Denitrifying bioreactor microbiome: Understanding pollution swapping and potential for improved performance

Hartfiel, Lindsey M.
Schaefer, Abby
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Iowa Nutrient Research Center
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The Iowa Nutrient Research Center was established to pursue science-based approaches to evaluating the performance of current and emerging nutrient management practices and providing recommendations on practice implementation and development. Publications in this digital repository are products of INRC-funded research. The INRC is headquartered at Iowa State University and operates in collaboration with the University of Iowa and the University of Northern Iowa. Additional project information is available at:
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Agricultural and Biosystems EngineeringCivil, Construction and Environmental EngineeringIowa Nutrient Research Center
Denitrifying woodchip bioreactors are a best management practice to reduce nitrate–nitrogen (NO3–N) loading to surface waters from agricultural subsurface drainage. Their effectiveness has been proven in many studies, although variable results with respect to performance indicators have been observed. This paper serves the purpose of synthesizing the current state of the science in terms of the microbial community, its impact on the consistency of bioreactor performance, and its role in the production of potential harmful by-products including greenhouse gases, sulfate reduction, and methylmercury. Microbial processes other than denitrification have been observed in these bioreactor systems, including dissimilatory nitrate reduction to ammonia (DNRA) and anaerobic ammonium oxidation (anammox). Specific gene targets for denitrification, DNRA, anammox, and the production of harmful by-products are identified from bioreactor studies and other environmentally relevant systems for application in bioreactor studies. Lastly, cellulose depletion has been observed over time via increasing ligno-cellulose indices, therefore, the microbial metabolism of cellulose is an important function for bioreactor performance and management. Future work should draw from the knowledge of soil and wetland ecology to inform the study of bioreactor microbiomes.
This is the published version of the following article: Hartfiel, Lindsey, Abby Schaefer, Adina Howe, and Michelle Soupir. "Denitrifying Bioreactor Microbiome: Understanding Pollution Swapping and Potential for Improved Performance." Journal of Environmental Quality (2021). DOI: 10.1002/jeq2.20302. Copyright 2021 The Authors. Attribution-NonCommercial 4.0 International (CC BY-NC 4.0). Posted with permission.