Complete ammonia oxidizing bacteria,or comammox bacteria(CAOB),can oxidize ammonium to nitrate on its own.Its discovery revolutionized our understanding of biological nitrification,and its distribution in both natural...Complete ammonia oxidizing bacteria,or comammox bacteria(CAOB),can oxidize ammonium to nitrate on its own.Its discovery revolutionized our understanding of biological nitrification,and its distribution in both natural and artificial systems has enabled a reevaluation of the relative contribution of microorganisms to the nitrogen cycle.Its wide distribution,adaptation to oligotrophic medium,and diverse metabolic pathways,means extensive research on CAOB and its application in water treatment can be promoted.Furthermore,the energy-saving characteristics of high oxygen affinity and low sludge production may also become frontier directions for wastewater treatment.This paper provides an overview of the discovery and environmental distribution of CAOB,as well as the physiological characteristics of the microorganisms,such as nutrient medium,environmental factors,enzymes,and metabolism,focusing on future research and the application of CAOB in wastewater treatment.Further research should be carried out on the physiological characteristics of CAOB,to analyze its ecological niche and impact factors,and explore its application potential in wastewater treatment nitrogen cycle improvement.展开更多
As one of the most important water pollutants, ammonia nitrogen emissions have increased year by year, which has attracted people＇s attention. Catalytic ozonation technology, which involves production of ·OH rad...As one of the most important water pollutants, ammonia nitrogen emissions have increased year by year, which has attracted people＇s attention. Catalytic ozonation technology, which involves production of ·OH radical with strong oxidation ability, is widely used in the treatment of organic-containing wastewater. In this work, MgO-Co3O4 composite metal oxide catalysts prepared with different fabrication conditions have been systematically evaluated and compared in the catalytic ozonation of ammonia（50 mg/L） in water. In terms of high catalytic activity in ammonia decomposition and high selectivity for gaseous nitrogen, the catalyst with MgO-Co3O4 molar ratio 8：2, calcined at 500°C for 3 hr, was the best one among the catalysts we tested, with an ammonia nitrogen removal rate of 85.2% and gaseous nitrogen selectivity of44.8%. In addition, the reaction mechanism of ozonation oxidative decomposition of ammonia nitrogen in water with the metal oxide catalysts was discussed. Moreover, the effect of coexisting anions on the degradation of ammonia was studied, finding that SO2-4 and HCO-3 could inhibit the catalytic activity while CO2-3 and Br-could promote it. The presence of coexisting cations had very little effect on the catalytic ozonation of ammonia nitrogen. After five successive reuses, the catalyst remained stable in the catalytic ozonation of ammonia.展开更多
基金supported by the Foundation for Innovation Research Groups of the National Natural Science Foundation of China(No.62021003)Biological Wastewater Treatment and Process Control Technology,Beijing International Science and technology Cooperation Baseand the Founding projects of Beijing Municipal Commission of Education.
文摘Complete ammonia oxidizing bacteria,or comammox bacteria(CAOB),can oxidize ammonium to nitrate on its own.Its discovery revolutionized our understanding of biological nitrification,and its distribution in both natural and artificial systems has enabled a reevaluation of the relative contribution of microorganisms to the nitrogen cycle.Its wide distribution,adaptation to oligotrophic medium,and diverse metabolic pathways,means extensive research on CAOB and its application in water treatment can be promoted.Furthermore,the energy-saving characteristics of high oxygen affinity and low sludge production may also become frontier directions for wastewater treatment.This paper provides an overview of the discovery and environmental distribution of CAOB,as well as the physiological characteristics of the microorganisms,such as nutrient medium,environmental factors,enzymes,and metabolism,focusing on future research and the application of CAOB in wastewater treatment.Further research should be carried out on the physiological characteristics of CAOB,to analyze its ecological niche and impact factors,and explore its application potential in wastewater treatment nitrogen cycle improvement.
基金supported the National Natural Science Foundation of China (Nos. 51164014 and 51568023)
文摘As one of the most important water pollutants, ammonia nitrogen emissions have increased year by year, which has attracted people＇s attention. Catalytic ozonation technology, which involves production of ·OH radical with strong oxidation ability, is widely used in the treatment of organic-containing wastewater. In this work, MgO-Co3O4 composite metal oxide catalysts prepared with different fabrication conditions have been systematically evaluated and compared in the catalytic ozonation of ammonia（50 mg/L） in water. In terms of high catalytic activity in ammonia decomposition and high selectivity for gaseous nitrogen, the catalyst with MgO-Co3O4 molar ratio 8：2, calcined at 500°C for 3 hr, was the best one among the catalysts we tested, with an ammonia nitrogen removal rate of 85.2% and gaseous nitrogen selectivity of44.8%. In addition, the reaction mechanism of ozonation oxidative decomposition of ammonia nitrogen in water with the metal oxide catalysts was discussed. Moreover, the effect of coexisting anions on the degradation of ammonia was studied, finding that SO2-4 and HCO-3 could inhibit the catalytic activity while CO2-3 and Br-could promote it. The presence of coexisting cations had very little effect on the catalytic ozonation of ammonia nitrogen. After five successive reuses, the catalyst remained stable in the catalytic ozonation of ammonia.
