The adsorption of heavy metals onto treated Azolla filiculoides
, as a cosmopolitan free-floating waterfern, was investigated from aqueous solutions in the batch biosorption experiments. The maximum uptake capacities of the collected Azolla
from rice field at the optimal conditions for Pb, Cd, Cu and Zn ions were approximately 228, 86, 62 and 48 mg/g (dry Azolla
), respectively. On the other hand, the maximum uptake capacities of the collected Azolla
from the Anzali International Wetland in the north part of Iran at the same conditions for these heavy metals were about 124, 58, 33 and 34 mg/g (dry Azolla
), respectively. Such decrease of uptakes is due to the pollution of Anzali International Wetland, which reduces the capacity uptake of metals. The recovery of biosorbed heavy metals from the rice field Azolla
was carried out by HCl and NaCl desorbents that the recovery of 64- 86% and 51-72% was occurred, respectively.