Use of two aquatic macrophytes for the removal of heavy metals from synthetic medium

The aim of the present study was investigation of two aquatic plants efficiency, duckweed Lemna gibba (floating-leaved hydrophyte) and coontail Ceratophyllum demersum L. (free-floating hydrophyte) on Cd and Ni removal from synthetic aqueous. Both aquatic plants were grown under greenhouse conditions in pots containing a nutrient solution amended with increasing doses of each of the contaminants tested (0, 1, 2, 4 and 6 mg L−1) in a completely randomized design with three replications. Plants dry matter production as well as heavy metals and nutrient tissue concentrations were measured at the end of the experiment. The results showed that increasing heavy metal concentrations in nutrient solution caused a decrease in both plants biomasses. L. gibba reduced the contamination level which was up to 91% for Cd and 50% for Ni. In addition, the efficiency of C. demersum was 82.01% for Cd and 52.5% for Ni. L. gibba uptake both heavy metals (5.07 mg for Ni and 9.70 mg for Cd) but C. demersum accumulated both heavy metals (4.5 mg for Ni and 3.87 mg for Cd) less and slower for Cd removal but a little more and faster for Ni than the other plant. The Ni and Cd BCF values for L. gibba ranged between 270.19 to 638.95 and 942.79 to 5093.27, respectively; and for C. demersum ranged between 104.16 to 200 and 75 to 707.92, respectively. The high efficiency of L. gibba and C. demersum in Cd and Ni removal from synthetic medium makes it a proper treatment method.