Optimization of Electrochemical Phosphate Recovery from Industrial Sludge Residue Generated from Supercritical Water Oxidation Treatment with H₂O₂

摘要

Hydrothermal oxidation in supercritical water (SCWO) is a unique and potential treatment technologyfor wastewater with high concentration of organics. In this process, oxidants and supercritical waterdissolved organic molecules make inorganic compounds more soluble, thus creating ash-freeinorganics from organic species at the bottom of SCWO reactor. This inorganic residue is very reactiveand can easily dissolve into some inorganic chemical species in solvents. Electrocoagulation (EC) is aprocess that metal anode electrodes are dissolved into the electrolyte solution when electrical currentpasses through the electrodes. Electrochemical dissolution of aluminium (Al) anodes in EC reactorproduces Al ions, which can be used to recover dissolved phosphate residue from acid solutions. Inthis study, electrochemically gained Al ions were used in the recovery of phosphate from SCWOresidue. Process parameters such as reaction time, current density and pH were investigated using BoxBehnken design (BBD) as a Response Surface Methodology (RSM). Optimum operating conditionswere evaluated, and the results showed accurate validities between the observed and predicted values.