Bipolar membrane electrodialysis for mixed salt water treatment: Evaluation of parameters on process performance

In the present study, bipolar membrane electrodialysis (BMED) process was employed as an alternative separation method to the distillation unit in the Solvay process for the synthetic soda ash production. The applicability of BMED was investigated by evaluating the effects of system parameters on process performance. Desalination ratio, salt based acid and base conversion ratio, flux, product purity, and energy consumption were defined as the process performance criteria for the BMED systems. Initial salt concentration, applied current and voltage, and initial acid and base concentrations were chosen as system parameters. The results of the study revealed that current/voltage and initial salt concentration are the most effective factors affecting all performance criteria. When all system parameters were considered, BMED provides the desalination ratio in between 90% and 98%, the acid and base conversion ratio of salt in between 60% and 80%, and the energy consumption in the range of 1.54-2.33 kWh/kg acid. Furthermore, the desalinated water can be reused as process water and the distillation unit waste problem can be resolved by the utilization of BMED system.