Application of Response Surface Methodology (RSM) for Modeling and Optimizing Coagulation Process for the Removal of Bromide Ions

In this paper, the response surface methodology and the central composite design are used to model and optimize bromide removal efficiency in the coagulation process. Bromide ions are naturally found in surface waters. Despite its non-toxicity, when exposed to disinfectants commonly used in water treatment, bromide ions produce disinfection byproducts which are more carcinogenic than their chlorinated counterparts. A key process in water treatment is coagulation. Most studies have recently focused on enhanced coagulation achieved by new coagulants known as inorganic polymer coagulants which exhibit a remarkable ability in both removing colloidal particles and reducing turbidity and the zeta potential from water. In the present experiments, poly-aluminum chloride (PAC) is used as a coagulant. Moreover, an experimental design is constructed using the Design-Expert software to develop an efficient model with a regression coefficient of 0.9925 which fitted the observed data on bromide removal efficiency. It is found that coagulant dosage and initial bromide concentration have direct impacts on bromide removal efficiency while a different behavior is observed in the case of pH.