Combined magnetic ion exchange and cation exchange for removal of DOC and hardness

Sarah E.H. Comstock, Treavor H. Boyer

Research output: Contribution to journalArticle

38 Scopus citations

Abstract

The overall goal of this research was to evaluate an innovative combined ion-exchange process for multi-contaminant treatment. Magnetically enhanced anion exchange resin and conventional cation exchange resin were used in a single completely mixed vessel for simultaneous removal of dissolved organic carbon (DOC) and hardness. Following treatment, exhausted anion exchange resin and cation exchange resin were regenerated together in a single completely mixed vessel using sodium chloride (NaCl). The performance of the combined ion-exchange process was evaluated using three groundwaters and two nanofiltration (NF) membrane concentrates. The test waters provided a wide range of water quality in terms of DOC (2.9-56mg/L), total hardness (300-1000mg/L as CaCO3), and sulfate (10-830mg/L). Combined ion-exchange treatment of groundwater achieved 76% DOC removal and 97% total hardness removal using a 20% (m/v) NaCl regeneration solution. Combined ion-exchange also achieved high removals of DOC (e.g., 83%) and total hardness (e.g., 86%) from NF concentrate using a 30% (m/v) NaCl regeneration solution. These results provide water treatment engineers with a new application of ion-exchange that can be used in place coagulation and precipitative softening or as an intermediate treatment step between primary and secondary NF or reverse osmosis membranes.

Original languageEnglish (US)
Pages (from-to)366-375
Number of pages10
JournalChemical Engineering Journal
Volume241
DOIs
StatePublished - Apr 1 2014
Externally publishedYes

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Keywords

  • Calcium
  • Ion exchange
  • MIEX
  • Membrane concentrate
  • Nanofiltration
  • Softening

ASJC Scopus subject areas

  • Chemistry(all)
  • Environmental Chemistry
  • Chemical Engineering(all)
  • Industrial and Manufacturing Engineering

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