A STUDY OF MANGANESE OXIDATION FROM THE TANNIC ACID PREGNANT LEACH SOLUTION USING BACILLUS VELEZENSIS STRAIN SKC/S-5 AND BACILLUS ARYABHATTAI STRAIN SKC-5

• Main Author: Rafly Cahya Saputra, Muhammad
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/68673
• Institution: Institut Teknologi Bandung

Conventionally, one of the pathways for the manufacture of MnO2 is through the process of oxidative precipitation. However, in pregnant leach solution (PLS) with tannic acid as a reductant, this process is difficult because the high tannic acid residue in PLS will consume oxidizing agents such as ozone, permanganate, hypochlorite and others. In nature, bacteria are known to play an important role in the oxidation-reduction cycle of manganese, such as in ocean waters and lakes. The manganese oxidation-reduction cycle by bacteria is known to be carried out through two mechanisms, namely enzymatically (directly) and non-enzymatically (indirectly). In this study, the manganese oxidation process was carried out using the bacteria Bacillus velezensis strain SKC/S-5 and Bacillus aryabhattai strain SKC-5 with manganese sources derived from PLS from low grade manganese ore with tannic acid as a reducing agent carried out by BPTM LIPI Lampung. This experiment begins with a literature study related to manganese bio-oxidation. The experiment began with qualitative and quantitative bacterial selection. Qualitative selection is carried out by visually looking at the sediment produced by bacteria. Then the stage is continued with quantitative selection by observing pH, Eh, and total suspended solids for making bacterial growth curves. From the selection stage, two bacteria were obtained, namely Bacillus velezensis strain SKC/S-5 and Bacillus aryabhattai strain SKC-5. Then the core bio-oxidation experiment was carried out with variations in the media used, the initial concentration of manganese, and the addition of Fe2+ ion. In the media variation, pH, total suspended solid, and manganese and iron concentrations were calculated with AAS at the beginning and end of the experiment with the results of thes observations getting the best media. Furthermore, variations in the initial concentration of manganese and the addition of Fe2+ ion were used. In this variation, the pH and AAS were observed in the experimental solution. And for the resulting sediment XRD, XRF, SEM-EDS, and FTIR observations were made to find out what precipitate was formed. The results showed that Bacillus velezensis strain SKC/S-5 and Bacillus aryabhattai strain SKC-5 could be used for manganese oxidation. For the Bacillus velezensis strain SKC/S-5, the optimal condition was obtained when the initial concentration of manganese was 600 ppm without the addition of Fe2+ ion in SKC- 2 media. Meanwhile, for the Bacillus aryabhattai strain SKC-5, the optimal condition was obtained when the initial concentration of manganese was 1000 ppm without the addition of Fe2+ cations in SKC-2 media. Both bacteria produced todorokit (T-MnO2)-type manganese oxide deposits.