Microalgae simultaneously promote antibiotic removal and antibiotic resistance genes/bacteria attenuation in algal-bacterial granular sludge system

• Published in: Journal of hazardous materials 2022-09, Vol.438, p.129286-129286, Article 129286
• Main Authors: Liu, Wenhao, Huang, Wenli, Cao, Zhenhua, Ji, Yuan, Liu, Dongfang, Huang, Weiwei, Zhu, Yanjing, Lei, Zhongfang
• Format: Article
• Language: English
• Subjects: Algal-bacterial granular sludge; Antibiotic; Antibiotic resistance genes; Antibiotic resistance genes hosts; Bacterial granular sludge
• ISSN: 0304-3894; 1873-3336
• DOI: 10.1016/j.jhazmat.2022.129286

This study investigated the effects of microalgae growth on antibiotic removal and the attenuation of antibiotic resistance genes (ARGs)/ARGs host bacteria in algal-bacterial granular sludge (ABGS) system. In the presence of tetracycline (TC) and sulfadiazine (SDZ) mixture (2–4 mg/L), microalgae could grow on bacterial granular sludge (BGS) to form ABGS, with a chlorophyll-a content of 7.68–8.13 mg/g-VSS being achieved. The removal efficiencies of TC and SDZ by ABGS were as high as 79.0 % and 94.0 %, which were 4.3–5.0 % higher than those by BGS. Metagenomic analysis indicated that the relative abundances of TC/SDZ- related ARGs and mobile genetic elements (MGEs) in BGS were 56.1 % and 22.1 % higher than those in ABGS. A total of 26 ARGs were detected from the granules, and they were identified to associate with 46 host bacteria. 13 out of 26 ARGs and 13 out of 46 hosts were shared ARGs and hosts, respectively. The total relative abundance of host bacteria in BGS was 30.8 % higher than that in ABGS. Scenedesmus and Chlorella were the dominant microalgae that may reduce the diversity of ARGs hosts. Overall, ABGS is a promising biotechnology for antibiotic-containing wastewater treatment. [Display omitted] •ABGS and BGS maintained high stability with 4 mg/L of TC and SDZ mixture addition.•ABGS possessed superior removal efficiencies of mixed antibiotics to BGS.•The abundances of ARGs/ARGs hosts in ABGS were evidently lower than those in BGS.•Scenedesmus and Chlorella were the two dominant microalgae in ABGS.•Different ARGs host bacteria in ABGS and BGS were identified.