Evaluation of the Performance of Vetiveria zizanioides in Removing Nutrients from Wastewater

The aim of this study was to evaluate the growth of Vetiveria zizanioides under hydroponic conditions and its efficiency in removing nitrogen and phosphorus compounds from wastewaters. For this purpose، a pilot plant was constructed with a net volume of 60 liters which was intermittently fed for three months with the effluent from a domestic wastewater treatment plant. It was found that Vetiver exhibited a significant capability for living in polluted waters under hydroponic condition as evidenced by the growth of its leaves to 130 cm. Moreover، the average values of total nitrogen، total phosphorus، and biochemical oxidation demand (BOD) removal efficiencies over four days of retention time were 91%، 97%، and 75%، respectively. If used as a tertiary treatment unit، the plant needs a minimum retention time of two days to allow adequate time for the removal of such vital compounds as Ammonia and Phosphate by 95%، which is the typical standard limit for wastewater reuse or free discharge. Finally، it was observed that the total values of nitrogen and phosphorus absorbed in the leaves were 17 and 2. 3 (mg/gr dry weight) while the same elements absorbed in the roots were measured as 13 and 1. 8 (mg/gr dry weight)، respectively.