Resource recovery and utilization of bittern wastewater from salt production: a review of recovery technologies and their potential applications

Abstract

ABSTRACT In addition to high-purity salts, salt farms and industries generate a substantial amount of highly concentrated brine (bittern) byproducts. The presence of high salinity in this waste stream may lead to adverse environmental impacts. Environmental concerns and strict regulations on its disposal have driven the development of innovative practices for bittern management to achieve sustainable resource use and recovery. Meanwhile, commercial materials (Li, Rb, and Cs) that may be contained in the bittern can be seen as attractive value-added resources. This review article comparatively discusses the available technologies for bittern recovery, their advantages and disadvantages in terms of their technical aspects, their estimated energy and/or technological costs, the recovery efficiency of the targeted products, and the possibility of the utilization of bittern to aim for both minimal and zero liquid discharge targets. Of the bittern recovery technologies evaluated, electrodialysis offers efficient and highly selective separation of ionic compounds, while evaporation and precipitation are the most efficient methods of obtaining solid salt products (MgCl2, NaCl, KCl, etc.). In a minimal liquid discharge system, electrodialysis can be coupled with a thermal process or precipitation to achieve a less concentrated bittern effluent for safe disposal. However, in a zero liquid discharge process, more complex recovery technologies are applied, before the utilization of liquid bittern as a CO2 absorbent, cooling agent, or coagulant. Finally, we highlight areas of future research regarding technological developments that aim to enhance the effectiveness at larger scales and to improve the sustainability of bittern recovery and utilization.