Insights into simultaneous nitrogen and phosphorus removal in biofilm: The overlooked comammox Nitrospira and the positive role of glycogen-accumulating organisms

• Published in: The Science of the total environment 2023-08, Vol.887, p.164130-164130, Article 164130
• Main Authors: Zhou, Tengzhi, Xiang, Yu, Liu, Shiyi, Shao, Zhiyu, Liu, Yiwen, Ma, Haiyuan, He, Qiang, Chai, Hongxiang
• Format: Article
• Language: English
• Subjects: Ammonia; Anaerobic ammonia oxidation; Bacteria; Biofilm structure; Biofilms; Bioreactors - microbiology; Complete ammonia oxidation; Endogenous denitrification; In Situ Hybridization, Fluorescence; Nitrates; Nitrification; Nitrites; Nitrogen; Nutrients removal; Oxidation-Reduction; Phosphorus; RNA, Ribosomal, 16S - genetics
• ISSN: 0048-9697; 1879-1026
• DOI: 10.1016/j.scitotenv.2023.164130

Simultaneous nitrogen and phosphorus removal (SNPR) biofilm system is an effective wastewater treatment process. However, the understanding on the mechanism of functional microorganisms driving SNPR is still limited, especially the role of complete ammonia oxidation (comammox) Nitrospira and glycogen-accumulating organisms (GAO). In this study, a sequencing batch biofilm reactor (SBBR) performing SNPR was operated for 249 d. Based on the 16S rRNA gene, comammox amoA amplicon sequencing, metagenomics and batch experiment, we found that comammox Nitrospira was the main ammonia-oxidizing microorganisms (AOM) and provided nitrite for anaerobic ammonia oxidation (anammox) bacteria (AnAOB). Besides, GAO was dominated by the bacteria of genus Defluviicoccus and played a primary role in reducing nitrate rather than nitrite. Fluorescent in situ hybridization (FISH) analysis confirmed that Nitrospira was enriched in the inner layer of the biofilm. Thus, we put forward a novel insight into the mechanism of SNPR biofilm system. Comammox Nitrospira was responsible for nitrite and nitrate production in the inner biofilm, and AnAOB consumed the produced nitrite during the anammox process. While GAO reduced nitrate to nitrite and polyphosphate-accumulating organisms (PAO) converted nitrite to dinitrogen via denitrifying phosphorus removal in the outer biofilm. These findings provide a new understanding in SNPR biofilm system. [Display omitted] •The role of comammox Nitrospira and GAO were investigated in SNPR biofilm system.•Comammox Nitrospira was the dominating AOM in the SNPR biofilm for nitrification.•Nitrospira was found enriched in the inner layer of biofilm.•Defluviicoccus-dominated GAO played a primary role in nitrate removal.•The PN/A in interior biofilm and DPR in exterior biofilm drive the SNPR in biofilm.