Evaluation of the common duckweed (Lemna minor) phytoremediation on nitrate, phosphate, cadmium and lead parameters reduction from aquaculture wastewater and determination of the heavy metals effects on this species growth inhibition

Nowadays, one of main environmental problems of the aquaculture wastewaters is the presence of nutrients and heavy metals in these sources. The aim of this study was to investigate the phytoremediation potential of the Common duckweed (Lemna minor) in reducing nitrate, phosphate, cadmium and lead from aquaculture wastewater and determining the inhibitory effect of cadmium and lead on the growth of this species. For this experiment, L. minor were collected from the margins of the wetlands and transferred to the laboratory and were treated by four experimental groups in triplicate. At the end of the 15-day experimental period, the concentrations of heavy metals cadmium, lead, nitrate and phosphate in the treatments were examined. Increasing L. minor surface coverage decreased cadmium, lead, nitrate and phosphate concentration in the treatments. The study also showed that both lead and cadmium reduced the growth factors of L. minor. So that increasing the amount of lead by 20 mg /l reduced the growth of L. minor by 84.11% and also cadmium by 30 mg /l reduced the growth of L. minor by 82.1%. Finally, according to the results, it can be concluded that the L. minor is a valuable species for phytoremediation purposes.