Multi-response optimization of the coagulation process of real textile wastewater using a natural coagulant

Abstract

The present study is an attempt to investigate the applicability of a natural coagulant Moringa Oleifera (MO) as a potential impending alternative for the treatment of textile wastewater. Face Central Composite Design in Response Surface Methodology was used to optimize the performance of the coagulation process in terms of turbidity and colour removal efficiency. Three independent variables which are pH (2-4), coagulant dosage (4-8 ml) and settling time (10-30 min) were investigated. Quadratic models were developed for each response and their statistical fitness was evaluated using ANOVA analysis. All models were proved to be statistically adequate with R2 higher than 96%. Of the investigated variables, pH was found to have significant effect on both responses (P-value <0.001), whereas, coagulant dosage affected the colour removal efficiency significantly. Multi-response optimization was applied to optimize the process variables for both responses simultaneously using the RSM desirability function approach. Maximum turbidity reduction by more than 81% and colour removal efficiencies by more than 77% were reached at the optimum conditions of pH 2, coagulant dosage 4 mL and settling time 21 min. These results prove that MO could be used as an alternative to the conventional coagulants for real textile wastewater treatment.