| As underdeveloped nations continue to industrialize and the world population continues to increase, the need for energy, natural resources, and goods will lead to ever increasing heavy metal concentrations in various waste streams that can have damaging effects on plant life, wildlife, and human health. The focus of this study is to understand the impact of individual heavy metals on Nannochloropsis salina microalgae growth and understand the potential of microalgae to be used as a bioremediation tool for contaminated water systems. Individual metals (As, Cd, Cr, Co, Cu, Pb, Ni, Hg, Se, and Zn) were introduced into growth media. For each metal a baseline concentration was determined based on reported concentrations at various municipal and industrial wastewater sites. In addition to the baseline concentrations, experimentation was conducted at 10X and 40X the baseline to evaluate the potential for severely contaminated systems. Biological growth experimentation was performed in triplicate at the various contaminant concentrations and at 3 different light intensities. Results show nickel significantly reduced growth, while the other metal contaminated systems showed growth between 89% and 99% of the control. Increased heavy metal concentrations resulted in progressively lower growth rates. Lipid analysis shows most baseline metal concentrations slightly decrease or have minimal effects in lipid content. Metals analysis on the biomass showed the majority of the metals in the systems containing Cd, Co, Cu, and Pb were sorbed by the microalgae with minimal metals remaining in the growth media illustrating the effectiveness of microalgae to effectively bioremediate contaminated systems when contamination levels are sufficiently low to not detrimentally impact productivity. Microalgal biomass in the systems containing As, Cr, Ni, and Se showed decreased ability to sorb metal ions. Results show at moderate contamination levels, microalgae can be an effective tool for bioremediation. |
