ARSENIC UPTAKE BY FRESH WATER GREEN ALGA, CHLAMYDOMONAS SPECIES

Removal of heavy metals from the water has been a long term-challenge. During the recent era of environmental protection, the use of microorganisms for the recovery of metals from contaminated water has generated growing attention. Many studies have demonstrated that both prokaryotes and eukaryotes have the ability to remove metals from contaminated water. The present study focused on isolating alga from the area around Matlab Upazila in southeastern Bangladesh, with elevated concentrations of arsenic in groundwater and studies on the removal of arsenic by algae from contaminated water. The alga was grown in the synthetic water with a composition similar to the average groundwater in the region around Matlab Upazila containing 50µg/L and 100 µg/L arsenic. The cultures were exposed for 16 hours light period to get substantial biomass. The major population of algae from the arsenic contaminated area has been identified as green alga, Chlamydomonas. The growth rate and arsenic removal was monitored in the presence of high and low phosphorus content at pH 5 and 7 in the media over a period of up to 45 days. The algae were able to grow at concentrations of arsenic up to 1 mg/L in the media. Results from this study shows that growth rate increased with time. At pH 5, the rate of arsenic removal was around 50% irrespective of the As concentrations. On the other hand, media containing high phosphorus and at pH 7, alga could remove 80% of the arsenic with initial concentration of 50µg/L arsenic; whereas at 100µg/L arsenic the reduction was up to 60%. Chlamydomonas was found to have capabilities of endurance against high concentration of arsenic and its accumulation in the cells that has a potential application for the removal of arsenic from contaminated water.