Elsevier

Water Research

Volume 224, 1 October 2022, 119110
Water Research

Bioregeneration of sulfate-laden anion exchange resin

https://doi.org/10.1016/j.watres.2022.119110Get rights and content
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open access

Highlights

  • Sulfate-reducing bacteria used for bioregeneration of commercial anion exchange resin.

  • Successful bioregeneration with both pure and mixed SRB cultures.

  • In batch mode, bioregeneration efficiency increased with contact time.

  • In column mode, almost complete bioregeneration of resin capacity.

Abstract

Ion exchange technology removes ionic compounds from waters effectively but treatment of the spent regenerant is expensive. The bioregeneration of sulfate-laden strong base anion exchange resin was successfully tested using both pure and mixed sulfate-reducing bacterial cultures. The resin was first used for removal of sulfate from neutral (pH 6.7 ± 0.5) synthetic sodium sulfate solutions, after which the spent resin was regenerated by incubating with a viable sulfate-reducing bacterial culture in batch and column modes. In the batch bioregeneration tests, the achieved bioregeneration was 36–95% of the original capacity of the fresh resin (112 mg SO42−/g) and it increased with regeneration time (1–14 days). The capacity achieved in the column tests during 24 hours of bioregeneration was 107 mg SO42−/g after the first regeneration cycle. During the bioregeneration, sulfate was mainly reduced by the sulfate-reducing bacteria (approx. 60%), but part of it was only detached from the resins (approx. 30%). The resin-attached sulfate was most likely replaced with ions present in the liquid sulfate-reducing bacterial culture (e.g., HCO3, HS, and Cl). During the subsequent exhaustion cycles with the bioregenerated resin, the pH of the treated sodium sulfate solution increased from the original 6.7 ± 0.5 to around 9. The study showed that biological sulfate reduction could be used for sulfate removal in combination with ion exchange, and that the exhausted ion exchange resins could be regenerated using a liquid sulfate-reducing bacterial culture without producing any brine.

Keywords

Bioregeneration
Bioremediation
Ion exchange column
Sulfate-reducing bacteria
Sulfate removal

Data Availability

  • Data will be made available on request.

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