Download arsenic removal by controlled biological iron oxidation reactions

ARSENIC REMOVAL BY CONTROL OF BIOLOGICAL IRON OXIDATION REACTIONS
*Paula Gonzalez Contreras1, Henk Dijkman1, Silvia Vega2, Irene Sánchez-Andrea3, Jan Weijma2, Cees
Buisman2
1
PAQUES B.V.
T de Boerstraat 2
Balk, The Netherlands
(*corresponding author: [email protected])
2
Sub Department of Environmental Technology
3
Laboratory of Microbiology
Wageningen University
The Netherlands
ABSTRACT
More than 20 years ago, Paques B.V. introduced innovative biotechnologies to recover metals and to remove
sulfate from aqueous streams. These technologies find their origin in the exploration of microorganisms involved
in the global sulfur cycle. Currently, several sulfur cycle biotechnologies are applied successfully at full-scale.
The sulfur cycle is closely linked with the iron cycle, and also the latter offers opportunities for application of
innovative biotechnology for the mining industry. Microorganisms of the natural iron cycle carry out reactions
that are not feasible by chemical methods such as ferrous iron oxidation with oxygen at pH below 4. Iron
oxidation with oxygen can be conducted using microorganisms living at pH between 0.5 and 7 and at
temperatures between 0 and 95ºC. Remarkably these microorganisms can also carry out arsenite oxidation at
similar acidic conditions and high temperatures. Making use of the extreme features of these microorganisms,
Paques and Wageningen University have developed a biological process to precipitate arsenic as scorodite,
which is regarded by metallurgists as the safest medium for long-term arsenic storage. This biological formation
of scorodite is a novel combination of biological oxidation and biocrystallization. Depending on the level of
saturation, biological oxidation rates and operational conditions, we could control the formation of the iron
precipitates such as jarosite and scorodite. Currently new microorganisms have been harvested from hot springs
and rock acid mine drainage to foster the growth of specialized microbial communities with potential high iron
and arsenic oxidation capacities and higher resistance to other metals. In our paper we address the ongoing
research and development of the bioscorodite process.
KEYWORDS
Biological oxidation, iron biological conversions, arsenic precipitation, jarosite, scorodite