Rhizofiltration of Pb by Azolla pinnata
2013
Plant based technologies such as phytoremediation, are cost effective and environmentally friendly for the removal of toxic heavy metals from polluted water ways. Aquatic plants are well known for accumulating and concentrating heavy metals. This study shows the potential of Azolla pinnata to remove Pb(II) from aqueous environment through rhizofiltration, which is one of the phytoremediation strategies. The effect of nutrient concentration, initial metal concentration and exposure period on lead uptake capacity of A. pinnata was studied. A modified Hoagland's nutrient solution was used as the growth medium. Lead uptake capacity in plants increased with decreasing nutrient concentration in growth medium. Increasing concentrations of lead in the growth medium increased the bio concentration factor of A. pinnata up to an optimum value of 1220 while the relative growth of the plants was significantly decreased. The results of the time course study showed that the efficiency of lead removal depends on the duration of exposure. The maximum uptake of lead was 1383 mg/kg of A. pinnata dry weight after four days of treatment where the lead concentration in the growth medium has reduced by 83%. It is concluded that A. pinnata is a potential candidate for the removal of Pb from polluted waterways.
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