BIOLEACHING OF LITHIUM MANGANESE OXIDE (LMO) BATTERY WASTES USING THE BACTERIUM BACILLUS ZANTHOXYLI STRAIN SKC/VA-2 WITH VARIATIONS IN SOLID PERCENTAGE AND MEDIUM COMPOSITION

• Main Author: Julius, Calvin
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/81822
• Institution: Institut Teknologi Bandung

The escalating demand for batteries has driven increased requirements for metals such as Li, Co, Mn, and Ni, which are essential components of batteries. To sustain these demands without depleting natural metal deposits, it is imperative to utilize secondary sources, such as end-of-life (EOL) batteries. Metal extraction from EOL batteries can be achieved through various methods, among which bioleaching stands out due to its environmental friendliness, energy efficiency, and costeffectiveness. This study investigated the extraction of metals from lithium manganese oxide (LMO) battery wastes using the bacterium Bacillus zanthoxyli strain SKC/VA-2. The process was optimized by varying the percent solids and medium composition to achieve the highest possible extraction percentages. A series of experiments were conducted to optimize metal extraction percentages from LMO battery wastes by investigating the impact of percent solids and medium composition. The batteries were processed to yield a blackmass with a particle size of -200# (74 ?m) through a sequence of discharging, drying, shredding, chopping, and sieving steps. Subsequently, five bacterial strains were cultured and adapted over three days using a medium composed of 0.3 g/L (NH4)2SO4, 0.5 g/L K2HPO4, 0.5 g/L MgSO4.7H2O, 0.1 g/L KCl, 6.5 g/L FeSO4.7H2O, 4 g/L glucose, and 5 g/L Na2S2O3.5H2O. The bioleaching process was then executed at room temperature (approximately 25°C), starting at a medium pH of 2, and involving 10% (v/v) of the adapted bacterial inoculum. This was agitated on a rotary shaker at 183 rpm for 10 days. The experimental design included variations in medium composition (sulfur + molasses, pyrite + molasses, and a mixed composition of sulfur + pyrite + molasses ) and percent solids (5%, 10%, and 20%). Metal extraction percentages over time under various bioleaching conditions were periodically measured using Atomic Absorption Spectrophotometry (AAS). The bioleaching experiment utilized Bacillus zanthoxyli strain SKC/VA-2 due to its superior performance in the adaptation phase, yielding the highest average metal extraction levels for Li and Mn. An increase in percent solids led to higher metal concentrations, which in turn created a more toxic environment for the bacteria, subsequently reducing the extraction efficiency. The variation with 5% solids achieved the highest average extraction percentages, specifically 53.43% for Li, 29.25% for Mn, and 0.46% for Fe. The incorporation of pyrite, sulfur, and molasses as nutrients enhanced the bioleaching efficiency by accelerating bacterial metabolism, which facilitated the production of sulfuric acid and the formation of biosurfactants, including EPS, which are high molecular weight biosurfactants. The combination of sulfur and molasses in the medium composition yielded the highest average extraction percentages: 50.12% for Li, 25.95% for Mn, and 0.74% for Fe. Consequently, the optimal parameters for the bioleaching process were identified as 5% solids and a medium composition of sulfur plus molasses.