The aim of this pilot study was to evaluate the bioaccumulation processes of Eichhornia crassipes exposed to a secondary effluent obtained from a Kraft pulp mill that drains the effluents into the River Uruguay, near Fray Bentos city, Rio Negro, Uruguay. The effluent was characterized before and after the Eichhornia culture, and organic halogens concentrations were determined in control and exposed specimens. Macroscopic changes were observed in the plant and the bioaccumulation routes were studied, the higher chlorinated organic compounds were found in the leaves (at a concentration of 9,4 µg/g by comparison to 2,1 µg/g of the control biomass). Nutrient removal was in the order of 90%. The results suggest that phytoremediation with floating plants can be advantageously alternative as a tertiary treatment methodology in subtropical and tropical countries to diminish the concentration of recalcitrant chlorinated organics and also to remove nitrate and phosphate from pulp mill effluents.