Optimization of electrocoagulation process for fluoride removal: a blending approach using gypsum plaster rich wastewater

A novel blending approach has been introduced for fluoride removal by means of electrocoagulation. A blend was prepared by mixing synthetic phosphoric acid plant wastewater and gypsum plaster (GP) rich wastewater. This study explores defluoridation of wastewater using the simultaneous effect of chemical precipitation and electrocoagulation. Fourier transform infrared spectroscopy analysis of sludge confirms the presence Ca-F bond, which proves that enhancement in fluoride removal with blending of GP rich wastewater is due to simultaneous action of chemical precipitation and electrocoagulation. Optimization and statistical modeling were done with the help of MINITAB 17 software. Response surface methodology was performed using Box-Behnken Design to predict the fluoride removal efficiency and energy consumption. R-2 values of 0.9485 and 0.9998 shows a good agreement between experimental and predicted values of responses. Kinetic study was done to determine the rate constant and it is found out that fluoride removal follows second order kinetic model. Blending approach confirmed the assistive role of GP rich wastewater in the enhancement of fluoride removal efficiency.