Biorecovery

The effect of As3+ and As5+ on Thiobacillus ferrooxidans was investigated in the laboratory using a shake flask technique. Results of Fe2+ oxidation in nutrient media containing different initial amounts of As3+ of As5+ show that Fe2+ is completely oxidized by thiobacillus ferrooxidans within 60 hours when no arsenic is present in the medium. Addition of As3+ and As5+ allows the determination of different inhibition effects on Thiobacillus ferrooxidans. As3+ is more toxic than As5+. As3+ content in the leachate decreases gradually due to Fe3+. The Thiobacillus ferrooxidans used can tolerate about 8 g/l As5+, but only 2.5 g/l As3+. The results of ore pretreatment indicates that arsenic is released from arsenopyrite initially as As3+, and then As3+ is oxidized to As5+ by Fe3+. The effect of total arsenic content on the bioleaching results of sulphide ores is discussed.The effect of As3+ and As5+ on Thiobacillus ferrooxidans was investigated in the laboratory using a shake flask technique. Results of Fe2+ oxidation in nutrient media containing different initial amounts of As3+ of As5+ show that Fe2+ is completely oxidized by thiobacillus ferrooxidans within 60 hours when no arsenic is present in the medium. Addition of As3+ and As5+ allows the determination of different inhibition effects on Thiobacillus ferrooxidans. As3+ is more toxic than As5+. As3+ content in the leachate decreases gradually due to Fe3+. The Thiobacillus ferrooxidans used can tolerate about 8 g/l As5+, but only 2.5 g/l As3+. The results of ore pretreatment indicates that arsenic is released from arsenopyrite initially as As3+, and then As3+ is oxidized to As5+ by Fe3+. The effect of total arsenic content on the bioleaching results of sulphide ores is discussed