The present study was undertaken to determine the efficacy of Lemna minor (duckweed) in stabilisation of untreated mixed wastewater. It was observed that Lemna can efficiently remove dissolved solids and organic matter in a microcosm operated under sunlight. The removal of BOD5 and COD was of the order of 50% and 75%, respectively. Microscopic examination of the roots confirmed the role of roots in entrapment of suspended solids and organic matter over the roots. The DO levels in wastewater increased to about three times during the treatment. The biomass, chlorophyll a and b, and carotenoid content had significant increase, and ratio of chlorophyll a/chlorophyll b was almost constant. No biochemical or physiological stress of wastewater over Lemna could be reported during the study. The study concluded that Lemna minor can be used for stabilisation of low strength mixed wastewater, particularly for remote and small communities.

Keywords: Lemna Minor; Rhizoremediation; Wastewater Stabilisation; Chlorophyll.