University of Oulu

Kiani, S., Kujala, K., T. Pulkkinen, J., Aalto, S. L., Suurnäkki, S., Kiuru, T., Tiirola, M., Kløve, B., & Ronkanen, A.-K. (2020). Enhanced nitrogen removal of low carbon wastewater in denitrification bioreactors by utilizing industrial waste toward circular economy. Journal of Cleaner Production, 254, 119973.

Enhanced nitrogen removal of low carbon wastewater in denitrification bioreactors by utilizing industrial waste toward circular economy

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Author: Kiani, Sepideh1; Kujala, Katharina1; Pulkkinen, Jani T.2;
Organizations: 1Water, Energy and Environmental Engineering Research Unit, Faculty of Technology, P.O. Box 4300, FI-90014, University of Oulu, Finland
2Natural Resources Institute Finland, Survontie 9A, 40500, Jyväskylä, Finland
3Department of Biological and Environmental Science, Nanoscience Center, 40014, University of Jyväskylä, Finland
4Department of Environmental and Biological Sciences, University of Eastern Finland, P.O. Box 1627, 70211, Kuopio, Finland
Format: article
Version: accepted version
Access: open
Online Access: PDF Full Text (PDF, 1.7 MB)
Persistent link:
Language: English
Published: Elsevier, 2020
Publish Date: 2022-01-06


Aquaculture needs practical solutions for nutrient removal to achieve sustainable fish production. Passive denitrifying bioreactors may provide an ecological, low-cost and low-maintenance approach for wastewater nitrogen removal. However, innovative organic materials are needed to enhance nitrate removal from the low carbon effluents in intensive recirculating aquaculture systems (RAS). In this study, we tested three additional carbon sources, including biochar, dried Sphagnum sp. moss and industrial potato residues, to enhance the performance of woodchip bioreactors treating the low carbon RAS wastewater. We assessed nitrate (NO₃⁻) removal and microbial community composition during a one-year in situ column test with real aquaculture wastewater. We found no significant differences in the NO₃⁻ removal rates between the woodchip-only bioreactor and bioreactors with a zone of biochar or Sphagnum sp. moss (maximum removal rate 31–33 g NO₃⁻-N m⁻³ d⁻¹), but potato residues increased NO₃⁻ removal rate to 38 g NO₃⁻-N m⁻³ d⁻¹, with stable annual reduction efficiency of 93%. The readily available carbon released from potato residues increased NO₃⁻-N removal capacity of the bioreactor even at higher inflow concentrations (>52 mg L⁻¹). The microbial community and its predicted functional potential in the potato residue bioreactor differed markedly from those of the other bioreactors. Adding potato residues to woodchip material enabled smaller bioreactor size to be used for NO₃⁻ removal. This study introduced industrial potato by-product as an alternative carbon source for the woodchip denitrification process, and the encouraging results may pave the way toward growth of blue bioeconomy using the RAS.

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Series: Journal of cleaner production
ISSN: 0959-6526
ISSN-E: 1879-1786
ISSN-L: 0959-6526
Volume: 254
Article number: 119973
DOI: 10.1016/j.jclepro.2020.119973
Type of Publication: A1 Journal article – refereed
Field of Science: 218 Environmental engineering
Funding: This study was funded by the Maa-ja vesitekniikan tuki ry. [grant no. 37413], Natural Resources Institute Finland (LUKE), KAUTE-säätiö and Olvi-säätiö, and by the European Union - BONUS programme (CLEANAQ project) partly funded by the Academy of Finland [grant no. 311984].
Academy of Finland Grant Number: 311984
Detailed Information: 311984 (Academy of Finland Funding decision)
Dataset Reference: Supplementary data:
Copyright information: © 2020 Elsevier Ltd. All rights reserved. This manuscript version is made available under the CC-BY-NC-ND 4.0 license http:/