Comparing the efficiency of Cyperus alternifolius and Phragmites australis in municipal wastewater treatment by subsurface constructed wetland.

Nowadays, application of natural wastewater treatment systems such as wetland not only reduces economic costs and energy consumption, but also decreases environmental pollution. This study aimed to compare efficiency of Cyperus alternifolius and Phragmites australis in Municipal wastewater treatment by Subsurface Constructed Wetland Method. This is an applied-interventionnal study in which three reactors (control pilot, Cyperus alternifolius (umbrella palm) plant pilot and Phragmites australis (reed) plant pilot were designed by subsurface constructed wetland method. Then 90 samples were taken from input and output of reactors with four-day retention time. These samples were tested and finally the data were analyzed by Paired Sample Test statistical analysis. The results showed that removal efficiency of the parameters such as COD, BOD5, TSS, NO3-N, NH3-N, PO4-P, total coliform and fecal coliform was 74, 73, 84, 40, 36, 70, 33 and 38% in Cyperus alternifolius plant wetland, 44, 34, 77, 15, 0.3, 1, 17 and 26% in control wetland and 59, 54, 73, 6, 3, 10, 93 and 50 in Phragmites australis plant wetland, respectively. This reduction rate in all parameters- except fecal coliform- was statistically significant (p = 0.05). The results of this study showed that Cyperus alternifolius plant had higher efficiency in the removal of chemical parameters, whereas Phragmites australis plant had appropriate efficiency in the removal of microbiological parameters. Therefore, it can be concluded that application of these two plants can be effective in wastewater treatment.