BIOLEACHING LOGAM TANAH JARANG DARI ABU DASAR HASIL PEMBAKARAN BATUBARA DI PLTU SURALAYA MENGGUNAKAN BAKTERI BACILLUS NITRATIREDUCENS STRAIN SKC/L-2

• Main Author: Zanuar Reza, Achmad
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/69172
• Institution: Institut Teknologi Bandung

Coal is a pledge energy source in Indonesia, especially for the power plant industry. However, the use of coal in the power plant industry causes a large environmental impact along with the production of waste in the form of fly ash (FA) and bottom ash (BA). Meanwhile, rare earth metals (REMs) is a metal group consisting of 15 elements of lanthanides, including scandium (Sc) and yttrium (Y). The everincreasing demand for REMs for various purposes has driven the work to find alternative sources of REMs. Bottom ash is one of the potential sources of REMs. On the other hand, bioleaching is an environmentally friendly technological innovation that potentially can be used to extract REMs from bottom ash. In this research, bioleaching of bottom ash from coal combustion at Suralaya Power Plant will be carried out to extract REMs with the help of the bacterium Bacillus nitratireducens strain SKC/L-2. A series of experiments were conducted to determine the effect of various leaching parameters, such as size fraction, pulp density, the addition of pyrite and pH of leaching medium on the bioleaching process. The experiment began with the preparation of bottom ash sample to be characterized with X-ray Fluorescence (XRF), X-ray Diffraction (XRD), Inductively Coupled Plasma Mass Spectrometry (ICP-MS) and Fourier Transform Infrared Spectroscopy (FTIR). The next step was inoculation of bacterium to determine the growth curve of Bacillus nitratireducens strain SKC/L-2. The bioleaching experiment was carried out for seven days with an erlenmeyer flask placed in an orbital shaker with a speed of 180 rpm. Sampling was carried out in time series to measure pH and redox potential (Eh). The leaching solution obtained from the sampling was then analyzed by ICP-MS, while the leaching residue was analyzed by FTIR. In the leaching experiment, the size fraction variation of -70# +100# resulted the biggest extraction percentage of REMs, which were 99,68% (Tb); 78,75% (Gd); and 67,48% (Lu) at 168 hours with conditions of 10% pulp density and 10% bacterial inoculum. Pulp density variation of 5% resulted the biggest extraction ercentage for Lu (40,65%) at 120 hours, while the biggest extraction percentage for Tb (63,43%) and Gd (50,56%) was obtained by 10% pulp density at 168 hours with condition of -120# +170# size fraction and 10% bacterial inoculum. Variations in the addition of 3 g/l pyrite resulted the biggest extraction percentage of REMs, which were 67,80% (Lu); 56,72% (Tb); and 48,91% (Gd) at 168 hours with conditions of -120# +170# size fraction, 10% pulp density, and 10% bacterial inoculum. Variation of pH of leaching medium resulted the biggest total extraction percentage of REMs at 168 hours, which is 11,3% with conditions of -120# +170# size fraction, 10% pulp density, and 10% bacterial inoculum.