Feasibility study of reverse osmosis–flow capacitive deionization (RO-FCDI) for energy-efficient desalination using seawater as the flow-electrode aqueous electrolyte

Hyun Jun Chung, Jungbin Kim, David Inhyuk Kim, Gimun Gwak, Seungkwan Hong

Research output: Contribution to journalArticle

3 Citations (Scopus)

Abstract

Seawater reverse osmosis (SWRO) is usually combined with brackish reverse osmosis (BWRO) to improve the water quality in seawater desalination; however, this configuration often results in high energy consumption. Consequently, membrane capacitive deionization (MCDI) has been suggested as a lower energy alternative technology, but cyclic operation within the cell (i.e., discontinuous operation of ad/desorption) is a main disadvantage. On the other hand, flow electrode capacitive deionization (FCDI) can be continuously operated by using a flow electrode. In this study, the feasibility of a SWRO-FCDI system was examined by using a suitable electrolyte in the flow electrode: seawater or SWRO concentrate. In addition, by employing a selective ion exchange membrane (IEM), the FCDI was able to selectively remove monovalent ions rather than divalent ions, unlike BWRO, thus producing a final product water containing divalent ions, which is more suitable for corrosion control in the subsequent pipe distribution systems. As a result, the remineralization process can be minimized. To test the SWRO-FCDI concept, actual SWRO permeate was first treated in a single mode with an electrolyte comprising real seawater in a flow electrode, and the feasibility of long-term operation was proven by batch-mode, which allowed the optimization of the FCDI active area.

Original languageEnglish
Article number114326
JournalDesalination
Volume479
DOIs
Publication statusPublished - 2020 Apr 1

Keywords

  • Flow electrode capacitive deionization (FCDI)
  • Flow electrodes
  • Perm-selective ion exchange membrane (IEM)
  • Seawater reverse osmosis (SWRO) desalination
  • Specific energy consumption (SEC)

ASJC Scopus subject areas

  • Chemistry(all)
  • Chemical Engineering(all)
  • Materials Science(all)
  • Water Science and Technology
  • Mechanical Engineering

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