Enrichment and characteristics of ammonia-oxidizing archaea in wastewater treatment process

High purity ammonia-oxidizing archaea (AOA) culture containing a single AOA strain was enriched from the filtering materials of biological aerated filter. The concentration of AOA reached 3.27\ua0×\ua010\ua0copies/mL, while its proportion was 91.40%. The AOA amoA gene sequence belonged to Nitrososphaera cluster. Ammonia concentration significantly influenced the growth of AOA in culture, while total organic carbon (TOC) concentration had no obvious effect. The optimum ammonia concentration, temperature, pH and DO concentration for growth of AOA were 1\ua0mM, 30\ua0°C, 7.5 and 2.65\ua0mg/L, respectively. Under the optimum growth conditions, the AOA abundance and ammonia oxidation rate were 3.53\ua0×\ua010\ua0copies/mL and 2.54\ua0×\ua010\ua0mg/(copies·d)