Immobilization of arsenic as scorodite by a thermoacidophilic mixed culture via As(III)-catalyzed oxidation with activated carbon

Silvia Vega-Hernandez, Jan Weijma*, Cees J.N. Buisman

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

8 Citations (Scopus)

Abstract

In this study we describe the immobilization of arsenic as scorodite (FeAsO4.2H2O) by a thermophilic iron-oxidizing mixed culture from an acidic sulfate medium containing 500 mg L-1 of Fe(II), 500 mg L-1 As(III) and granular activated carbon (GAC) as the main arsenite oxidant. This study shows that crystalline scorodite can only be precipitated in the presence of the ferrous iron-oxidizing mixed culture (pH 1.3 and 70 °C). The efficiency of arsenite oxidation was over 99% with a maximum specific oxidation rate of 280 mgAs(III) gGAC-1 day-1. Ferrous iron and arsenite were also oxidized in the absence of the mixed culture, however, no scorodite precipitated under these conditions; consequently, scorodite precipitation was biologically induced. The precipitated scorodite particles had a size between 0.5 and 10 μm with an average of 5 μm, resulting in low settling rates. Ion activity product calculations and observations by Scanning Electron Microscopy (SEM) indicated that microbial cells served as surface for heterogeneous nucleation. The potential of the thermophilic mixed culture for the scorodite formation explored in this study provides the basis of a new approach for the treatment of As(III) polluted streams.

Original languageEnglish
Pages (from-to)221-227
JournalJournal of Hazardous Materials
Volume368
DOIs
Publication statusPublished - 15 Apr 2019

Keywords

  • arsenic removal
  • arsenite oxidation
  • biogenic scorodite
  • ferrous iron oxidation
  • granular activated carbon
  • thermoacidophilic mixed culture

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