Abstract
Anaerobic ammonia oxidation (anammox) is considered a high-efficiency and low-consumption biological nitrogen removal process. In this study, synthetic wastewater was used to start an up-flow anaerobic sludge bed reactor with a starting temperature of 20–31℃, and subsequently, the activated sludge samples were used to analyze the changes in bacterial community and antibiotic resistance genes (ARGs) by metagenomic sequencing. The results showed that the reaction successfully started up after 132 days of cultivation, achieving NH4+-N and NO2−-N removal rates over 99.5%. Candidatus Kuenenia, an anammox bacterium, increased from 0.01 to 50.86%. The denitrifying bacteria Delftia, Acidovorax, Thauera and Alicycliphilus decreased from 18.70, 8.02, 4.94 and 4.59% to 7.01, 1.77, 3.06 and 3.96%, respectively. The ammonia-oxidizing bacterium Nitrosomonas decreased from 2.91 to 1.87%. After cultivation, the relative abundance of ARGs in sludge decreased from 90.23 to 64.29 ppm, with sulfonamide, macrolide-lincosamide-streptogramin, tetracycline, aminoglycoside and multidrug ARGs being the main types. Additionally, the ARG subtypes sul1, msrE and tetX decreased, while ermF, sul2 and floR increased. These results contribute to knowledge of the nitrogen removal performance, changes in bacterial community composition and ARGs in an anammox reactor, providing the guidance for the removal of ARGs by anammox.