Response and self-regulation of PD/A granular sludge to oxytetracycline stress

• Published in: The Science of the total environment Vol. 943; p. 173674
• Main Authors: Hu, Lifeng, Al-Dhabi, Naif Abdullah, Zhu, Zixuan, Zhang, Xiaonong, Tang, Wangwang, Wu, Peng
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 15.09.2024
• Subjects: Bacterial self-regulation mechanism; Extracellular polymeric substances; Granular sludge; Oxytetracycline; Partial denitrification/anammox; Oxytetracycline; Partial denitrification/anammox; Extracellular polymeric substances; Granular sludge; Bacterial self-regulation mechanism
• ISSN: 0048-9697; 1879-1026; 1879-1026
• DOI: 10.1016/j.scitotenv.2024.173674

This paper investigated the operational characteristics and self-regulation mechanism of the partial denitrification/anammox (PD/A) granular system under the stress of oxytetracycline (OTC), an emerging pollutant that accumulates in municipal wastewater treatment plants through various pathways, posing significant challenges for its future promotion in engineering applications. The results indicated that OTC concentrations below 100 mg/L intensified its short-term inhibition on the PD/A granular sludge system, decreasing functional bacterial activity, while between 150 and 300 mg/L, PD's NO3−-N to NO2−-N conversion ability diminished, and Anammox activity was significantly suppressed. Under long-term high OTC stress (20–30 mg/L), nitrogen removal suffered, and batch tests revealed significant inhibition of PD's NO3−-N to NO2−-N conversion, dropping from 73.77 % to 50.17 %. Anammox bacteria activity sharply declined from 1.81 to 0.39 mg N/gVSS/h under OTC stress. Extracellular polymeric substances (EPS) content rose from 185.39 to 210.86 mg/gVSS, indicating PD/A sludge's self-protection mechanism. However, EPS content fell due to cell lysis at high OTC (30 mg/L). The decreasing relative abundance of Candidatus_Brocadia (2.32 % to 0.93 %) and Thaure (12.63 % to 7.82 %) was a key factor in the gradual deterioration of denitrification performance. This study was expected to provide guidance for the PD/A process to cope with the interference of antibiotics and other emerging pollutants (short-term shock and long-term stress). [Display omitted] •Self-regulation mechanism of PD/A granular system under OTC stress was revealed.•OTC's short-term shock (100 mg/L) boosted the inhibition on PD and Anammox.•OTC's long-term stress (10 mg/L) gradually weakened the activity of PD and Anammox.•OTC stress triggered EPS self-protection, while excess caused cell lysis.•The performance of Key bacteria under OTC stress offered insights of the PD/A.