Dalarna Science Park

Wastewater irrigation of Salix Plantations – Hedemora Energy

The largest and northern most full-scale system for wastewater irrigation of Salix plantations in Sweden. The local community in Hedemora has long experience in producing biofuel from Salix plantations. The cooperation between Hedemora Energi AB and local farmers has resulted in irrigation of 75 acres of Salix Plantations. The local farmers in the project are guaranteed to sell their biofuel to the local municipal heating plant. As a result the project is contributing to the local production and consumption.

Hedemora Energi AB is irrigating Salix plantations, during the growth period, in the area of Hovran using secondary treated wastewater from Brunna wastewater treatment plant. Between the irrigated land and the river Dalälven there is an area of wetlands where further uptake of nutrients will take place. The project contributes to a more ecologically sustainable society mainly with the following: reduction of eutrophication of rivers, secure water and nutrient supply to the Salix plantations, wastewater treatment without chemicals, and production of renewable energy.
The pressure on the environment is reduced through a decrease in discharged wastewater to the river of Dalälven. On a yearly basis the reduction equals to approximately 25 % of the total discharge of nutrients from the wastewater treatment plant.
The use of energy is improved as renewable biofuel is produced. Approximately 30MWh is required annually for pumping and distributing the irrigation water. At the same time the use of energy is reduce due to less sewage sludge dewatering in the treatment process and less production of precipitation chemicals and polymers. To produce the same amount of nutrients through fertilizers, excluding transport and distribution, approximately 30 MWh will be required annually.
The effective use of natural resources is improved as the amount of chemicals uses is reduced. Approximately 40m3 of liquid chemicals is saved every year. This is equal to 12% of the annual consumption. The consumption of polymers for sludge dewatering is also reduced.
Reuse and recycling are improved as the nutrients in the wastewater are reused as a resource in the Salix plantations. Recycling of phosphorous is important as phosphorous is not a renewable resource.
The biodiversity is strengthened as Salix plantations and wetlands are attractive to wildlife.

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