Constructed wetlands for wastewater treatment: Adaptation to cold climate (2020-2023)

This project investigates the suitability of using a two-stage vertical-flow constructed wetland as wastewater treatment method for small communities in subarctic climate. The work is funded by the Swedish Research Council Formas and the municipality of Luleå with "LOVA" funding from the regional authority.

Sweden has 3200 small wastewater treatment plants for 25–2000 PE, many facing problems regarding their operation and function. Especially sludge handling (transport) is resource-demanding. The two-stage vertical-flow constructed wetland (VFCW) with reed, is a well-established technology with e.g. 4,000 applications in France. Without primary clarification, the wastewater enters the first wetland stage where the solids compost on the surface. Due to its simplicity, it is a promising technology for the Swedish rural context that demands simple solutions for sludge handling. However, it has not yet been tested in subarctic climate. Further, the removal of microplastics in VFCW has not yet been investigated. Phosphorus removal, as required in e.g. Sweden, can be achieved using an additional filter or chemical treatment. This project aims at investigating the suitability of using the two-stage VFCW as wastewater treatment

method for small communities in subarctic climate. We will design and test the performance of a pilot-scale wetland in subarctic climate, also with regard to microplastics, and compare the VFCW to currently used technologies in terms of sustainability using a multi-criteria approach. The design of the classical two-stage VFCW will be adapted to subarctic climate in collaboration with an experienced wetland researcher. A pilot wetland will be constructed in collaboration with Luleå municipality.

The project is a collaboration of Luleå University of Technology, Irstea in France and the municipality of Luleå.

Inga Herrmann, Annelie Hedström, Rasmus Klapp and Maria Viklander