Journal
WATER RESEARCH X
Volume 11, Issue -, Pages -Publisher
ELSEVIER
DOI: 10.1016/j.wroa.2021.100098
Keywords
Nitrification; Denitrification; Activated sludge microbiome; Physico-chemical monitoring; Amplicon sequencing
Funding
- Swiss Federal Office for the Environment (FOEN)
- Swiss National Foundation for Scientific Research (SNF)
- canton of Bern (AWA)
- canton of BaselLandschaft (AIB)
- canton of Thurgau (AfU)
- canton of Zurich (AWEL)
- TBF + Partner AG Consulting Engineers
- Holinger AG
- Hunziker Betatech AG
- Alpha Wassertechnik AG
- arabern WWTP
- REAL Luzern WWTP
- Cham WWTP (GVRZ)
- ERZ Zurich
- Giubiasco WWTP
- Entsorgung St. Gallen
- Uster WWTP
- SNF Synergia project [CRSII5_170876]
- Swiss National Science Foundation (SNF) [CRSII5_170876] Funding Source: Swiss National Science Foundation (SNF)
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This study reveals the correlation between nitrification failure, N2O peak emissions, poor settleability of activated sludge, turbid effluent, reduction in microbial community diversity, and shifts in community composition in a full-scale WWTP. The findings demonstrate that disturbances in the sludge microbiome affect key structural and functional microbial groups, leading to seasonal N2O emission patterns.
Nitrous oxide (N2O) is a strong greenhouse gas and causal for stratospheric ozone depletion. During biological nitrogen removal in wastewater treatment plants (WWTP), high N2O fluxes to the atmosphere can occur, typically exhibiting a seasonal emission pattern. Attempts to explain the peak emission phases in winter and spring using physico-chemical process data from WWTP were so far unsuccessful and new approaches are required. The complex and diverse microbial community of activated sludge used in biological treatment systems also exhibit substantial seasonal patterns. However, a potentially causal link between the seasonal patterns of microbial diversity and N2O emissions has not yet been investigated. Here we show that in a full-scale WWTP nitrification failure and N2O peak emissions, bad settleability of the activated sludge and a turbid effluent strongly correlate with a significant reduction in the microbial community diversity and shifts in community composition. During episodes of impaired performance, we observed a significant reduction in abundance for filamentous and nitrite oxidizing bacteria in all affected reactors. In some reactors that did not exhibit nitrification and settling failures, we observed a stable microbial community and no drastic loss of species. Standard engineering approaches to stabilize nitrification, such as increasing the aerobic sludge age and oxygen availability failed to improve the plant performance on this particular WWTP and replacing the activated sludge was the only measure applied by the operators to recover treatment performance in affected reactors. Our results demonstrate that disturbances of the sludge microbiome affect key structural and functional microbial groups, which lead to seasonal N2O emission patterns. To reduce N2O emissions from WWTP, it is therefore crucial to understand the drivers that lead to the microbial population dynamics in the activated sludge. (C) 2021 The Author(s). Published by Elsevier Ltd.
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