Microalgae offer a sustainable approach for removing heavy metals from industrial effluents. This study evaluated the ability of Chlorella minutissima to tolerate and remove Cd²⁺, Cr⁶⁺, Pb²⁺, and Zn²⁺ from synthetic wastewater under optimized growth conditions (27 ± 1 °C, pH 7.5, 14:10 h light: dark cycle, 2000–2500 lux, 100 mgL⁻¹ glucose, initial density ≥10⁶ cells mL⁻¹). Growth responses and metal uptake were assessed across concentrations of 0.5–10 mgL⁻¹. Results showed strong variability among metals. At 0.5 mgL⁻¹, the highest removal percentage was recorded for Zn²⁺ (98.63%), followed by Pb²⁺ (93.15%), Cr⁶⁺ (85.69%), and Cd²⁺ (40.49%). However, Pb²⁺ exhibited the highest absolute uptake amount (6.86 µg per 100 mL) at 3 mgL⁻¹, while Cr⁶⁺ underwent significant intracellular reduction to Cr³⁺. Growth inhibition was most pronounced under Cd²⁺ exposure, followed by Cr⁶⁺, Pb²⁺, and Zn²⁺. Negative controls confirmed normal growth in the absence of metals. These findings indicate that C. minutissima is an effective biosorbent for low concentrations of Pb²⁺, Zn²⁺, and Cr⁶⁺ under laboratory conditions. While the results highlight its potential for wastewater treatment, further studies using real effluents and pilot-scale systems are necessary to establish practical applicability.
Chlorella minutissima, Heavy metals, Bioremoval, Bioadsorption, Bioabsorption, Bioreduction, Wastewater treatment
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