Electro dialytic recovery of bittern wastewater generated from salt industry

Bittern in the salt industry generates considerable wastewater. This wastewater contains dissolved materials such as chloride, sulfate, calcium, magnesium, sodium, and potassium ions and other minor compounds. Electrodialysisis one of the effective recovery technologies for desalination and fractionation processes. The number of compartments and the applied voltage may affect the efficiency of salt removal and recovery. Therefore, this study aims to evaluate the electrodialysis performance of bittern wastewater to recover the salt compounds. A laboratory scale of three- and five-compartment electrodialysis cell separated by anion and cation exchange membrane was used. Carbon graphite and stainless steel was used as the anode and the cathode, respectively. The electrodialysis was performed by applying 3, 5, 7, and 9 V for 5-hour operating time. The highest removal efficiency was 94.72%, 61.10%, 85.33%, 86.74%, 74.42% and 90.87%, achieved at 9V and five-compartments, for Cl-, SO42-, Ca2+, Mg2+, Na+, and K+, respectively. Interestingly, the efficiency of those ionic product recovery was 14.90%, 14.19%, 21.48%, 0.72%, 15.39% and 10.58% for Cl-, SO42-, Ca2+, Mg2+, Na+, and K+, respectively. This implies that the ionic compounds were also converted into chlorine gas in the case of chloride oxidation and precipitates identified as aragonite, halite and brucite.