Nutrient removal from a stormwater detention pond using duckweed

Different species of Lemnaceae (duckweed) were grown in pure and mixed cultures to examine nutrient absorption capacity in a stormwater detention pond. The duckweed was grown in 0.4 m² equilateral triangular floating Pens in a stormwater retention pond, which is part of a constructed wetland in Roseville, Minnesota. Both biomass productivity and nutrient (phosphorus and nitrogen) removal were measured for each species. It was concluded that: (1) monoculture Lemna minor consistently removed the largest amount of ammonia from stormwater and had the largest biomass density; and (2) a polyculture of Lemna minor and Spirodela polyrhiza was the most stable nutrient sink and removed the largest amount of phosphorus from stormwater in eight weeks.