University of Oulu

Heini Postila, Elisangela Heiderscheidt, Function and biomass production of willow wetlands applied in the polishing phase of sewage treatment in cold climate conditions, Science of The Total Environment, Volume 727, 2020, 138620, ISSN 0048-9697,

Function and biomass production of willow wetlands applied in the polishing phase of sewage treatment in cold climate conditions

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Author: Postila, Heini1; Heiderscheidt, Elisangela1
Organizations: 1Water, Energy and Environmental Engineering, P.O. Box 4300, FIN-90014, University of Oulu, Oulu, Finland
Format: article
Version: accepted version
Access: open
Online Access: PDF Full Text (PDF, 0.5 MB)
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Language: English
Published: Elsevier, 2020
Publish Date: 2022-04-14


Willow wetlands can offer a low-cost solution for recovery of nutrients contained in sewage water and simultaneously produce plant biomass, which can be used in energy production. Willow (Salix spp.) is considered an excellent crop for this purpose, due to its good nutrient uptake and biomass production. Although willow wetlands have been used in sewage treatment in e.g. Denmark, Sweden and southern Finland, their use in northern regions is challenging due to the detrimental effects cold climate conditions can have on plant survival rates and wastewater purification efficiency. In this study, a pilot constructed wetland in northern Finland receiving effluent from a small-scale wastewater treatment plant was investigated. Four willow varieties were planted (Gudrun, Karin, Klara and one local variety) and retention of nutrients in the wetland and willow plant survival rate, biomass production and nutrient uptake were evaluated. Good retention of nutrients (e.g. Tot. N 66–86% and Tot. P 30–87%) was achieved throughout the study period. After two growing seasons, the variety Gudrun showed the best survival rate and significantly higher biomass production (5.7 t/ha) than Karin, Klara and the local variety (1.7, 3.0 and 0.02 t/ha, respectively). Thus, willow wetlands are suitable systems for nutrient recovery from pre-treated wastewater in cold climate regions. However, the willow variety used should be chosen carefully, as there can be significant differences in survival rate and biomass production between varieties.

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Series: Science of the total environment
ISSN: 0048-9697
ISSN-E: 1879-1026
ISSN-L: 0048-9697
Volume: 727
Article number: 138620
DOI: 10.1016/j.scitotenv.2020.138620
Type of Publication: A1 Journal article – refereed
Field of Science: 218 Environmental engineering
Funding: This work was funded by the European Regional Development Fund as part of the HuJa project, “Enhancing the treatment of metal containing storm waters and wastewaters by using natural materials (2015–2018)”. The other funding bodies and partners in project were Outokumpu Chrome Oy, Oulun Jätehuolto Oy, Pudasjärven vesiosuuskunta, Taivalkosken vesihuolto, Oulun Vesi, Pölkky Oy, Kuusamon energia- ja vesiosuuskunta, Naturpolis Oy, City of Kuusamo, Finnish Water Utilities Association, Maa-ja vesitekniikan tuki ry, Ranuan Vesihuolto Oy, Napapiirin Energia ja Vesi Oy, Vesikolmio Oy, Aquaminerals Finland Oy and University of Oulu.
Copyright information: © 2020. This manuscript version is made available under the CC-BY-NC-ND 4.0 license