Process optimization of boron and hardness removal from boron mining wastewater using mixed-bed ion exchange resin by response surface Methodology (RSM)

Abstract

The treatment of boron mine wastewater containing high concentrations of boron and hardness iscritically important due to its environmental impact and reuse limitations. In this study, the simulta-neous removal of boron and total hardness from boron mining wastewater was investigated usinga mixed-bed ion exchange resin (Tulsion® MB-115). The process was modeled and optimized byresponse surface methodology (RSM) based on central composite design (CCD) to evaluate the effectsof pH (6–10), solid/liquid ratio (S/L) (20–60 g L−1), and temperature (T) (15–35 °C). Maximum hardnessremoval of 98.6% was achieved at pH 8.5, S/L 45.5 g L−1, and 25°C, while maximum boron removal of73.2% was obtained at pH 9.2, S/L 60 g L−1, and 22°C. Under optimized simultaneous conditions (pH 10,S/L 52.8 g L−1, 15 °C), removal efficiencies reached 97.5% for hardness and 71.1% for boron. Analysis ofvariance (ANOVA) confirmed the statistical significance of the quadratic models (R2 = 85.26% forhardness; R2 = 98.57% for boron). The S/L was the most influential factor for hardness removal, whereasboron removal was significantly influenced by pH, solid/liquid ratio, and temperature.