Analysis of dissolved oxygen distribution effects on nitrogen removal efficiency in oxidation ditch systems

Optimizing dissolved oxygen (DO) distribution is critical for enhancing nitrogen removal in oxidation ditch systems, yet requires robust statistical validation. This study investigates the impact of strategic aerator positioning on biological treatment performance using a pilot-scale oxidation ditch treating municipal wastewater. Three distinct aeration configurations were systematically evaluated across successive operational cycles. Performance was rigorously assessed using SPSS for Pearson correlation, ANOVA, and post-hoc LSD tests.The results revealed a tightly coupled relationship between ammonium (NH₄⁺) and total nitrogen (TN) removal (r = 0.972, p < 0.01). A key finding was the achievement of a high total nitrogen (TN) removal efficiency, reaching 80% in the optimized third cycle. However, a significant inverse correlation was identified between maximizing TN removal and the calculated SND efficiency (r = –0.899, p < 0.01), indicating a critical functional trade-off. ANOVA confirmed that modifying the aeration strategy yielded statistically significant improvements in performance across the cycles (p < 0.001), with a dominant effect size (η2 ≈ 0.89).This study statistically validates that simple, low-cost adjustments to aerator configuration can fundamentally enhance nitrogen removal efficiency. The findings provide a data-driven framework for designing more effective and sustainable decentralized wastewater treatment systems.