Wastewater treatment and renovation by different duckweed species

The results of outdoor experiments with three different duckweed species grown in miniponds may prove to be highly competitive in comparison with those of existing secondary treatment methods. The duckweed biomass, with a crude protein content of over 30% of dry weight, may be used as a protein rich alternative fodder. The ease of duckweed harvesting makes the potential treatment system even more economically attractive. The treated wastewater is at an acceptable level and can be reused for agricultural irrigation. The range of organic loading for adequate performance of the duckweed was defined on the basis of outdoor studies. Organic loading in the miniponds was given by the ratio of COD and NH⁺ ₄ in raw domestic sewage. This ratio was checked for three species of duckweed with varying retention times of the wastes in the ponds, and the protein production by the floating vascular plants was subsequently examined.