A speculative hybrid reverse osmosis/electrodialysis unit operation

Hybrid Reverse Osmosis‐Capacitive Deionization versus Two‐Stage Reverse Osmosis: A Comparative Analysis

“…An overview of the hybrid desalination processes of RO combined with multistage flash, multiple‐effect distillation, vapor compression, or nanofiltration (NF) is presented in 15, 16. The hybrid electrodialysis‐RO system has been studied by many researchers 17–19. Li et al 18 have presented a hybrid reverse electrodialysis‐RO system to substantially reduce the SEC and provide better brine management.…”

Electrodialysis‐based separation technologies: A critical review

“…These integrated processes are mainly classified as follows: The integration of ED with chemical unit operations, such as ion exchange, adsorption, electrolysis, extraction, complexation, stripping, absorption, and distillation, which are widely used in chemical separation and environmental protection 4, 13, 23–27 The integration of ED with pressure‐driven membrane processes, such as microfiltration, ultrafiltration, nanofiltration, and reverse osmosis, which are often used in water treatment, feed pretreatment, fractionation of biochemical species, and concentration and desalination of sea water 28–38 The integration of ED with biochemical unit operations, such as fermentation, and membrane biological reactors, which are widely used in separation of biochemicals, production of organic acids from fermentation broth, and treatment of waste water 4, 39, 40…”

“…The integration of ED with pressure‐driven membrane processes, such as microfiltration, ultrafiltration, nanofiltration, and reverse osmosis, which are often used in water treatment, feed pretreatment, fractionation of biochemical species, and concentration and desalination of sea water 28–38…”

“…A more interesting example is water desalination using RO‐CED integration, which was recently proposed by Pellegrino et al38 As shown in Figure 13a, the RO membranes are hollow‐fibers or tubes and form channels between alternating anion‐ and cation‐exchange membranes. The packing density of fibers or tubes may be similar to that for CED spacers or other turbulence promoters.…”

“…As compared to CED followed by RO, this integration has lower energy consumption in regard to CED because all the channels are filled with higher concentration of salts and thus the entire stack has lower electrical resistance. The energy savings range from 10 to 20%; however, the conductivity of ion‐exchange membranes is the limiting factor on energy savings 38…”