Constructed wetland for post-treatment of phosphorus in wastewater : An initial assessment of potential design and application to a small-scale water treatment plant in Åre municipality, Sweden

Sammanfattning: In recent years, the treatment of phosphorus in Nyland's water treatment plant (located in Åre municipality) has been substandard. The problem has persisted despite attempts to lower the concentration to meet the emission requirements. A desire to find alternative, more environmentally friendly treatment methods has therefore been expressed from the municipality.Aside from the requirements, there is a desire to keep nutrient levels in the recipient (Indalsälven) low to preserve its natural state. A recognized method for treating wastewater is the use of constructed wetlands, where the characteristics of a natural wetland are enhanced and taken advantage of.The assessment of which type of constructed wetland that would be most beneficial to apply, was done by rating and weighting a number of characteristics of importance for lowering the phosphorus concentration. A first-order area-based model was used to estimate the size of the wetland.This report found that there is a suitable site to build a free water surface wetland in the vicinity of the water treatment plant. The wetland would act as a polishing step in the treatment train. As there is an element of uncertainty in treatment performance when a living ecosystem as wetlandis used, it is advised to enlarge this study and include more design aspects to refine the layout and configuration.