Microbial and Physicochemical Characteristics of Compact Anaerobic Ammonium-Oxidizing Granules in an Upflow Anaerobic Sludge Blanket Reactor

• Published in: Applied and Environmental Microbiology 2010-04, Vol.76 (8), p.2652-2656
• Main Authors: Ni, Bing-Jie, Hu, Bao-Lan, Fang, Fang, Xie, Wen-Ming, Kartal, Boran, Liu, Xian-Wei, Sheng, Guo-Ping, Jetten, Mike, Zheng, Ping, Yu, Han-Qing
• Format: Article
• Language: English
• Subjects: Ammonium; Anaerobiosis; Bacteria; Bacteria - metabolism; Biological and medical sciences; Bioreactors; Bioreactors - microbiology; Biotechnology; Cells; Colony Count, Microbial - methods; Environmental Microbiology; Fluorescence in situ hybridization; Fundamental and applied biological sciences. Psychology; In Situ Hybridization, Fluorescence; Methods. Procedures. Technologies; Microbiology; Nutrient removal; Oxidation; Oxidation-Reduction; Particulate Matter; Physical chemistry; Quaternary Ammonium Compounds - metabolism; RNA, Ribosomal, 16S - genetics; Sewage - chemistry; Sewage - microbiology; Sludge; Various methods and equipments; Water Purification
• ISSN: 0099-2240; 1098-5336; 1098-6596
• DOI: 10.1128/aem.02271-09

Anaerobic ammonium oxidation (anammox) is a promising new process to treat high-strength nitrogenous wastewater. Due to the low growth rate of anaerobic ammonium-oxidizing bacteria, efficient biomass retention is essential for reactor operation. Therefore, we studied the settling ability and community composition of the anaerobic ammonium-oxidizing granules, which were cultivated in an upflow anaerobic sludge blanket (UASB) reactor seeded with aerobic granules. With this seed, the start-up period was less than 160 days at a NH₄⁺-N removal efficiency of 94% and a loading rate of 0.064 kg N per kg volatile suspended solids per day. The formed granules were bright red and had a high settling velocity (41 to 79 m h⁻¹). Cells and extracellular polymeric substances were evenly distributed over the anaerobic ammonium-oxidizing granules. The high percentage of anaerobic ammonium-oxidizing bacteria in the granules could be visualized by fluorescent in situ hybridization and electron microscopy. The copy numbers of 16S rRNA genes of anaerobic ammonium-oxidizing bacteria in the granules were determined to be 4.6 x 10⁸ copies ml⁻¹. The results of this study could be used for a better design, shorter start-up time, and more stable operation of anammox systems for the treatment of nitrogen-rich wastewaters.