[Aerobic Granular Sludge Operation and Nutrient Removal Mechanism from Domestic Sewage in an Anaerobic/Aerobic Alternating Continuous Flow System].

Mature aerobic granular sludge was inoculated at room temperature in an anaerobic/aerobic alternating continuous flow system. The system consisted of two independent anaerobic and aerobic tanks. Actual domestic sewage was used as the influent to explore the influence of the gas intensity and hydraulic residence time on the continuous flow system. The results revealed that the conditions of a reflux ratio of 2, lower aeration intensity (0.6 mL·min-1), and proper hydraulic residence time (9 h) were more conducive to the removal of pollutants. Under such conditions, the average removal rate of TP was 80.43%, the average removal rate of TN was 83.6%, the average removal rate of COD was 90.39%, the sludge concentration was approximately 2100 mg·L-1, the sludge volume index was maintained below 50 mL·g-1, and the particle size was 700-800 nm. The EEM-PARAFAC model was used to characterize and analyze the EPS at different stages. The results revealed that changing the parameters could change the composition of EPS. The hydraulic residence time had a greater impact on the continuous flow system than the aeration intensity. In addition, a preliminary conceptual reaction process model in the anaerobic/aerobic alternating continuous flow system was built using high-throughput pyrosequencing and phylogenetic assignment. Eleven major functional bacteria related to nitrogen and phosphorus removal were found in the system.