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Electrodialysis reversal (EDR) is an electrodialysis reversal water desalination membrane process that has been commercially used since the early 1960s.[1] An electric current migrates dissolved salt ions, including fluorides, nitrates and sulfates, through an electrodialysis stack consisting of alternating layers of cationic and anionic ion exchange membranes. Periodically (3-4 times per hour), the direction of ion flow is reversed by reversing the polarity of the applied electric current.[2][1]
Current reversal reduces clogging of membranes, as salt deposits in the membrane gets dissolved when the current flow is reversed. Electrodialysis reversal causes a small decrease in the diluted feed quality and requires increased complexity infrastructures, as reversible valves are required to change the flow direction of diluted and concentrated streams. However, it greatly increases ion exchange membranes durability, and membrane cleaning prevents electrical resistance increase of membrane as deposits accumulate in the membrane pores.[3]
The polarity reversal of EDR alternately exposed membrane surfaces and the water flow paths to concentrate with a tendency to precipitate scale and desalted water that tends to dissolve scale. This allows the process to operate with supersaturated concentrate streams up to specific limits without chemical additions to prevent scale formation.[4]
See also
editReferences
edit- ^ a b Katz, William E. (January 1979). "The electrodialysis reversal (EDR) process". Desalination. 28 (1): 31–40. Bibcode:1979Desal..28...31K. doi:10.1016/S0011-9164(00)88124-2.
- ^ Panagopoulos, Argyris; Haralambous, Katherine-Joanne; Loizidou, Maria (2019-11-25). "Desalination brine disposal methods and treatment technologies - A review". Science of the Total Environment. 693: 133545. Bibcode:2019ScTEn.69333545P. doi:10.1016/j.scitotenv.2019.07.351. ISSN 0048-9697. PMID 31374511. S2CID 199387639.
- ^ Benvenuti, Tatiane; Giacobbo, Alexandre; Scarazzato, Tatiana; de Moraes da Trindade, Carolina; Santana Barros, Kayo (2022). Chapter 14 - Electrodialysis, electrodialysis reversal and capacitive deionization technologies, Advancement in Polymer-Based Membranes for Water Remediation. Elsevier. pp. 505–539. doi:10.1016/B978-0-323-88514-0.00014-0. ISBN 9780323885140.
- ^ Tanaka, Yoshinobu (2007). Chapter 2 Electrodialysis Reversal, Membrane Science and Technology. Elsevier. pp. 383–404. ISBN 9780444519825.
External links
edit- Article: Water issues prompt new look at desalination Archived 2010-03-08 at the Wayback Machine