Efficient nitrogen removal from refractory digestion filtrate: microbial functions in one-stage partial
Jing Huang1, Xiaoyu Han2, Shujun Zhang2
1College of Architecture and Civil Engineering, Beijing University of Technology, Beijing 100124, PR China; Beijing Drainage Group Co. Ltd. (BDG), Beijing 100124, PR China; Beijing Engineering Research Center, Beijing 100124, PR China.
None:
Thermal hydrolysis pretreatment (THP) enhances anaerobic digestion efficiency but produces filtrate (TAF) with high ammonia nitrogen and refractory organics, posing challenges for downstream treatment. A 500 m3 pilot-scale one-stage partial nitritation/anammox granular sludge (PN/AnGS) system was established for TAF treatment. Optimized aeration alleviated humic substances' inhibition of ammonia-oxidizing and anammox bacteria, achieving a nitrogen removal rate of 0.61 kg N/m3/day and promoting functional bacterial enrichment. Transient high-pH (>9.0) shocks markedly inhibited nitrogen removal, requiring up to 90 days for recovery; however, dense granular sludge maintained structural integrity and community stability. Analysis of microbial networks and metabolic pathways revealed that functional coupling may occur between anammox and denitrifying bacteria via nitric oxide, enhancing synergistic nitrogen removal and system robustness. These findings demonstrate that PN/AnGS offers an effective, resilient solution for TAF treatment and provides mechanistic insight into microbial stress adaptation in engineered wastewater ecosystems.
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