Wastewater treatment is essential to ensure public health. One solution for the additional treatment of municipal wastewater is the use of surface and subsurface constructed wetlands. In order to evaluate the proportion of total nitrogen (TN) and total phosphorus (TP) removal attributed to storage in plants, three wetland plant species ( Phragmites australis , Typha and Rush ) were planted in separate cells. In order to compare the statistical analysis of the three plants, for each plant, four cells were considered to be tested in a completely randomized design having 4 replications. Three cells were also considered for the three plants growing using regular water (control cells), to be compared to that of treatment cells and thus the effect of plants on wastewater treatment would be determined. In order to study the effect of cells and porous media on reducing nutrients, a cell without plant was considered and sampled from cell outflow at several times to obtain average concentrations of nutrients in this cell. After 12 and 24 weeks, the plants were sampled to determine the nutrient’s accumulation rate; also, the capacity of these species to retain the nutrients in above and below-ground plant tissues was reported.The statistical analysis showed that after 12 weeks only in the accumulation of phosphorus in above-ground tissue, common reed has no significant difference by two other plant species. But in other cases, all of the three plant species have the significant differences in level of 0.01%. But after 24 weeks, in the accumulation of phosphorus in above-ground tissues, common reed has no significant difference in comparison with the other two plant species and in the accumulation of phosphorus in below-ground tissues, common reed and Rush has no significant difference. However, in the accumulation of Nitrogen in above and below-ground tissues, all of the three plant species had the significant differences in a level of 0.01%.The uptakes of nutrients by Rush, Common Reed and Typha from the pilot system after 12 weeks were 49.39% TKN; 17.98% P and 44.62% TKN; 13.22% P and 27.62% TKN; 9.46% P, respectively and after 24 weeks, the uptakes of nutrients by Rush, Common Reed and Typha were 58.6% TKN; 35.71% P, 56.48% TKN; 30.35% P and 32.19% TKN; 14.28% P, respectively. Comparing two stage of samples, showed that the biomass and nutrient content of both above- and belowground tissues varied considerably over the course of the growing season and long term monitoring and maintenance are crucial to ensure the performance of the wetland plants.The results can be applied in plant species selection in the design of constructed wetlands in Isfahan as well as in optimizing the performance of these systems.
