Phytoremediation technology using aquatic plants is being used increasingly in constructed wetlands to purify wastewater. The physiological responses of water lettuce(Pistia stratiotes) and its effectiveness in removing fluoride(F~–) from water are described in this article. The results indicate that Pistia stratiotes has the ability to accumulate F~–. The removal efficiency ranged from 27.79% to 56.32% for the various initial F~– concentrations tested, and was highest(56.32%) in the highest initial concentration group 60 mg/L. The F~– concentrations in control groups(without Pistia stratiotes) changed very little, from –1.135% to –0.007% of the initial concentrations. At the highest removal rate, the bioconcentration factor was 7.84. The rate of purification conformed to the Michaelis-Menten equation, and the correlation coefficients(R^2) were all greater than 0.97. The Specific Growth Rates(SGR) of the treatment groups were –8.03% to –1.22%, and the SGR of plants under F~– stress decreased during the experimental period. The partial correlation analysis showed that concentrations of F~– in water were strongly linearly correlated with peroxidase.
