Application of response surface methodology to water/wastewater treatment using Coccinia indica

This study investigates he optimization of coagulation-flocculation process for turbid water using Coccinia indica as a coagulant by the use of response surface methodology (RSM). To minimize residual turbidity, the experiments were carried out using jar test for low, medium, and high turbid water by varying pH and dosages of C. indica. A central composite design, which is the standard design of RSM, was used to evaluate the effects and interactions of three major factors: coagulant dosage, initial turbidity, and pH on the turbidity removal efficiency with 2(3)-factorial design having three star points, six center points, and two replications. The quadratic model developed for the response studied indicates the optimum conditions to be 0.6 mg/L, 6.5, and 300 NTU for coagulant dosage, coagulation pH, and initial turbidity, respectively. At optimum conditions, turbidity removal was found to be 92.60%. The experimental findings were in close agreement with the model predictions. The response model was developed in this study with the value of R-2 as 94.1 and R-2 adjusted as 92.6%. Thus, RSM has demonstrated to be an appropriate approach for the optimization of the coagulation-flocculation process by statistical evaluation.