Simultaneous oxidation and precipitation of iron using jarosite immobilized Acidithiobacillus ferrooxidans and its relevance to acid mine drainage

The most commonly used process for treating acid mine drainage (AMD) involves the addition of neutralizing agents. To improve the treatment efficiency and reduce the problems associated with the bulky sludge produced, iron removal is required prior to the neutralization. This study investigated the iron removal performance of simultaneous biooxidation and precipitation by using the jarosite product for immobilization of Acidithiobacillus ferrooxidans. It was found that the viable biomass immobilized on jarosite was about 3 × 108 cells g− 1 after six successive cultures. The oxidative capability obtained per gram of inoculated jarosite was about 50 mg Fe2+ L− 1 h− 1. Increasing the amount of inoculated jarosite not only increased the rate of Fe2+ oxidation, but also improved the efficiency of Fe3+ removal. With 1 g of inoculated jarosite, the Fe3+ removal efficiency was 39% at 96 h, while in the presence of 10 g of inoculated jarosite, 49% of Fe3+ was precipitated within 48 h. The use of jarosite as a biomass carrier can both improve Fe2+ oxidation by maintaining a high cell concentration and enhance Fe3+ precipitation by simultaneously acting as jarosite seed, thereby facilitating the removal of iron from acidic, ferrous- and sulfate-rich solutions.

► Iron was removed from acidic sulfate solutions by biooxidation and precipitation.
► The jarosite product was used as bacterial carrier to improve Fe2+ oxidation.
► The presence of jarosite also favored Fe3+ precipitation by acting as seed crystal.