Phytoremediation of Heavy Metals by Azolla microphylla from Industrial Effluents (Research Article)

Author(s): E. Mohan, S. Shanmugam*, M. Kannan and K. Rajendran

Abstract: An aquatic fern, Azolla microphylla was tested to determine their growing capacity and heavy metal removal efficiency in different industrial effluents with different concentrations. Untreated industrial effluent samples were collected from three different sources (SE-1, SE-2 and SE-3) and poured in separate cement tanks and 5 grams of A. microphylla were introduced into each tank. After 30 days, the growth parameters such as fresh weight, doubling time and relative growth rate were assessed. The results revealed that the highest fresh weight, doubling time and relative growth rate of Azolla were observed in SE-3 than SE-1 and SE-2 samples. In SE-3, 50% concentration exhibited greater growth than other concentrations such as 25%, 75% and 100%. In general, the growth was greater in 50% concentration of effluent samples. At the concentrations of 25% and 100% the growth was found less and/or inhibited especially in the effluent samples of SE-1 and SE-2. A. microphylla expressed significant removal efficiency on all the four heavy metals tested and the removal efficiency was in the order of zinc > lead > cadmium > nickel. Based on these results, it was concluded that A. microphylla can be used in wastewater treatment.

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