Growth of Freshwater Microalga, Botryococcus sp. in Heavy Metal Contaminated Industrial Wastewater

Abstract

The aim of this study was to determine the growth and the bioremoval capacity of the green microalga, Botryococcus sp. grown in industrial wastewater contaminated with heavy metals. The freshwater green microalga, Botryococcus sp. was cultured in different concentrations of wastewater (25%, 50% and 100%) with an initial cell concentration of 1000 cells/ml for a period of 12 days. Bold basal medium and sterile distilled water were used as positive and negative control, respectively. The Botryococcus sp. grown in Bold’s basal medium showed the highest (P<0.05) average growth rate (7.8 × 10⁶ cells/ml) after a period of 12 days, whereas, the lowest (P<0.05) growth was observed in 50% concentration of wastewater (4.8 × 10⁴ cells/ml). Similar results were obtained for the specific growth rate (µ/day) with an average of 1.93µ/day and 1.22µ/day for the positive control and the 50% concentration respectively. Highest reduction of heavy metals was achieved for chromium which is equivalent to 94%, followed by copper (45%), arsenic (9%) and cadmium (2%). The results of this study suggest the potential of Botryococcus sp. as bioremediator of wastewater contaminated with heavy metals.