Improvement of Cr phytoremediation by Pistia stratiotes in presence of nutrients.

The effects of different concentrations of P and N, added separately or combined, on the Cr(III) accumulation capacity of P. stratiotes were studied. Plants and pond water with the addition of contaminant(s) were placed in plastic aquaria. Cr concentration was 5 mg L–1, while P and N concentrations were 5 mg L–1or 10 mg L–1. Nutrient addition significantly favoured Cr removal and enhanced Cr translocation to leaves. In Cr treatments a high detritus formation from loss of root biomass was observed probably due to its toxicity. Cr was mainly accumulated in the detrital fraction, whereas P and N were retained fundamentally in leaves. A toxic effect was observed in the Cr + P10 and Cr + N10 treatments. These results could be applied to enhance Cr removal efficiency of constructed wetlands using P. stratiotes, where nutrient enrichment could be attained by treating sewage together with the industrial effluents.