Abstract

Heavy metals such as arsenic (As), copper (Cu), chromium (Cr), Hg, lead (Pb) and cobalt (Co) cause adverse effects on living organisms by their toxic nature. To remove heavy metals, a variety of conventional treatment technologies have been tested which are not economical and user friendly. So, natural remediation method such as phytoremediation is becoming more popular where plants are used. Phytoremediation is a cost effective and eco-friendly method. This paper accounts the study to exercise the phytoremediation potential of the aquatic plant Spirodela polyrhiza for arsenic and copper removal from water. To carry out the study, six plastic bowls each carrying 1 L distilled water were taken where arsenic and copper of known concentration was added for preparing a solution, which contained 1.0, 0.9, 0.7, 0.6, 0.5, and 0.3 mg/L of arsenic and 5.0, 4.6, 4.2, 3.8, 3.4 and 3.0 mg/L of copper. 50 g of S. polyrhiza plant was placed in water of each bowl. The concentration of arsenic and copper in water was measured by spectrophotometer using Silver diethyldithiocarbamate (SDDC) and Bicinchoninate methods, respectively and test was performed for 7 days after placing plants in solution. Gross effective floating period for S. polyrhiza was found 96 h up to initial concentration of 0.6 mg/L to treat arsenic contaminated water and 3.4 mg/L to treat copper contaminated water. The extraction capacity of S. polyrhiza was found more than 80% for all concentration of arsenic and more than 60% for all concentration of copper after 96 h. The removal of arsenic and copper was found to follow the first order kinetics except copper with initial concentration of 5.0 and 4.6 mg/L.

Key words: Spirodela polyrhiza, phytoremediation, first order kinetic