Removal of nutrients and microplastics in treatment wetlands purifying sewage water in cold climate regions
In sewage treatment, wetlands are widely applied in warmer and to a lesser extent in cold climate regions. Low temperatures, snow and ice cover as well as soil frost can affect purification. Although nutrient removal in wetlands is feasible also in the wintertime, the effect of cold climate on occurring processes is not entirely clear. Thus, there is still a lack of understanding regarding pollutant removal (e.g., N, P and SO42-) under winter conditions especially with respect to the effect of freezing and thawing.
In recent years, public awareness regarding the occurrence of microplastics in water has increased significantly. Microplastics are contained in e.g., cosmetics, personal care products, and clothing; thus they occur in high concentration in sewage water. Despite the fact that microplastics are efficiently removed (~90%) in WWTPs, when dealing with such large volumes of effluent even the low concentrations contained in the outflowing waters can result in significant amounts of microplastics being constantly discharged into streams, lakes, and the Baltic Sea. Treatment wetlands are normally used in Finland as an additional treatment step (polishing phase), further retention of microplastics in such systems could lead to a significant decrease in the release of microplastics into the environment. However, the capacity of wetlands to retain microplastics is largely unknown.
Project aim and tasks
The objectives of the project are to bridge the knowledge gap referent to the removal of nutrients and microplastics in wetlands purifying sewage water in cold climate regions. To achieve these objectives, the project will make use of knowhow, purposely designed and built pilot systems, equipment and measurement data that have been developed and/or gathered during previous projects conducted by the research group. These will be combined with the monitoring of real wetlands to produce the required data and knowledge needed to clarify occurring processes and the effect of cold climate related factors on purification efficiency.
The objectives will be targeted in 4 work packages:
1) Project management and dissemination of results
2) Effect of winter conditions on nutrient removal: pilot scale tests
3) Removal of nutrient and biomass production in willow wetlands: pilot scale tests
4) Year-around removal of nutrients and microplastics in wetlands purifying sewage water: case study.
RaMiKo project will run for a period three years (1.1.2019-31.12.2021) and the budget is 250 000 €. The project team is composed of researchers from the Water, Energy and Environmental Engineering research unit from the University of Oulu. The project is mainly funded by European Regional Development Fund via the Centre for Economic Development, Transport and the Environment for North Ostrobothnia. Other funders and partners are: Pohjois-Suomen Vesivaliokunta (OUKE), Kempeleen vesihuolto Oy, Taivalkosken Vesihuolto, Kuusamon Energia- ja Vesiosuuskunta, Maa- ja Vesitekniikan tuki ry and the University of Oulu.
Dr. Elisangela Heiderscheidt Dr. Heini Postila
Water, Energy and Environmental Engineering Research Unit
P.O. BOX 4300
90014 University of Oulu
Last updated: 6.11.2019