Phycoremediation is an application of algae for remediate environmental pollution by reducing or eliminating toxicity of such components in waste water. One of environmental problem in Indonesia is heavy metals pollution. Heavy metals are required by microalgae in a trace concentration, but in a high concentration heavy metals are toxic. Spirulina platensis is a microalgae belong to Cyanobacteria that has been used as a single cell protein, feed fish, and supplement. Many researchs on S. platensis had been done to optimize the product. Research on the use of S. platensis for remediation environmental pollution were also had been conducted. But, research on the use of local S. platensis to reduce the concentration of Pb 2+ , Cd 2+ , Cu 2+ and Cr 2+ , had not yet well developed. Therefore, this research was conducted in order to find out the effect of 1, 3, and 5 mg/L concentrations of Pb 2+ , Cd 2+ , Cu 2+ and Cr 2+ on the S. platensis population growth and its accumulation. A laboratory experiment was developed with those different concentrations with 3 replications and control. The initial concentration of heavy metals were measured as well as the 7 and 15 days treatment to determine the bioaccumulation of heavy metals by S.platensis . Based on this research, the concentration of 1 mg/L heavy metals may induced the population growth of S. platensis, due to improvement enzymatic process, the concentration of 3 mg/L heavy metals inhibit population growth, and the concentration of 5 mg/L heavy metals was toxic for S. platensis. Since S. platensis was found high tolerance to Pb 2+ , Cd 2+ , Cu 2+ and Cr 2+ at low concentration, it was recommended that for phycoremediation process using S. platensis more appropriate to be applied for low concentration contaminated water. It was suggested that S. platensis can be used as a metal absorbent and can be cultivated from wastewaters after phycoremediation process for other uses such as fertilizer, with the note that heavy metal contamination in waste water should not exceed 1 mg/L. S. platensis will be better if apply 15 days in contaminated wastewater to get the highest removal heavy metals.
