Response of the Chlorella vulgaris microalgae response in heavy media contaminated with lead

Water is a fundamental resource for life, essential for domestic, agricultural, and industrial use. The increasing demand for clean water due to population and industrial growth has led to significant pollution challenges, particularly from untreated wastewater and the excessive use of chemicals. Heavy metal contamination, specifically lead (Pb), poses severe risks to aquatic ecosystems and human health. Pb pollution in coastal and port waters, such as Tanjung Emas Port in Indonesia, has been documented to exceed permissible limits, necessitating effective remediation strategies. Microalgae offer sustainable and cost-effective solutions for heavy metal removal through biosorption and bioaccumulation mechanisms. This study explored the potential through the responses of Chlorella vulgaris, a green microalga, in saline and Pb-contaminated media. The research was conducted in a laboratory using a controlled photobioreactor with 20%o salinity and varying Pb concentrations, 0 mg/L as control, 1 mg/L, 3 mg/L, 5 mg/L, 7 mg/L, and 9 mg/L. The response of Chlorella vulgaris was monitored and analyzed by the key parameters, including cell density, growth rate, pH, temperature, and CO₂ concentration over 14 days to assess the ability of Chlorella vulgaris to survive in saline and contaminated media. The research found that Chlorella vulgaris with an initial cell density of + 347 × 10⁴ cells/mL can survive and grow in media with 20%o of salinity and a heavy metal concentration of up to 9 mg/L. Over 14 days, cell density observations revealed optimal growth in a reactor with 3 L/min aeration, 20%o salinity, and a Pb concentration of 3 mg/L. The cell density value was 16.58 × 10⁶ cells/mL, the same as the cell density in the control reactor, 18.78 × 10⁶ cells/mL.