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

WATER RESEARCH

卷:123

Article

Fernandez-Rojo, L.¹  Hery, M.¹  Le Pape, P.²  Braungardt, C.^1,3  Desoeuvre, A.¹  Torres, E.¹  Tardy, V.¹  Resongles, E.¹  Laroche, E.¹  Delpoux, S.¹  Joulian, C.⁴  Battaglia-Brunet, F.⁴  Boisson, J.⁵  Grapin, G.⁶  Morin, G.²  Casiot, C.¹ 

[1] UMR 5569 CNRS IRD UM, Hydrosci Montpellier, CC57, 163 Rue Auguste Broussonet, F-34090 Montpellier, France

[2] UMR 7590 CNRS UPMC IRD MNHN, IMPMC, 4 Pl Jussieu, F-75252 Paris 05, France

[3] Plymouth Univ, Fac Sci & Engn, Sch Geog Earth & Environm Sci, Plymouth, Devon, England

[4] French Geol Survey BRGM, 3 Ave Claude Guillemin,BP 36009, F-45060 Orleans, France

[5] IRH Ingenieur Conseil, 197 Ave Fronton, F-31200 Toulouse, France

[6] IRH Ingenieur Conseil, 427 Rue Lavoisier,CS 50155, F-54714 Ludres, France

关键词: Arsenic precipitation;    Bioremediation;    Iron oxidation;    Water treatment;    aioA genes;    Schwertmannite;   

DOI  :  10.1016/j.watres.2017.06.059

来源: Elsevier

【 摘 要 】

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 (similar to 30-40 mg L-1). In this bioreactor, As removal proceeds via the formation of biogenic precipitates consisting of iron- and arsenic-rich mineral phases encrusting a microbial biofilm. Ferrous iron (Fe(II)) oxidation and iron (Fe) and arsenic removal rates were monitored at two different water heights (4 and 25 mm) and with/without forced aeration. A maximum of 80% As removal was achieved within 500 min at the lowest water height. This operating condition promoted intense Fe(II) microbial oxidation and subsequent precipitation of As-bearing schwertmannite and amorphous ferric arsenate. Higher water height slowed down Fe(II) oxidation, Fe precipitation and As removal, in relation with limited oxygen transfer through the water column. The lower oxygen transfer at higher water height could be partly counteracted by aeration. The presence of an iridescent floating film that developed at the water surface was found to limit oxygen transfer to the water column and delayed Fe(II) oxidation, but did not affect As removal. The bacterial community structure in the biogenic precipitates in the bottom of the bioreactor differed from that of the inlet water and was influenced to some extent by water height and aeration. Although potential for microbial mediated As oxidation was revealed by the detection of aioA genes, removal of Fe and As was mainly attributable to microbial Fe oxidation activity. Increasing the proportion of dissolved As(V) in the inlet water improved As removal and favoured the formation of amorphous ferric arsenate over As-sorbed schwertmannite. This study proved the ability of this bioreactor-system to treat extreme As concentrations and may serve in the design of future in-situ bioremediation system able to treat As-rich AMD. (C) 2017 Elsevier Ltd. All rights reserved.

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