Phycoremediation of mercury in the aquatic environment

Phycoremediation refers to the technology of using microalgae to reduce pollutants in the aquatic environment. The purpose of this study was to analyze the reduction of mercury heavy metal in the media by using several species of microalgae such as Spirulina maxima, Nannochloropsis oculata, Chlorella vulgaris, and Porphyridium cruentum. The algae were exposed to mercury during eight days of cultivation. A randomized design was set with three different concentrations of mercury, namely 1, 3, and 5 mg/dm3, with three replications for each concentration. The initial concentration of microalgae was set to 10 000 cells/cm3 for S. maxima and N. oculata, while the concentration for C. vulgaris and P. cruentum was set to 100 000 cells/cm3. The concentration of mercury was measured at the beginning (1st day), the middle (4th day), and the end of microalgae cultivation (8th day) by using the atomic absorption spectroscopy (AAS) tool. The result demonstrated a reduction of mercury concentration during the experiment in all experimental media, where the highest reduction was found at 1 mg/dm3 (p < 0.05). In conclusion, microalgae have their limited ability to absorb and adsorb heavy metals. Therefore, the utilization of low-concentration microalgae on reducing heavy metal such mercury is recommended and merits further investigation