Optimization Of Environmental And Nutritional Conditions For Heavy Metal Removal From Polluted Effluents

Abstract

Heavy metal contamination in industrial effluents is one of the most critical environmental concerns due to the toxic and non-biodegradable nature of metals such as copper (Cu²⁺) and zinc (Zn²⁺). In this study, bacterial strains were isolated from polluted effluent samples collected from Thoothukudi District, Tamil Nadu, to identify efficient metal-removing microorganisms. Fifteen isolates (T01–T15) were screened on nutrient agar and minimal salt medium supplemented with Cu²⁺ and Zn²⁺ salts. Among these, isolate T12 exhibited the highest metal removal efficiency, achieving 92.4% Cu²⁺ and 88.6% Zn²⁺ removal. Based on morphological, biochemical, and 16S rRNA gene sequence analysis, T12 was identified as Cedecea neteri. Optimization studies revealed that the strain performed best at moderate conditions—pH 5–6, temperature 25 °C, and metal concentrations of 20–30 mg/L. Beyond these levels, removal efficiency declined due to metal toxicity and binding site saturation. The biosorption process was exothermic, indicating higher metal uptake at lower temperatures. These results suggest that Cedecea neteri is an efficient and eco-friendly biosorbent for the removal of copper and zinc from industrial effluents, offering a sustainable alternative to conventional physicochemical methods.