Dosage and settling time course optimization of Moringa oleifera in municipal wastewater treatment using response surface methodology

Abstract

The efficacy of the Moringa oleifera (MO) in wastewater treatment has been well studied and documented. However, there exists a significant gap in exploring the operating conditions to opti mize the wastewater treatment process. This study investigated and optimized the removal efficiency of turbidity, biochemical oxygen demand (BOD), and chemical oxygen demand (COD) from munic ipal wastewater under the operating conditions of pH (5–7), MO dosage (50–200 mg/L), and settling time courses (60–240 min) using face-centered central composite design (FCCCD) of response sur face methodology. The experimental results of FCCCD were fitted to the second-order quadratic model to approximate the effects of each variable factor and their interactions on the responses of interest in a mathematical relationship and consequently, predict the process responses. The obtained results revealed that under the optimum operating conditions of pH, MO dosage, and settling time of 6.01, 182.74 mg/L, and 228.08 min, respectively, the predicted values of turbidity, BOD, and COD removal efficiencies were 98.20%, 92.96%, and 78.82%, respectively, with the desirability of 1.000. This study demonstrated the effectiveness of FCCCD with a desirability function to optimize the process conditions (pH, MO dosage, and settling time) of coagulation for the turbidity, BOD, and COD removal efficiencies.