Growth, Biomass Production, Pollutant Removal Capacity of Chlorella Vulgaris Cultivated in Water Polluted with Phosphates, Nitrates, Cadmium and Lead Ions; A Possible Strategy for Bioremediation, Carbon Dioxide Utilization and Simultaneous Biodiesel Productivity

The main objective of the work reported herein was to study the possibility of simultaneous use of microalgae for bioremediation and biodiesel production. Determination of optimum nitrate and phosphate concentrations for the maximum algal growth in the presence of heavy metal ions in the growth media was the other objective. In this regard, Chlorellavulgaris, a microalga, was cultivated separately for 30 days at ~28 °C in the presence and absence of known cadmium, lead, phosphate ion concentrations in growth media containing an optimum nitrate ion concentration. The concentrations of these ions in the growth media, dry algal biomass and extractable algal-oil percentage after 30 days of their growth were determined. According to the study, the optimum total nitrate and total phosphate concentrations required for the maximum algal growth were 200 mg L-1 and 10 mg L-1, respectively. The maximum tolerable Pb2+ and Cd2+ concentrations were 8 mg L-1 and 2.5 mg L-1, respectively. The results revealed that Chlorellavulgaris has a high capacity for both removing these ions (> 70%) from the growth medium, and generating algal biomass, simultaneously. Moreover, the algal biomass generated under these harsh conditions yields algal-oil (~41% in terms of dry algal biomass) that is free from these ions.