community and metabolic in PFMS-mediated anammox system were investigated by multi-omics analysis, and the results showed that a novel Fe-N coupling metabolic mode was established in the system. Furthermore, the mechanism underlying the enhancement of anammox system by PFMS was summarized. This study constitutes the inaugural application of MOF-derived materials in anammox biotechnology and provides a novel strategy for operating a robust anammox process in practical engineering applications.