Developing a novel electrocatalytic anammox process to drive high-efficiency nitrogen removal under ultra-low nitrite conditions in an up-flow electrochemical anaerobic membrane bioreactor
The proposed EAPND system overcomes the conventional anammox reliance on nitrite by achieving 89.7% TN removal with only NH4+-N/NO2--N = 1:0.4 in the influent. Under 2.5 V applied voltage, electrochemical stimulation promoted direct ammonium oxidation by anammox bacteria while enabling electron transfer to cathodic DNB for nitrate reduction to nitrite. Effluent reflux (1:1 ratio) enhanced nitrite reuse, as supported by Random Forest modeling. Microbial analysis revealed dominant enrichment of Candidatus_Brocadia at the anode, with anode-derived protein-like substances stimulating functional genera such as norank_o__Fimbriimonadales(13.8%) and Denitratisoma (5.7%). Notably, the system maintained 60.8% TN removal without nitrite supply, highlighting its electrochemical independence. Compared to PDA and PNA processes, the EAPND system offers superior efficiency and cost-effectiveness by eliminating organic carbon and aeration requirements, providing a novel electrochemical-anammox route for sustainable nitrogen removal.