Pulsed Electric Field Enhancement of Nitrogen Removal Performance and Microbial Community Structure Response in Anammox Granular Sludge

• • At NLR < 1,155 mg·(L·d)−1, PEF (1.5 V, 4 h/cycle) increased TRE by 7.5–17.0%, SAA by 21–71%, and EPS by 54–77% compared to control, indicating enhanced metabolic activity and sludge stability. • • At NLR > 1,320 mg·(L·d)−1, PEF enhancement was negated by nitrite toxicity; increased membrane permeability facilitated toxic influx, leading to reduced performance and microbial richness, revealing a 'double-edged sword' effect. • • PEF enriched Planctomycetes and key anammox genera (Candidatus Brocadia, Candidatus Jettenia) at low-to-moderate NLR, while at high NLR, community diversity and richness declined, indicating load-dependent microbial responses. • • Multivariate analyses (PCA, RDA) identified PEF as the primary driver of community shifts at low NLR, but nitrite concentration became the dominant factor at high NLR, underscoring the need for load-adaptive PEF control strategies.