Enrichment and Nitrogen Removal Characteristics of Marine Anaerobic Ammonium Oxidizing Bacteria

: In this work, enrichment and nitrogen removal characteristics of marine anaerobic ammonium oxidizing bacteria were investigated by seeding sediment sludge from the Jiaozhou bay. Experimental results showed that the whole process could be divided into four phases:bacterial lysis phase (1-15 d), lag phase (16-152 d), exponential growth phase (153-183 d) and stationary phase (184-192 d). Compared to freshwater anaerobic ammonium oxidizing bacteria, the lag phase (137 d) was longer. However, the exponential growth phase (30 d) was shorter. Besides, marine anaerobic ammonium oxidizing bacteria were more sensitive to variation in substrate concentration and HRT. The activity delay time caused by inflow and effluent was 5 h, which was far longer than fresh anaerobic ammonium oxidizing bacteria. As a result, the adaptive ability of marine anaerobic ammonium oxidizing bacteria was weaker and it was harder to enrich. After successful enrichment of 192 d, the removal rates of ammonia nitrogen and nitrite nitrogen were 96.98% and 95.66%, respectively. n(NH4+-N):n(NO2--N):n(NO3--N) was 1:(1.2±0.2):(0.22±0.06), which was close to the theoretical ratio. NRRNH4+-Nwas 0.080 kg·(m3·d)-1, which indicated that the activity of marine anaerobic ammonium oxidizing bacteria increased significantly. The enrichment of marine anaerobic ammonium oxidizing bacteria was achieved. The sludge characteristics changed from black to red. SEM observation confirmed that the red granule was cenobium, which consisted of closely spaced micrococcus with smooth surface and crateriform shape.