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Updated: May 18, 2026

Removal of Arsenic Using a Cationic Polymer Gel Impregnated with Iron Hydroxide
Published on: June 28, 2019
Continuous bioscorodite crystallization in CSTRs for arsenic removal and disposal
Paula González-Contreras1, Jan Weijma, Cees J N Buisman
1Sub Department of Environmental Technology, Wageningen University, Bornse Weilanden 9, P.O. Box 17, 6708 WG Wageningen, The Netherlands. paulaa.gonzalezcontreras@wur.nl
This study demonstrates a robust continuous process for arsenic removal using biologically oxidized ferrous iron to crystallize scorodite. The method achieves over 99% arsenic removal, yielding stable bioscorodite sludge with low leaching rates for safe disposal.
Area of Science:
- Environmental Engineering
- Biotechnology
- Materials Science
Background:
- Arsenic contamination poses significant environmental and health risks.
- Effective arsenic removal and stable disposal methods are crucial for remediation.
- Biological oxidation and scorodite crystallization offer a promising approach.
Purpose of the Study:
- To evaluate a continuous process for arsenic removal via biological oxidation and scorodite crystallization in CSTRs.
- To assess the efficiency, stability, and characteristics of bioscorodite formation.
- To determine the arsenic leaching potential from the resulting sludge.
Main Methods:
- Utilized continuous stirred-tank reactors (CSTRs) with biological oxidation of ferrous iron and scorodite crystallization.
- Operated at controlled conditions: pH 1.2, 72°C, HRT of 40 h, and specific feed concentrations of arsenate and ferrous iron.
- Analyzed effluent arsenic concentrations, solid yield, precipitate morphology (SE microscopy, XRD), and arsenic leaching (TCLP).
Main Results:
- Achieved >99% arsenic removal efficiency at Fe/As molar ratios of 1-2, with effluents at 29 ± 18 mg As/L.
- Demonstrated stable operation for up to 200 days without seed addition or recirculation.
- Produced bioscorodite with a solid yield of 3.2 g/g arsenic removed and low arsenic leaching (0.4 mg/L after 100 days).
Conclusions:
- The continuous CSTR process is robust and highly efficient for arsenic removal.
- Bioscorodite sludge exhibits low arsenic leaching, making it suitable for safe disposal.
- This biotechnological approach offers a viable solution for arsenic remediation.
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