Accumulation of heavy metals (Cu, Cr, Pb and Cd) in freshwater micro algae (Chlorella sp.)

Abstract

Some selected micro algae were used for the removal of heavy metals from wastewater. In this present investigation, Chlorella sp was studied for accumulation of heavy metals, namely copper, chromium, lead and cadmium. The salts containing heavy metals were dissolved in Blue Green 11 medium at different concentrations in a glass jar of 10 litre capacity each and subsequently they were bubbled with air for 12 days at a temperature of 33 degrees C and light intensity of 2200 lux. The removal rates of heavy metals were recorded for every 4 days during the experimental period. Chlorella sp. removed 37%, 43% and 67% of copper after 4, 8, 12 days respectively. The percentage removal of chromium was 34%, 43% and 50% respectively at 4, 8, and 12 days. Lead removal rates of Chlorella sp were 56% after 4 days, 69% after 8 days and 77% after 12 days. The reduction of cadmium in the culture medium after 12 days was 93%. From the present investigation, it is concluded that heavy metal removal ability of Chlorella sp. can be exploited for metal detoxification and environmental clean up.