Jornal de Biorremediação e Biodegradação

Abstrato

Bioaccumulation of Cadmium in Blue Green Algae Spirulina (Arthrospira) Indica

Siva Kiran RR, Madhu GM, Satyanarayana SV and Bindiya P

In the present paper, toxic effects and bioaccumulation of cadmium (II) ions by blue-green algae Spirulina (Arthrospira) indica were discussed. Lab scale open race way ponds (0.5 m long, 0.4 m wide and 0.075 m deep) with Zarrouk medium and S. (Arthrospira) indica culture was loaded with various initial cadmium (II) ion concentrations (1-10 mg/L). The growth of S. (Arthrospira) indica was monitored for eight days. The growth of S. (Arthrospira) indica was adversely affected by Cd (II) at high concentrations (>1 mg/L), however at low concentrations upto 1 mg/L, Cd (II) could stimulate its growth slightly. The toxic effect of cadmium (II) ions was modeled by assuming Monod growth kinetics with competitive inhibition. The percentage decrease in the S. (Arthrospira) indica biomass was found to be 54.32% at 4 mg/L Cd (II) after 7 days. The lethal concentration and time (LCt50) of Cd (II) ions for seven days was measured as 3.61 mg/L. The organism was found tolerant up to 1 mg/L of Cd (II) and can have potential applications in removal of low concentration of Cd (II) ions from contaminated waters. The biosorption experiment was conducted at various initial Cd (II) concentrations (1-4 mg/L) with live S. (Arthrospira) indica . The biosorption equilibrium time was found to be 6 min. It had been observed that at the initial stage (0-5 min) the adsorption rate was so rapid that 80% of the metal had been biologically adsorbed. The experimental equilibrium data was verified using Langmuir and Freundlich adsorption isotherms. The maximum biosorption capacity of live S. (Arthrospira) indica was estimated to be 66.97 mg Cd (II) per gdw of S. (Arthrospira) indica . The study provides a new insight into the impact of cadmium (II) ions on S. (Arthrospira) indica , especially with regard to its toxicity, bioaccumulation and bioremediation potential.