Dynamics of Bacterial Communities Mediating the Treatment of an As-Rich Acid Mine Drainage in a Field Pilot.

Passive treatment based on iron biological oxidation is a promising strategy for Arsenic (As)-rich acid mine drainage (AMD) remediation. In the present study, we characterized by 16S rRNA metabarcoding the bacterial diversity in a field-pilot bioreactor treating extremely As-rich AMD , over a 6 months monitoring period. Inside the bioreactor, the bacterial communities responsible for iron and arsenic removal formed a biofilm ("biogenic precipitate") whose composition varied in time and space.

A field-pilot for passive bioremediation of As-rich acid mine drainage.

A field-pilot bioreactor exploiting microbial iron (Fe) oxidation and subsequent arsenic (As) and Fe co-precipitation was monitored during 6 months for the passive treatment of As-rich acid mine drainage (AMD). It was implemented at the Carnoulès mining site (southern France) where AMD contained 790-1315 mg L Fe(II) and 84-152 mg L As, mainly as As(III) (78-83%). The bioreactor consisted in five shallow trays of 1.

Hydraulic retention time affects bacterial community structure in an As-rich acid mine drainage (AMD) biotreatment process.

Arsenic removal consecutive to biological iron oxidation and precipitation is an effective process for treating As-rich acid mine drainage (AMD). We studied the effect of hydraulic retention time (HRT)-from 74 to 456 min-in a bench-scale bioreactor exploiting such process. The treatment efficiency was monitored during 19 days, and the final mineralogy and bacterial communities of the biogenic precipitates were characterized by X-ray absorption spectroscopy and high-throughput 16S rRNA gene sequencing.

Temperature and nutrients as drivers of microbially mediated arsenic oxidation and removal from acid mine drainage.

Microbial oxidation of iron (Fe) and arsenic (As) followed by their co-precipitation leads to the natural attenuation of these elements in As-rich acid mine drainage (AMD). The parameters driving the activity and diversity of bacterial communities responsible for this mitigation remain poorly understood. We conducted batch experiments to investigate the effect of temperature (20 vs 35 °C) and nutrient supply on the rate of Fe and As oxidation and precipitation, the bacterial diversity (high-throughput sequencing of 16S rRNA gene), and the As oxidation potential (quantification of aioA gene) in AMD from the Carnoulès mine (France).

Biological attenuation of arsenic and iron in a continuous flow bioreactor treating acid mine drainage (AMD).

Passive water treatments based on biological attenuation can be effective for arsenic-rich acid mine drainage (AMD). However, the key factors driving the biological processes involved in this attenuation are not well-known. Here, the efficiency of arsenic (As) removal was investigated in a bench-scale continuous flow channel bioreactor treating As-rich AMD (∼30-40 mg L).