Optimization of bioscorodite crystallization for treatment of as(III)-bearing wastewaters

Masahito Tanaka, Tsuyoshi Hirajima, Keiko Sasaki, Naoko Okibe

Research output: Chapter in Book/Report/Conference proceedingConference contribution

3 Citations (Scopus)


Arsenic (As) is a major impurity contaminating metal refinery wastewaters. To immobilize As ions, we have previously reported microbial scorodite (FeAsO4·2H2O) crystallization using the thermo-acidophilic iron-oxidizing archaeon, Acidianus brierleyi. In order to extend the applicable range of As(III)-bearing metal refinery wastewaters (especially for dilute As(III) concentrations of 250–1500 ppm), this study investigated the effect of several factors possibly affecting the bioscorodite crystallization efficiency; (i) [Fe(II)]ini/[As(III)]ini molar ratio at different target As(III) concentrations, (ii) initial pH, and (iii) seed scorodite with different morphologies. The [Fe(II)]ini/[As(III)]ini molar ratio strongly affected the bioscorodite crystallization efficiency at each target As(III) concentration. Whilst the [Fe(II)]ini/[As(III)]ini molar ratio of 1.4 was most effective at 500–1500 ppm As(III), the optimal molar ratios for treating more dilute concentrations (< 500 ppm) were shown to be relatively higher. However, further increasing the [Fe(II)]ini/[As(III)]ini molar ratio resulted in formation of unwanted potassium jarosite (KFe3(OH)6(SO4)2) together with scorodite. Lowering the initial pH from 1.5 to 1.2 resulted in earlier scorodite nucleation, but lower overall As immobilization. Feeding chemical- and bio-scorodite seed crystals differently affected the reaction speed and the stability of newly-precipitated bioscorodite. The TCLP test indicated that scorodite formed on bioscorodite seeds is more stable than that formed on chemically-synthesized scorodite seeds.

Original languageEnglish
Title of host publication22nd International Biohydrometallurgy Symposium
EditorsSabrina Hedrich, Axel Schippers, Kathrin Rubberdt, Franz Glombitza, Wolfgang Sand, Wolfgang Sand, Mario Vera Veliz, Sabine Willscher
PublisherTrans Tech Publications Ltd
Number of pages4
ISBN (Print)9783035711806
Publication statusPublished - 2017
Event22nd International Biohydrometallurgy Symposium, 2017 - Freiberg, Germany
Duration: Sept 24 2017Sept 27 2017

Publication series

NameSolid State Phenomena
Volume262 SSP
ISSN (Print)1012-0394
ISSN (Electronic)1662-9779


Other22nd International Biohydrometallurgy Symposium, 2017

All Science Journal Classification (ASJC) codes

  • Atomic and Molecular Physics, and Optics
  • General Materials Science
  • Condensed Matter Physics


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