Aerobic biodegradation of quinoline under denitrifying conditions in membrane-aerated biofilm reactor

Hailong Tian; Yuanyuan Li; Hui Chen; Jisheng Zhang; Ming Hui; Xingjian Xu; Qingxian Su; Barth F Smets

doi:10.1016/j.envpol.2023.121507

Aerobic biodegradation of quinoline under denitrifying conditions in membrane-aerated biofilm reactor

Environ Pollut. 2023 Jun 1:326:121507. doi: 10.1016/j.envpol.2023.121507. Epub 2023 Mar 25.

Authors

Hailong Tian¹, Yuanyuan Li¹, Hui Chen¹, Jisheng Zhang¹, Ming Hui¹, Xingjian Xu², Qingxian Su³, Barth F Smets⁴

Affiliations

¹ College of Bioengineering, Henan University of Technology, Zhengzhou 450001, PR China.
² Hinggan League Academy of Agriculture and Animal Husbandry, Ulanhot, Inner Mongolia 137400, PR China.
³ Center for Water Research, Advanced Institute of Natural Sciences, Beijing Normal University at Zhuhai, 519087, China; Department of Environmental and Resource Engineering, Technical University of Denmark, 2800 Kgs. Lyngby, Denmark. Electronic address: qisu@dtu.dk.
⁴ Department of Environmental and Resource Engineering, Technical University of Denmark, 2800 Kgs. Lyngby, Denmark.

PMID: 36972812
DOI: 10.1016/j.envpol.2023.121507

Abstract

Aerobic denitrification is being investigated as a novel biological nitrogen removal process, yet the knowledge on aerobic denitrification is limited to pure culture isolations and its occurrence in bioreactors remains unclear. This study investigated the feasibility and capacity of applying aerobic denitrification in membrane aerated biofilm reactor (MABR) for biological treatment of quinoline-laden wastewater. Stable and efficient removals of quinoline (91.5 ± 5.2%) and nitrate (NO₃^-) (86.5 ± 9.3%) were obtained under different operational conditions. Enhanced formation and function of extracellular polymeric substances (EPS) were observed at increasing quinoline loadings. MABR biofilm was highly enriched with aerobic quinoline-degrading bacteria, with a predominance of Rhodococcus (26.9 ± 3.7%) and secondary abundance of Pseudomonas (1.7 ± 1.2%) and Comamonas (0.94 ± 0.9%). Metagenomic analysis indicated that Rhodococcus contributed significantly to both aromatic degradation (24.5 ± 21.3%) and NO₃^- reduction (4.5 ± 3.9%), indicating its key role in aerobic denitrifying quinoline biodegradation. At increasing quinoline loadings, abundances of aerobic quinoline degradation gene oxoO and denitrifying genes of napA, nirS and nirK increased; there was a significant positive correlation of oxoO with nirS and nirK (p < 0.05). Aerobic quinoline degradation was likely initiated by hydroxylation, encoded by oxoO, followed by stepwise oxidations through 5,6-dihydroxy-1H-2-oxoquinoline or 8-hydroxycoumarin pathway. The results advance our understanding of quinoline degradation during biological nitrogen removal, and highlight the potential implementation of aerobic denitrification driven quinoline biodegradation in MABR for simultaneous removal of nitrogen and recalcitrant organic carbon from coking, coal gasification and pharmaceutical wastewaters.

Keywords: Aerobic denitrification; Biodegradation pathway; Extracellular polymeric substances; Metabolic modules; Nitrogen-heterocyclic compound.

MeSH terms

Bacteria, Aerobic
Biofilms
Bioreactors / microbiology
Denitrification
Nitrogen
Pseudomonas
Quinolones*
Wastewater*

Substances

Wastewater
Quinolones
Nitrogen