Geochemical challenges associated with water treatment at abandoned or neglected mines in Southeast Yukon

Rainey, Don

doi:10.14288/1.0391915

Cited by 1 publication

(1 citation statement)

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“…To date, biological treatment processes have been established as the best available technology (BAT) to reduce toxic Se oxyanions (selenate and selenite) to less soluble and biologically inert elemental selenium (Se 0 ), or to volatile selenides 1,3,4 . However, such biological reduction processes have been found to generate potently toxic organoselenium compounds (e.g., selenomethionine (Se-Met) [5][6][7][8] , selenocyanate [9][10][11][12] , methylated selenium compounds [13][14][15] ) as treatment by-products, orders of magnitude more bioaccumulative than inorganic Se oxyanions 5,13,14,16-22 8 . Indeed, although the total Se removal efficiency of biological reduction processes can exceed 90% 4 , Se tissue concentrations in downstream biota have reportedly increased up to 7× following treatment, attributed to formation of organoselenium treatment by-products 3,15,17,18 .…”

Section: Introductionmentioning

confidence: 99%

Photocatalytic treatment of organoselenium in synthetic mine-impacted effluents

Martin¹,

Chai²,

Leshuk³

et al. 2022

Preprint

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Biological selenium reduction processes are commonly employed as the best available technology (BAT) for selenium removal, however, as a by-product they produce trace amounts of organoselenium compounds with orders of magnitude greater bioaccumulation potential and toxicity. Here we assessed buoyant photocatalysts (BPCs) as a potential passive advanced oxidation process (P-AOP) for organoselenium treatment. Using a synthetic mine-impacted water solution, spiked with selenomethionine (96 µg/L) as a representative organoselenium compound, photocatalysis with BPCs fully eliminated selenomethionine to <0.01 µg/L with conversion to selenite and selenate. A theoretical reaction pathway was inferred, and a kinetics model developed to describe the treatment trends and intermediates. Given the known toxic responses of Lepomis macrochirus and Daphnia magna to organoselenium, it was estimated that photocatalysis could effectively eliminate organoselenium acute toxicity within a UV dose of 8 kJ/L (1-2 days solar equivalent exposure), by transformation of selenomethionine to less hazardous oxidized Se species. Solar photocatalysis may therefore be a promising passive treatment technology for selenium-impacted mine water management.

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