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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 R 1 and iron salt for the reactor R 2 , 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., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

Nanoparticles and antibiotics, the two most frequently detected emerging pollutants from different wastewater sources, are eventually discharged into wastewater treatment plants. In this study, the widely used materials CuNPs and oxytetracycline (OTC) were selected as target pollutants to investigate their joint effects on anaerobic ammonium oxidation (anammox). The results indicated that the environmental concentration slightly inhibited the performance of the reactors, while the performance rapidly deteriorated within a week under high-level combined shocks (5.0 mg L -1 CuNPs and 2.0 mg L -1 OTC). After the second shock (2.5 mg L -1 CuNPs and 2.0 mg L -1 OTC), the resistance of anammox bacteria was enhanced, with an elevated relative abundance of Candidatus Kuenenia and absolute abundance of hzsA, nirS, and hdh. Moreover, the extracellular polymeric substance (EPS) content and specific anammox activity (SAA) showed corresponding changes. Improved sludge resistance was observed with increasing CuNP and OTC doses, which accelerated the recovery of performance., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

The widespread use of copper nanoparticles (CuNPs) has attracted increasing concern because of their potential effects on biological wastewater treatment. However, their effect on granule-based denitrification systems is unclear. Hence, the effects of CuNPs on denitrifying granules were investigated during long-term operation. The results showed that 51.9% of nitrogen removal capacity was lost after exposure to 5 mg L -1 CuNPs, with the amount of Cu(II) gradually increasing with elevating CuNP levels. Moreover, the relative abundance of denitrifying bacteria (Castellaniella) and denitrifying functional genes (nirK, napA, narG and nosZ) obviously decreased. Meanwhile, the specific denitrification activity, the content of extracellular polymeric substances and dehydrogenase activity decreased by 44.0%, 15.2% and 99.9%, respectively, compared to their values in the initial sludge. Considering the downtrend in the abundance of copper resistance genes, it was deduced that the toxicity of CuNPs was mainly or at least partially due to the release of Cu(II)., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

High-rate denitrification is a popular and efficient process for treatment of nitrate-rich wastewater. Knowing the effect of heavy metals on denitrification is essential for industrial development. In the present study, the long-term impacts of Zn(II) on denitrifying granular sludge were investigated. The suppression threshold of Zn(II) on denitrifying bacteria was 10 mg L -1 for long-term exposure. The nitrogen removal rate was decreased by long-term addition of 10 mg L -1 Zn(II). Castellaniella and Klebsiella were the two dominant genera under Zn(II) stress. The relative abundance of Klebsiella sharply decreased to 4.64% after the addition of 10 mg L -1 Zn(II), whereas Castellaniella was susceptible to 2 mg L -1 Zn(II), revealing that Castellaniella mainly was devoted to denitrification under no or low Zn(II) stress conditions, whereas Klebsiella was effective under high Zn(II) stress., (Copyright © 2019 Elsevier Ltd. All rights reserved.)