Phytoremediation is an effective method used to control the accumulation of certain contaminants found in industrial or city wastewater. Among the species with high efficacy are Eichhornia crassipes (water hyacinth), Lemna minor (common duckweed), and Pistia stratiotes (water lettuce). In this study, the application of these species in the context of two municipal wastewater treatment facilities in Cluj County, Romania, is evaluated. To determine the efficacy of bioaccumulation, we measured the content of nitrogen species (ammoniacal nitrogen, nitrites, and nitrates), phosphorous, iron, and chromium before and after the addition of plant material to effluent and treated wastewater. The results showed that E. crassipes, L. minor, and P. stratiotes presented high phytoremediation yields for these common wastewater pollutants after one week of contact, with yields as high as 99–100% for ammoniacal nitrogen, 95% for phosphorous, 96% for iron, and 94% for chromium. However, the remediation capacity for nitrate and nitrite was less significant.