Efficient nitrogen removal and stable operation of a dynamic membrane bioreactor (DMBR) for landfill leachate treatment

This study proposed a novel anoxic/4-stage aerobic/self-forming dynamic membrane bioreactor (DMBR) process for treating landfill leachate with low carbon-to-nitrogen ratio (COD/N). When the influent COD and NH4+-N were 3689 +/- 425 and 1042 +/- 96 mg/L, high removal efficiencies of 87 % for COD and 79 % for TN can be achieved. The mature dynamic membrane (DM) was rapidly established within 1 h, allowing one operational cycle to last over 20 days with the permeate turbidity below 5 NTU. The primary cause of biofouling was identified as the accumulation of small particles, proteins, polysaccharides, and inorganic components such as Ca2+ and Mg2+ in the DM layer. In addition, significant up-regulation of genes associated with quorum sensing signaling molecules (such as pac, trpE, dgcB), extracellular polymeric substances secretion (exoP, exoQ, algA), and biofilm formation (lasA) were observed in the DM layer, while some genus, like Thauera, Anaerolinea and Caldilinea were highly enriched in DM layer. These findings indicate that DMBR offers cost-effective and technically advantageous operations, making it a promising candidate for the treatment of high-strength landfill leachate.