Integrated Valorization of Desalination Brine through NaOH Recovery: Opportunities and Challenges

Abstract

The rising use of seawater desalination for fresh water production is driving a parallel rise in the discharge of high‐salinity brine into the ocean. Better utilization of this brine would have a positive impact on the energy use, cost, and environmental footprint of desalination. Furthermore, intermittent renewable energy can easily power the brine utilization and, for reverse osmosis technology, the entire desalination plant. One pathway toward these goals is to convert the otherwise discharged brine into useful chemicals; waste could be transformed into sodium hydroxide or caustic soda (NaOH) and hydrochloric acid (HCl). In this Minireview, we discuss opportunities and challenges for integrated valorization of desalination brine through NaOH and HCl recovery.

Asymmetric bipolar membrane electrodialysis for acid and base production

“…Despite the economic and environmental benefits of the BMED process, the industrial implementation of BMED technology is currently far behind the other pressure-driven membrane processes or the conventional electrodialysis. 12,37,38 To our knowledge, the sluggish development of the BMED is attributed to the large consumption of the expensive bipolar membranes and the unmatching behavior between water splitting and ion migration. 39 On one hand, the BMED is usually assembled in a plate-and-frame membrane module that the effective area of each piece of bipolar membrane is identical to that of the monopolar membrane.…”

Decreasing Seawater Desalination Footprint by Integrating Bipolar-Membrane Electrodialysis in a Single-Pass Reverse Osmosis Scheme

“…It stems from these studies ,− that BMED is a potentially eco-friendly, cost-effective method for SWRO brine management, yet techno-economical barriers and the lack of sufficient knowledge still limit the application of BMED on an industrial scale . Indeed, very few studies ,,, have included an economic evaluation related to the production of an acid and base from SWRO brine by BMED. Thiel et al emphasized that using real SW concentrated streams (pretreated by NF or other methods) is critical for determining the techno-economic feasibility of BMED.…”

In-Situ Combination of Bipolar Membrane Electrodialysis with Monovalent Selective Anion-Exchange Membrane for the Valorization of Mixed Salts into Relatively High-Purity Monoprotic and Diprotic Acids

“…BMED is an advanced electro-membrane process that combines the water splitting in the bipolar membrane and directional migration of ionic components in the conventional electrodialysis process [11,12]. The saline wastewater inputted to the BMED system can be effectively converted to acids and bases, achieving a closed loop industrial production.…”