Tian Hailong, Li Yuanyuan, Chen Hui, Zhang Jisheng, Hui Ming, Xu Xingjian, Su Qingxian, Smets Barth F
College of Bioengineering, Henan University of Technology, Zhengzhou 450001, PR China.
Hinggan League Academy of Agriculture and Animal Husbandry, Ulanhot, Inner Mongolia 137400, PR China.
Environ Pollut. 2023 Jun 1;326:121507. doi: 10.1016/j.envpol.2023.121507. Epub 2023 Mar 25.
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 (NO) (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 NO 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.
需氧反硝化作为一种新型生物脱氮工艺正在被研究，但目前对需氧反硝化的认识仅限于纯培养分离，其在生物反应器中的发生情况仍不明确。本研究调查了在膜曝气生物膜反应器（MABR）中应用需氧反硝化处理含喹啉废水的可行性和能力。在不同运行条件下，喹啉（91.5±5.2%）和硝酸盐（NO）（86.5±9.3%）实现了稳定高效的去除。随着喹啉负荷增加，观察到胞外聚合物（EPS）的形成和功能增强。MABR生物膜中富含需氧喹啉降解菌，其中红球菌占优势（26.9±3.7%），其次是假单胞菌（1.7±1.2%）和丛毛单胞菌（0.94±0.9%）。宏基因组分析表明，红球菌对芳香族化合物降解（24.5±21.3%）和NO还原（4.5±3.9%）均有显著贡献，表明其在需氧反硝化喹啉生物降解中起关键作用。随着喹啉负荷增加，需氧喹啉降解基因oxoO以及反硝化基因napA、nirS和nirK的丰度增加；oxoO与nirS和nirK之间存在显著正相关（p<0.05）。需氧喹啉降解可能由oxoO编码的羟基化引发，随后通过5,6-二羟基-1H-2-氧代喹啉或8-羟基香豆素途径逐步氧化。这些结果增进了我们对生物脱氮过程中喹啉降解的理解，并突出了在MABR中实施需氧反硝化驱动的喹啉生物降解以同时去除焦化、煤气化和制药废水中氮和难降解有机碳的潜力。
