PHYTOREMEDIATION POTENTIAL OF AQUATIC MACROPHYTE AZOLLA PINNATA R.BR. AND SALVINIA MOLESTA MITCHELL TO REMOVE CHROMIUM FROM WASTE WATER.

The process of phytoremediation by using aquatic plants is a new, low cost and ecofriendly method for improving water quality and waste water. In the present study the ability of Azolla pinnata R.Br. and Salvinia molesta Mitchell to uptake Cr (VI) from aqueous environment as well as their potential application for phytoremediation were assessed. During 15 days of the experiment the ferns were grown on the nutrient solution containing hexavalent chromium ions, each in a concentration of control, 0.07, 0.09, 0.11 and 0.13 mg/l. The biomass productivity and relative growth of Azolla pinnata R.Br. was increased and in case of Salvinia molesta Mitchell it was decreased with increase in the metal concentration of the treatment medium. The protein content in different concentration of chromium was more as compared to the control but showed a decreasing trend with increasing concentration. After 15 days of treatment, the concentration of Cr (VI) in the medium decreased between 72.86 - 97.69 % and 75.71 - 90 % by Azolla pinnata R.Br. and Salvinia molesta Mitchell respectively. Both the fern took a lesser quantity of metal from 0.07 mg/l treatments compared to 0.09 mg/l, 0.11 mg/l and 0.13 mg/l treatments. In the Azolla pinnata R.Br. tissue the concentration of heavy metal under investigation ranged from 0.106 - 0.216 mg/gm dry weight and for Salvinia molesta Mitchell ranged from 0.094 - 0.321 mg/gm dry weight. Increasing concentration of Cr (VI) in the growth medium increased the bioconcentration factor of Azolla pinnata R.Br. and Salvinia molesta Mitchell up to an optimum value of 1630.76 and 2469.23 respectively. In the present study the higher BCF of Salvinia molesta Mitchell shows that it is a better candidate for phytoremediation of Cr (VI) from the treatment solution than Azolla pinnata R.Br. Overall results indicate that Azolla pinnata R.Br. and Salvinia molesta Mitchell can be used for phytoremediation of Cr (VI) from polluted water as it is a low cost method satisfying the discharge standards. [ABSTRACT FROM AUTHOR]