Evaluating ozone dose for AOC removal in two-step GAC filters

R. Vahala, T. Ala-Peijari, J. Rintala, R. Laukkanen

Research output: Contribution to journalArticleScientificpeer-review

9 Citations (Scopus)


Upgrading an existing post-ozonation plant with two-step granular activated carbon (GAG) filtration for assimilable organic carbon (AOC) removal was studied. The effects of ozone dose on AOC formation and its removal in the subsequent two-step GAC filtration was studied using chemically pretreated 2 to 14°C humic lake water. Two parallel pilot-plant trains with different ozone doses (0 to 1.2 mgO3/mgTOC) and a short-term ozonation study were performed. The optimum ozone dose for maximum AOC formation was 0.4 - 0.5 mgO3/mgTOC. The AOC-P17 of ozonated water was three-fold higher and AOC-NOX over ten-fold higher than in non-ozonated water, while the following biofiltration (first step) removed 51% and 72% of AOC-P17 and AOC-NOX, respectively. The adsorber (second step) contributed to less than 10% of the overall AOC reduction. It appeared that biofiltration is a feasible method in upgrading water treatment plants for AOC removal even when treating cold humic waters, while the subsequent adsorber seems to have less significance for AOC removal.

Original languageEnglish
Pages (from-to)113-120
Number of pages8
JournalWater Science and Technology
Issue number9
Publication statusPublished - 1998
Externally publishedYes
Publication typeA1 Journal article-refereed


  • Adsorption
  • Assimilable organic carbon
  • Biological drinking-water treatment
  • Granular activated carbon
  • Natural organic matter
  • Ozonation
  • Two-step filtration

ASJC Scopus subject areas

  • Water Science and Technology


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