Application of a 2-step process for the biological treatment of sulfidic spent caustics

C.M. de Graaff, J.B.M. Klok, M.F.M. Bijmans, G. Muyzer, A.J.H. Janssen

Research output: Contribution to journalArticleAcademicpeer-review

63 Citations (Scopus)

Abstract

This research demonstrates the feasibility and advantages of a 2-step process for the biological treatment of sulfidic spent caustics under halo-alkaline conditions (i.e. pH 9.5; Na+ = 0.8 M). Experiments with synthetically prepared solutions were performed in a continuously fed system consisting of two gas-lift reactors in series operated at aerobic conditions at 35 °C. The detoxification of sulfide to thiosulfate in the first step allowed the successful biological treatment of total-S loading rates up to 33 mmol L-1 day-1. In the second, biological step, the remaining sulfide and thiosulfate was completely converted to sulfate by haloalkaliphilic sulfide oxidizing bacteria. Mathematical modeling of the 2-step process shows that under the prevailing conditions an optimal reactor configuration consists of 40% ‘abiotic’ and 60% ‘biological’ volume, whilst the total reactor volume is 22% smaller than for the 1-step process.
Original languageEnglish
Pages (from-to)723-730
JournalWater Research
Volume46
Issue number3
DOIs
Publication statusPublished - 2012

Keywords

  • sulfur-oxidizing bacteria
  • oxidation processes
  • alkaline conditions
  • hydrogen-sulfide
  • soda lakes
  • kinetics

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