Du Rui, Li Cong, Cao Shenbin, Peng Yongzhen
National Engineering Laboratory for Advanced Municipal Wastewater Treatment and Reuse Technology, Beijing University of Technology, Beijing 100124, PR China.
National Engineering Laboratory for Advanced Municipal Wastewater Treatment and Reuse Technology, Beijing University of Technology, Beijing 100124, PR China.
Environ Res. 2025 Sep 2;286(Pt 1):122754. doi: 10.1016/j.envres.2025.122754.
Partial denitrification coupled with anammox (PD/A) has emerged as a promising low-carbon strategy for energy-efficient nitrogen removal from municipal wastewater. However, the reactivation of PD/A systems following operational disturbances remains challenging, particularly under continuous-flow conditions, where microbial interactions and process stability are more complex than in sequencing batch reactors. This study systematically and first evaluated the recovery dynamics of a continuous-flow PD/A process seeded with low-activity granular sludge stored at 4 °C for three months. The recovery was conducted through seven operational phases, targeting sequential restoration of partial denitrification and anammox activities via modulation of influent nitrate concentrations, carbon source dosing patterns, and bioaugmentation. Denitrifying bacteria exhibited faster reactivation than anammox bacteria, resulting in insufficient nitrite (NO) accumulation for sustained anammox activity. Increasing influent NO-N to 80 mg/L improved the NO-to-NO transformation ratio (NTR) to 49.1 %, yet failed to meet NO demands. Intermittent carbon dosing further elevated NTR to 87.4 %, although the specific NO reduction rate remained suboptimal (13.5 mg N/g VSS/h). Direct supplementation of NH and NO for anammox recovery yielded a nitrogen removal efficiency (NRE) of only 0.7 %, indicating that nitrite availability-not merely presence-governs system recovery. Bioaugmentation with fresh PD/A sludge significantly accelerated reactivation, achieving a stable NRE of 88.2 %. Microbial community analysis revealed dynamic shifts in sludge morphology and dominant populations during recovery of PD/A process. Granular sludge supported the retention of anammox bacteria but also enriched Chloroflexi (41 %), which was regarded as competitor with denitrifiers for carbon sources. Meanwhile, flocculent sludge dominated by Zoogloea (40.9 %) emerged during instability, contributing to extracellular polymeric substance production and system heterogeneity. This study provides mechanistic insight into microbial competition and process limitations during PD/A system recovery under continuous-flow conditions, offering practical guidance for robust implementation in full-scale applications.
短程反硝化耦合厌氧氨氧化（PD/A）已成为一种很有前景的低碳策略，可实现城市污水中氮的高效去除。然而，在运行干扰后重新激活PD/A系统仍然具有挑战性，特别是在连续流条件下，此时微生物相互作用和过程稳定性比序批式反应器中更为复杂。本研究系统地首次评估了以在4℃储存三个月的低活性颗粒污泥接种的连续流PD/A工艺的恢复动力学。通过七个运行阶段进行恢复，目标是通过调节进水硝酸盐浓度、碳源投加模式和生物强化，依次恢复短程反硝化和厌氧氨氧化活性。反硝化细菌的重新激活速度比厌氧氨氧化细菌快，导致亚硝酸盐（NO）积累不足，无法维持厌氧氨氧化活性。将进水NO-N提高到80mg/L可将NO到NO的转化率（NTR）提高到49.1%，但仍无法满足NO需求。间歇性投加碳进一步将NTR提高到87.4%，尽管特定的NO还原率仍然次优（13.5mg N/g VSS/h）。直接补充NH和NO以恢复厌氧氨氧化，氮去除效率（NRE）仅为0.7%，这表明亚硝酸盐的可用性（不仅仅是存在）决定了系统的恢复。用新鲜的PD/A污泥进行生物强化显著加速了重新激活，实现了88.2%的稳定NRE。微生物群落分析揭示了PD/A工艺恢复过程中污泥形态和优势种群的动态变化。颗粒污泥支持厌氧氨氧化细菌的保留，但也富集了绿弯菌（41%），绿弯菌被认为是与反硝化菌竞争碳源的对手。同时，在不稳定期间出现了以动胶菌属（40.9%）为主的絮凝污泥，这有助于细胞外聚合物的产生和系统的异质性。本研究为连续流条件下PD/A系统恢复过程中的微生物竞争和过程限制提供了机理见解，为全规模应用中的稳健实施提供了实际指导。
