Aerobic Granular Sludge System with Multiple Influent-Aeration Operation Strategy

Abstract

SBR reactors R1 and R2 were used to inoculate activated sludge from a sewage treatment plant, and domestic sewage was used as the influent. The operation was carried out using a single and multiple influent-aeration operation strategy, respectively, and the particle size change and removal effect during the operation was studied. The results show that R1 and R2 successfully achieved sludge granulation after 56 days and 39 days of operation, respectively. The concentrations (mg·L-1) of chemical oxygen demand, total nitrogen, and total phosphorus (TP) in the effluent of R1 and R2 after stable operation were 29.7, 13.7, 0.31, 19.2, 8.1, and 0.37, respectively. The removal rates were respectively 87.7%, 75.6%, 95.1%, and 90.1%, 85.6%, and 94.2%, and the average particle size of the particles reached 740 μm for R1 and 791 μm for R2. The results showed that for the same running time, the effluent NO3--N concentration and TP concentration in R2 were lower than those in R1. In the later stage of operation, the ratio of denitrifying phosphorus-accumulating organisms (DPAO) to total phosphorus-accumulating organisms (PAOs) in R1 and R2 increased from an initial 11.17% to 25.47% and 34.08%, respectively. Compared with the one influent-aeration operation strategy, the multiple influent-aeration operation strategy had a lower concentration of NO3--N in the initial stage of the startup, the PAOs received less impact, the DPAO enrichment was better, the phosphorus removal performance was better, and it helped to form aerobic granular sludge.