Abstract
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 language | English |
|---|---|
| Title of host publication | 22nd International Biohydrometallurgy Symposium |
| Publisher | Trans Tech Publications Ltd |
| Pages | 555-558 |
| Number of pages | 4 |
| ISBN (Print) | 9783035711806 |
| DOIs | |
| Publication status | Published - Jan 1 2017 |
| Event | 22nd International Biohydrometallurgy Symposium, 2017 - Freiberg, Germany Duration: Sep 24 2017 → Sep 27 2017 |
Publication series
| Name | Solid State Phenomena |
|---|---|
| Volume | 262 SSP |
| ISSN (Electronic) | 1662-9779 |
Other
| Other | 22nd International Biohydrometallurgy Symposium, 2017 |
|---|---|
| Country | Germany |
| City | Freiberg |
| Period | 9/24/17 → 9/27/17 |
Fingerprint
All Science Journal Classification (ASJC) codes
- Atomic and Molecular Physics, and Optics
- Materials Science(all)
- Condensed Matter Physics
Cite this
Optimization of bioscorodite crystallization for treatment of as(III)-bearing wastewaters. / Tanaka, Masahito; Hirajima, Tsuyoshi; Sasaki, Keiko; Okibe, Naoko.
22nd International Biohydrometallurgy Symposium. Trans Tech Publications Ltd, 2017. p. 555-558 (Solid State Phenomena; Vol. 262 SSP).Research output: Chapter in Book/Report/Conference proceeding › Conference contribution
}
TY - GEN
T1 - Optimization of bioscorodite crystallization for treatment of as(III)-bearing wastewaters
AU - Tanaka, Masahito
AU - Hirajima, Tsuyoshi
AU - Sasaki, Keiko
AU - Okibe, Naoko
PY - 2017/1/1
Y1 - 2017/1/1
N2 - 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.
AB - 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.
UR - http://www.scopus.com/inward/record.url?scp=85029007011&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85029007011&partnerID=8YFLogxK
U2 - 10.4028/www.scientific.net/SSP.262.555
DO - 10.4028/www.scientific.net/SSP.262.555
M3 - Conference contribution
AN - SCOPUS:85029007011
SN - 9783035711806
T3 - Solid State Phenomena
SP - 555
EP - 558
BT - 22nd International Biohydrometallurgy Symposium
PB - Trans Tech Publications Ltd
ER -