摘要：Abstract This study used crystallization in a fluidized-bed reactor as an alternative technology to the conventional chemical precipitation to remove sulfate. The Box-Behnken Design was used to study the effects and interactions of seed dosage of synthetic gypsum, initial sulfate concentration and molar ratio of calcium to sulfate on conversion and removal of sulfate. The optimum conditions of conversion and removal of sulfate were determined and used to treat the simulated acid mine drainage (AMD) wastewater. The effect of inorganic ions CO 3 2 − , NH 4 + and Al3+ on sulfate conversion was also investigated. Experimental results indicated that seed dosage, initial sulfate concentration and molar ratio of calcium to sulfate are all significant parameters in the sulfate removal by fluidized-bed crystallization. The optimal conditions of 4 g seed L−1, 119.7 mM of initial sulfate concentration and [ Ca 2 + ] / [ SO 4 2 − ] molar ratio of 1.48 resulted in sulfate conversion of 82% and sulfate removal of 67%. Conversion and removal of sulfate in the simulated AMD wastewater were 79 and 63%, respectively. When ammonium or aluminum was added to the synthetic sulfate wastewater, significant conversion of sulfate was achieved. Highlights • Use of fluidized-bed reactor as alternative technology for sulfate removal. • Determined parameter effect on conversion and sulfate removal by Box-Behnken Design. • Optimal conditions for sulfate removal: 4 g seed L−1, 119.7 mM sulfate concentration. • The XRD results showed that materials from FBC were gypsum. • Conversion and removal of sulfate were 79% and 63%, respectively.
