Combined UV treatment and ozonation for the removal of by-product precursors in swimming pool water

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Abstract

Both UV treatment and ozonation are used to reduce different types of disinfection by-products (DBPs) in swimming pools. UV treatment is the most common approach, as it is particularly efficient at removing combined chlorine. However, the UV treatment of pool water increases chlorine reactivity and the formation of chloro-organic DBPs such as trihalomethanes. Based on the similar selective reactivity of ozone and chlorine, we hypothesised that the created reactivity to chlorine, as a result of the UV treatment of dissolved organic matter in swimming pool water, might also be expressed as increased reactivity to ozone. Moreover, ozonation might saturate the chlorine reactivity created by UV treatment and mitigate increased formation of a range of volatile DBPs. We found that UV treatment makes pool water highly reactive to ozone. The subsequent reactivity to chlorine decreases with increasing ozone dosage prior to contact with chlorine. Furthermore, ozone had a half-life of 5 min in non-UV treated pool water whereas complete consumption of ozone was obtained in less than 2 min in UV treated pool water. The ozonation of UV-treated pool water induced the formation of some DBPs that are not commonly reported in this medium, in particular trichloronitromethane, which is noteworthy for its genotoxicity, though this issue was removed by UV treatment when repeated combined UV/ozone treatment interchanging with chlorination was conducted over a 24-h period. The discovered reaction could form the basis for a new treatment method for swimming pools.
Original languageEnglish
JournalWater Research
Volume110
Pages (from-to)141-149
ISSN0043-1354
DOIs
Publication statusPublished - 2017

Keywords

  • Ozone
  • UV
  • Swimming pool
  • Trihalomethane
  • Disinfection by-products

Activities

  • 3 Conference presentations
  • 1 Participating in or organising a conference

7th International Conference

Kamilla Marie Speht Kaarsholm (Participant) & Henrik Rasmus Andersen (Chairman)

2 May 20175 May 2017

Activity: Attending an eventParticipating in or organising a conference

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Destruction of DBPs and their precursors in swimming pool water by combined UV-treatment and ozonation

Waqas Akram Cheema (Speaker)

2 May 20175 May 2017

Activity: Talks and presentationsConference presentations

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2016 IUVA World Congress

Waqas Akram Cheema (Speaker)

31 Jan 20163 Feb 2016

Activity: Talks and presentationsConference presentations

Prizes

Best Presentation Award at 7th International Conference Swimming Pool & Spa

Waqas Akram Cheema (Recipient), 5 May 2017

Prize: Prizes, scholarships, distinctions

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