The experimental conditions at this global point were determined to be pH(0)=3.97, C(0)=43.4 ppm, and t(C)=68.7 min, and the corresponding Pb(II) removal efficiency was found to be about 100%. The optimum coded values of three test variables were computed as x(1)=0.125, x(2)=0.707, and x(3)=0.107 by using a LOQO/AMPL optimization algorithm. The optimum values of the selected variables were obtained by solving the quadratic regression model, as well as by analysing the response surface contour plots. The standardized effects of the independent variables and their interactions on the dependent variable were also investigated by preparing a Pareto chart. The significance of independent variables and their interactions were tested by means of the analysis of variance (ANOVA) with 95% confidence limits (alpha=0.05). Three independent variables (initial pH of solution (pH(0)) ranging from 2.0 to 5.5, initial concentration of Pb(II) ions (C(0)) ranging from 5 to 50 ppm, and contact time (t(C)) ranging from 5 to 120 min) were consecutively coded as x(1), x(2) and x(3) at three levels (-1, 0 and 1), and a second-order polynomial regression equation was then derived to predict responses.
Furthermore, Response Surface Model elaborated as well, to demonstrate the effect of retention time and number of discs on the removal of CODĪ three factor, three-level Box-Behnken experimental design combining with response surface modeling (RSM) and quadratic programming (QP) was employed for maximizing Pb(II) removal from aqueous solution by Antep pistachio (Pistacia vera L.) shells based on 17 different experimental data obtained in a lab-scale batch study. The best possible optimum level of COD with respect to removal was 51.53984. In Response Surface Model (RSM) revealed that number of discs or disc area increment has significant effect on the removal of COD as corresponding p-values are less than 0.01, while linear and quadratic effect of retention time has no significant effect on the removal of COD as the p values are 0.301 and 0.071 respectively. The effect of two factors, hydraulic retention time and number of discs were observed on the elimination of Chemical Oxygen Demand (COD) through Rotating Biological Contactor (RBC) In the present study. Most important contribution originally in the field of Response Surface Methodology was done by Box and Wilson (1951) and Box and Hunter (1957) originated from British chemical Industry. Abstract: Response Surface Methodology (RSM) is a significant Statistical instrument utilized to explore the optimum levels of contribution factor(s).