Genera complying denitrifying phosphorus removal community contribute excellent SND-PR in a pilot cyclic SBR: Effect...

This work investigated the role of operational conditions and typical functional microbes to maximize the nutrient removal efficiency of a pilot-scale sequencing batch reactor (SBR) system (100 m³/d) that treated municipal wastewater. The pilot system was operated in five phases, including start-up and four runs at variable cycle times (2.0, 1.5, 1.7, 2.0, and 3.0h) with an average readily biodegradable chemical oxygen demand (rbCOD) to chemical oxygen demand (COD) ratio of ∼15.3%. The best TN removal 'η_max' of 75.6 ± 5.6% (TN_influent = 27.5 ± 6.5 mg/L, TN_effluent ≤ 5.9 mg/L) and TP removal 'p_max' 77.9 ± 6.3% (TP_influent = 3.8 ± 1.3 mg/L, TP_effluent ≤ 1.0 mg/L) along with the COD, biochemical oxygen demand (BOD), and total suspended solids (TSS) removal efficiencies of 87.3 ± 4.5%, 92.7 ± 2.8%, 92.0 ± 3.5%, respectively, were observed during run 3 (2h cycle) at settling/total cycle times ratio (S/T) of 0.33 and recirculation/total cycle times ratio (R/T) of 0.017 (6.4%), and operating DO of 0.5-2.5 mg/L. The denitrifying polyphosphate accumulating organisms 'DPAOs' of Burkholderia (17.0%), Rhodocyclales (6.1%), and Flavobacterium (8.7%) classes, and Nitrifiers of Nitrospira (5.4%) and Nitrosomonas (5.4%) classes were dominant in accomplishing simultaneous nitrification, denitrification, and phosphorus removal (SND-PR) in the pilot system.