Application and mechanisms of wastewater load regulation for enhanced partial denitrification in constructed...

Achieving robust nitrogen removal in constructed wetlands (CWs) is often hindered by the inhibitory effects of high pollutant loads on microbial activity. This study validates that influent load regulation is a pivotal strategy for engineering a partial denitrification (PD)-dominant microbial ecosystem, effectively overcoming such limitations. Comparing low-load (LL), medium-load (ML), and high-load (HL) conditions, the LL group achieved superior total nitrogen removal (up to 97.11%), outperforming the ML and HL groups by 9.28% and 16.21%, respectively. The underlying mechanism involves the alleviation of free ammonia (FA) inhibition at lower loads, which permitted the enrichment of crucial PD-related genera like Pseudomonas and Flavobacterium. This engineered community structure facilitated the stable production of nitrite, a key substrate that subsequently fueled downstream processes such as anammox and DAMO, thereby creating a synergistic nitrogen removal network. Consequently, our findings confirm that managing influent load is a critical and practical method for engineering a stable, PD-dominant microbial ecosystem to achieve robust and sustainable nitrogen removal in CWs.