Nitrogen removal performance using anaerobic ammonium oxidation at low temperatures

• Published in: FEMS microbiology letters 2008-05, Vol.282 (1), p.32-38
• Main Authors: Isaka, Kazuichi, Date, Yasuhiro, Kimura, Yuya, Sumino, Tatsuo, Tsuneda, Satoshi
• Format: Article
• Language: English
• Subjects: Ammonia; Ammonia - metabolism; Ammonia-oxidizing bacteria; Ammonium; anaerobic; Anaerobic processes; Anaerobiosis; anammox; Bacteria; Bacteria - classification; Bacteria - genetics; Bacteria - metabolism; Biodegradation, Environmental; Biological and medical sciences; Bioreactors; Conversion; DNA, Bacterial - genetics; DNA, Ribosomal - genetics; Feeding; Fundamental and applied biological sciences. Psychology; gel entrapment; immobilization; Industrial wastes; Industrial wastewater; Industrial wastewater treatment; Low temperature; Microbiology; Nitrogen; Nitrogen removal; Oxidation; Oxidation-Reduction; Phylogeny; RNA, Ribosomal, 16S - genetics; Sewage - microbiology; Temperature; Temperature dependence; Temperature effects; Waste Disposal, Fluid; Wastewater treatment; Water treatment
• ISSN: 0378-1097; 1574-6968
• DOI: 10.1111/j.1574-6968.2008.01095.x

An anaerobic ammonium oxidation (anammox) process for ammonia-rich wastewater treatment has not been reported at temperatures below 15 °C. This study used a gel carrier with entrapped anammox bacteria to obtain a stable nitrogen removal performance at low temperatures. In a continuous feeding test, a high nitrogen conversion rate (6.2 kg N m⁻³ day⁻¹) was confirmed at 32 °C. Nitrogen removal activity decreased gradually with decreasing operation temperature; however, it still occurred at 6 °C. Nitrogen conversion rates at 22 and 6.3 °C were 2.8 and 0.36 kg N m⁻³ day⁻¹, respectively. Moreover, the stability of anammox activity below 20 °C was confirmed for more than 130 days. In batch experiments, anammox gel carriers were characterized with respect to temperature. The optimum temperature for anammox bacteria was found to be 37 °C. Furthermore, it was clear that the temperature dependence changed at about 28 °C. The apparent activation energy in the temperature range from 22 to 28 °C was calculated as 93 kJ mol⁻¹, and that in the range from 28 to 37 °C was 33 kJ mol⁻¹. This value agrees with the result of a continuous feeding test (94 kJ mol⁻¹, between 6 and 22 °C). The nitrogen removal performance demonstrated at the low temperatures used in this study will open the door for the application of anammox processes to many types of industrial wastewater treatment.