Evaluating the Potential of Microalgal Species in the Phytoremediation of Cadmium and Lead Contaminated Waters

Abstract

The persistent and bio-accumulative nature of Cd and Pb, two of the most hazardous heavy metals, poses serious risks to human health and the environment. In this study, two microalgal species Tetraselmis sp. and Gonyostomum sp. exposed to Cd and Pb at concentrations of 3, 5, and 7 ppm over the course of an 8-day culture period were examined for their capacity of phytoremediation. At the end of the trial, important metrics like optical density, biomass productivity, lipid accumulation, pigment stability, and metal removal efficiency were measured. Tetraselmis sp. showed much better (p < 0.001) extraordinary resilience and remediation capabilities, with a bioconcentration factor peaking at 56,167.4 L/kg and maximum removal efficiencies of 83.33% for Cd and 71% for Pb. Gonyostomum sp., on the other hand, showed reduced lipid yields and growth resulting more vulnerable to metal-induced stress, especially from Cd. Remarkably, Tetraselmis sp. experienced a hormetic response to low Pb levels, which raised biomass production and lipid productivity. Furthermore, during heavy metal stress, Tetraselmis sp. demonstrated a statistically significant (p <0.001) lipid productivity of roughly 6.35 ppm/day as opposed to Gonyostomum sp., which peaked at just 2.73 ppm/day. According to these results, Tetraselmis sp. is a promising option for dual uses in microalgal biofuel production and bioremediation, while also addressing the gap in comparative performance analysis of underexplored microalgal species.