Remediation of chromium(VI) containing wastewater using Chrysopogon zizanioides (vetiver grass)

Abstract

Remediation of heavy metal contaminated soil and water has been investigated through various methods, most of these have been shown to be expensive and sometimes result in the generation of toxic sludge. In situ methods such as phytoremediation have therefore been explored for their green, economical and less environmentally disruptive advantages. This study investigates the use of vetiver grass in the remediation of chromium(VI) from wastewater. The grass is known to grow in both soil and water. The efficiency of the vetiver grass in the removal of Cr(VI) was examined using 2 L solutions of varying concentrations. The initial concentrations of Cr(VI) chosen for the study were 5 ppm, 10 ppm, 30 ppm and 70 ppm. In a seven (7) week period, 87 % reduction in Cr(VI) concentration was observed in the 5 ppm bucket, while 51 % Cr(VI) removal was measured in the 10 ppm bucket. The 30 ppm bucket had a removal efficiency of 28 % in 5 weeks and 12 % removal efficiency in 4 weeks was measured in the 70 ppm bucket. The absorption of chromium was higher in the roots than the leaves at 5 ppm and 10 ppm, whereas it was higher in the leaves than in the roots at 30 ppm and 70 ppm. The results show the potential of vetiver grass in phytoextraction of chromium and its hyperaccumulator potential for other heavy metals.