Wet air oxidation (WAO) as a precursor to biological treatment of substituted phenols: Refractory nature of the WAO intermediates

M. Eugenia Suárez-Ojeda, Julián Carrera, Ian S. Metcalfe, Josep Font

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26 Citations (Scopus)

Abstract

Wet air oxidation (WAO) was investigated as a suitable precursor for the biological treatment of industrial wastewaters that contained high concentrations of phenol, o-cresol or 2-chlorophenol. Two hours WAO semi-batch experiments were conducted at 2 and 9 bar of oxygen partial pressure (PO2) and at 215, 240 and 265 °C with total organic carbon (TOC) abatement up to 86%. The influence of hydroxyl-, methyl- and chloride ring substitution on the oxidation mechanism of aromatic compounds was established. Also, the readily biodegradable COD fraction (%CODRB) of the WAO effluents was found by respirometric techniques. The maximum %CODRB was 24% for phenol WAO at 265 °C and 9 bar of PO2, 10% for o-cresol WAO at 265 °C and 9 bar of PO2 and 19% for 2-chlorophenol WAO at 215 °C and 2 bar of PO2. These results allow comparison of whether or not the WAO effluents were suitable for a conventional activated sludge plant with non-acclimated biomass. Also, the results were compared to those obtained from a previous study for the same model compounds but using catalytic WAO (CWAO) with activated carbon (AC) as a catalyst [1]. This comparison allows us to establish whether or not the WAO effluents were less biodegradable or had more refractory intermediates than CWAO effluents. © 2008 Elsevier B.V. All rights reserved.
Original languageEnglish
Pages (from-to)205-212
JournalChemical Engineering Journal
Volume144
Issue number2
DOIs
Publication statusPublished - 15 Oct 2008

Keywords

  • Biodegradability
  • Substituted phenols
  • Wet air oxidation

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