Enhanced recovery of aluminum from wastewater using a fluidized bed homogeneously dispersed granular reactor

Abstract

The recovery of aluminum from wastewater is one of the main environmental issues that need to be addressed in the aluminum finishing industry. A new technique of converting a soft slurry into hard granules using the homogeneous granulation process in the fluidized-bed reactor (FBR) can respond to this problem. It is a better method of remediation than producing a slurry containing 70% water. This study deals with the recovery of aluminum from aqueous solutions using Fluidized-bed homogeneous granulation process (FBHGP) without seeds. The hydraulic operating conditions were optimized using Box-Behnken Design (BBD) to attain the optimum aluminum removal (AR%) and granulation ratio (GR%). Optimum values of AR% = 98.8% and GR% = 96.9% were attained at the following conditions: influent aluminum concentration, 334.1 mg L−1; precipitant pH, 10.4; molar ratio (MR) of precipitant to metal [OH−]in/[Al3+]in, 2.5. The characteristics of the granules were comparable with those of orthorhombic structure of aluminum oxide (Al2.66O4). FBHGP was proven to be effective as dictated by the reaction mechanism in the recovery of aluminum from aluminum-rich aqueous solutions.