Coagulants put phosphate-accumulating organisms at a competitive disadvantage with glycogen-accumulating organisms in enhanced biological phosphorus removal system. (February 2022) - Xia, Wen-Jing
Graphical abstract: Highlights: The coercive effect of coagulants on EBPR system was investigated. EPS secretion was increased as a response to metal salt stress in the short term. Coagulants can cause damage to cells through mediating the formation of ROS. Metal salts put PAOs at a disadvantage position in competition with GAOs. Abstract: Enhanced biological phosphorus removal (EBPR) process is susceptible to the changed operation condition, which results in an unstable treatment performance. In this work, long-term effect of coagulants addition, aluminum salt for the reactor R1 and iron salt for the reactor R2, on EBPR systems was comprehensively evaluated. Results showed that during the initial 30 days' coagulant addition, effluent chemical oxygen demand and phosphorus can be reduced below 25 and 0.5 mg·L -1, respectively. Further supply of metal salts would stimulate microbial extracellular polymeric substance excretion and induce reactive oxygen species accumulation, which destroyed the cell membrane integrity and deteriorated the phosphorus removal performance. Moreover, coagulants would decrease the relative abundance of Candidatus Accumulibacter while increase the relative abundance of Candidatus Competibacter, leading phosphors accumulating organisms in a disadvantage position. The results of this work might be valuable for the operation of chemical assisted biological phosphorus removal bioreactor.