University of Oulu

Vidal, B., Kinnunen, J., Hedström, A., Heiderscheidt, E., Rossi, P., & Herrmann, I. (2023). Treatment efficiency of package plants for on-site wastewater treatment in cold climates. Journal of Environmental Management, 342, 118214.

Treatment efficiency of package plants for on-site wastewater treatment in cold climates

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Author: Vidal, Brenda1; Kinnunen, Juho2; Hedström, Annelie1;
Organizations: 1Department of Civil, Environmental and Natural Resources Engineering, Luleå University of Technology, SE 971 87, Sweden
2Water, Energy and Environmental Engineering Research Facility, Faculty of Technology, 90014, University of Oulu, Finland
Format: article
Version: published version
Access: open
Online Access: PDF Full Text (PDF, 2.9 MB)
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Language: English
Published: Elsevier, 2023
Publish Date: 2023-08-25


Package plants (PP) are implemented around the world to provide on-site sanitation in areas not connected to a sewage network. The efficiency of PP has not been comprehensively studied at full scale, and the limited number of available studies have shown that their performance varies greatly. Their performance under cold climate conditions and the occurrence of micropollutants in PP effluents have not been sufficiently explored. PP are exposed to environmental factors such as low temperature, especially in cold regions with low winter temperatures and deep frost penetration, that can adversely influence the biochemical processes. The aim of this study was to investigate the treatment efficiency and possible effects of cold temperatures on PP performance, with focus on traditional contaminants (organics, solids, nutrients and indicator bacteria) and an additional assessment of micropollutants on two PP. Eleven PP hosting different treatment processes were monitored. Removal of biological oxygen demand (BOD) was high in all plants (>91%). Six out of the 11 PP provided good phosphorus removal (>71%). Small degrees of nitrification were observed in almost all the facilities, despite the low temperatures, while denitrification was only observed in two plants which achieved the highest nitrification rates (>51%) and had sludge recirculation. No strong correlation between wastewater temperature and BOD, nutrients and indicator bacteria concentration in the effluents was found. The high data variability and the effects of other process parameters as well as snow-melt water infiltration are suggested as possible reasons for the lack of correlation. However, weak negative relations between effluent concentrations and wastewater temperatures were detected in specific plants, indicating that temperature does have effects. When managed adequately, package plants can provide high BOD and phosphorus removal, but nitrogen and bacteria removal remain challenging, especially at low temperatures. Pharmaceutical compounds were detected in the effluents at concentrations within or above ranges reported for large treatment plants while phthalate ester concentrations were below commonly reported effluent concentrations.

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Series: Journal of environmental management
ISSN: 0301-4797
ISSN-E: 1095-8630
ISSN-L: 0301-4797
Volume: 342
Article number: 118214
DOI: 10.1016/j.jenvman.2023.118214
Type of Publication: A1 Journal article – refereed
Field of Science: 218 Environmental engineering
Funding: This work was supported by the Interreg Nord European Regional Development Fund (grant no. NYPS, 20201833), Region Norrbotten (grant no. NYPS, 20201991), the Swedish Agency for Marine and Water Management (1:11-anslag för havs-och vattenmiljö, grant nos. 1634/20 and 00929-2021) and J. Gust. Richert foundation.
Dataset Reference: The raw data is available in the Swedish National Data Service (SND) with the following DOI number
Copyright information: © 2023 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY license (