Ponente
Descripción
The use of full factorial designs generates maximum information about the removal process, defining the relevant factors and identifying the interactions among them. The present study was focused on Cd (II) and Pb (II) removal by indigenous heavy metal-resistant bacterium isolated from Almendares River, Havana, Cuba. The optimal removal conditions, specifically pH, Cd (II) and Pb (II) initial concentration, and biomass initial concentration were determined by using a full factorial design at two levels. The results showed that Bacillus subtilis AL-25 was highly efficient in removing Cd (II) and Pb (II). The analysis of variance (ANOVA) results indicated that the three factors and the interaction terms (pH- metal initial concentration), were a significant influence on Cd (II) and Pb (II) removal yield. Moreover, the prescribed first-order regression model fitted well to the experimental data with a high coefficient of determination (R2 = 0.98). According to the response optimizer of Design-Expert software, the optimum conditions for Cd (II) and Pb (II) removal were: a pH of 7.0, a metal initial concentration of 3 mM and a biomass initial concentration of 1 g L-1. Under these conditions the experimental metal removal percentage was found to be about 92.9% which is close to the predicted value by the statistical design (94.4%). Thus, the use of full factorial design was found to be a suitable statistical tool in improving heavy metals removal efficiency and standardizing optimum conditions.
