Accelerated sludge granulation of novel complete ammonium and nitrate removal via denitratation anammox over nitrite
Ziyi Cheng1, Jinyan Wang1, Xinping Liu1
1College of Architecture and Civil Engineering, Faculty of Architecture, Civil and Transportation Engineering (FACTE), Beijing University of Technology, Beijing 100124, China.
Abstract:
The Complete Ammonium and Nitrate Removal via Denitratation Anammox Over Nitrite (CANDAN) process was evaluated for rapid sludge granulation in a lab-scale sequencing batch reactor. Over 119 days under increasing nitrogen loading rates (NLRs), the system finally achieved average 89.2 % total nitrogen removal at 1.93 kg N/m3/d NLR, with sludge particle sizes increasing from 215.6 μm to 924.5 μm. Higher NLRs significantly increased extracellular polymeric substances, especially hydrophobic proteins, enhancing sludge hydrophobicity and aggregation. Metagenomic analysis identified Candidatus Brocadia and Thauera as predominant and key microbial genera for nitrogen removal. Furthermore, the upregulation of carbon metabolism under heightened NLRs facilitated the synthesis of hydrophobic amino acids, promoting sludge granulation. These findings demonstrate NLR-driven granulation mechanisms, highlight optimizing NLR as key for accelerating granulation, providing insights to improve start-up and operational efficiency of CANDAN systems.
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