Effects of Mn2+ on the removal efficiency and microbial community diversity of A/O-BAF

Abstract:

[Objective] In order to investigate the influence of Mn²⁺ on the removal efficiency and microbial community diversity of A/O-BAF system, the removal efficiency of Anoxic and Aerobic Biological Aerated Filter were analyzed under different concentration of Mn²⁺ at 15.[Methods] Manganese ions were added into the influent water to investigate the change of reactor treatment efficiency under the temperature of 15, hydraulic load 0.50 m³/(m²·h), gas water conditions than 10:1. The BAF biofilm samples were analyzed by high-throughput sequencing.[Results] The results showed that the removal efficiency of COD, NH₄⁺-N, TN and TP in Anoxic and Aerobic Biological Aerated Filter under concentration of 2.0 mg/L Mn²⁺ were increased by 3.51%, 2.21%, 6.26% and 12.13%. Under the concentration of 4.0 mg/L Mn²⁺, the removal efficiency of COD, NH₄⁺-N, TN and TP were increased by 4.24%, 1.92%, 7.75% and 10.73%, respectively. The number of denitrifying bacteria and Nitrobacteria increased significantly, and the number of Nitrosomonas decreased. The number and activity of biofilms also increased. The results of high-throughput sequencing showed that the community diversity increased significantly under 2.0 mg/L and 4.0 mg/L Mn²⁺, and the number of OTU samples increased from 4 430 to 5 659 and 5 556. The relative abundance of Proteobacteria, Firmicutes, Xanthomonas, Rhodocyclaceae, Comamonadacea, Comamonas, Aedonia, Denitratisoma, Sulfuritalea and Thermomonas increased in BAF. The relative abundance of some microorganisms, such as Denitratisoma, Sulfuritalea, and Thermomonas, decreases with higher concentrations of manganese ions. The relative abundance of Nitrosospira and Nitrospirae decreased under the action of manganese ions.[Conclusion] Manganese ion can improve the removal effect of pollutants in the Anoxic and Aerobic Biological Aerated Filter mainly by promoting the nitrification and denitrification and the growth of phosphorus removing microorganisms at 15, but the promotion effect on nitrification is not obvious. Nitrosomonas are more susceptible to the toxic effects of manganese ions.