1. Evaluation of the process performance of comammox-like nitrospira dominant down-flow hanging sponge reactor with reduced nitrous oxide emissions
- Author
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Sota Kabasawa, Takahiro Watari, Yuki Sato, Yuga Hirakata, Masashi Hatamoto, Tsutomu Okubo, Carols Lopez Vazquez, Jules B. van Lier, and Takashi Yamaguchi
- Subjects
Sponge-based trickling filter ,Comammox ,Nitrous oxide, Nitrification, Wastewater treatment ,Environmental technology. Sanitary engineering ,TD1-1066 - Abstract
Nitrification/denitrification mitigates excess nitrogen in wastewater and reduces nutrient pollution in recipient surface waters but emits substantial amounts of nitrous oxide (N₂O). Complete ammonia-oxidizing (comammox) bacteria provide novel opportunities to mitigate N₂O emissions from wastewater treatment systems. In this study, a down-flow hanging sponge (DHS) reactor with low-strength ammonia-based synthetic wastewater was used to culture comammox bacteria, to study the microbial community structure, and to assess the nitrogen removal performance. The results showed a high NH4+-N removal efficiency of 98 ± 4 % and complete nitrification during the entire experimental period. 16S rRNA gene sequencing and metagenomic analysis showed that comammox-like Nitrospira dominated the DHS-retained sludge, and that comammox-like Nitrospira and ammonia-oxidizing archaea may have coexisted symbiotically. The dissolved N₂O emissions per NH4+-N removed from the DHS reactor were much lower than those from conventional activated sludge processes, indicating that the DHS reactor could be effective in reducing N₂O emissions during wastewater treatment.
- Published
- 2025
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