Immobilization of arsenite from the refining discharge using Acidianus brierleyi in the presence of pyrite

摘要

Arsenite ( As ( III)) is known as more toxic species than arsenate ( As ( V) ) with one fifth of LD50 values, and more difficult to remove from drainages in the refining process of Cu ores compared with arsenate ( As ( V) ). In the present study, immobilization of the dissolved arsenite was investigated from acidic refining discharge at 701 using a thermophilic archaeon, Acidianus brierleyi. Addition of pyrite contributed to maintaining the cell populations, leading to effective As immobilization in the microbiologically mediated system. Acclimatizing A. brierleyi cells to pyrite grains lead to improved growth of the archaeon in the presence of pyrite, resulting in enhanced precipitation of secondary minerals such as jarosite and scorodite. Arsenite and/or arsenate could be immobilised through co-precipitatation with jarosite ( KFe3 ( SO4 )2 ( OH )'6 ) , and/or precipitation as scorodite (FeAsO4 ? 2H2O). This study demonstrates advantages in utilizing a thermophile, which is known as one of the dominant species in bioleaching, in combination with pyrite, in the treatment process of refining discharge.