Abstract

Bacillus fusiformis was embedded in powdered activated carbon to prepare immobilized granules. Then, the immobilized granules were used to remove Cr(VI) in tannery wastewater at different pH, temperature and initial Cr(VI) concentrations to optimize the process. At the optimum condition, the Cr(VI) in tannery wastewater was treated with the granules with the powdered activated carbon and the Bacillus fusiformis as controls. After treatment, the Bacillus fusiformis in the granules was observed by SEM. The results showed that the removal of Cr(VI) by the immobilized Bacillus fusiformis was better than either using powdered activated carbon or Bacillus fusiformis alone. The SEM images showed that the Bacillus fusiformis in the granules grew well. In the experiment, the total chromium and the Cr(VI) in the solution and the granules were measured before and after 48 hours’ treatment. It was found that both the Cr(VI) in the solution and the granules decreased, but the total chromium was unchanged, which indicated that removal of Cr(VI) with the granules was mainly as the results of both the adsorption of activated carbon and the chromate reduction of Bacillus fusiformis. The kinetic data of Cr(VI) removed by the immobilized Bacillus fusiformis could be described by the pseudo-second-order rate model. The experiments demonstrated that the immobilized Bacillus fusiformis could be used as a new biomaterial to remove Cr(VI) in tannery wastewater.