Effect of dissolved metals on the organic load removal efficiency of Lemna gibba

This work is focused on assessing the potentialities of Lemna gibba in the treatment of metal polluted wastewaters. This was done by evaluating the effects of various metals on plant growth, bioaccumulation and organic pollutant removal rate. In particular, several experiments were carried out using synthetic wastewaters contaminated with AlIII, CuII, CrVI, FeIII and ZnII at various concentrations. It was found that wastewaters containing organic load with FeIII (up to about 20 mg/l), ZnII (up to about 20 mg/l) and AlIII (less than 30 mg/l) do not affect the performance of a treatment based on Lemna gibba. On the other hand, concentrations of chromium higher than about 0.1 mg/l and copper larger than about 1 mg/l have a detrimental effect on the plant performance.